The 50 most-cited articles in BMJ, 2017

The number of published systematic reviews of studies of healthcare interventions has increased rapidly and these are used extensively for clinical and policy decisions. Systematic reviews are subject to a range of biases and increasingly include non-randomised studies of interventions. It is important that users can distinguish high quality reviews. Many instruments have been designed to evaluate different aspects of reviews, but there are few comprehensive critical appraisal instruments. AMSTAR was developed to evaluate systematic reviews of randomised trials. In this paper, we report on the updating of AMSTAR and its adaptation to enable more detailed assessment of systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. With moves to base more decisions on real world observational evidence we believe that AMSTAR 2 will assist decision makers in the identification of high quality systematic reviews, including those based on non-randomised studies of healthcare interventions.

Objectives To assess the overall effect of vitamin D supplementation on risk of acute respiratory tract infection, and to identify factors modifying this effect. Design Systematic review and meta-analysis of individual participant data (IPD) from randomised controlled trials. Data sources Medline, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, ClinicalTrials.gov, and the International Standard Randomised Controlled Trials Number registry from inception to December 2015. Eligibility criteria for study selection Randomised, double blind, placebo controlled trials of supplementation with vitamin D3 or vitamin D2 of any duration were eligible for inclusion if they had been approved by a research ethics committee and if data on incidence of acute respiratory tract infection were collected prospectively and prespecified as an efficacy outcome. Results 25 eligible randomised controlled trials (total 11 321 participants, aged 0 to 95 years) were identified. IPD were obtained for 10 933 (96.6%) participants. Vitamin D supplementation reduced the risk of acute…

Background While the patient and public involvement (PPI) evidence base has expanded over the past decade, the quality of reporting within papers is often inconsistent, limiting our understanding of how it works, in what context, for whom, and why. Objective To develop international consensus on the key items to report to enhance the quality, transparency, and consistency of the PPI evidence base. To collaboratively involve patients as research partners at all stages in the development of GRIPP2. Methods The EQUATOR method for developing reporting guidelines was used. The original GRIPP (Guidance for Reporting Involvement of Patients and the Public) checklist was revised, based on updated systematic review evidence. A three round Delphi survey was used to develop consensus on items to be included in the guideline. A subsequent face-to-face meeting produced agreement on items not reaching consensus during the Delphi process. Results 143 participants agreed to participate in round one, with an 86% (123/143) response for round two and a 78% (112/143) response for round three. The…

Objective To compare the risk for all cause and overdose mortality in people with opioid dependence during and after substitution treatment with methadone or buprenorphine and to characterise trends in risk of mortality after initiation and cessation of treatment. Design Systematic review and meta-analysis. Data sources Medline, Embase, PsycINFO, and LILACS to September 2016. Study selection Prospective or retrospective cohort studies in people with opioid dependence that reported deaths from all causes or overdose during follow-up periods in and out of opioid substitution treatment with methadone or buprenorphine. Data extraction and synthesis Two independent reviewers performed data extraction and assessed study quality. Mortality rates in and out of treatment were jointly combined across methadone or buprenorphine cohorts by using multivariate random effects meta-analysis. Results There were 19 eligible cohorts, following 122 885 people treated with methadone over 1.3-13.9 years and 15 831 people treated with buprenorphine over 1.1-4.5 years. Pooled all cause mortality rates were…

Objectives To develop and validate updated QRISK3 prediction algorithms to estimate the 10 year risk of cardiovascular disease in women and men accounting for potential new risk factors. Design Prospective open cohort study. Setting General practices in England providing data for the QResearch database. Participants 1309 QResearch general practices in England: 981 practices were used to develop the scores and a separate set of 328 practices were used to validate the scores. 7.89 million patients aged 25-84 years were in the derivation cohort and 2.67 million patients in the validation cohort. Patients were free of cardiovascular disease and not prescribed statins at baseline. Methods Cox proportional hazards models in the derivation cohort to derive separate risk equations in men and women for evaluation at 10 years. Risk factors considered included those already in QRISK2 (age, ethnicity, deprivation, systolic blood pressure, body mass index, total cholesterol: high density lipoprotein cholesterol ratio, smoking, family history of coronary heart disease in a first degree relative…

Implementation studies are often poorly reported and indexed, reducing their potential to inform initiatives to improve healthcare services. The Standards for Reporting Implementation Studies (StaRI) initiative aimed to develop guidelines for transparent and accurate reporting of implementation studies. Informed by the findings of a systematic review and a consensus-building e-Delphi exercise, an international working group of implementation science experts discussed and agreed the StaRI Checklist comprising 27 items. It prompts researchers to describe both the implementation strategy (techniques used to promote implementation of an underused evidence-based intervention) and the effectiveness of the intervention that was being implemented. An accompanying Explanation and Elaboration document (published in BMJ Open, doi:10.1136/bmjopen-2016-013318) details each of the items, explains the rationale, and provides examples of good reporting practice. Adoption of StaRI will improve the reporting of implementation studies, potentially facilitating translation of research into practice and…

