Investigating causes of heterogeneity in systematic reviews

Use of regenerative medicine in the treatment of endometritis in mares: A systematic review and meta-analysis

Defining the optimal therapy for endometritis remains a significant challenge for clinicians. Given the public health threat posed by antibiotic resistance and the inconclusiveness of traditional therapies, regenerative medicine has been proposed as an alternative. The objective of this study was to conduct a comprehensive systematic review and meta-analysis, to investigate the efficacy of regenerative medicine products in the treatment of both post-breeding persistent and chronic degenerative endometritis (PBIE/CDE) in mares, following the PRISMA guidelines. This research could be a comprehensive scientific reference for determining appropriate treatments and clinical strategies. All studies exploring the use of regenerative medicine therapies (i.e., plasma products, autologous conditioned serum, mesenchymal stem cells MSCs, and MSC derivatives) in the treatment of PBIE/CDE were included, regardless of the specific protocol used, the evaluated outcomes, or the diagnostic method employed. Two authors independently gathered data and evaluated the risk of bias for each study. Treatment effects were assessed using risk ratios for dichotomous data, accompanied by 95 % confidence intervals. Data were aggregated utilizing the fixed-effects model. The quality of evidence for each outcome was evaluated using GRADE criteria. Eighteen studies were included in the systematic review, while fifteen trials were included in the meta-analysis. A sub-meta-analysis was conducted separately on platelet-derived products, as well as on MSCs and their derivatives. The results demonstrated an overall positive effect of regenerative therapies in treating PBIE/CDE, particularly those involving MSCs and their derivatives. The positive outcomes include an anti-inflammatory effect, characterized by reduced intrauterine fluid accumulation, neutrophils, and cytokine concentrations. Additionally, improvements in pregnancy, foaling, and embryo recovery rates have been observed in some cases. Despite the limited number of randomized controlled studies and the high variability among protocols, including the timing of treatment, type, and volume of products used, the use of regenerative products, especially MSCs and their derivatives, has promising results in terms of both efficacy and safety for treating PBIE/CDE in mares.

Use of Autologous Conditioned Serum (ACS) for Osteoarthritis Treatment in Horses: A Systematic Review of Clinical Data

The utilization of Autologous Conditioned Serum (ACS) for treating osteoarthritis (OA) in horses has seen a notable increase in recent years. In vitro studies have consistently identified ACS as a promising therapy for OA joints, contributing to its growing popularity in OA treatment. Despite this, there is a noticeable absence of systematic reviews focused solely on the clinical data of OA patients treated with ACS, excluding the in vitro perspective. This study aims to address this gap by systematically reviewing the latest literature, concentrating solely on clinical data in in vivo studies to evaluate the efficacy of ACS in OA lesions. All clinical studies involving ACS treatments for horses with OA were included in the assessment. Surprisingly, only six trials met the inclusion criteria for this systematic review. The results indicate that the majority of the considered articles support the use of ACS as a treatment for horses, albeit with a control group provided in only one study. However, the absence of a control group and the exclusion of histological evaluation diminish the validity of the majority of clinical research. While several studies suggest a beneficial effect of ACS on OA horses without significant adverse effects, this systematic review affirms that there is no definitive evidence for its effectiveness. Therefore, further investigation of the efficacy of ACS products as a treatment for OA is warranted, emphasizing the need for more controlled trials. Poorly designed and biased studies, lacking blinding or control and adopting inadequate outcome measures, may favor positive results and, thus, necessitate a more rigorous approach to validate the efficacy of ACS in OA treatment.

Risk of lung cancer among welders and flame cutters: A systematic review and meta-analysis of case controlled studies

OBJECTIVES

The process of flame-cutting and welding is believed to be highly hazardous for workers involved in related industries. The study aims to provide a comprehensive quantitative effect of the risk of lung cancer due to exposure to welding fumes.

METHODS

A systematic review was conducted to extract published estimates of Odd's Ratio (OR) of the association of lung cancer and exposure to welding fumes, till 2022. Studies were extracted from the PubMed and Cochrane database and Google Scholar. Studies from all parts of the world were considered. Through a meta-analysis conducted with random effects model, a forest plot was created, and publication bias was checked using a funnel plot.

RESULTS

The meta-analysis yielded an OR of 1.28 (95% CI 1.055-1.55), with a moderately high heterogeneity between the studies [I2=72%; T2=0.0524;Q=36.12(P<0.001)]. The sensitivity and influence analysis confirmed the absence of highly influential studies that may have led to potentially distorted outcomes. The funnel plot showed no evidence of publication bias among the studies included in this analysis.

CONCLUSION

As the association between lung cancer and occupational hazards from exposure to welding fumes is certain, there is a need to control and regulate industrial activities that involve welding and flame cutting. Already, restrictions on safe levels of fume in the workplace are in operation.

Comparison of the Efficacy of Cisplatin/Paclitaxel Versus Carboplatin/Paclitaxel in Improving Survival and Quality of Life in the Advanced Ovarian Cancer Patient Population: A Systematic Review and Meta-Analysis of Randomized Control Trials

Ovarian cancer, being one of the prevalent gynecological cancers, warrants a therapy that's both effective and well tolerated. After extensive drug testing, combination regimens with paclitaxel plus platinum-based agents such as cisplatin/carboplatin and taxanes, have shown promising results for advanced ovarian cancer. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to compare the efficacy of two treatment regimens for advanced ovarian cancer: cisplatin/paclitaxel and carboplatin/paclitaxel.  PubMed (Medline), Science Direct, and Cochrane Library were searched from inception to March 2023. The meta-analysis included patients with histologically verified International Federation of Gynaecology and Obstetrics (FIGO) stages IIB to IV ovarian carcinoma who received either carboplatin/paclitaxel or cisplatin/paclitaxel. The primary outcomes were progression-free survival (PFS), overall survival (OS), quality of life (QOL), complete response rate (CRR), and partial response rate (PRR). The revised Cochrane Risk of Bias Tool 2.0 was used to assess the quality of the RCTs The five RCTs chosen for this statistical analysis consisted of a total of 2239 participants, with 1109 receiving paclitaxel/cisplatin for treatment and the remaining 1130 receiving carboplatin/paclitaxel. Among all included outcomes, these reported significant findings: QoL (p-value=0.0002), thrombocytopenia (p=<0.00001), neurological toxicity (p-value=0.003), nausea/vomiting (p-value=<0.00001), myalgia/arthralgia (p-value=0.02), and febrile neutropenia (p-value=0.01). We concluded that the carboplatin/paclitaxel doublet endows a better quality of life (QOL) to patients along with significantly fewer gastrointestinal and neurological toxicities when compared with the cisplatin/paclitaxel combination. However, the myelosuppressive effects of carboplatin/paclitaxel remain a point of concern and may require clinical management.

The bidirectional association between chronic musculoskeletal pain and sleep-related problems: a systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis synthesizes the evidence on prospective bidirectional associations between sleep-related problems (SRP) and chronic musculoskeletal pain (CMP).

METHODS

A literature search for cohort studies available in the PubMed, Scopus, Web of Science, PsycINFO and Cochrane Library databases as of 19 July 2022 was performed. Pooled odds ratios and effect sizes were calculated through random effects meta-analysis. Subgroup and meta-regression analyses were performed to explore differences by follow-up time, proportion of each sex and mean age. The Meta-analysis Of Observational Studies in Epidemiology guidelines were strictly followed.

