A basic introduction to fixed-effect and random-effects models for meta-analysis

Reduced Mortality With Partial-Breast Irradiation for Early Breast Cancer: A Meta-Analysis of Randomized Trials

PURPOSE

With earlier detection and more effective treatment, mortality from breast cancer continues to fall and it has become increasingly important to reduce the toxicity of treatments. Partial-breast radiation therapy, which focuses radiation to the tumor bed, may achieve this aim. We analyzed mortality differences in randomized trials of partial-breast irradiation (PBI).

METHODS AND MATERIALS

We included data from published randomized trials of PBI (alone or as part of a risk-adapted approach) versus whole-breast irradiation (WBI) for invasive breast cancer suitable for breast-conserving therapy. We identified trials using PubMed and Google searches with the terms "partial breast irradiation" OR "intraoperative radiotherapy" OR "IMRT" OR ("accelerated" AND "radiation") AND "randomised/randomized," as well as through discussion with colleagues in the field. We calculated the proportion of patients who had events in each randomized arm at 5 years' follow-up and created a forest plot using Stata, version 14.1.

RESULTS

We identified 9 randomized trials of PBI versus WBI in invasive breast cancer; 5-year outcomes were available for non-breast cancer mortality in 5 trials (n=4489) and for breast cancer mortality in 4 trials (n=4231). The overall mortality was 4.9%. There was no detectable heterogeneity between the trials for any of the outcomes. There was no difference in the proportion of patients dying of breast cancer (difference, 0.000% [95% confidence interval (CI), -0.7 to +0.7]; P=.999). Non-breast cancer mortality with PBI was lower than with WBI (difference, 1.1% [95% CI, -2.1% to -0.2%]; P=.023). Total mortality with PBI was also lower than with WBI (difference, 1.3% [95% CI, -2.5% to 0.0%]; P=.05).

CONCLUSIONS

Use of PBI instead of WBI in selected patients results in a lower 5-year non-breast cancer and overall mortality, amounting to a 25% reduction in relative terms. This information should be included when breast-conserving therapy is proposed to a patient.

Alternative measures of between-study heterogeneity in meta-analysis: Reducing the impact of outlying studies

Meta-analysis has become a widely used tool to combine results from independent studies. The collected studies are homogeneous if they share a common underlying true effect size; otherwise, they are heterogeneous. A fixed-effect model is customarily used when the studies are deemed homogeneous, while a random-effects model is used for heterogeneous studies. Assessing heterogeneity in meta-analysis is critical for model selection and decision making. Ideally, if heterogeneity is present, it should permeate the entire collection of studies, instead of being limited to a small number of outlying studies. Outliers can have great impact on conventional measures of heterogeneity and the conclusions of a meta-analysis. However, no widely accepted guidelines exist for handling outliers. This article proposes several new heterogeneity measures. In the presence of outliers, the proposed measures are less affected than the conventional ones. The performance of the proposed and conventional heterogeneity measures are compared theoretically, by studying their asymptotic properties, and empirically, using simulations and case studies.

Hypertonic dextrose injections (prolotherapy) in the treatment of symptomatic knee osteoarthritis: A systematic review and meta-analysis

Hypertonic dextrose injections (prolotherapy) is an emerging treatment for symptomatic knee osteoarthritis (OA) but its efficacy is uncertain. We conducted a systematic review with meta-analysis to synthesize clinical evidence on the effect of prolotherapy for knee OA. Fifteen electronic databases were searched from their inception to September 2015. The primary outcome of interest was score change on the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Three randomized controlled trials (RCTs) of moderate risk of bias and one quasi-randomized trial were included, with data from a total of 258 patients. In the meta-analysis of two eligible studies, prolotherapy is superior to exercise alone by a standardized mean difference (SMD) of 0.81 (95% CI: 0.18 to 1.45, p = 0.012), 0.78 (95% CI: 0.25 to 1.30, p = 0.001) and 0.62 (95% CI: 0.04 to 1.20, p = 0.035) on the WOMAC composite scale; and WOMAC function and pain subscale scores respectively. Moderate heterogeneity exists in all cases. Overall, prolotherapy conferred a positive and significant beneficial effect in the treatment of knee OA. Adequately powered, longer-term trials with uniform end points are needed to better elucidate the efficacy of prolotherapy.

Candidate genes in panic disorder: meta-analyses of 23 common variants in major anxiogenic pathways

The utilization of molecular genetics approaches in examination of panic disorder (PD) has implicated several variants as potential susceptibility factors for panicogenesis. However, the identification of robust PD susceptibility genes has been complicated by phenotypic diversity, underpowered association studies and ancestry-specific effects. In the present study, we performed a succinct review of case-control association studies published prior to April 2015. Meta-analyses were performed for candidate gene variants examined in at least three studies using the Cochrane Mantel-Haenszel fixed-effect model. Secondary analyses were also performed to assess the influences of sex, agoraphobia co-morbidity and ancestry-specific effects on panicogenesis. Meta-analyses were performed on 23 variants in 20 PD candidate genes. Significant associations after correction for multiple testing were observed for three variants, TMEM132D rs7370927 (T allele: odds ratio (OR)=1.27, 95% confidence interval (CI): 1.15-1.40, P=2.49 × 10(-6)), rs11060369 (CC genotype: OR=0.65, 95% CI: 0.53-0.79, P=1.81 × 10(-5)) and COMT rs4680 (Val (G) allele: OR=1.27, 95% CI: 1.14-1.42, P=2.49 × 10(-5)) in studies with samples of European ancestry. Nominal associations that did not survive correction for multiple testing were observed for NPSR1 rs324891 (T allele: OR=1.22, 95% CI: 1.07-1.38, P=0.002), TPH1 rs1800532 (AA genotype: OR=1.46, 95% CI: 1.14-1.89, P=0.003) and HTR2A rs6313 (T allele: OR=1.19, 95% CI: 1.07-1.33, P=0.002) in studies with samples of European ancestry and for MAOA-uVNTR in female PD (low-active alleles: OR=1.21, 95% CI: 1.07-1.38, P=0.004). No significant associations were observed in the secondary analyses considering sex, agoraphobia co-morbidity and studies with samples of Asian ancestry. Although these findings highlight a few associations, PD likely involves genetic variation in a multitude of biological pathways that is diverse among populations. Future studies must incorporate larger sample sizes and genome-wide approaches to further quantify the observed genetic variation among populations and subphenotypes of PD.

Assisted reproductive technology and risk of asthma and allergy in the offspring: protocol for a systematic review and meta-analysis

INTRODUCTION

The use of assisted reproductive technology (ART) procedures has increased globally over the last three decades. Recent observational studies suggest that children conceived through ART may be at increased risk of asthma and atopic disease compared with children conceived naturally, but findings are mixed. We aim to synthesise the evidence on the impact of ART on the risk of asthma and atopic disease in the offspring.

METHODS AND ANALYSIS

We will identify relevant studies by searching MEDLINE, EMBASE, Cochrane Library, ISI Web of Science, CINAHL, Scopus, Google Scholar, AMED, Global Health, PsychINFO, CAB International and the WHO Global Health Library from 1978 to 2016. We will locate additional studies through searching databases of the proceedings of international conferences, contacting international experts in the field, and searching the references cited in identified studies. We will include analytic observational studies (cohort studies, case-control studies and cross-sectional studies) that have investigated the impact of any type of ART on offspring's asthma and atopic disease. Screening of identified records, data extraction from eligible studies and risk of bias assessment of eligible studies will be independently undertaken by two reviewers, with arbitration by a third reviewer. The Effective Public Health Practice Project will be employed for risk of bias assessment. Estimates from studies judged to be clinically, methodologically and statistically homogeneous will be synthesised using random-effects meta-analysis.