Obesity is the most common medical condition in women of reproductive age. Obesity during pregnancy has short term and long term adverse consequences for both mother and child. Obesity causes problems with infertility, and in early gestation it causes spontaneous pregnancy loss and congenital anomalies. Metabolically, obese women have increased insulin resistance in early pregnancy, which becomes manifest clinically in late gestation as glucose intolerance and fetal overgrowth. At term, the risk of cesarean delivery and wound complications is increased. Postpartum, obese women have an increased risk of venous thromboembolism, depression, and difficulty with breast feeding. Because 50-60% of overweight or obese women gain more than recommended by Institute of Medicine gestational weight guidelines, postpartum weight retention increases future cardiometabolic risks and prepregnancy obesity in subsequent pregnancies. Neonates of obese women have increased body fat at birth, which increases the risk of childhood obesity. Although there is no unifying mechanism responsible for the…

Objectives To revise an existing three-talk model for learning how to achieve shared decision making, and to consult with relevant stakeholders to update and obtain wider engagement. Design Multistage consultation process. Setting Key informant group, communities of interest, and survey of clinical specialties. Participants 19 key informants, 153 member responses from multiple communities of interest, and 316 responses to an online survey from medically qualified clinicians from six specialties. Results After extended consultation over three iterations, we revised the three-talk model by making changes to one talk category, adding the need to elicit patient goals, providing a clear set of tasks for each talk category, and adding suggested scripts to illustrate each step. A new three-talk model of shared decision making is proposed, based on “team talk,” “option talk,” and “decision talk,” to depict a process of collaboration and deliberation. Team talk places emphasis on the need to provide support to patients when they are made aware of choices, and to elicit their goals as a means…

Objectives To evaluate the existing evidence for associations between coffee consumption and multiple health outcomes. Design Umbrella review of the evidence across meta-analyses of observational and interventional studies of coffee consumption and any health outcome. Data sources PubMed, Embase, CINAHL, Cochrane Database of Systematic Reviews, and screening of references. Eligibility criteria for selecting studies Meta-analyses of both observational and interventional studies that examined the associations between coffee consumption and any health outcome in any adult population in all countries and all settings. Studies of genetic polymorphisms for coffee metabolism were excluded. Results The umbrella review identified 201 meta-analyses of observational research with 67 unique health outcomes and 17 meta-analyses of interventional research with nine unique outcomes. Coffee consumption was more often associated with benefit than harm for a range of health outcomes across exposures including high versus low, any versus none, and one extra cup a day. There was evidence of a…

Objective To determine the frequency of prescriptions for short term use of oral corticosteroids, and adverse events (sepsis, venous thromboembolism, fractures) associated with their use. Design Retrospective cohort study and self controlled case series. Setting Nationwide dataset of private insurance claims. Participants Adults aged 18 to 64 years who were continuously enrolled from 2012 to 2014. Main outcome measures Rates of short term use of oral corticosteroids defined as less than 30 days duration. Incidence rates of adverse events in corticosteroid users and non-users. Incidence rate ratios for adverse events within 30 day and 31-90 day risk periods after drug initiation. Results Of 1 548 945 adults, 327 452 (21.1%) received at least one outpatient prescription for short term use of oral corticosteroids over the three year period. Use was more frequent among older patients, women, and white adults, with significant regional variation (all P<0.001). The most common indications for use were upper respiratory tract infections, spinal conditions, and allergies. Prescriptions were…

Objective To evaluate the strength and validity of the evidence for the association between adiposity and risk of developing or dying from cancer. Design Umbrella review of systematic reviews and meta-analyses. Data sources PubMed, Embase, Cochrane Database of Systematic Reviews, and manual screening of retrieved references. Eligibility criteria Systematic reviews or meta-analyses of observational studies that evaluated the association between indices of adiposity and risk of developing or dying from cancer. Data synthesis Primary analysis focused on cohort studies exploring associations for continuous measures of adiposity. The evidence was graded into strong, highly suggestive, suggestive, or weak after applying criteria that included the statistical significance of the random effects summary estimate and of the largest study in a meta-analysis, the number of cancer cases, heterogeneity between studies, 95% prediction intervals, small study effects, excess significance bias, and sensitivity analysis with credibility ceilings. Results 204 meta-analyses investigated associations…

Validation of prediction models is highly recommended and increasingly common in the literature. A systematic review of validation studies is therefore helpful, with meta-analysis needed to summarise the predictive performance of the model being validated across different settings and populations. This article provides guidance for researchers systematically reviewing and meta-analysing the existing evidence on a specific prediction model, discusses good practice when quantitatively summarising the predictive performance of the model across studies, and provides recommendations for interpreting meta-analysis estimates of model performance. We present key steps of the meta-analysis and illustrate each step in an example review, by summarising the discrimination and calibration performance of the EuroSCORE for predicting operative mortality in patients undergoing coronary artery bypass grafting.