RESULTS

Twenty studies with a total of 208 190 adults (aged 34.4-71.7 years) were included, with 17 of them being used in the meta-analysis. Individuals with SRP at baseline had a 1.79-fold higher incidence (odds ratio [OR] = 1.79; 95% CI: 1.55, 2.08; I2 = 84.7%; P < 0.001) and a 2.04-fold higher persistence (OR = 2.04; 95% CI: 1.42, 2.94; I2 = 88.5%; P < 0.005) of CMP than those without SRP. In the subgroup analysis of the association between SRP and CMP, the longer the follow-up time of the studies, the higher the heterogeneity between them. In the corresponding meta-regression, no significant effect was observed for follow-up time, sex proportion or age. Individuals with CMP at baseline had a 2.02-fold higher incidence of SRP (OR = 2.02; 95% CI: 1.62, 2.53; I2 = 90.0%; P < 0.001) than those without CMP.

CONCLUSION

This study provides robust evidence concerning the longitudinal association between SRP and incidence-persistence of CMP in adults. In addition, the available prospective studies support the existence of a bidirectional relationship between CMP and SRP.

PROSPERO REGISTRATION NUMBER

CRD42020212360.

The effectiveness of tobacco cessation programs for university students: A systematic review and meta-analysis

INTRODUCTION

This systematic review and meta-analysis aimed to explore the existing tobacco interventions and synthesize whether those interventions affected tobacco use among university students.

METHODS

We searched and found 1799 studies in PubMed, ClinicalKey for Nursing, Embase, and SCOPUS between 2009 and 2022. The risk of bias was assessed using similar criteria for RCT and non-randomized studies guided by the Cochrane Handbook for Systematic Reviews. The heterogeneity of studies was evaluated using Cochran's Q and I² index. The GRADE system was used to distinguish the quality of evidence, and Egger's linear regression test was performed to assess publication bias.

RESULTS

Eighteen studies used data extraction and analyses, and only eleven were meta-analyzed, which found that the estimate obtained via the fixed-effects model was statistically significant. Technology-based and motivational interview interventions found pooled ORs of statical significance, while reinforcer interventions showed the smallest effect size. The level of heterogeneity was considered substantial. The assessment for quality of evidence showed low overall certainty of evidence due to imprecision of outcome and suspicion of publication bias. Egger's test showed no publication bias among included studies (p=0.38).

CONCLUSIONS

There were numerous tobacco cessation interventions for university students, but the most effective intervention to change tobacco consumption behavior was still inconclusive and uncertain.

TRIAL REGISTRATION

This systematic review was registered with PROSPERO. The registration number is CRD42019142491.

The impacts of physical activity on psychological and behavioral problems, and changes in physical activity, sleep and quality of life during the COVID-19 pandemic in preschoolers, children, and adolescents: A systematic review and meta-analysis

Background

The COVID-19 pandemic has greatly affected the level of physical activity (PA). However, little is known about its effect on health outcomes.

Methods

Articles without language restrictions published from the database inception through March 16, 2022, were retrieved using the CINAHL Complete, Cochrane Library, EMBASE, Medline, PubMed, and PsycINFO databases. High-quality articles assessing the effect of PA on psychological and behavioral problems. Additionally, PA, QoL, and/or sleep problems before and during the pandemic were included. Articles without data regarding PA or involving non-general populations were excluded. The PRISMA and MOOSE guidelines were followed. Data quality of the selected articles was assessed using the Newcastle-Ottawa Scale and GRADE approach. Data were pooled using a random-effects model and sensitivity analysis if heterogenicity was high (I 2 ≥ 50%). The relationship between PA and psychological and behavioral problems; and changes in PA, QoL, and sleeping patterns before and during the pandemic in preschoolers, children, and adolescents were investigated. A meta-analysis was conducted; odds ratios (ORs), mean differences (MD), and standardized MDs (SMDs) were calculated.

Results

Thirty-four articles involving 66,857 participants were included. The results showed an overall significant protective effect between PA and psychological and/or behavioral problems (OR = 0.677; 95% CI = 0.630, 0.728; p-value <0.001; I 2   = 59.79%). This relationship was also significant in the subgroup analysis of children (OR = 0.690; 95% CI = 0.632, 0.752; p-value <0.001; I 2   = 58.93%) and adolescents (OR = 0.650; 95% CI = 0.570, 0.741; p-value <0.001; I 2   = 60.85%); however, no data on the relationship in preschoolers were collected. In addition, the overall time spent on PA significantly decreased by 23.2 min per day during the COVID-19 pandemic (95% CI = -13.5, -32.9; p-value <0.001; I 2   = 99.82%). Moreover, the results showed an overall significant decrease in QoL (SMD = -0.894, 95% CI = -1.180, -0.609, p-value <0.001, I 2   = 96.64%). However, there was no significant difference in sleep duration during the COVID-19 pandemic (MD = 0.01 h per day, 95% CI = -0.027, 0.225; p-value = 0.125; I 2   = 98.48%).

Conclusion

During the pandemic, less PA was contributed to poor QoL and sleep quality. However, increases in PA are associated with reduced occurrences of psychological and behavioral problems. Implementing recovery plans to address the health effect of the pandemic is essential.

Cross-contamination rate of reusable flexible bronchoscopes: A systematic literature review and meta-analysis

Background

Bronchoscopy is generally a safe and efficient procedure. However, the risk of cross-contamination with reusable flexible bronchoscopes (RFB) has been detected in several outbreaks worldwide.

Aim

To estimate the average cross-contamination rate of patient-ready RFBs based on available published data.

Methods

We performed a systematic literature review in PubMed and Embase to investigate the cross-contamination rate of RFB. Included studies identified indicator organisms or colony forming units (CFU) levels, and total number of samples >10. The Contamination threshold was defined according to the European Society of Gastrointestinal Endoscopy and European Society of Gastrointestinal Endoscopy Nurse and Associates (ESGE-ESGENA) guidelines. To calculate the total contamination rate, a random effects model was applied. Heterogeneity was analysed via a Q-test and illustrated in a forest plot. Publication bias was analysed via the Egger’s regression test and illustrated in a funnel plot.

Results

Eight studies fulfilled our inclusion criteria. The random effects model included 2169 samples and 149 events (positive tests). The total RFB cross-contamination rate was 8.69% ± 1.86 (standard division [SD]) (95% confidence interval [CI]: 5.06–12.33%). The result showed significant heterogeneity of 90% and publication bias.

Discussion

Significant heterogeneity and publication bias is likely associated with varying methodology and aversion towards publishing negative findings, respectively. Based on the cross-contamination rate an infection control paradigm shift is needed to ensure patient safety. We recommend to follow the Spaulding classification and classify RFBs as critical items. Accordingly, infection control measures such as obligatory surveillance, and implementing single-use alternatives must be considered where feasible.

The effects of khat use during pregnancy on perinatal and maternal outcomes: a meta-analysis

Chewing khat during pregnancy adversely affects maternal and fetal health, but available studies are scarce and inconsistent, and it is difficult to conclude the relationship between khat consumption and perinatal outcomes. We aimed to investigate the available studies on the effect of khat use during pregnancy on perinatal and maternal outcomes. For this meta-analysis, we conducted a thorough search of articles published in PubMed, Embase, Scopus, and Web of Science up to the date this search was undertaken (03.01.2022). We used random effect model with the Mantel-Haenszel method to calculate the pooled odds ratio and mean difference. We found that khat use during pregnancy was significantly associated with increased odds of low birth weight (OR:2.51; 95% CI: 1.60 to 3.94), congenital anomalies (OR:3.17; 95% CI: 1.30 to 7.73), premature rupture of membrane (OR: 1.99; 95% CI: 1.59 to 2.50), perinatal mortality (OR: 1.95; 95% CI: 1.26 to 3.03), and lower APGAR scores at the fifth minute (MD: -1.7; 95% CI: -2.32 to -1.07). Also, increased odds for developing maternal psychological stress and anemia were reported in women using khat during pregnancy. There were no statistically significant differences in stillbirth and preterm birth between women using khat during pregnancy and their counterparts. Since prenatal khat use is associated with adverse perinatal and maternal outcomes, we strongly recommend equitable and easily accessible health services through the implementation of integrated addiction treatment with maternity services to address khat use during pregnancy and encourage the practice of healthy behavior of women.