ETHICS AND DISSEMINATION

As this study is based solely on the published literature, no ethics approval is required. We will publish our findings in a peer-reviewed scientific journal and present the results at national and international scientific conferences.

PROTOCOL REGISTRATION

We will register a detailed protocol for the review with the International Prospective Register of Systematic Reviews (PROSPERO) prior to starting the review.

A systematic review and individual patient data meta-analysis of prognostic factors for foot ulceration in people with diabetes: the international research collaboration for the prediction of diabetic foot ulcerations (PODUS)

BACKGROUND

Annual foot risk assessment of people with diabetes is recommended in national and international clinical guidelines. At present, these are consensus based and use only a proportion of the available evidence.

OBJECTIVES

We undertook a systematic review of individual patient data (IPD) to identify the most highly prognostic factors for foot ulceration (i.e. symptoms, signs, diagnostic tests) in people with diabetes.

DATA SOURCES

Studies were identified from searches of MEDLINE and EMBASE.

REVIEW METHODS

The electronic search strategies for MEDLINE and EMBASE databases created during an aggregate systematic review of predictive factors for foot ulceration in diabetes were updated and rerun to January 2013. One reviewer applied the IPD review eligibility criteria to the full-text articles of the studies identified in our literature search and also to all studies excluded from our aggregate systematic review to ensure that we did not miss eligible IPD. A second reviewer applied the eligibility criteria to a 10% random sample of the abstract search yield to check that no relevant material was missed. This review includes exposure variables (risk factors) only from individuals who were free of foot ulceration at the time of study entry and who had a diagnosis of diabetes mellitus (either type 1 or type 2). The outcome variable was incident ulceration.

RESULTS

Our search identified 16 cohort studies and we obtained anonymised IPD for 10. These data were collected from more than 16,000 people with diabetes worldwide and reanalysed by us. One data set was kept for independent validation. The data sets contributing IPD covered a range of temporal, geographical and clinical settings. We therefore selected random-effects meta-analysis, which assumes not that all the estimates from each study are estimates of the same underlying true value, but rather that the estimates belong to the same distribution. We selected candidate variables for meta-analysis using specific criteria. After univariate meta-analyses, the most clinically important predictors were identified by an international steering committee for inclusion in the primary, multivariable meta-analysis. Age, sex, duration of diabetes, monofilaments and pulses were considered most prognostically important. Meta-analyses based on data from the entire IPD population found that an inability to feel a 10-g monofilament [odds ratio (OR) 3.184, 95% confidence interval (CI) 2.654 to 3.82], at least one absent pedal pulse (OR 1.968, 95% CI 1.624 to 2.386), a longer duration of a diagnosis of diabetes (OR 1.024, 95% CI 1.011 to 1.036) and a previous history of ulceration (OR 6.589, 95% CI 2.488 to 17.45) were all predictive of risk. Female sex was protective (OR 0.743, 95% CI 0.598 to 0.922).

LIMITATIONS

It was not possible to perform a meta-analysis using a one-step approach because we were unable to procure copies of one of the data sets and instead accessed data via Safe Haven.

CONCLUSIONS

The findings from this review identify risk assessment procedures that can reliably inform national and international diabetes clinical guideline foot risk assessment procedures. The evidence from a large sample of patients in worldwide settings show that the use of a 10-g monofilament or one absent pedal pulse will identify those at moderate or intermediate risk of foot ulceration, and a history of foot ulcers or lower-extremity amputation is sufficient to identify those at high risk. We propose the development of a clinical prediction rule (CPR) from our existing model using the following predictor variables: insensitivity to a 10-g monofilament, absent pedal pulses and a history of ulceration or lower-extremities amputations. This CPR could replace the many tests, signs and symptoms that patients currently have measured using equipment that is either costly or difficult to use.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42011001841.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Systematic review and meta-analysis of music interventions in hypertension treatment: a quest for answers

Background

Adverse effects, treatment resistance and high costs associated with pharmacological treatment of hypertension have led to growing interest in non-pharmacological complementary therapies such as music interventions. This meta-analysis aims to provide an overview of reported evidence on the efficacy of music interventions in the treatment of hypertension.

Methods

A systematic literature search was conducted for publications on the effect of music interventions on blood pressure in adult hypertensive subjects published between January 1990-June 2014. Randomized controlled trials with a follow-up duration ≥28 days were included. Blood pressure measures were pooled using inverse variance weighting.

Results

Of the 1689 abstracts reviewed, 10 randomized controlled trials were included. Random-effects pooling of the music intervention groups showed a trend toward a decrease in mean systolic blood pressure (SBP) from 144 mmHg(95 % CI:137–152) to 134 mmHg(95 % CI:124–144), and in mean diastolic blood pressure (DBP) from 84 mmHg(95 % CI:78–89) to 78 mmHg(95 % CI:73–84). Fixed-effect analysis of a subgroup of 3 trials with valid control groups showed a significant decrease in pooled mean SBP and DBP in both intervention and control groups. A comparison between music intervention groups and control groups was not possible due to unavailable measures of dispersion.

Conclusions

This systematic review and meta-analysis revealed a trend towards a decrease in blood pressure in hypertensive patients who received music interventions, but failed to establish a cause-effect relationship between music interventions and blood pressure reduction. Considering the potential value of this safe, low-cost intervention, well-designed, high quality and sufficiently powered randomized studies assessing the efficacy of music interventions in the treatment of hypertension are warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0244-0) contains supplementary material, which is available to authorized users.

Ambient temperature and risk of cardiovascular hospitalization: An updated systematic review and meta-analysis

The association between temperatures and risk of cardiovascular mortality has been recognized but the association drawn from previous meta-analysis was weak due to the lack of sufficient studies. This paper presented a review with updated reports in the literature about the risk of cardiovascular hospitalization in relation to different temperature exposures and examined the dose-response relationship of temperature-cardiovascular hospitalization by change in units of temperature, latitudes, and lag days. The pooled effect sizes were calculated for cold, heat, heatwave, and diurnal variation using random-effects meta-analysis, and the dose-response relationship of temperature-cardiovascular admission was modelled using random-effect meta-regression. The Cochrane Q-test and index of heterogeneity (I(2)) were used to evaluate heterogeneity, and Egger's test was used to evaluate publication bias. Sixty-four studies were included in meta-analysis. The pooled results suggest that for a change in temperature condition, the risk of cardiovascular hospitalization increased 2.8% (RR, 1.028; 95% CI, 1.021-1.035) for cold exposure, 2.2% (RR, 1.022; 95% CI, 1.006-1.039) for heatwave exposure, and 0.7% (RR, 1.007; 95% CI, 1.002-1.012) for an increase in diurnal temperature. However no association was observed for heat exposure. The significant dose-response relationship of temperature - cardiovascular admission was found with cold exposure and diurnal temperature. Increase in one-day lag caused a marginal reduction in risk of cardiovascular hospitalizations for cold exposure and diurnal variation, and increase in latitude was associated with a decrease in risk of cardiovascular hospitalizations for diurnal temperature only. There is a significant short-term effect of cold exposure, heatwave and diurnal variation on cardiovascular hospitalizations. Further research is needed to understand the temperature-cardiovascular relationship for different climate areas.

Prevalence of passive smoking in the community population aged 15 years and older in China: a systematic review and meta-analysis

OBJECTIVES

To estimate the prevalence and distribution of passive smoking in the community population aged 15 years and older in China.