Objective To examine the effect of surgeon sex on postoperative outcomes of patients undergoing common surgical procedures. Design Population based, retrospective, matched cohort study from 2007 to 2015. Setting Population based cohort of all patients treated in Ontario, Canada. Participants Patients undergoing one of 25 surgical procedures performed by a female surgeon were matched by patient age, patient sex, comorbidity, surgeon volume, surgeon age, and hospital to patients undergoing the same operation by a male surgeon. Interventions Sex of treating surgeon. Main outcome measure The primary outcome was a composite of death, readmission, and complications. We compared outcomes between groups using generalised estimating equations. Results 104 630 patients were treated by 3314 surgeons, 774 female and 2540 male. Before matching, patients treated by female doctors were more likely to be female and younger but had similar comorbidity, income, rurality, and year of surgery. After matching, the groups were comparable. Fewer patients treated by female surgeons died, were readmitted to…

Objective To determine the availability of data on overall survival and quality of life benefits of cancer drugs approved in Europe. Design Retrospective cohort study. Setting Publicly accessible regulatory and scientific reports on cancer approvals by the European Medicines Agency (EMA) from 2009 to 2013. Main outcome measures Pivotal and postmarketing trials of cancer drugs according to their design features (randomisation, crossover, blinding), comparators, and endpoints. Availability and magnitude of benefit on overall survival or quality of life determined at time of approval and after market entry. Validated European Society for Medical Oncology Magnitude of Clinical Benefit Scale (ESMO-MCBS) used to assess the clinical value of the reported gains in published studies of cancer drugs. Results From 2009 to 2013, the EMA approved the use of 48 cancer drugs for 68 indications. Of these, eight indications (12%) were approved on the basis of a single arm study. At the time of market approval, there was significant prolongation of survival in 24 of the 68 (35%). The magnitude of the…

Abstract Objective To compare the efficacy, safety, and cost effectiveness of direct acting oral anticoagulants (DOACs) for patients with atrial fibrillation. Design Systematic review, network meta-analysis, and cost effectiveness analysis. Data sources Medline, PreMedline, Embase, and The Cochrane Library. Eligibility criteria for selecting studies Published randomised trials evaluating the use of a DOAC, vitamin K antagonist, or antiplatelet drug for prevention of stroke in patients with atrial fibrillation. Results 23 randomised trials involving 94 656 patients were analysed: 13 compared a DOAC with warfarin dosed to achieve a target INR of 2.0-3.0. Apixaban 5 mg twice daily (odds ratio 0.79, 95% confidence interval 0.66 to 0.94), dabigatran 150 mg twice daily (0.65, 0.52 to 0.81), edoxaban 60 mg once daily (0.86, 0.74 to 1.01), and rivaroxaban 20 mg once daily (0.88, 0.74 to 1.03) reduced the risk of stroke or systemic embolism compared with warfarin. The risk of stroke or systemic embolism was higher with edoxaban 60 mg once daily (1.33, 1.02 to 1.75) and rivaroxaban 20 mg once…

Objective To characterise the determinants, time course, and risks of acute myocardial infarction associated with use of oral non-steroidal anti-inflammatory drugs (NSAIDs). Design Systematic review followed by a one stage bayesian individual patient data meta-analysis. Data sources Studies from Canadian and European healthcare databases. Review methods Eligible studies were sourced from computerised drug prescription or medical databases, conducted in the general or an elderly population, documented acute myocardial infarction as specific outcome, studied selective cyclo-oxygenase-2 inhibitors (including rofecoxib) and traditional NSAIDs, compared risk of acute myocardial infarction in NSAID users with non-users, allowed for time dependent analyses, and minimised effects of confounding and misclassification bias. Exposure and outcomes Drug exposure was modelled as an indicator variable incorporating the specific NSAID, its recency, duration of use, and dose. The outcome measures were the summary adjusted odds ratios of first acute myocardial infarction after study entry for each…

Objectives To identify trends in concurrent use of a benzodiazepine and an opioid and to identify the impact of these trends on admissions to hospital and emergency room visits for opioid overdose. Design Retrospective analysis of claims data, 2001-13. Setting Administrative health claims database. Participants 315 428 privately insured people aged 18-64 who were continuously enrolled in a health plan with medical and pharmacy benefits during the study period and who also filled at least one prescription for an opioid. Interventions Concurrent benzodiazepine/opioid use, defined as an overlap of at least one day in the time periods covered by prescriptions for each drug. Main outcome measures Annual percentage of opioid users with concurrent benzodiazepine use; annual incidence of visits to emergency room and inpatient admissions for opioid overdose. Results 9% of opioid users also used a benzodiazepine in 2001, increasing to 17% in 2013 (80% relative increase). This increase was driven mainly by increases among intermittent, as opposed to chronic, opioid users. Compared with opioid…

Abstract Objective To synthesise the evidence on the overall and differential effects of interventions based on diet and physical activity during pregnancy, primarily on gestational weight gain and maternal and offspring composite outcomes, according to women’s body mass index, age, parity, ethnicity, and pre-existing medical condition; and secondarily on individual complications. Design Systematic review and meta-analysis of individual participant data (IPD). Data sources Major electronic databases from inception to February 2017 without language restrictions. Eligibility criteria for selecting studies Randomised trials on diet and physical activity based interventions in pregnancy. Data synthesis Statistical models accounted for clustering of participants within trials and heterogeneity across trials leading to summary mean differences or odds ratios with 95% confidence intervals for the effects overall, and in subgroups (interactions). Results IPD were obtained from 36 randomised trials (12 526 women). Less weight gain occurred in the intervention group than control group (mean…

Research into the microbiome-the indigenous microbial communities (microbiota) and the host environment that they inhabit-has changed clinicians' ideas about microbes in human health and disease. Perhaps the most radical change is the realization that most of the microbes that inhabit our body supply crucial ecosystem services that benefit the entire host-microbe system. These services include the production of important resources, bioconversion of nutrients, and protection against pathogenic microbes. Thus disease can result from a loss of beneficial functions or the introduction of maladaptive functions by invading microbes. This review will show how an understanding of the dynamics and function of the indigenous microbiota has altered our view of microbes in maintaining homeostasis and causing disease. It will discuss how disruption of the beneficial functions of the microbiota can lead to disease. Methods for studying the microbiota will be introduced as part of a conceptual framework for using these methods to delineate novel roles for microbes in health. Key associations…