Heterogeneity estimation in meta-analysis of standardized mean differences when the distribution of random effects departs from normal: A Monte Carlo simulation study

BACKGROUND

Advantages of meta-analysis depend on the assumptions underlying the statistical procedures used being met. One of the main assumptions that is usually taken for granted is the normality underlying the population of true effects in a random-effects model, even though the available evidence suggests that this assumption is often not met. This paper examines how 21 frequentist and 24 Bayesian methods, including several novel procedures, for computing a point estimate of the heterogeneity parameter ([Formula: see text]) perform when the distribution of random effects departs from normality compared to normal scenarios in meta-analysis of standardized mean differences.

METHODS

A Monte Carlo simulation was carried out using the R software, generating data for meta-analyses using the standardized mean difference. The simulation factors were the number and average sample size of primary studies, the amount of heterogeneity, as well as the shape of the random-effects distribution. The point estimators were compared in terms of absolute bias and variance, although results regarding mean squared error were also discussed.

RESULTS

Although not all the estimators were affected to the same extent, there was a general tendency to obtain lower and more variable [Formula: see text] estimates as the random-effects distribution departed from normality. However, the estimators ranking in terms of their absolute bias and variance did not change: Those estimators that obtained lower bias also showed greater variance. Finally, a large number and sample size of primary studies acted as a bias-protective factor against a lack of normality for several procedures, whereas only a high number of studies was a variance-protective factor for most of the estimators analyzed.

CONCLUSIONS

Although the estimation and inference of the combined effect have proven to be sufficiently robust, our work highlights the role that the deviation from normality may be playing in the meta-analytic conclusions from the simulation results and the numerical examples included in this work. With the aim to exercise caution in the interpretation of the results obtained from random-effects models, the tau2() R function is made available for obtaining the range of [Formula: see text] values computed from the 45 estimators analyzed in this work, as well as to assess how the pooled effect, its confidence and prediction intervals vary according to the estimator chosen.

Long-Term Safety and Effectiveness of Erenumab in Patients with Migraine: A Systematic Review and Single-Arm Meta-analysis

BACKGROUND AND OBJECTIVE

Several studies on use of erenumab for migraine treatment have been published over recent years. However, its long-term safety and effectiveness have not been consistently established in the literature yet. We aimed to perform a qualitative and quantitative analysis of the long-term safety and effectiveness of erenumab for the treatment of migraine headaches.

METHODS

Long-term follow-up was defined as ≥ 1 year. PubMed, Embase and Cochrane Library were systematically searched from inception to 14 June 2022 for studies meeting the inclusion criteria. Risk of bias was assessed using the Newcastle-Ottawa Scale.

RESULTS

Fourteen studies, comprising 3574 patients, were included. The total follow-up period ranged from 48 to 268 weeks (i.e., 1 year to 5.6 years). Pooled estimate rates for all adverse events (AEs) were 63% (95% CI 46-78); for serious AEs, 3% (95% CI 1-7); and for AEs leading to discontinuation of erenumab, 3% (95% CI 2-5). Reduction in monthly migraine days (MMDs) was -6.98 (95% CI -8.90 to -5.05) and in migraine-specific medication days (MSMDs) was - 6.09 (95% CI - 9.43 to - 2.75). More than half (57%; 95% CI 51-63) and around one-third (35%; 95% CI 28-42) of patients presented with reductions of ≥ 50% and ≥ 75% in MMDs, respectively. Headache Impact Test-6 (HIT-6) score was decreased by -9.68 points (95% CI - 12.03 to - 7.34). Nine studies were considered of poor methodological quality and five of fair quality.

CONCLUSIONS

Erenumab has a favorable safety profile, with a low incidence of serious AEs, and sustained efficacy over ≥1 year of follow-up in the treatment of migraine.

The use of interleukin-6 as a biomarker of lung cancer: A systematic review and meta-analysis

BACKGROUND

Lung cancer is known for its fatality due to diagnosis at a late stage, indicating the need for the discovery of novel diagnostic biomarkers. Interleukin-6 (IL-6) belongs to a family of inflammatory cytokines shown to be elevated in cancer patients. Hence, in this study, a systematic review and meta-analysis was undertaken to evaluate the association of IL-6 levels between lung cancer patients and healthy individuals, as this would further support its use as a clinical biomarker.

METHODS

All major electronic databases were systematically searched to find the existing literature from 2012 until September 2022 on the association of IL-6 levels with lung cancer. Mean and standard deviation of IL-6 levels of lung cancer patients and controls were recorded from the included case-control studies. The natural logarithm of the ratio of means (RoM) between patients and controls with its respective 95% confidence intervals was calculated to retrieve a pooled RoM value.

RESULTS

Eight studies involving 559 lung cancer patients and 462 healthy controls were in included in the meta-analysis and a random-effects model was used due to high heterogeneity (I2 = 99.38%). Overall, IL-6 was found to be higher in lung cancer patients (pooled ln RoM = 1.20, 95% CI: 0.72-1.69, P < 0.0001) and all included studies were found to carry a low risk of bias after quality assessment.

CONCLUSIONS

This meta-analysis revealed that IL-6 levels are higher in biological samples of lung cancer patients, indicating that they could be used as a biomarker for diagnosing lung cancer without complications. Further research should be undertaken to evaluate its diagnostic accuracy, in order to obtain more concrete evidence for its clinical use.

A systematic review of clinical outcomes for outpatient vs. inpatient shoulder arthroplasty

BACKGROUND

Outpatient shoulder arthroplasty is growing in popularity as a cost-effective and potentially equally safe alternative to inpatient arthroplasty. The aim of this study was to investigate literature relating to outpatient shoulder arthroplasty, looking at clinical outcomes, complications, readmission, and cost compared to inpatient arthroplasty.

METHODS

We conducted a systematic review of Medline, Embase and Cochrane Library databases from inception to 6 April 2020. Methodological quality was assessed using MINORS and GRADE criteria.

RESULTS

We included 17 studies, with 11 included in meta-analyses and 6 in narrative review. A meta-analysis of hospital readmissions demonstrated no statistically significant difference between outpatient and inpatient cohorts (OR = 0.89, p = 0.49). Pooled post-operative complications identified decreased complications in those undergoing outpatient surgery (OR = 0.70, p = 0.02). Considerable cost saving of between $3614 and $53,202 (19.7-69.9%) per patient were present in the outpatient setting. Overall study quality was low and presented a serious risk of bias.

DISCUSSION

Shoulder arthroplasty in the outpatient setting appears to be as safe as shoulder arthroplasty in the inpatient setting, with a significant reduction in cost. However, this is based on low quality evidence and high risk of bias suggests further research is needed to substantiate these findings.