DESIGN

A systematic review and meta-analysis of cross-sectional studies reporting the prevalence of passive smoking in China and a series of subgroup, trend and sensitivity analyses were conducted in this study.

DATA SOURCE

The systematic review and meta-analysis, which included 46 studies with 381,580 non-smokers, estimated the prevalence and distribution of passive smoking in China. All studies were published between 1997 and 2015.

RESULTS

The pooled prevalence of passive smoking was 48.7% (95% CI 44.8% to 52.5%) and was relatively stable from 1995 to 2013. The prevalence in the subgroups of gender, area, age and time varied from 35.1% (95% CI 31.8% to 38.3%) in the elderly (≥60 years) to 48.6% (95% CI 42.9% to 54.2%) in urban areas. The prevalence was lower in the elderly (≥60 years) than in those between 15 and 59 years of age (OR 1.61, 95% CI 1.44 to 1.81). The difference between females and males in urban and rural areas was not statistically significant (OR: 1.27, 95% CI 0.93 to 1.74 and OR: 1.14, 95% CI 0.82 to 1.58, respectively). In addition, a significantly increasing trend was found among males from 2002 to 2010. Heterogeneity was high in all pooled estimates (I(2)>98%, p<0.001).

CONCLUSIONS

The high and stable prevalence of passive smoking in China is raising increasing national concern regarding specific research and tobacco control programmes. Attention should be focused on young, middle-aged and male non-smokers regardless of region.

Quantification of the smoking-associated cancer risk with rate advancement periods: meta-analysis of individual participant data from cohorts of the CHANCES consortium

BACKGROUND

Smoking is the most important individual risk factor for many cancer sites but its association with breast and prostate cancer is not entirely clear. Rate advancement periods (RAPs) may enhance communication of smoking related risk to the general population. Thus, we estimated RAPs for the association of smoking exposure (smoking status, time since smoking cessation, smoking intensity, and duration) with total and site-specific (lung, breast, colorectal, prostate, gastric, head and neck, and pancreatic) cancer incidence and mortality.

METHODS

This is a meta-analysis of 19 population-based prospective cohort studies with individual participant data for 897,021 European and American adults. For each cohort we calculated hazard ratios (HRs) for the association of smoking exposure with cancer outcomes using Cox regression adjusted for a common set of the most important potential confounding variables. RAPs (in years) were calculated as the ratio of the logarithms of the HRs for a given smoking exposure variable and age. Meta-analyses were employed to summarize cohort-specific HRs and RAPs.

RESULTS

Overall, 140,205 subjects had a first incident cancer, and 53,164 died from cancer, during an average follow-up of 12 years. Current smoking advanced the overall risk of developing and dying from cancer by eight and ten years, respectively, compared with never smokers. The greatest advancements in cancer risk and mortality were seen for lung cancer and the least for breast cancer. Smoking cessation was statistically significantly associated with delays in the risk of cancer development and mortality compared with continued smoking.

CONCLUSIONS

This investigation shows that smoking, even among older adults, considerably advances, and cessation delays, the risk of developing and dying from cancer. These findings may be helpful in more effectively communicating the harmful effects of smoking and the beneficial effect of smoking cessation.

The aetiology of post-traumatic stress following childbirth: a meta-analysis and theoretical framework

There is evidence that 3.17% of women report post-traumatic stress disorder (PTSD) after childbirth. This meta-analysis synthesizes research on vulnerability and risk factors for birth-related PTSD and refines a diathesis-stress model of its aetiology. Systematic searches were carried out on PsycINFO, PubMed, Scopus and Web of Science using PTSD terms crossed with childbirth terms. Studies were included if they reported primary research that examined factors associated with birth-related PTSD measured at least 1 month after birth. In all, 50 studies (n = 21 429) from 15 countries fulfilled inclusion criteria. Pre-birth vulnerability factors most strongly associated with PTSD were depression in pregnancy (r = 0.51), fear of childbirth (r = 0.41), poor health or complications in pregnancy (r = 0.38), and a history of PTSD (r = 0.39) and counselling for pregnancy or birth (r = 0.32). Risk factors in birth most strongly associated with PTSD were negative subjective birth experiences (r = 0.59), having an operative birth (assisted vaginal or caesarean, r = 0.48), lack of support (r = -0.38) and dissociation (r = 0.32). After birth, PTSD was associated with poor coping and stress (r = 0.30), and was highly co-morbid with depression (r = 0.60). Moderator analyses showed that the effect of poor health or complications in pregnancy was more apparent in high-risk samples. The results of this meta-analysis are used to update a diathesis-stress model of the aetiology of postpartum PTSD and can be used to inform screening, prevention and intervention in maternity care.

Prognostic Significance of Carbonic Anhydrase IX Expression in Cancer Patients: A Meta-Analysis

Hypoxia is a characteristic of many solid tumors and an adverse prognostic factor for treatment outcome. Hypoxia increases the expression of carbonic anhydrase IX (CAIX), an enzyme that is predominantly found on tumor cells and is involved in maintaining the cellular pH balance. Many clinical studies investigated the prognostic value of CAIX expression, but most have been inconclusive, partly due to small numbers of patients included. The present meta-analysis was therefore performed utilizing the results of all clinical studies to determine the prognostic value of CAIX expression in solid tumors. Renal cell carcinoma was excluded from this meta-analysis due to an alternative mechanism of upregulation. 958 papers were identified from a literature search performed in PubMed and Embase. These papers were independently evaluated by two reviewers and 147 studies were included in the analysis. The meta-analysis revealed strong significant associations between CAIX expression and all endpoints: overall survival [hazard ratio (HR) = 1.76, 95% confidence interval (95%CI) 1.58–1.98], disease-free survival (HR = 1.87, 95%CI 1.62–2.16), locoregional control (HR = 1.54, 95%CI 1.22–1.93), disease-specific survival (HR = 1.78, 95%CI 1.41–2.25), metastasis-free survival (HR = 1.82, 95%CI 1.33–2.50), and progression-free survival (HR = 1.58, 95%CI 1.27–1.96). Subgroup analyses revealed similar associations in the majority of tumor sites and types. In conclusion, these results show that patients having tumors with high CAIX expression have higher risk of locoregional failure, disease progression, and higher risk to develop metastases, independent of tumor type or site. The results of this meta-analysis further support the development of a clinical test to determine patient prognosis based on CAIX expression and may have important implications for the development of new treatment strategies.