Objective To investigate the association between active commuting and incident cardiovascular disease (CVD), cancer, and all cause mortality. Design Prospective population based study. Setting UK Biobank. Participants 263 450 participants (106 674 (52%) women; mean age 52.6), recruited from 22 sites across the UK. The exposure variable was the mode of transport used (walking, cycling, mixed mode v non-active (car or public transport)) to commute to and from work on a typical day. Main outcome measures Incident (fatal and non-fatal) CVD and cancer, and deaths from CVD, cancer, or any causes. Results 2430 participants died (496 were related to CVD and 1126 to cancer) over a median of 5.0 years (interquartile range 4.3-5.5) follow-up. There were 3748 cancer and 1110 CVD events. In maximally adjusted models, commuting by cycle and by mixed mode including cycling were associated with lower risk of all cause mortality (cycling hazard ratio 0.59, 95% confidence interval 0.42 to 0.83, P=0.002; mixed mode cycling 0.76, 0.58 to 1.00, P<0.05), cancer incidence (cycling 0.55, 0.44 to 0.69,…

Shared decision making requires a shift in attitudes at all levels but can become part of routine practice with the right support, say Natalie Joseph-Williams and colleagues Adoption of shared decision making into routine practice has been remarkably slow, despite 40 years of research and considerable policy support.12345678 In 2010, the Health Foundation in the UK commissioned the MAGIC (Making Good Decisions in Collaboration) programme to design, test, and identify the best ways to embed shared decision making into routine primary and secondary care using quality improvement methods (box 1).910 #### Box 1: Summary of MAGIC programme ##### Phase 1 (August 2010–February 2012): Designing and testing the best ways to implement shared decision making in routine clinical settings Clinical areas ##### Phase 2 (February 2012–October 2013): Demonstrate that shared decision making can become part of routine clinical care (wider dissemination, implementation and sustainability) and build practical and transferable knowledge about the conditions for success Cardiff Newcastle

Objectives To describe neurodevelopmental outcomes at 2 years corrected age for children born alive at 22-26, 27-31, and 32-34 weeks’ gestation in 2011, and to evaluate changes since 1997. Design Population based cohort studies, EPIPAGE and EPIPAGE-2. Setting France. Participants 5567 neonates born alive in 2011 at 22-34 completed weeks’ gestation, with 4199 survivors at 2 years corrected age included in follow-up. Comparison of outcomes reported for 3334 (1997) and 2418 (2011) neonates born alive in the nine regions participating in both studies. Main outcome measures Survival; cerebral palsy (2000 European consensus definition); scores below threshold on the neurodevelopmental Ages and Stages Questionnaire (ASQ; at least one of five domains below threshold) if completed between 22 and 26 months corrected age, in children without cerebral palsy, blindness, or deafness; and survival without severe or moderate neuromotor or sensory disabilities (cerebral palsy with Gross Motor Function Classification System levels 2-5, unilateral or bilateral blindness or deafness). Results are given…

OBJECTIVE: To assess whether continuity of care with a general practitioner is associated with hospital admissions for ambulatory care sensitive conditions for older patients. DESIGN: Cross sectional study. SETTING: Linked primary and secondary care records from 200 general practices participating in the Clinical Practice Research Datalink in England. PARTICIPANTS: 230 472 patients aged between 62 and 82 years and who experienced at least two contacts with a general practitioner between April 2011 and March 2013. MAIN OUTCOME MEASURE: Number of hospital admissions for ambulatory care sensitive conditions (those considered manageable in primary care) per patient between April 2011 and March 2013. RESULTS: We assessed continuity of care using the usual provider of care index, which we defined as the proportion of contacts occurring between April 2011 and March 2013 that were with the most frequently seen general practitioner. On average, the usual provider of care index score was 0.61. Continuity of care was lower among practices with more doctors (average score 0.59 in large…

Objective To assess whether weight loss interventions for adults with obesity affect all cause, cardiovascular, and cancer mortality, cardiovascular disease, cancer, and body weight. Design Systematic review and meta-analysis of randomised controlled trials (RCTs) using random effects, estimating risk ratios, and mean differences. Heterogeneity investigated using Cochran’s Q and I2 statistics. Quality of evidence assessed by GRADE criteria. Data sources Medline, Embase, the Cochrane Central Register of Controlled Trials, and full texts in our trials’ registry for data not evident in databases. Authors were contacted for unpublished data. Eligibility criteria for selecting studies RCTs of dietary interventions targeting weight loss, with or without exercise advice or programmes, for adults with obesity and follow-up ≥1 year. Results 54 RCTs with 30 206 participants were identified. All but one trial evaluated low fat, weight reducing diets. For the primary outcome, high quality evidence showed that weight loss interventions decrease all cause mortality (34 trials, 685 events; risk…