A systematic review of bone marrow stromal cells and periosteum-derived cells for bone regeneration

Bone marrow stromal cells (BMSCs) and periosteum-derived cells (PDCs) represent promising skeletal stem cell sources to treat critical-size bone defects. However, the large number of preclinical tests with a variety of in vivo data complicates the selection of cells for further clinical translation. This systematic review aims to analyze the in vivo bone-forming efficacy of BMSCs- and PDCs-based approaches in all published preclinical experiments until November 2020. For this purpose, four databases (PubMed, Embase, Cochrane Central Register of Controlled Trial, and Web of Science) were searched for eligible literature, which yielded a total of 94 full-text articles for systematic review. This review generated an evidence-based list of BMSC- or PDC-based approaches, which have been evaluated for bone formation in different animal models. Among them, 74 studies were included for pairwise and network meta-analysis. The results revealed that both PDC and BMSC had beneficial bone-forming efficacy compared to bare scaffold. In addition, BMSC- and PDC-based approaches had no significant difference regarding in vivo bone-forming efficacy. However, BMSC-based approach had a higher probability to be ranked better than PDC-based approach. Furthermore, the review discusses (i) the possible risk of bias of the in vivo evaluation of cell-based approaches, (ii) the difficulty in replication of such experiments due to frequent poor reporting of the methods and results, and (iii) the clinical relevance of the currently utilized BMSC- and PDC-based approaches. Systematic review registration: The study was prospectively registered in PROSPERO, Registration No. CRD42021270922.

Exploring women's experiences participating in yoga after a cancer diagnosis: a protocol for a meta-synthesis

BACKGROUND

The benefits of yoga for clinical and non-clinical populations have been summarized in published systematic reviews. The vast majority of systematic reviews on the topic are syntheses of quantitative research that evaluated the effects of yoga. As qualitative research related to women's experiences participating in yoga after a cancer diagnosis is growing in quantity, systematic synthesis and integration of qualitative research are necessary to facilitate the transfer of knowledge. This paper describes the protocol for a meta-synthesis of qualitative research exploring women's experiences participating in yoga after a cancer diagnosis.

METHODS

Using a meta-study methodology, six electronic databases were searched to identify relevant articles. Additionally, the reference lists of relevant articles retrieved during the electronic database search were scanned to identify other relevant articles. Two reviewers independently screened the titles and abstracts, retaining those that appeared to relate to the review objectives. Next, they reviewed the retained full-text articles to assess eligibility according to four inclusion criteria. They will extract data from eligible studies and assess the quality of included studies. Data analysis will involve three main analytical steps: meta-data analysis, meta-method analysis, and meta-theory analysis. Findings from the three analytical steps will be interpreted collectively to generate additional insights beyond the findings of the primary studies to facilitate a more comprehensive understanding of women's experiences participating in yoga after a cancer diagnosis.

DISCUSSION

By systematically collecting, analysing, and interpreting findings across multiple primary qualitative studies, we will develop an overarching narrative and interpretation of the role and value of yoga for women diagnosed with cancer. A synthesis of qualitative research is vital as it embraces the heterogeneity of the research so as to provide important context for understanding the experiences of various women participating in yoga.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021229253.

How effects on health equity are assessed in systematic reviews of interventions

BACKGROUND

Enhancing health equity is endorsed in the Sustainable Development Goals. The failure of systematic reviews to consider potential differences in effects across equity factors is cited by decision-makers as a limitation to their ability to inform policy and program decisions.  OBJECTIVES: To explore what methods systematic reviewers use to consider health equity in systematic reviews of effectiveness.

SEARCH METHODS

We searched the following databases up to 26 February 2021: MEDLINE, PsycINFO, the Cochrane Methodology Register, CINAHL, Education Resources Information Center, Education Abstracts, Criminal Justice Abstracts, Hein Index to Foreign Legal Periodicals, PAIS International, Social Services Abstracts, Sociological Abstracts, Digital Dissertations and the Health Technology Assessment Database. We searched SCOPUS to identify articles that cited any of the included studies on 10 June 10 2021. We contacted authors and searched the reference lists of included studies to identify additional potentially relevant studies.

SELECTION CRITERIA

We included empirical studies of cohorts of systematic reviews that assessed methods for measuring effects on health inequalities. We define health inequalities as unfair and avoidable differences across socially stratifying factors that limit opportunities for health. We operationalised this by assessing studies which evaluated differences in health across any component of the PROGRESS-Plus acronym, which stands for Place of residence, Race/ethnicity/culture/language, Occupation, Gender or sex, Religion, Education, Socioeconomic status, Social capital. "Plus" stands for other factors associated with discrimination, exclusion, marginalisation or vulnerability such as personal characteristics (e.g. age, disability), relationships that limit opportunities for health (e.g. children in a household with parents who smoke) or environmental situations which provide limited control of opportunities for health (e.g. school food environment).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data using a pre-tested form. Risk of bias was appraised for included studies according to the potential for bias in selection and detection of systematic reviews.  MAIN RESULTS: In total, 48,814 studies were identified and the titles and abstracts were screened in duplicate. In this updated review, we identified an additional 124 methodological studies published in the 10 years since the first version of this review, which included 34 studies. Thus, 158 methodological studies met our criteria for inclusion. The methods used by these studies focused on evidence relevant to populations experiencing health inequity (108 out of 158 studies), assess subgroup analysis across PROGRESS-Plus (26 out of 158 studies), assess analysis of a gradient in effect across PROGRESS-Plus (2 out of 158 studies) or use a combination of subgroup analysis and focused approaches (20 out of 158 studies). The most common PROGRESS-Plus factors assessed were age (43 studies), socioeconomic status in 35 studies, low- and middle-income countries in 24 studies, gender or sex in 22 studies, race or ethnicity in 17 studies, and four studies assessed multiple factors across which health inequity may exist. Only 16 studies provided a definition of health inequity. Five methodological approaches to consider health equity in systematic reviews of effectiveness were identified: 1) descriptive assessment of reporting and analysis in systematic reviews (140 of 158 studies used a type of descriptive method); 2) descriptive assessment of reporting and analysis in original trials (50 studies); 3) analytic approaches which assessed differential effects across one or more PROGRESS-Plus factors (16 studies); 4) applicability assessment (25 studies) and 5) stakeholder engagement (28 studies), which is a new finding in this update and examines the appraisal of whether relevant stakeholders with lived experience of health inequity were included in the design of systematic reviews or design and delivery of interventions. Reporting for both approaches (analytic and applicability) lacked transparency and was insufficiently detailed to enable the assessment of credibility.

AUTHORS' CONCLUSIONS

There is a need for improvement in conceptual clarity about the definition of health equity, describing sufficient detail about analytic approaches (including subgroup analyses) and transparent reporting of judgments required for applicability assessments in order to consider health equity in systematic reviews of effectiveness.

Effect of prone positioning on survival in adult patients receiving venovenous extracorporeal membrane oxygenation for acute respiratory distress syndrome: a systematic review and meta-analysis

Purpose

Previous studies support the potential efficacy of venovenous extracorporeal membrane oxygenation (vvECMO) for improving survival in severe acute respiratory distress syndrome (ARDS) cases. Prone positioning (PP) has been shown to improve the outcomes of moderate-to-severe ARDS patients. Few studies and no randomized controlled trials have evaluated the effect of PP performed in ECMO patients.

Methods

We performed a systematic review and meta-analysis examining the effect of prone positioning for ARDS patients receiving vvECMO on survival. All authors were contacted to obtain complementary information not mentioned in the original articles. The main objective was to compare 28-day survival in vvECMO patients with PP to vvECMO patients without PP (controls).