Contemporary outcomes after surgical aortic valve replacement with bioprostheses and allografts: a systematic review and meta-analysis

Many observational studies have reported outcomes after surgical aortic valve replacement (AVR), but there are no recent systematic reviews and meta-analyses including all available bioprostheses and allografts. The objective of this study is to provide a comprehensive and up-to-date overview of the outcomes after AVR with bioprostheses and allografts reported in the last 15 years. We conducted a systematic literature review (PROSPERO register: CRD42015017041) of studies published between 2000–15. Inclusion criteria were observational studies or randomized controlled trials reporting on outcomes of AVR with bioprostheses (stented or stentless) or allografts, with or without coronary artery bypass grafting (CABG) or valve repair procedure, with study population size n ≥ 30 and mean follow-up length ≥5 years. Fifty-four bioprosthesis studies and 14 allograft studies were included, encompassing 55 712 and 3872 patients and 349 840 and 32 419 patient-years, respectively. We pooled early mortality risk and linearized occurrence rates of valve-related events, reintervention and late mortality in a random-effects model. Sensitivity, meta-regression and subgroup analyses were performed to investigate the influence of outliers on the pooled estimates and to explore sources of heterogeneity. Funnel plots were used to investigate publication bias. Pooled early mortality risks for bioprostheses and allografts were 4.99% (95% confidence interval [CI], 4.44–5.62) and 5.03% (95% CI, 3.61–7.01), respectively. The late mortality rate was 5.70%/patient-year (95% CI, 4.99–5.62) for bioprostheses and 1.68%/patient-year (95% CI, 1.23–2.28) for allografts. Pooled reintervention rates for bioprostheses and allografts were 0.75%/patient-year (95% CI, 0.61–0.91) and 1.87%/patient-year (95% CI, 1.52–2.31), respectively. There was substantial heterogeneity in most outcomes. Meta-regression analyses identified covariates that could explain the heterogeneity: implantation period, valve type, patient age, gender, pre-intervention New York Heart Association class III/IV, concomitant CABG, study design and follow-up length. There is possible publication bias in all outcomes. This comprehensive systematic review and meta-analysis provides an overview of the outcomes after AVR with bioprostheses and allografts reported during the last 15 years. The results of this study can support patients and doctors in the prosthetic valve choice and can be used in microsimulation models to predict patient outcomes and estimate the cost-effectiveness of AVR with bioprostheses or allografts compared with current and future heart valve prostheses.

Can illness beliefs, from the common-sense model, prospectively predict adherence to self-management behaviours? A systematic review and meta-analysis

OBJECTIVE

To determine whether people's beliefs about their illness, conceptualised by the common sense model (CSM), can prospectively predict adherence to self-management behaviours (including, attendance, medication, diet and exercise) in adults with acute and chronic physical illnesses.

DESIGN AND MAIN OUTCOME MEASURES

Electronic databases were searched in September 2014, for papers specifying the use of the 'CSM' in relation to 'self-management', 'rehabilitation' and 'adherence' in the context of physical illness. Six hundred abstracts emerged. Data from 52 relevant studies were extracted. Twenty-one studies were meta-analysed, using correlation coefficients in random effects models. The remainder were descriptively synthesised.

RESULTS

The effect sizes for individual illness belief domains and adherence to self-management behaviours ranged from .04 to .13, indicating very weak, predictive relationships. Further analysis revealed that predictive relationships did not differ by the: type of self-management behaviour; acute or chronic illness; or duration of follow-up.

CONCLUSION

Individual illness belief domains, outlined by the CSM, did not predict adherence to self-management behaviours in adults with physical illnesses. Prospective relationships, controlling for past behaviour, also did not emerge. Other factors, including patients' treatment beliefs and inter-relationships between individual illness beliefs domains, may have influenced potential associations with adherence to self-management behaviours.

Pre-diagnostic vitamin D concentrations and cancer risks in older individuals: an analysis of cohorts participating in the CHANCES consortium

The associations of circulating 25-hydroxyvitamin D [25(OH)D] concentrations with total and site-specific cancer incidence have been examined in several epidemiological studies with overall inconclusive findings. Very little is known about the association of vitamin D with cancer incidence in older populations. We assessed the association of pre-diagnostic serum 25(OH)D levels with incidence of all cancers combined and incidence of lung, colorectal, breast, prostate and lymphoid malignancies among older adults. Pre-diagnostic 25(OH)D concentrations and cancer incidence were available in total for 15,486 older adults (mean age 63, range 50-84 years) participating in two cohort studies: ESTHER (Germany) and TROMSØ (Norway); and a subset of previously published nested-case control data from a another cohort study: EPIC-Elderly (Greece, Denmark, Netherlands, Spain and Sweden) from the CHANCES consortium on health and aging. Cox proportional hazards or logistic regression were used to derive multivariable adjusted hazard and odds ratios, respectively, and their 95% confidence intervals across 25(OH)D categories. Meta-analyses with random effects models were used to pool study-specific risk estimates. Overall, lower 25(OH)D concentrations were not significantly associated with increased incidence of most of the cancers assessed. However, there was some evidence of increased breast cancer and decreased lymphoma risk with higher 25(OH)D concentrations. Our meta-analyses with individual participant data from three large European population-based cohort studies provide at best limited support for the hypothesis that vitamin D may have a major role in cancer development and prevention among European older adults.

Meta-analyses of Theory Use in Medication Adherence Intervention Research

OBJECTIVE

This systematic review applied meta-analytic procedures to integrate primary research that examined theory- or model-linked medication adherence interventions.

METHODS

Extensive literature searching strategies were used to locate trials testing interventions with medication adherence behavior outcomes measured by electronic event monitoring, pharmacy refills, pill counts, and self-reports. Random-effects model analysis was used to calculate standardized mean difference effect sizes for medication adherence outcomes.

RESULTS

Codable data were extracted from 146 comparisons with 19,348 participants. The most common theories and models were social cognitive theory and motivational interviewing. The overall weighted effect size for all interventions comparing treatment and control participants was 0.294. The effect size for interventions based on single-theories was 0.323 and for multiple-theory interventions was 0.214. Effect sizes for individual theories and models ranged from 0.041 to 0.447. The largest effect sizes were for interventions based on the health belief model (0.477) and adult learning theory (0.443). The smallest effect sizes were for interventions based on PRECEDE (0.041) and self-regulation (0.118).

CONCLUSION

These findings suggest that theory- and model-linked interventions have a significant but modest effect on medication adherence outcomes.

A Systematic Review of Meta-analyses Published in Arthroscopy: The Journal of Arthroscopic and Related Surgery

PURPOSE

To determine whether the number of meta-analyses published by Arthroscopy: The Journal of Arthroscopic and Related Surgery has increased from the inception of the Journal through 2014.

METHODS

A literature search of the Journal's Web site and Medline was carried out. All studies described as a "meta-analysis" as well as systematic reviews that pooled data were included. The number of published meta-analyses was calculated and summarized by year of publication, region, topic, and level of evidence.

RESULTS

The Journal's Web site search resulted in 517 citations for review, and the Medline search resulted in 400. After the results of each search were combined and duplicates were removed, a total of 60 studies were included in this review. The first published meta-analysis appeared in 2001. Of the 60 meta-analyses, 36 (60%) were published between 2013 and 2014. In light of the increase in the number of publications, a review of the design and conduct of a meta-analysis is presented in a straightforward question-and-answer format.

CONCLUSIONS

The number of meta-analyses appearing in Arthroscopy has increased over the past 2 decades. This increase highlights the importance of developing an understanding of the premise and components of a meta-analysis to allow the reader to critically appraise these studies.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I through IV meta-analyses.

Patient-Centered Outcomes of Medication Adherence Interventions: Systematic Review and Meta-Analysis

OBJECTIVE

Using meta-analytic procedures to synthesize changes in patient-centered outcomes after medication adherence interventions.

METHODS

Strategies to locate studies included online searches of 13 databases and 19 research registries, hand searches of 57 journals, and author and ancestry searches of all eligible studies. Search terms included patient compliance, medication adherence, and related terms. Searches were conducted for all studies published since 1960. Eligible published or unpublished primary studies tested medication adherence interventions and reported medication knowledge, quality of life, physical function, and symptom outcomes. Primary study attributes and outcome data were reliably coded. Overall standardized mean differences (SMDs) were analyzed using random-effects models. Dichotomous and continuous moderator analyses and funnel plots were used to explore risks of bias.