Objectives To investigate whether moderate alcohol consumption has a favourable or adverse association or no association with brain structure and function. Design Observational cohort study with weekly alcohol intake and cognitive performance measured repeatedly over 30 years (1985-2015). Multimodal magnetic resonance imaging (MRI) was performed at study endpoint (2012-15). Setting Community dwelling adults enrolled in the Whitehall II cohort based in the UK (the Whitehall II imaging substudy). Participants 550 men and women with mean age 43.0 (SD 5.4) at study baseline, none were “alcohol dependent” according to the CAGE screening questionnaire, and all safe to undergo MRI of the brain at follow-up. Twenty three were excluded because of incomplete or poor quality imaging data or gross structural abnormality (such as a brain cyst) or incomplete alcohol use, sociodemographic, health, or cognitive data. Main outcome measures Structural brain measures included hippocampal atrophy, grey matter density, and white matter microstructure. Functional measures included cognitive decline over…

Objective To quantify the accuracy and reproducibility of pathologists’ diagnoses of melanocytic skin lesions. Design Observer accuracy and reproducibility study. Setting 10 US states. Participants Skin biopsy cases (n=240), grouped into sets of 36 or 48. Pathologists from 10 US states were randomized to independently interpret the same set on two occasions (phases 1 and 2), at least eight months apart. Main outcome measures Pathologists’ interpretations were condensed into five classes: I (eg, nevus or mild atypia); II (eg, moderate atypia); III (eg, severe atypia or melanoma in situ); IV (eg, pathologic stage T1a (pT1a) early invasive melanoma); and V (eg, ≥pT1b invasive melanoma). Reproducibility was assessed by intraobserver and interobserver concordance rates, and accuracy by concordance with three reference diagnoses. Results In phase 1, 187 pathologists completed 8976 independent case interpretations resulting in an average of 10 (SD 4) different diagnostic terms applied to each case. Among pathologists interpreting the same cases in both phases, when pathologists diagnosed a…

Abstract Objective To test the hypotheses that physical activity in midlife is not associated with a reduced risk of dementia and that the preclinical phase of dementia is characterised by a decline in physical activity. Design Prospective cohort study with a mean follow-up of 27 years. Setting Civil service departments in London (Whitehall II study). Participants 10 308 participants aged 35-55 years at study inception (1985-88). Exposures included time spent in mild, moderate to vigorous, and total physical activity assessed seven times between 1985 and 2013 and categorised as “recommended” if duration of moderate to vigorous physical activity was 2.5 hours/week or more. Main outcome measures A battery of cognitive tests was administered up to four times from 1997 to 2013, and incident dementia cases (n=329) were identified through linkage to hospital, mental health services, and mortality registers until 2015. Results Mixed effects models showed no association between physical activity and subsequent 15 year cognitive decline. Similarly, Cox regression showed no association…

OBJECTIVE: To compare the predictive accuracy and clinical utility of five risk scoring systems in the assessment of patients with upper gastrointestinal bleeding. DESIGN: International multicentre prospective study. SETTING: Six large hospitals in Europe, North America, Asia, and Oceania. PARTICIPANTS: 3012 consecutive patients presenting over 12 months with upper gastrointestinal bleeding. MAIN OUTCOME MEASURES: Comparison of pre-endoscopy scores (admission Rockall, AIMS65, and Glasgow Blatchford) and post-endoscopy scores (full Rockall and PNED) for their ability to predict predefined clinical endpoints: a composite endpoint (transfusion, endoscopic treatment, interventional radiology, surgery, or 30 day mortality), endoscopic treatment, 30 day mortality, rebleeding, and length of hospital stay. Optimum score thresholds to identify low risk and high risk patients were determined. RESULTS: The Glasgow Blatchford score was best (area under the receiver operating characteristic curve (AUROC) 0.86) at predicting intervention or death compared with the full Rockall score (0.70), PNED…

Objective To map the diverse health outcomes associated with serum uric acid (SUA) levels. Design Umbrella review. Data sources Medline, Embase, Cochrane Database of Systematic Reviews, and screening of citations and references. Eligibility criteria Systematic reviews and meta-analyses of observational studies that examined associations between SUA level and health outcomes, meta-analyses of randomised controlled trials that investigated health outcomes related to SUA lowering treatment, and Mendelian randomisation studies that explored the causal associations of SUA level with health outcomes. Results 57 articles reporting 15 systematic reviews and144 meta-analyses of observational studies (76 unique outcomes), 8 articles reporting 31 meta-analyses of randomised controlled trials (20 unique outcomes), and 36 articles reporting 107 Mendelian randomisation studies (56 unique outcomes) met the eligibility criteria. Across all three study types, 136 unique health outcomes were reported. 16 unique outcomes in meta-analyses of observational studies had P<10-6, 8 unique outcomes in…

#### What you need to know Low back pain is the leading cause of long term disability worldwide.1 The lifetime incidence of low back pain is 58-84%,2 and 11% of men and 16% of women have chronic low back pain.3 Back pain accounts for 7% of GP consultations and results in the loss of 4.1 million working days a year.2 More than 30% of people still have clinically significant symptoms after a year after onset of sciatica.4 This guideline replaces the National Institute for Health and Care Excellence (NICE) guideline on early management of low back pain in adults (2009) and expands its remit. It summarises the updated recommendations from NICE for the assessment and management of low back pain and sciatica.5 For a visual summary, please see infographic. It is intended to overcome patchy commissioning of back pain pathways and pain management programmes6 and poor implementation due to clinicians’ beliefs that previous recommendations were constraining clinical practice.7 NICE recommendations are based on systematic reviews of best available evidence and explicit consideration of cost…