Results

Thirteen studies with a combined population of 1836 patients satisfied the inclusion criteria. PP was associated with a significant improvement in 28-day survival (503 survivors among 681 patients in the PP group [74%; 95% CI 71–77] vs. 450 survivors among 770 patients in the control group [58%, 95% CI 55–62]; RR 1.31 [95% CI 1.21–1.41]; I² 22% [95% CI 0–62%]; P < 0.0001). Survival was also improved in terms of other endpoints (60-day survival, 90-day survival, ICU survival, and hospital survival). In contrast, the duration of mechanical ventilation was increased in vvECMO patients with PP (mean difference 11.4 days [95% CI 9.2–13.5]; 0.64 [95% CI 0.50–0.78]; I² 8%; P < 0.0001).

Conclusion

According to this meta-analysis, survival was improved when prone positioning was used in ARDS patients receiving vvECMO. The impact of this combination on survival should be investigated in prospective randomized controlled trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-021-06604-x.

Estimating the Complier Average Causal Effect in a Meta-Analysis of Randomized Clinical Trials With Binary Outcomes Accounting for Noncompliance: A Generalized Linear Latent and Mixed Model Approach

Noncompliance, a common problem in randomized clinical trials (RCTs), can bias estimation of the effect of treatment receipt using a standard intention-to-treat analysis. The complier average causal effect (CACE) measures the effect of an intervention in the latent subpopulation that would comply with their assigned treatment. Although several methods have been developed to estimate the CACE in analyzing a single RCT, methods for estimating the CACE in a meta-analysis of RCTs with noncompliance await further development. This article reviews the assumptions needed to estimate the CACE in a single RCT and proposes a frequentist alternative for estimating the CACE in a meta-analysis, using a generalized linear latent and mixed model with SAS software (SAS Institute, Inc.). The method accounts for between-study heterogeneity using random effects. We implement the methods and describe an illustrative example of a meta-analysis of 10 RCTs evaluating the effect of receiving epidural analgesia in labor on cesarean delivery, where noncompliance varies dramatically between studies. Simulation studies are used to evaluate the performance of the proposed method.

Metaplot: A new Stata module for assessing heterogeneity in a meta-analysis

Background

The proposed sequential and combinatorial algorithm, suggested as a standard tool for assessing, exploring, and reporting heterogeneity in the meta-analysis, is useful but time-consuming particularly when the number of included studies is large. Metaplot is a novel graphical approach that facilitates performing sensitivity analysis to distinguish the source of substantial heterogeneity across studies with ease and speed.

Method

Metaplot is a Stata module based on Stata’s commands, known informally as "ado". Metaplot presents a two-way (x, y) plot in which the x-axis represents the study codes and the y-axis represents the values of I² statistics excluding one study at a time (n-1 studies). Metaplot also produces a table in the ’Results window’ of the Stata software including details such as I² and χ² statistics and their P-values omitting one study in each turn.

Results

Metaplot allows rapid identification of studies that have a disproportionate impact on heterogeneity across studies, and communicates to what extent omission of that study may reduce the overall heterogeneity based on the I² and χ² statistics. Metaplot has no limitations regarding the number of studies or types of outcome data (binomial or continuous data).

Conclusions

Metaplot is a simple graphical approach that gives a quick and easy identification of the studies having substantial influences on overall heterogeneity at a glance.

Antibacterial agents used in COVID-19: A systematic review and meta-analysis

There have been speculations regarding rise in antimicrobial resistance (AMR) globally owing to indiscriminate antibiotic usage during the COVID-19 pandemic. To curb the menace through decisive policies, it is essential to assess the antibiotics, particularly the antibacterial agents. This systematic review and meta-analysis were performed to assess antibiotic use in COVID-19 patients. A thorough systematic search was undertaken in databases like PubMed, Cochrane library, Google Scholar, World Health Organization (WHO) database and clinicaltrials.gov by two independent reviewers for articles in English published from January 1, 2019 to October 31, 2020. Studies were included if they assessed confirmed COVID-19 cases and mentioned the use of antibiotics. The primary outcome was the proportion of COVID-19 patients subjected to specific antibacterial agents. An attempt to stratify the data based on study settings and disease severity was also performed. Of the total 6012 studies screened, 40 were eligible for qualitative review and 19 for meta-analysis. Specific antibacterial agents were mentioned in 23 studies (57.5%). In the random effect meta-analysis, pooled prevalence of azithromycin use was 24.5% (95% CI 22.9-26.2%) followed by cephalosporins as 26.6% (95% CI 24.9-28.4). None of the studies clearly specified indications for antibiotic use. Ten studies (25%) mentioned empirical use of antibiotics. Bacterial co-infections/secondary infections were documented in four studies with mean prevalence of infection of 1.9% (95% CI 1.2-2.8%). There is lack of data on use of specific antibacterial agents, indications for their use based on severity of infections and microbiological evidence of bacterial co-infections.

Systematic Reviews in Hematopoietic Cell Transplantation and Cellular Therapy: Considerations and Guidance from the American Society for Transplantation and Cellular Therapy, European Society for Blood and Marrow Transplantation, and Center for International Blood and Marrow Transplant Research Late Effects and Quality of Life Working Committee

Systematic reviews apply rigorous methodologies to address a prespecified, clearly formulated clinical research question. The conclusion that results is often cited to more robustly inform decision making by clinicians, third-party payers, and managed care organizations about the clinical question of interest. Although systematic reviews provide a rigorous standard, they may be infeasible when the task is to create general disease-focused guidelines comprising multiple clinical practice questions versus a single major clinical practice question. Collaborating transplantation and cellular therapy society committees also recognize that the quantity and or quality of reference sources may be insufficient for a meaningful systematic review. As the conduct of systematic reviews has evolved over time in terms of grading systems, reporting requirements, and use of technology, here we provide current guidance on methodologies, resources for reviewers, and approaches to overcome challenges in conducting systematic reviews in transplantation and cellular therapy.

Systematic reviews in hematopoietic cell transplantation and cellular therapy: considerations and guidance from the American Society for Transplantation and Cellular Therapy, European Society for Blood and Marrow Transplantation, and the Center for International Blood and Marrow Transplant Research late effects and quality of life working committee

Systematic reviews apply rigorous methodologies to address a pre-specified, clearly formulated clinical research question. The conclusion that results is often cited to more robustly inform decision-making by clinicians, third-party payers and managed care organizations about the clinical question of interest. While systematic reviews provide a rigorous standard, they may be unfeasible when the task is to create general disease-focused guidelines comprised of multiple clinical practice questions versus a single major clinical practice question. Collaborating transplantation and cellular therapy societal committees also recognize that the quantity and or quality of reference sources may be insufficient for a meaningful systematic review. As the conduct of systematic reviews has evolved over time in terms of grading systems, reporting requirements and use of technology, here we provide current guidance in methodologies, resources for reviewers, and approaches to overcome challenges in conducting systematic reviews in transplantation and cellular therapy.

Early oral protein-containing diets following elective lower gastrointestinal tract surgery in adults: a meta-analysis of randomized clinical trials

Background

Although current guidelines make consensus recommendations for the early resumption of oral intake after surgery, a recent comprehensive meta-analysis failed to identify any patient-centered benefits. We hypothesized this finding was attributable to pooling studies providing effective protein-containing diets with ineffective non-protein liquid diets. Therefore, the aim of this paper was to investigate the safety and efficacy of early oral protein-containing diets versus later (traditional) feeding after elective lower gastrointestinal tract surgery in adults.