RESULTS

Thorough searching located 141 eligible reports. The reports included 176 eligible comparisons between treatment and control subjects across 23,318 subjects. Synthesis across all comparisons yielded statistically significant SMDs for medication knowledge (d = 0.449), quality of life (d = 0.127), physical function (d = 0.142), and symptoms (d = 0.182). The overall SMDs for studies focusing on subsamples of patients with specific illnesses were more modest but also statistically significant. Of specific symptoms analyzed (depression, anxiety, pain, energy/vitality, cardiovascular, and respiratory), only anxiety failed to show a significant improvement after medication adherence interventions. Most SMDs were significantly heterogeneous, and risk of bias analyses suggested links between study quality and SMDs.

CONCLUSIONS

Modest but significant improvements in patient-centered outcomes were observed after medication adherence interventions.

Effects of Testosterone Replacement Therapy on Lower Urinary Tract Symptoms: A Systematic Review and Meta-analysis

CONTEXT

There is a potential risk that testosterone replacement therapy (TRT) may exacerbate lower urinary tract symptoms (LUTS) among aging men with late-onset hypogonadism (LOH) because of testosterone's growth-promoting effects on the prostate.

OBJECTIVE

To compare the change in LUTS severity as assessed using the International Prostate Symptom Score (IPSS) between men receiving TRT versus placebo for the treatment of LOH.

EVIDENCE ACQUISITION

Systematic search of MEDLINE, Embase, ClinicalTrials.gov, and The Cochrane Library for randomized controlled trials of TRT for LOH published between January 1992 and September 2015. Studies were eligible for inclusion if they were a randomized control trial, used TRT, and assessed LUTS outcomes using the IPSS. Estimates were pooled using random effects meta-analysis. Differences by study-level characteristics were estimated using meta-regression.

EVIDENCE SYNTHESIS

Data were extracted from 14 trials involving 2029 participants. The average age was 64.5 yr and the average follow-up was 34.4 mo. Seven studies used topical, five used injectable, and two used oral testosterone. There was no statistically significant difference in pooled changes in IPSS from baseline to follow up in men treated with TRT compared with those receiving placebo (-0.41 points [95% confidence interval: -0.89 to 0.07; I(2)=0%, p=0.28] vs. 0.12 points [95% confidence interval: -0.32 to 0.55; I(2)=0%, p=0.81], between-group difference p>0.05). No between-group differences were noted in subanalyses that controlled for potential confounders such as type of testosterone, change in testosterone, aging male symptom scale, or prostate-specific antigen levels (p>0.05 for all comparisons).

CONCLUSIONS

In this meta-analysis of 14 clinical trials of TRT for LOH, the change in IPSS was similar among men receiving TRT versus placebo, suggesting that TRT treatment does not worsen LUTS among men with LOH.

PATIENT SUMMARY

In this analysis of 14 clinical trials, testosterone replacement therapy did not worsen lower urinary tract symptoms among men being treated for late-onset hypogonadism.

Use of theta-burst stimulation in changing excitability of motor cortex: A systematic review and meta-analysis

Noninvasive brain stimulation has been demonstrated to modulate cortical activity in humans. In particular, theta burst stimulation (TBS) has gained notable attention due to its ability to induce lasting physiological changes after short stimulation durations. The present study aimed to provide a comprehensive meta-analytic review of the efficacy of two TBS paradigms; intermittent (iTBS) and continuous (cTBS), on corticospinal excitability in healthy individuals. Literature searches yielded a total of 87 studies adhering to the inclusion criteria. iTBS yielded moderately large MEP increases lasting up to 30 min with a pooled SMD of 0.71 (p<0.00001). cTBS produced a reduction in MEP amplitudes lasting up to 60 min, with the largest effect size seen at 5 min post stimulation (SMD=-0.9, P<0.00001). The collected studies were of heterogeneous nature, and a series of tests conducted indicated a degree of publication bias. No significant change in SICI and ICF was observed, with exception to decrease in SICI with cTBS at the early time point (SMD=0.42, P=0.00036). The results also highlight several factors contributing to TBS efficacy, including the number of pulses, frequency of stimulation and BDNF polymorphisms. Further research investigating optimal TBS stimulation parameters, particularly for iTBS, is needed in order for these paradigms to be successfully translated into clinical settings.

Association between two CHRNA3 variants and susceptibility of lung cancer: a meta-analysis

Genome-wide association studies (GWAS) have identified two CHRNA3 polymorphisms (rs578776 and rs938682) associated with lung cancer risk. Furthermore, these polymorphisms were investigated and genotyped by PCR analysis. All eligible case-control studies published up to Mar 1st 2015 were identified by searching Pubmed and Embase database. Negative association between rs578776-T allele and risk of lung cancer was obtained without obvious heterogeneity (OR: 0.83, 95% CI: 0.79-0.86; p = 0.898 for Q test). Rs938682-C allele carriers had a 12% to 28% decreased risk. Genotype model analysis showed results of dominant model for rs578776 (OR with 95% CI: 0.839(0.718-0.981)), dominant model for rs938682 (OR with 95% CI: 0.778(0.663-0.912)) and homozygous model for rs938682 (OR with 95% CI: 0.767(0.708-0.831)) were statistically significant. Subgroup analysis indicated rs578776-T variant had protective effect in Smokers, Caucasians, two histology subgroups, and two match subgroups. Meanwhile, rs938682-C allele was associated with decreased risk in Smokers, Caucasians, Lung cancer, and two match subgroups. Meta-regression suggested ethnicity might be the major source of heterogeneity in allele model and homozygous model for rs938682. Moreover, smoking status might contribute to part of heterogeneity under allele model. In summary, this meta-analysis suggested both rs578776 and rs938682 were significantly associated with the susceptibility of lung cancer.

Sadism and Violent Reoffending in Sexual Offenders

A diagnosis of sadism in sexual offenders is commonly regarded as indicative of high risk for violent reoffending. The purpose of the current two studies was to evaluate whether sadism is indeed associated with higher rates of violent (including sexual) reoffending. In Study 1 (meta-analysis), the rate of violent and sexual recidivism was assessed across seven samples of male sex offenders (total N = 2,169) as a function of diagnoses of sexual sadism. In Study 2 (N = 768) the outcome (violent recidivism yes/no) was regressed on sadism, along with behavioral indicators of sexually sadistic offending, and scores from violence risk assessment instruments. In Study 1 (meta-analysis), the overall risk of sadists compared with nonsadists with respect to violent (including sexual contact) reoffending was slightly elevated (by a factor of 1.18), yet not significantly increased. Similarly, the risk of sexual reoffending among sadists was slightly, but not significantly, higher than among nonsadists (factor 1.38). According to Study 2, only a measure of sadistic behavior, not the clinical diagnosis, was associated with violent reoffending. This association, however, was not present once age and customary risk assessment instruments for violence risk were included in the regression. A clinical diagnosis of sexual sadism and behavioral measures of sadism are related to the risk of violent reoffending in sexual offenders. These associations, however, are weak and do not hold once variables relevant for the prediction of violence are controlled for. At the individual level, the risk for future violence in sadists can therefore be adequately described by customary risk assessment instruments.