Objective To assess the effect of specialist palliative care on quality of life and additional outcomes relevant to patients in those with advanced illness. Design Systematic review with meta-analysis. Data sources Medline, Embase, Cochrane Central Register of Controlled Trials, PsycINFO, and trial registers searched up to July 2016. Eligibility criteria for selecting studies Randomised controlled trials with adult inpatients or outpatients treated in hospital, hospice, or community settings with any advanced illness. Minimum requirements for specialist palliative care included the multiprofessional team approach. Two reviewers independently screened and extracted data, assessed the risk of bias (Cochrane risk of bias tool), and evaluated the quality of evidence (GRADE tool). Data synthesis Primary outcome was quality of life with Hedges’ g as standardised mean difference (SMD) and random effects model in meta-analysis. In addition, the pooled SMDs of the analyses of quality of life were re-expressed on the global health/QoL scale (item 29 and 30, respectively) of the European…

Objectives To estimate small for gestational age birth prevalence and attributable neonatal mortality in low and middle income countries with the INTERGROWTH-21st birth weight standard. Design Secondary analysis of data from the Child Health Epidemiology Reference Group (CHERG), including 14 birth cohorts with gestational age, birth weight, and neonatal follow-up. Small for gestational age was defined as infants weighing less than the 10th centile birth weight for gestational age and sex with the multiethnic, INTERGROWTH-21st birth weight standard. Prevalence of small for gestational age and neonatal mortality risk ratios were calculated and pooled among these datasets at the regional level. With available national level data, prevalence of small for gestational age and population attributable fractions of neonatal mortality attributable to small for gestational age were estimated. Setting CHERG birth cohorts from 14 population based sites in low and middle income countries. Main outcome measures In low and middle income countries in the year 2012, the number and proportion of…

Neck pain imposes a considerable personal and socioeconomic burden-it is one of the top five chronic pain conditions in terms of prevalence and years lost to disability-yet it receives a fraction of the research funding given to low back pain. Although most acute episodes resolve spontaneously, more than a third of affected people still have low grade symptoms or recurrences more than one year later, with genetics and psychosocial factors being risk factors for persistence. Nearly half of people with chronic neck pain have mixed neuropathic-nociceptive symptoms or predominantly neuropathic symptoms. Few clinical trials are dedicated solely to neck pain. Muscle relaxants and non-steroidal anti-inflammatory drugs are effective for acute neck pain, and clinical practice is mostly guided by the results of studies performed for other chronic pain conditions. Among complementary and alternative treatments, the strongest evidence is for exercise, with weaker evidence supporting massage, acupuncture, yoga, and spinal manipulation in different contexts. For cervical radiculopathy and facet…

Abstract Objective To determine which potentially modifiable risk factors, including socioeconomic, lifestyle/dietary, cardiometabolic, and inflammatory factors, are associated with Alzheimer’s disease. Design Mendelian randomisation study using genetic variants associated with the modifiable risk factors as instrumental variables. Setting International Genomics of Alzheimer’s Project. Participants 17 008 cases of Alzheimer’s disease and 37 154 controls. Main outcome measures Odds ratio of Alzheimer’s per genetically predicted increase in each modifiable risk factor estimated with Mendelian randomisation analysis. Results This study included analyses of 24 potentially modifiable risk factors. A Bonferroni corrected threshold of P=0.002 was considered to be significant, and P<0.05 was considered suggestive of evidence for a potential association. Genetically predicted educational attainment was significantly associated with Alzheimer’s. The odds ratios were 0.89 (95% confidence interval 0.84 to 0.93; P=2.4×10−6) per year of education completed and 0.74 (0.63 to 0.86; P=8.0×10−5) per…

OBJECTIVE: To examine the role of psychological distress (anxiety and depression) as a potential predictor of site specific cancer mortality. DESIGN: Pooling of individual participant data from 16 prospective cohort studies initiated 1994-2008. SETTING: Nationally representative samples drawn from the health survey for England (13 studies) and the Scottish health survey (three studies). PARTICIPANTS: 163 363 men and women aged 16 or older at study induction, who were initially free of a cancer diagnosis, provided self reported psychological distress scores (based on the general health questionnaire, GHQ-12) and consented to health record linkage. MAIN OUTCOME MEASURE: Vital status records used to ascertain death from 16 site specific malignancies; the three Scottish studies also had information on cancer registration (incidence). RESULTS: The studies collectively contributed an average of 9.5 years of mortality surveillance during which there were 16 267 deaths (4353 from cancer). After adjustment for age, sex, education, socioeconomic status, body mass index (BMI), and smoking and…

Objectives To examine temporal trends in sex and age specific incidence of self harm in children and adolescents, clinical management patterns, and risk of cause specific mortality following an index self harm episode at a young age. Design Population based cohort study. Setting UK Clinical Practice Research Datalink—electronic health records from 674 general practices, with practice level deprivation measured ecologically using the index of multiple deprivation. Patients from eligible English practices were linked to hospital episode statistics (HES) and Office for National Statistics (ONS) mortality records. Participants For the descriptive analytical phases we examined data pertaining to 16 912 patients aged 10-19 who harmed themselves during 2001-14. For analysis of cause specific mortality following self harm, 8638 patients eligible for HES and ONS linkage were matched by age, sex, and general practice with up to 20 unaffected children and adolescents (n=170 274). Main outcome measures In the first phase, temporal trends in sex and age specific annual incidence were examined.…