Methods

PubMed, Embase, and the China National Knowledge Infrastructure databases were searched from inception until 1 August 2019. Reference lists of retrieved studies were hand searched to identify randomized clinical trials reporting mortality. No language restrictions were applied. Study selection, risk of bias appraisal and data abstraction were undertaken independently by two authors. Disagreements were settled by obtaining an opinion of a third author. Majority decisions prevailed. After assessment of underlying assumptions, a fixed-effects method was used for analysis. The primary outcome was mortality. Secondary outcomes included surgical site infections, postoperative nausea and vomiting, serious postoperative complications and other key measures of safety and efficacy.

Results

Eight randomized clinical trials recruiting 657 patients were included. Compared with later (traditional) feeding, commencing an early oral protein-containing diet resulted in a statistically significant reduction in mortality (odds ratio [OR] 0.31, P = 0.02, I² = 0%). An early oral protein-containing diet also significantly reduced surgical site infections (OR 0.39, P = 0.002, I² = 32%), postoperative nausea and vomiting (OR 0.62, P = 0.04, I² = 37%), serious postoperative complications (OR 0.60, P = 0.01, I² = 25%), and significantly improved other major outcomes. No harms attributable to an early oral protein-containing diet were identified.

Conclusions

The results of this systematic review can be used to upgrade current guideline statements to a grade A recommendation supporting an oral protein-containing diet commenced before the end of postoperative day 1 after elective lower gastrointestinal surgery in adults.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13741-021-00179-3.

The Use of Platelet-Rich Plasma for Treatment of Tenodesmic Lesions in Horses: A Systematic Review and Meta-Analysis of Clinical and Experimental Data

The use of platelet-rich plasma (PRP) to enhance tenodesmic lesion healing has been questioned over the years. The aim of this study was to evaluate current literature to establish the effectiveness of PRP for treating tenodesmic lesions through a systematic review, in accordance with the PRISMA guidelines, and a meta-analysis. Studies comparing PRP with placebo or other treatments for horses with tenodesmic injuries or evaluated PRP effect on tendon and ligament explants were included. Outcomes were clinical, ultrasound, histologic, molecular evaluation, and adverse effects. Two authors independently extracted data and assessed each study's risk of bias. Treatment effects were evaluated using risk ratios for dichotomous data, together with 95% CI. Data were pooled using the random-effects model. The quality of the evidence for each outcome was assessed using GRADE criteria. Twenty-four trials met inclusion criteria for systematic review, while fifteen studies were included in the meta-analysis. Results showed no significant differences in the outcomes between PRP and control groups. Finally, there is no definitive evidence that PRP enhances tendons and ligaments healing. Therefore, there is a need for more controlled trials to draw a firmer conclusion about the efficacy of PRP as a treatment for tenodesmic lesions in the horse.

The Relationship between Age-Related Macular Degeneration and Cardiovascular Disease: A Meta-Analysis

Background:

Age-related macular degeneration (AMD) and cardiovascular disease (CVD) share pathogenic mechanisms, and their lead-lag relationship remains unclear. We performed a meta-analysis of data from longitudinal studies to evaluate the interactive association between age-related macular degeneration (AMD) and cardiovascular disease (CVD).

Methods:

A literature search was performed in PubMed, Embase, and Cochrane Library up to Feb 2019. Estimates were pooled by study quality and type of AMD and CVD. Publication bias was assessed by Begg’s test.

Results:

We identified nine studies for the risk of AMD in CVD and ten studies for the risk of CVD in AMD. Overall, evidence for the risk of CVD in AMD patients was most robust. Both early and late AMD preceded CVD, but more solid significance existed in late AMD. Among the types of CVD, stroke was more tightly associated with AMD than coronary heart disease. Publication bias was not significant in either direction.

Conclusion:

AMD is a risk factor for CVD, which is primarily driven by the increased risk of stroke in patients with late AMD. Moreover, these results suggested that AMD treatment and screening for CVD in AMD patients may have unexplored clinical benefits.

Resilience in Familial Caregivers of Children with Developmental Disabilities: A Meta-analysis

The aim of this meta-analysis was to investigate factors associated with resilience in familial caregivers of children with developmental disabilities. The protocol was registered in the PROSPERO database, with the registration number CRD42018105180. Several electronic databases were searched for studies. A random-effects meta-analysis was performed on 26 selected studies that associated resilience to an array of other variables (i.e., psychological distress, social support, coping, perceived health, life satisfaction). Overall, the significant pooled effect sizes were small to medium, ranging from r = 0.291 for coping to r = 0.442 for social support. Although the literature on the topic has improved, there is a lot of study heterogeneity and the need for focusing on male caregivers becomes evident.

A brief introduction of meta-analyses in clinical practice and research

With the explosive growth of medical information, it is almost impossible for healthcare providers to review and evaluate all relevant evidence to make the best clinical decisions. Meta‐analyses, which summarize all existing evidence and quantitatively synthesize individual studies, have become the best available evidence for informing clinical practice. This article introduces the common methods, steps, principles, strengths and limitations of meta‐analyses and aims to help healthcare providers and researchers obtain a basic understanding of meta‐analyses in clinical practice and research.

Neural decoding of continuous upper limb movements: a meta-analysis

OBJECTIVE

EEG-based motion trajectory decoding makes a promising approach for neurotechnology which can be used for neural control of motion reconstruction and neurorehabilitation tools. However, the feasibility and validity of continuous motion decoding by non-invasive brain activity are not clear. The main aim of this study was to perform a meta-analysis across studies that examined the ability of EEG-based continuous motion decoding of upper limb movements.

APPROACH

Pearson's correlation coefficient (CC) was used to evaluate the model performance of the studies and considered as an effect size. To estimate the overall effect size of neural decoding of motion trajectory across studies, characteristics of included studies were addressed and the random effect model was applied to the heterogeneous studies which estimated overall effect size distribution. Furthermore, the significant difference between the two subgroups of imagined and executed movements was analysed.

MAIN RESULTS

The mean of the overall effect size was computed 0.46 across the nonhomogeneous studies. The results showed no significant difference between imagined and executed movements (Chi²=0.28, df = 1, p = 0.60).

SIGNIFICANCE

Meta-analysis results confirm that imagination like execution movements can be used for neural decoding of motion trajectory in neural motor control systems. Also, nonlinear compare with linear model statistically confirmed to be more beneficial for complex movements. Furthermore, a new approach of synergy-based motion decoding can be significantly effective to increase model performance and more research needs to evaluate this method for different levels of complexity of movements.IMPLICATIONS FOR REHABILITATIONNeural decoding methods base on EEG as a non-invasive brain activity, are more user friendly for neurorehabilitation than invasive methods that developing of it makes it more applicable for reconstructing activities of daily living.Neurotechnology for neural control of motion reconstruction, makes the rehabilitation tools to be more synchrony with human intentional movement that can be used to improve the brain neuroplastisity in stroke or other paralysed people.The feasibility and validity of imagined movements equal with executed movements show that amputee people also can benefit EEG-based motion decoding for controling rehabilitation tools just by imagination of their intentional movements.For neurorehabilitation tools, comparing the study outcomes illucidate that the approach of synergy-based motor control in brain activities concluded significantly high performance that highlighted the need it to more investigated in future research.