Chicken Essence for Cognitive Function Improvement: A Systematic Review and Meta-Analysis

Chicken essence (CE) is a popular traditional remedy in Asia, which is believed to improve cognitive functions. CE company claimed that the health benefits were proven with research studies. A systematic review was conducted to determine the cognitive-enhancing effects of CE. We systematically searched a number of databases for randomized controlled trials with human subjects consuming CE and cognitive tests involved. Cochrane’s Risk of Bias (ROB) tool was used to assess the quality of trials and meta-analysis was performed. Seven trials were included, where six healthy subjects and one subject with poorer cognitive functions were recruited. One trial had unclear ROB while the rest had high ROB. For executive function tests, there was a significant difference favoring CE (pooled standardized mean difference (SMD) of −0.55 (−1.04, −0.06)) and another with no significant difference (pooled SMD of 0.70 (−0.001, 1.40)). For short-term memory tests, no significant difference was found (pooled SMD of 0.63 (−0.16, 1.42)). Currently, there is a lack of convincing evidence to show a cognitive enhancing effect of CE.

Efficacy and safety of rivaroxaban compared with vitamin K antagonists for peri-procedural anticoagulation in catheter ablation of atrial fibrillation: a systematic review and meta-analysis

Rivaroxaban is increasingly used in patients undergoing catheter ablation of atrial fibrillation (AF). In the absence of large controlled trials, a comprehensive meta-analysis of the literature appears to be the best way to obtain reliable evidence on rare peri-procedural outcomes such as thromboembolic or bleeding events. We aimed to provide a detailed analysis of currently available data on safety and efficacy of peri-procedural rivaroxaban in patients undergoing AF ablation. We performed a systematic search of the English language literature for studies comparing peri-procedural rivaroxaban therapy with vitamin K antagonists (VKAs) and reporting detailed data on bleeding and/or thromboembolic complications. The Peto odds ratio (POR) was used to pool data into a fixed-effect meta-analysis. A total of 7400 patients undergoing catheter ablation were included in 15 observational and 1 randomized studies of which 1994 were receiving rivaroxaban and 5406 VKA. The risk of thromboembolism trended to be lower in the rivaroxaban group [4/1954 vs. 19/5219, POR 0.40, 95% confidence interval (CI), 0.16–1.01, P = 0.052]. Major bleeding events occurred in 23 of 1994 cases (1.15%) in the rivaroxaban and 90 of 5406 (1.66%) in the VKA group (POR 0.74, 95% CI, 0.46–1.21, P = 0.23). A total of 87 minor bleeding events were reported in 1753 patients (4.96%) in the rivaroxaban group and in 165 of 4009 patients (4.12%) in the VKA group (POR 0.84, 95% CI 0.63-1.11, p = 0.22). In patients undergoing AF ablation, rivaroxaban appears to be an effective and safe alternative to VKA.

Acute exercise and gastric emptying: a meta-analysis and implications for appetite control

BACKGROUND

Gastric emptying (GE) could influence exercise-induced changes in appetite and energy intake. GE also could contribute to changes in gastric symptoms and the availability of nutrients during exercise, which will subsequently affect performance.

OBJECTIVE

The objective of this review was to determine the effects of acute exercise on GE using a systematic review and meta-analysis. The most common parameters to determine GE were selected, consisting of half-emptying time and volume emptied. Oral-caecal transit time (OCTT) was also examined.

DATA SOURCES

Research databases (PubMed, Scopus, Google Scholar, EBSCOhost, SPORTDiscus) were searched through November 2013 for original studies, abstracts, theses and dissertations that examined the influence of acute exercise on GE.

STUDY SELECTION

Studies were included if they evaluated GE or OCTT during and/or after exercise and involved a resting control trial.

STUDY APPRAISAL AND SYNTHESIS

Initially, 195 studies were identified. After evaluation of study characteristics and quality and validity, data from 20 studies (35 trials) involving 221 participants (157 men; 52 women; 12 unknown) were extracted for meta-analysis. Random-effects meta-analyses were utilised for the three main outcome variables, and effect sizes (ES) are reported as Hedge's g due to numerous small sample sizes.

RESULTS

Random-effects modelling revealed non-significant and small/null main effect sizes for volume emptied (ES = 0.195; 95% CI -0.25 to 0.64), half-time (ES = -0.109, 95% CI -0.66 to 0.44) and OCTT (ES = 0.089; 95% CI -0.64 to 0.82). All analyses exhibited significant heterogeneity and numerous variables moderated the results. There was a dose response of exercise intensity; at lower intensities GE was faster, and at high exercise intensities GE was slower. Walking was associated with faster GE and cycling with slower GE. Greater volume of meal/fluid ingested, higher osmolality of beverage and longer exercise duration were also associated with slower GE with exercise.

LIMITATIONS

The major limitation is that the majority of studies utilised a liquid bolus administered pre-exercise to determine GE; the relationship to post-exercise appetite and energy intake remains unknown. Study populations were also generally active or trained individuals. Furthermore, our review was limited to English language studies and studies that utilised resting control conditions.

CONCLUSIONS

These results suggest that exercise intensity, mode, duration and the nature of meal/fluid ingested all influence GE during and after acute exercise. The relationship of GE parameters with appetite regulation after exercise remains largely unexplored. Further integrative studies combining GE and alterations in gut hormones, as well as in populations such as overweight and obese individuals are needed.

Diagnostic accuracy of rapid immunoassays for heparin-induced thrombocytopenia. A systematic review and meta-analysis

The platelet factor 4/heparin ELISA has limited specificity for heparin-induced thrombocytopenia (HIT) and frequently does not provide same-day results. Rapid immunoassays (RIs) have been developed which provide results in 30 minutes or less. We conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of RIs for HIT. We searched the literature for studies in which samples from patients with suspected HIT were tested using a RI and a functional assay against which the performance of the RI could be measured. We performed sensitivity analyses of studies that directly compared different RIs with each other and with ELISAs. Estimates of sensitivity and specificity for each RI were calculated. Twenty-three articles, collectively involving six different RIs, met eligibility criteria. All RIs exhibited high sensitivity (0.96 to 1.00); there was wider variability in specificity (0.68 to 0.94). Specificity of the IgG-specific chemiluminescent assay (IgG-CA) was greater than the polyspecific chemiluminescent assay [0.94 (95 %CI 0.89-0.99) vs 0.82 (0.77-0.87)]. The particle gel immunoassay demonstrated greater specificity than the polyspecific ELISA [0.96 (0.95-0.97) vs 0.91 (0.89-0.92)]. The IgG-CA and lateral flow immunoassay [0.94 (0.91-0.97)] exhibited greater specificity than the IgG-specific ELISA [0.86 (0.82-0.90)]. Given their high sensitivity and rapid turnaround time, RIs are a reliable means of excluding HIT at the point-of-care in patients with low or intermediate clinical probability. Additionally, some RIs have greater specificity than HIT ELISAs. In summary, IgG-specific RIs appear to have improved diagnostic accuracy compared with ELISAs in patients with suspected HIT and may reduce misdiagnosis and overtreatment.

On the need for increased rigour and care in the conduct and interpretation of network meta-analyses in drug development

The rise over recent years in the use of network meta-analyses (NMAs) in clinical research and health economic analysis is little short of meteoric driven, in part, by a desire from decision makers to extend inferences beyond direct comparisons in controlled clinical trials. But is the increased use and reliance of NMAs justified? Do such analyses provide a reliable basis for the relative effectiveness assessment of medicines and, in turn, for critical decisions relating to healthcare access and provisioning? And can such analyses also be used earlier, as part of the evidence base for licensure? Despite several important publications highlighting inherently unverifiable assumptions underpinning NMAs, these assumptions and associated potential for serious bias are often overlooked in the reporting and interpretation of NMAs. A more cautious, and better informed, approach to the use and interpretation of NMAs in clinical research is warranted given the assumptions that sit behind such analyses.