Objective To examine whether the increase in use of electronic cigarettes in the USA, which became noticeable around 2010 and increased dramatically by 2014, was associated with a change in overall smoking cessation rate at the population level. Design Population surveys with nationally representative samples. Setting Five of the US Current Population Survey-Tobacco Use Supplement (CPS-TUS) in 2001-02, 2003, 2006-07, 2010-11, and 2014-15. Participants Data on e-cigarette use were obtained from the total sample of the 2014-15 CPS-TUS (n=161 054). Smoking cessation rates were obtained from those who reported smoking cigarettes 12 months before the survey (n=23 270). Rates from 2014-15 CPS-TUS were then compared with those from 2010-11 CPS-TUS (n=27 280) and those from three other previous surveys. Main outcome measures Rate of attempt to quit cigarette smoking and the rate of successfully quitting smoking, defined as having quit smoking for at least three months. Results Of 161 054 respondents to the 2014-15 survey, 22 548 were current smokers and 2136 recent quitters. Among them,…

Objective To evaluate efficacies of anthelmintic drugs against soil transmitted helminths in terms of cure rates and egg reduction rates. Design Systematic review and network meta-analysis. Data Sources PubMed, ISI Web of Science, Embase, ScienceDirect, the Cochrane Central Register of Clinical Trials, and the World Health Organization library database from 1960 until 31 December 2016. Study selection Randomised controlled trials evaluating the efficacy of a single dose regimen of albendazole, mebendazole, levamisole, and pyrantel pamoate against Ascaris lumbricoides, hookworm (Necator americanus and Ancylostoma duodenale) and Trichuris trichiura. The primary outcomes included cure rates analysed by network meta-analysis with mixed logistic regression models and egg reduction rates with mixed linear models. Results 55 and 46 randomised controlled trials were included in the analysis of cure rates and egg reduction rates, respectively. All drugs were highly efficacious against A lumbricoides. Albendazole showed the highest efficacy against hookworm infections with a cure rate of…

Objective To examine clinical effectiveness and safety of apixaban 2.5 mg, dabigatran 110 mg, and rivaroxaban 15 mg compared with warfarin among patients with atrial fibrillation who had not previously taken an oral anticoagulant. Design Propensity weighted (inverse probability of treatment weighted) nationwide cohort study. Setting Individual linked data from three nationwide registries in Denmark. Participants Patients with non-valvular atrial fibrillation filling a first prescription for an oral anticoagulant from August 2011 to February 2016. Patients who filled a prescription for a standard dose non-vitamin K antagonist oral anticoagulant (novel oral anticoagulants, NOACs) were excluded. To control for baseline differences in the population, a propensity score for receipt of either of the four treatment alternatives was calculated to apply an inverse probability treatment weight. Intervention Initiated anticoagulant treatment (dabigatran 110 mg, rivaroxaban 15 mg, apixaban 2.5 mg, and warfarin). Main outcome measures Patients were followed in the registries from onset of…

Health system resilience begins with measurement of critical capacities ahead of crisis say Margaret E Kruk and colleagues

Many exposures of epidemiological interest are time varying, and the values of potential confounders may change over time leading to time varying confounding. The aim of many longitudinal studies is to estimate the causal effect of a time varying exposure on an outcome that requires adjusting for time varying confounding. Time varying confounding affected by previous exposure often occurs in practice, but it is usually adjusted for by using conventional analytical methods such as time dependent Cox regression, random effects models, or generalised estimating equations, which are known to provide biased effect estimates in this setting. This article explains time varying confounding affected by previous exposure and outlines three causal methods proposed to appropriately adjust for this potential bias: inverse-probability-of-treatment weighting, the parametric G formula, and G estimation.

Objectives To determine how soon after delivery the risk of post-pregnancy hypertension increases in women with hypertensive disorders of pregnancy and how the risk evolves over time. Design Nationwide register based cohort study. Setting Denmark. Populations 482 972 primiparous women with a first live birth or stillbirth between 1995 and 2012 (cumulative incidence analyses), and 1 025 118 women with at least one live birth or stillbirth between 1978 and 2012 (Cox regression analyses). Main outcome measures 10 year cumulative incidences of post-pregnancy hypertension requiring treatment with prescription drugs, and hazard ratios estimated using Cox regression. Results Of women with a hypertensive disorder of pregnancy in a first pregnancy in their 20s, 14% developed hypertension in the first decade post partum, compared with 4% of women with normotensive first pregnancies in their 20s. The corresponding percentages for women with a first pregnancy in their 40s were 32% and 11%, respectively. In the year after delivery, women with a hypertensive disorder of pregnancy had 12-fold to…