Association of ACE I/D, -240A > T and AT1R A1166C polymorphisms with susceptibility to breast cancer: a systematic review and meta-analysis based on 35 case-control studies

The objective of this meta-analysis was to estimate the association of ACE I/D, -240 A > T and AT1R 1166 A > C polymorphisms with breast cancer (BC) risk. A comprehensive search on databases was conducted to identify all eligible case-control studies. Finally, 35 case-control studies, including 20 studies for ACE I/D, seven studies for ACE 240 A > T, and eight studies for AT1R 1166 A > C were included. The pooled analysis showed a significant association between ACE I/D polymorphism and BC risk under three genetic models, i.e., heterozygote (ID vs. DD: OR = 0.707, 95% CI 0.528-0.946, p = 0.020), homozygote (II vs. DD: OR = 0.662, 95% CI 0.462-0.947, p = 0.024), and dominant (II + ID vs. DD: OR = 0.691, 95% CI 0.507-0.941, p = 0.019). A significant association was also observed in ACE I/D polymorphism with BC risk among Asians and Caucasians. However, ACE -240 A > T and AT1R 1166 A > C polymorphisms were not associated with BC. Stratified analyses by ethnicity showed a significant association of ACE -240 A > T and AT1R 1166 A > C polymorphisms with BC risk in Latinos populations, but not in Asians. This meta-analysis inconsistence with all previous meta-analyses suggests that the ACE I/D might be associated with BC in overall and by ethnicity. However, the ACE -240 A > T and AT1R 1166 A > C were associated with BC risk only among Latinos populations.

A systematic review of Amblyopia prevalence among the children of the world

Objective: to assess the prevalence of Amblyopia disease in the children of the world. Methods: In order to perform this systematic review, PICO was considered as the research question. Then, the preferred keywords were searched in Medline (via PubMed), Embase, Scopus, Web of Science, and ProQuest databases. The retrieved citations were reviewed by two independent inspectors in a three-step process in terms of the title, abstract, and full-text, based on the inclusion criteria. The studies included in the review were critically evaluated and then were extracted by two dependent expert reviewers. Finally, the prevalence of Amblyopia disease in the children of the world was pooled by meta-analysis CMA v.2 software. The heterogeneity of the selected studies was evaluated using I2 and chi-square. Also, subgroup-analysis was performed using designs and continents. Results: Out of 952 retrieved citations, 131 studies were included. The total prevalence of Amblyopia in the children of the world was calculated to be 4.3% [Pooled Prevalence: 4.3%, 95% CI: 2.6%-7.00%, P-value 0.0001]. In addition, the heterogeneity of the studies was reported to be high (Q: 48281.18, df: 56, p-value 0.001, I-square: 99.88). The subgroup analysis showed that America had the highest (5.57%, 95% CI: 2.23%-13.94%, P-value 0.0001) prevalence, and the lowest prevalence of Amblyopia in the children of the world was seen in Africa (7.1%, 95% CI: 0.003%-172.53%, P-value 0.05). Conclusion: It can be concluded that the total prevalence of Amblyopia is 3.4%, but this estimate varies in all continents, especially in Africa. The major reason for this variation was reported to be the heterogeneity of studies. These assessments have investigated different populations in terms of severity of illness, age, and gender. Therefore, further worldwide high-quality and valid studies should be carried out to allow the calculation of the real prevalence of Amblyopia among children of the world. Abbreviations: VA = visual acuity, ALSPAC = Avon Longitudinal Study of Parents and Children, JBI = Joanna Briggs Institute, PRISMA = Systematic Review and Meta-analysis, CMA = Comprehensive Meta-analysis Software.

Cumulative Evidence for Association Between IL-8 -251T>A and IL-18 -607C>A Polymorphisms and Colorectal Cancer Susceptibility: a Systematic Review and Meta-analysis

PURPOSE

The correlation of IL-8 and IL-18 gene polymorphisms with colorectal cancer (CRC) was investigated by previous studies, though the results remained conflicting. Thus, the meta-analysis was performed to investigate the association of IL-8 -251T>A and IL-18 -607C>A polymorphisms with CRC risk.

METHODS

A comprehensive search of the PubMed, Web of Science, CNKI, SciELO, and Wanfang databases was performed up to February 20, 2020. The strength of the associations was calculated with odds ratios (ORs) and their corresponding 95% of confidence intervals (CIs).

RESULTS

A total of 16 case-control studies including 13 studies with 3908 cases and 5005 controls on IL-8 -251T>A polymorphism and three studies with 396 cases and 560 controls on IL-18 -607C>A polymorphism were selected. Pooled data revealed that the IL-8 -251T>A and IL-18 -607C>A polymorphisms were not significantly associated with an increased risk of CRC in global population. When stratified by ethnicity, source of controls, sample size, and Hardy-Weinberg equilibrium (HWE), there were still no significant association between IL-8 -251T>A polymorphism and risk of CRC.

CONCLUSIONS

Our results revealed that the IL-8 -251T>A and IL-18 -607C>A polymorphisms were not associated with an increased susceptibility to CRC. We strongly call for further studies with larger sample sizes and different ethnicities to confirm our findings.

Bioinorganic supplementation of calcium phosphate-based bone substitutes to improve in vivo performance: a systematic review and meta-analysis of animal studies

Supplementation of CaP-based bone graft substitutes with bioinorganics such as strontium, zinc or silicon is an interesting approach to increase the biological performance in terms of bone regenerative potential of calcium phosphate (CaP)-based bone substitutes. However, the in vivo efficacy of this approach has not been systematically analyzed, yet. Consequently, we performed a systematic review using the available literature regarding the effect of bioinorganic supplementation in CaP-based biomaterials on new bone formation and material degradation in preclinical animal bone defect models and studied this effect quantitatively by performing a meta-analysis. Additional subgroup analyses were used to study the effect of different bioinorganics, animal model, or phase category of CaP-based biomaterial on bone formation or material degradation. Results show that bioinorganic supplementation increases new bone formation (standardized mean difference [SMD]: 1.43 SD, confidence interval [CI]: 1.13-1.73). Additional subgroup analysis showed that strontium, magnesium and silica significantly enhanced bone formation, while zinc did not have any effect. This effect of bioinorganic supplementation on new bone formation was stronger for DCPD or β-TCP and biphasic CaPs than for HA or α-TCP (p < 0.001). In general, material degradation was slightly hindered by bioinorganic supplementation (mean difference [MD]: 0.84%, CI: 0.01-1.66), with the exception of strontium that significantly enhanced degradation. Overall, bioinorganic supplementation represents an effective approach to enhance the biological performance of CaP-based bone substitutes.

Oral non-steroidal anti-inflammatory drugs versus other oral analgesic agents for acute soft tissue injury

BACKGROUND

Acute soft tissue injuries are common and costly. The best drug treatment for such injuries is not certain, although non-steroidal anti-inflammatory drugs (NSAIDs) are often recommended. There is concern about the use of oral opioids for acute pain leading to dependence. This is an update of a Cochrane Review published in 2015.

OBJECTIVES

To assess the benefits or harms of NSAIDs compared with other oral analgesics for treating acute soft tissue injuries.

SEARCH METHODS

We searched the CENTRAL, 2020 Issue 1, MEDLINE (from 1946), and Embase (from 1980) to January 2020; other databases were searched to February 2019.

SELECTION CRITERIA

We included randomised or quasi-randomised controlled trials involving people with acute soft tissue injury (sprain, strain, or contusion of a joint, ligament, tendon, or muscle occurring within 48 hours of inclusion in the study), and comparing oral NSAIDs versus paracetamol (acetaminophen), opioid, paracetamol plus opioid, or complementary and alternative medicine. The outcomes were pain, swelling, function, adverse effects, and early re-injury.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for eligibility, extracted data, and assessed risk of bias. We assessed the quality of the evidence using GRADE methodology.