Improving Water Quality in an Iconic Estuary: An Internal Meta-analysis of Property Value Impacts around the Chesapeake Bay

This study conducts a meta-analysis and benefit transfer of the value of water clarity in the Chesapeake Bay estuary to estimate the property value impacts of pollution reduction policies. Estimates of the value of water clarity are derived from separate hedonic property value analyses of 14 counties bordering the Bay. The meta-analysis allows us to: 1) estimate the average effect of water clarity in the Chesapeake Bay, 2) investigate heterogeneity of effects across counties based on socioeconomic and ecological factors, 3) evaluate different measures of water clarity used in the original hedonic equations, and 4) transfer the values to Bayfront counties in nearby jurisdictions to estimate the property value impacts of the Total Maximum Daily Load (TMDL), a policy to reduce nutrient and sediment pollution entering the Bay that is expected to improve water clarity and ecological health. We also investigate the in-sample and out-of-sample predictive power of different transfer strategies and find that a simpler unit value transfer can outperform more complex function transfers. We estimate that aggregate near-waterfront property values could increase by roughly $400 million to $700 million in response to water clarity improvements from the TMDL.

The effect of physical activity on cognitive function in patients with dementia: A meta-analysis of randomized control trials

Non-pharmacological therapies, such as physical activity interventions, are an appealing alternative or add-on to current pharmacological treatment of cognitive symptoms in patients with dementia. In this meta-analysis, we investigated the effect of physical activity interventions on cognitive function in dementia patients, by synthesizing data from 802 patients included in 18 randomized control trials that applied a physical activity intervention with cognitive function as an outcome measure. Post-intervention standardized mean difference (SMD) scores were computed for each study, and combined into pooled effect sizes using random effects meta-analysis. The primary analysis yielded a positive overall effect of physical activity interventions on cognitive function (SMD[95% confidence interval]=0.42[0.23;0.62], p<.01). Secondary analyses revealed that physical activity interventions were equally beneficial in patients with Alzheimer's disease (AD, SMD=0.38[0.09;0.66], p<.01) and in patients with AD or a non-AD dementia diagnosis (SMD=0.47[0.14;0.80], p<.01). Combined (i.e. aerobic and non-aerobic) exercise interventions (SMD=0.59[0.32;0.86], p<.01) and aerobic-only exercise interventions (SMD=0.41[0.05;0.76], p<.05) had a positive effect on cognition, while this association was absent for non-aerobic exercise interventions (SMD=-0.10[-0.38;0.19], p=.51). Finally, we found that interventions offered at both high frequency (SMD=0.33[0.03;0.63], p<.05) and at low frequency (SMD=0.64[0.39;0.89], p<.01) had a positive effect on cognitive function. This meta-analysis suggests that physical activity interventions positively influence cognitive function in patients with dementia. This beneficial effect was independent of the clinical diagnosis and the frequency of the intervention, and was driven by interventions that included aerobic exercise.

Social attention in ASD: A review and meta-analysis of eye-tracking studies

Determining whether social attention is reduced in Autism Spectrum Disorder (ASD) and what factors influence social attention is important to our theoretical understanding of developmental trajectories of ASD and to designing targeted interventions for ASD. This meta-analysis examines data from 38 articles that used eye-tracking methods to compare individuals with ASD and TD controls. In this paper, the impact of eight factors on the size of the effect for the difference in social attention between these two groups are evaluated: age, non-verbal IQ matching, verbal IQ matching, motion, social content, ecological validity, audio input and attention bids. Results show that individuals with ASD spend less time attending to social stimuli than typically developing (TD) controls, with a mean effect size of 0.55. Social attention in ASD was most impacted when stimuli had a high social content (showed more than one person). This meta-analysis provides an opportunity to survey the eye-tracking research on social attention in ASD and to outline potential future research directions, more specifically research of social attention in the context of stimuli with high social content.

Towards better meta-analyses in assisted reproductive technology: Fixed, random or multivariate models?

AIM: To study the validity of the fixed, random, and multivariate meta-analytical models applied in meta-analyses in artificial reproduction technique.

METHODS: Based on common characteristics of in vitro fertilization (IVF) meta-analyses, we simulated a large number of data to compare results issued from the fixed model (FM) with the random model (RM). For multiple endpoints meta-analysis (MA), we compared the univariate RM with the multivariate model (MM). Finally, we illustrate our findings in re-analyzing a recent MA.

RESULTS: In our review, although a homogeneous effect was excluded in 89% of the MAs (11%), FM was utilized in 41 studies (82%). From simulations, a concordance of 59% ± 6% was found between the two tests, with up to 65% of falsely significant results with FM. The Q-test on studies characterized by substantial heterogeneity falsely accepted homogeneity in 46% of studies. Comparing separate univariate RM and MM on multiple endpoints studies, MM reduces the between endpoint discrepancy (BED) of 68%, and increases the power of 57% ± 8%. In the example dealing with the controversial effect of luteneizing hormone supplementation to follicle stimulating hormone during ovarian stimulation in IVF cycles, MM reduced BED by 66%, and consistent effects were found for all the endpoints, irrespective of partial reporting.

CONCLUSION: The FM generally may produce falsely significant differences. The RM should always be used. For multiple endpoints, the MM constitutes the best option.

Prevalence of Depression and Depressive Symptoms Among Resident Physicians: A Systematic Review and Meta-analysis

IMPORTANCE

Physicians in training are at high risk for depression. However, the estimated prevalence of this disorder varies substantially between studies.

OBJECTIVE

To provide a summary estimate of depression or depressive symptom prevalence among resident physicians.

DATA SOURCES AND STUDY SELECTION

Systematic search of EMBASE, ERIC, MEDLINE, and PsycINFO for studies with information on the prevalence of depression or depressive symptoms among resident physicians published between January 1963 and September 2015. Studies were eligible for inclusion if they were published in the peer-reviewed literature and used a validated method to assess for depression or depressive symptoms.

DATA EXTRACTION AND SYNTHESIS

Information on study characteristics and depression or depressive symptom prevalence was extracted independently by 2 trained investigators. Estimates were pooled using random-effects meta-analysis. Differences by study-level characteristics were estimated using meta-regression.

MAIN OUTCOMES AND MEASURES

Point or period prevalence of depression or depressive symptoms as assessed by structured interview or validated questionnaire.

RESULTS

Data were extracted from 31 cross-sectional studies (9447 individuals) and 23 longitudinal studies (8113 individuals). Three studies used clinical interviews and 51 used self-report instruments. The overall pooled prevalence of depression or depressive symptoms was 28.8% (4969/17,560 individuals, 95% CI, 25.3%-32.5%), with high between-study heterogeneity (Q = 1247, τ2 = 0.39, I2 = 95.8%, P < .001). Prevalence estimates ranged from 20.9% for the 9-item Patient Health Questionnaire with a cutoff of 10 or more (741/3577 individuals, 95% CI, 17.5%-24.7%, Q = 14.4, τ2 = 0.04, I2 = 79.2%) to 43.2% for the 2-item PRIME-MD (1349/2891 individuals, 95% CI, 37.6%-49.0%, Q = 45.6, τ2 = 0.09, I2 = 84.6%). There was an increased prevalence with increasing calendar year (slope = 0.5% increase per year, adjusted for assessment modality; 95% CI, 0.03%-0.9%, P = .04). In a secondary analysis of 7 longitudinal studies, the median absolute increase in depressive symptoms with the onset of residency training was 15.8% (range, 0.3%-26.3%; relative risk, 4.5). No statistically significant differences were observed between cross-sectional vs longitudinal studies, studies of only interns vs only upper-level residents, or studies of nonsurgical vs both nonsurgical and surgical residents.