Abstract Objectives To investigate the association between alcohol consumption and cardiovascular disease at higher resolution by examining the initial lifetime presentation of 12 cardiac, cerebrovascular, abdominal, or peripheral vascular diseases among five categories of consumption. Design Population based cohort study of linked electronic health records covering primary care, hospital admissions, and mortality in 1997-2010 (median follow-up six years). Setting CALIBER (ClinicAl research using LInked Bespoke studies and Electronic health Records). Participants 1 937 360 adults (51% women), aged ≥30 who were free from cardiovascular disease at baseline. Main outcome measures 12 common symptomatic manifestations of cardiovascular disease, including chronic stable angina, unstable angina, acute myocardial infarction, unheralded coronary heart disease death, heart failure, sudden coronary death/cardiac arrest, transient ischaemic attack, ischaemic stroke, intracerebral and subarachnoid haemorrhage, peripheral arterial disease, and abdominal aortic aneurysm. Results 114 859…

Objectives To assess diagnostic accuracy of screening tests for pre-diabetes and efficacy of interventions (lifestyle or metformin) in preventing onset of type 2 diabetes in people with pre-diabetes. Design Systematic review and meta-analysis. Data sources and method Medline, PreMedline, and Embase. Study protocols and seminal papers were citation-tracked in Google Scholar to identify definitive trials and additional publications. Data on study design, methods, and findings were extracted onto Excel spreadsheets; a 20% sample was checked by a second researcher. Data extracted for screening tests included diagnostic accuracy and population prevalence. Two meta-analyses were performed, one summarising accuracy of screening tests (with the oral glucose tolerance test as the standard) for identification of pre-diabetes, and the other assessing relative risk of progression to type 2 diabetes after either lifestyle intervention or treatment with metformin. Eligibility criteria Empirical studies evaluating accuracy of tests for identification of pre-diabetes. Interventions (randomised…

The Montgomery case in 2015 was a landmark for informed consent in the UK. Two years on, Sarah Chan and colleagues discuss the consequences for practising doctors

Objective To forecast dementia prevalence with a dynamic modelling approach that integrates calendar trends in dementia incidence with those for mortality and cardiovascular disease. Design Modelling study. Setting General adult population of England and Wales. Participants The English Longitudinal Study of Ageing (ELSA) is a representative panel study with six waves of data across 2002-13. Men and women aged 50 or more years, selected randomly, and their cohabiting partners were recruited to the first wave of ELSA (2002-03). 11392 adults participated (response rate 67%). To maintain representativeness, refreshment participants were recruited to the study at subsequent waves. The total analytical sample constituted 17 906 people. Constant objective criteria based on cognitive and functional impairment were used to ascertain dementia cases at each wave. Main outcome measures To estimate calendar trends in dementia incidence, correcting for bias due to loss to follow-up of study participants, a joint model of longitudinal and time-to-event data was fitted to ELSA data. To forecast…

Objective To determine the association of different types of meat intake and meat associated compounds with overall and cause specific mortality. Design Population based cohort study. Setting Baseline dietary data of the NIH-AARP Diet and Health Study (prospective cohort of the general population from six states and two metropolitan areas in the US) and 16 year follow-up data until 31 December 2011. Participants 536 969 AARP members aged 50-71 at baseline. Exposures Intake of total meat, processed and unprocessed red meat (beef, lamb, and pork) and white meat (poultry and fish), heme iron, and nitrate/nitrite from processed meat based on dietary questionnaire. Adjusted Cox proportional hazards regression models were used with the lowest fifth of calorie adjusted intakes as reference categories. Main outcome measure Mortality from any cause during follow-up. Results An increased risk of all cause mortality (hazard ratio for highest versus lowest fifth 1.26, 95% confidence interval 1.23 to 1.29) and death due to nine different causes associated with red meat intake was observed. Both…

Objective To estimate the risks of major congenital malformations in the offspring of mothers who are underweight (body mass index (BMI) <18.5), overweight (BMI 25 to <30), or in obesity classes I (BMI 30 to <35), II (35 to <40), or III (≥40) compared with offspring of normal weight mothers (BMI 18.5 to <25) in early pregnancy. Design Population based cohort study. Setting Nationwide Swedish registries. Participants 1 243 957 liveborn singleton infants from 2001 to 2014 in Sweden. Data on maternal and pregnancy characteristics were obtained by individual record linkages. Exposure Maternal BMI at the first prenatal visit. Main outcome measures Offspring with any major congenital malformation, and subgroups of organ specific malformations diagnosed during the first year of life. Risk ratios were estimated using generalised linear models adjusted for maternal factors, sex of offspring, and birth year. Results A total of 43 550 (3.5%) offspring had any major congenital malformation, and the most common subgroup was for congenital heart defects (n=20 074; 1.6%). Compared with offspring…

With little evidence that failing to complete a prescribed antibiotic course contributes to antibiotic resistance, it’s time for policy makers, educators, and doctors to drop this message, argue Martin Llewelyn and colleagues

Cluster randomised trials have diminishing returns in power and precision as cluster size increases. Making the cluster a lot larger while keeping the number of clusters fixed might yield only a very small increase in power and precision, owing to the intracluster correlation. Identifying the point at which observations start making a negligible contribution to the power or precision of the study—which we call the point of diminishing returns—is important for designing efficient trials. Current methods for identifying this point are potentially useful as rules of thumb but don’t generally work well. We introduce several practical aids to help researchers design cluster randomised trials in which all observations make a material contribution to the study. Power curves enable identification of the point at which observations begin to make a negligible contribution to a study for a given target difference. Under this paradigm, the number needed per arm under individual randomisation gives an upper bound on the cluster size, which should not be exceeded. Corresponding precision curves…