CONCLUSIONS AND RELEVANCE

In this systematic review, the summary estimate of the prevalence of depression or depressive symptoms among resident physicians was 28.8%, ranging from 20.9% to 43.2% depending on the instrument used, and increased with calendar year. Further research is needed to identify effective strategies for preventing and treating depression among physicians in training.

Occupational exposure to pesticides and prostate cancer: a systematic review and meta-analysis

Epidemiological studies on exposure to pesticides and risk of prostate cancer (PC) provide inconsistent results. We aimed to explore various potential sources of heterogeneity not previously assessed and to derive updated risk estimates from homogenous studies. We searched PubMed, Web of Science and Scopus databases for case-control and cohort studies published from 1985 to April 2014. We assessed the quality of the articles using the Newcastle-Ottawa Scale. Pooled estimates were calculated using random-effects models. Heterogeneity was explored using subset analyses and metaregression. Fifty-two studies were included in the review and 25 in the meta-analysis. No association was found between low exposure to pesticides and PC, but association was significant for high exposure, pooled OR 1.33 (1.02 to 1.63), I(2)=44.8%, p=0.024. Heterogeneity was explained by a number of variables including method used to assess exposure. Pooled OR was weak and non-significant for studies measuring serum pesticide level, 1.12 (0.74 to 1.50), I(2)=0.00%, p=0.966. For studies applying self-reporting of exposure, pooled estimate was 1.34 (0.91 to 1.77), I(2)=0.00%, p=0.493, while a high significant association was detected for grouped exposure assessment, 2.24 (1.36 to 3.11), I(2)=0.00%, p=0.955. In spite of a weak significant association detected when pooling ORs for high occupational exposure to pesticides, the magnitude of the association was related to the method of exposure assessment used by the original studies. A family history-pesticide exposure interaction was also observed for a number of pesticides.

High Ambient Temperatures and Risk of Motor Vehicle Crashes in Catalonia, Spain (2000-2011): A Time-Series Analysis

BACKGROUND

Experimental studies have shown a decrease in driving performance at high temperatures. The epidemiological evidence for the relationship between heat and motor vehicle crashes is not consistent.

OBJECTIVES

We estimated the impact of high ambient temperatures on the daily number of motor vehicle crashes and, in particular, on crashes involving driver performance factors (namely distractions, driver error, fatigue, or sleepiness).

METHODS

We performed a time-series analysis linking daily counts of motor vehicle crashes and daily temperature or occurrence of heat waves while controlling for temporal trends. All motor vehicle crashes with victims that occurred during the warm period of the years 2000-2011 in Catalonia (Spain) were included. Temperature data were obtained from 66 weather stations covering the region. Poisson regression models adjusted for precipitation, day of the week, month, year, and holiday periods were fitted to quantify the associations.

RESULTS

The study included 118,489 motor vehicle crashes (an average of 64.1 per day). The estimated risk of crashes significantly increased by 2.9% [95% confidence interval (CI): 0.7%, 5.1%] during heat wave days, and this association was stronger (7.7%, 95% CI: 1.2%, 14.6%) when restricted to crashes with driver performance-associated factors. The estimated risk of crashes with driver performance factors significantly increased by 1.1% (95% CI: 0.1%, 2.1%) for each 1 °C increase in maximum temperature.

CONCLUSIONS

Motor vehicle crashes involving driver performance-associated factors were increased in association with heat waves and increasing temperature. These findings are relevant for designing preventive plans in a context of global warming.

A SYSTEMATIC REVIEW AND META-ANALYSIS OF DROPOUT RATES IN YOUTH SOCCER

Despite the many benefits of involvement in youth sports, participation in them declines throughout childhood and adolescence. The present study performed a systematic review and meta-analysis of 12 studies reporting dropout rates in youth soccer, involving a total of 724,036 youths ages 10-18 years from five countries. The mixed effects meta-regression analyses took into account age and sex as statistical moderators of dropout rate. Potential articles were identified through computerized searches of the databases PubMed, MedLine, Embase, and SportDiscus up until August 2014, without any further time limit. Based on results reported in the 10 included articles, the annual weighted mean dropout rate is 23.9% across the included cohorts. Meta-regression indicated that annual dropout rates are stable from the ages of 10-19 years, with higher rates for girls (26.8%) compared to boys (21.4%). The present study suggests that youth soccer players are prone to dropout rates in which close to one-fourth of players leave the sport annually, which appears to be a consistent finding across ages 10-18 years.

Mortality and drug therapy in patients with chronic obstructive pulmonary disease: a network meta-analysis

BACKGROUND

Increasing evidence suggests pharmacological treatments may impact on overall survival in Chronic Obstructive Pulmonary Disease (COPD) patients. Individual clinical trials are rarely powered to detect mortality differences between treatments and may not include all treatment options relevant to healthcare decision makers.

METHODS

A systematic review was conducted to identify RCTs of COPD treatments reporting mortality; evidence was synthesised using network meta-analysis (NMA). The analysis included 40 RCTs; a quantitative indirect comparison between 14 treatments using data from 55,220 patients was conducted.

RESULTS

The analysis reported two treatments reducing all-cause mortality; salmeterol/fluticasone propionate combination (SFC) was associated with a reduction in mortality versus placebo in the fixed effects (HR 0.79; 95 % Crl 0.67, 0.94) but not the random effects model (0.79; 0.56, 1.09). Indacaterol was associated with a reduction in mortality versus placebo in fixed (0.28; 0.08 to 0.85) and random effects (0.29; 0.08, 0.89) models. Mean estimates and credible intervals for hazard ratios for indacaterol versus placebo are based on a small number of events; estimates may change when the results of future studies are included. These results were maintained across a variety of assumptions and provide evidence that SFC and indacaterol may lead to improved survival in COPD patients.

CONCLUSION

Results of an NMA of COPD treatments suggest that SFC and indacaterol may reduce mortality. Further research is warranted to strengthen this conclusion.

Is Pilocarpine Effective in Preventing Radiation-Induced Xerostomia? A Systematic Review and Meta-analysis

PURPOSE

To evaluate the efficacy of concomitant administration of pilocarpine on radiation-induced xerostomia in patients with head and neck cancers.

METHODS AND MATERIALS

The PubMed, Web of Science, Cochrane Library, and ClinicalTrials were searched to identify randomized, controlled trials studying the effect of concomitant administration of pilocarpine for radiation-induced xerostomia. Included trials were systematically reviewed, and quantifiable outcomes were pooled for meta-analysis. Outcomes of interest included salivary flow, clinician-rated xerostomia grade, patient-reported xerostomia scoring, quality of life, and adverse effects.

RESULTS

Six prospective, randomized, controlled trials in 8 articles were included in this systematic review. The total number of patients was 369 in the pilocarpine group and 367 in the control group. Concomitant administration of pilocarpine during radiation could increase the unstimulated salivary flow rate in a period of 3 to 6 months after treatment, and also reduce the clinician-rated xerostomia grade. Patient-reported xerostomia was not significantly impacted by pilocarpine in the initial 3 months but was superior at 6 months. No significant difference of stimulated salivary flow rate could be confirmed between the 2 arms. Adverse effects of pilocarpine were mild and tolerable.

CONCLUSIONS

The concomitant administration of pilocarpine during radiation increases unstimulated salivary flow rate and reduces clinician-rated xerostomia grade after radiation. It also relieves patients' xerostomia at 6 months and possibly at 12 months. However, pilocarpine has no effect on stimulated salivary flow rate.