MAIN RESULTS

We included 20 studies, with 3305 participants. Three studies included children only. The others included predominantly young adults; approximately 60% were male. Seven studies recruited people with ankle sprains only. Most studies were at low or unclear risk of bias; however, two were at high risk of selection bias, three were at high risk of bias from lack of blinding, and five were at high risk of selective outcome reporting bias. Some evidence relating to pain relief was high certainty. Other evidence was either moderate, low or very low certainty, reflecting study limitations, indirectness, imprecision, or combinations of these. Thus, we are certain or moderately certain about some of the estimates, and uncertain or very uncertain of others. Eleven studies, involving 1853 participants compared NSAIDs with paracetamol. There were no differences between the two groups in pain at one to two hours (1178 participants, 6 studies; high-certainty evidence), at days one to three (1232 participants, 6 studies; high-certainty evidence), and at day seven or later (467 participants, 4 studies; low-certainty evidence). There was little difference between the groups in numbers of participants with minimal swelling at day seven or later (77 participants, 1 study; low-certainty evidence). Very low-certainty evidence from three studies (386 participants) means we are uncertain of the finding of little difference between the two groups in return to function at day seven or later. There was low-certainty evidence from 10 studies (1504 participants) that NSAIDs may slightly increase the risk of gastrointestinal adverse events compared with paracetamol. There was low-certainty evidence from nine studies (1679 participants) of little difference in neurological adverse events between the NSAID and paracetamol groups. Six studies, involving 1212 participants compared NSAIDs with opioids. There was moderate-certainty evidence of no difference between the groups in pain at one hour (1058 participants, 4 studies), and low-certainty evidence for no difference in pain at days four or seven (706 participants, 1 study). There was very low-certainty evidence of no important difference between the groups in swelling (84 participants, 1 study). Participants in the NSAIDs group were more likely to return to function in 7 to 10 days (542 participants, 2 studies; low-certainty evidence). There was moderate-certainty evidence (1143 participants, 5 studies) that NSAIDs were less likely to result in gastrointestinal or neurological adverse events compared with opioids. Four studies, involving 240 participants, compared NSAIDs with the combination of paracetamol and an opioid. The applicability of findings from these studies is in question because the dextropropoxyphene combination analgesic agents used are no longer in general use. Very low-certainty evidence means we are uncertain of the findings of no differences between the two interventions in the numbers with little or no pain at day one (51 participants, 1 study), day three (149 participants, 2 studies), or day seven (138 participants, 2 studies); swelling (230 participants, 3 studies); return to function at day seven (89 participants, 1 study); and the risk of gastrointestinal or neurological adverse events (141 participants, 3 studies). No studies reported re-injury rates. No studies compared NSAIDs with oral complementary and alternative medicines, AUTHORS' CONCLUSIONS: Compared with paracetamol, NSAIDs make no difference to pain at one to two hours and at two to three days, and may make no difference at day seven or beyond. NSAIDs may result in a small increase in gastrointestinal adverse events and may make no difference in neurological adverse events compared with paracetamol. Compared with opioids, NSAIDs probably make no difference to pain at one hour, and may make no difference at days four or seven. NSAIDs probably result in fewer gastrointestinal and neurological adverse effects compared with opioids. The very low-certainly evidence for all outcomes for the NSAIDs versus paracetamol with opioid combination analgesics means we are uncertain of the findings of no differences in pain or adverse effects. The current evidence should not be extrapolated to adults older than 65 years, as this group was not well represented in the studies.

Medical cannabis for orthopaedic patients with chronic musculoskeletal pain: does evidence support its use?

The treatment of chronic, non-cancer musculoskeletal pain has become a topic growing interest as it is believed to be one of the reasons for the current opioid epidemic. The medicinal use of cannabis has a long history as a number of active compounds in cannabis have been shown to interact with the body's endocannabinoid system to reduce pain. This position paper provides a history on the evolution of cannabis, the science behind its therapeutic effects, and review of the evidence and current guideline recommendations on its use as a treatment for patients with chronic, non-cancer musculoskeletal pain. Results from systematic reviews have demonstrated a statistically significant reduction in chronic pain conditions with cannabinoids, compared with placebo, although the effects might be considered small and did not reach the minimally important difference. More adverse events were reported in the cannabinoid group than in the placebo group with longer than 2 weeks of treatment. There is a lack of evidence on dependence. With changes to policies, patients' perception has changed to be more positive toward the use of medical cannabis. Current recommendations from North America, Latin America, Europe, Australia and Iran support the use of medical cannabis for chronic, non-cancer pain. Based on the current evidence, it is our position that cannabinoids may be considered as an adjunctive therapy after recommended first- and second-line therapies have failed to provide sufficient efficacy or tolerability. Patients should consider the balance between the desirable and undesirable effects of taking cannabis for chronic pain, and comprehensively consider their own values and preferences, as well as cost-effectiveness factors, based on the information provided by their physician.

Thiazide Diuretic-Induced Change in Fasting Plasma Glucose: a Meta-analysis of Randomized Clinical Trials

BACKGROUND

Prior meta-analyses measuring thiazide-induced glycemic change have demonstrated an increased risk of incident diabetes; however, this measure's definition has changed over time.

AIM

To determine the magnitude of change in fasting plasma glucose (FPG) for thiazide diuretics.

DATA SOURCES

A research librarian designed and conducted searches in Medline®, EMBASE, and EBM Reviews-Cochrane Central Register of Controlled Trials (inception through July 2018) and International Pharmaceutical Abstracts (inception to December 2014).

STUDY SELECTION

Randomized, controlled trials comparing a thiazide or thiazide-like diuretic to any comparator reporting FPG were identified. Trials enrolling < 50 participants, those with a follow-up period of < 4 weeks, and conference abstracts were excluded.

DATA EXTRACTION

Independent duplicate screening of citations and full-text articles, data extraction, and assessment of risk of bias was conducted.

DATA SYNTHESIS

Ninety-five studies were included (N = 76,608 participants), with thiazides compared with placebo, beta-blockers, calcium channel blockers, renin-angiotensin-aldosterone-system inhibitors, potassium-sparing diuretic, and others alone or in combination. Thiazide diuretics marginally increased FPG (weighted mean difference 0.20 mmol/L (95% CI 0.15-0.25); I2 = 84%) (1 mmol/L = 18 mg/dL). Results did not change substantially when considering dose or duration, comparing thiazides with placebo or an active comparator, or using thiazides as monotherapy or combination therapy, even when combined with a potassium-correcting agent.

CONCLUSION

Thiazide diuretics have a small and clinically unimportant impact on FPG.

Association between body mass index and dental caries in the Kingdom of Saudi Arabia: Systematic review

OBJECTIVE

The Kingdom of Saudi Arabia (KSA) has one of the highest prevalence of both obesity and dental caries. To date, there has not been any documented evidence linking these two factors. Therefore, the objective was to conduct a systematic review of published studies that have analysed the association between body mass index and dental caries in the KSA for both children and adults.

METHODS

A systematic database search [PubMed, EMBASE, Web of Science, CINAHL and Cochrane Library] was conducted following the PRISMA guidelines. The inclusion criteria were observational studies, with no limit on the publication date. Search terms included: dental caries, obesity, overweight, body mass index, BMI 'AND' Saudi Arabia. The independent variable was body mass index (BMI), and the primary outcome measure was dental caries prevalence and severity.

RESULTS

From 951 search results, 935 citations were identified and excluded. Of the 16 potentially eligible studies, two citations were excluded, because the studies did not meet the inclusion criteria. This left fourteen studies meeting the criteria to be included in this systematic review. Ten studies outlined children, and four studies assessed adults. For children, two studies resulted in a positive association between high BMI and caries, six studies resulted in a negative association, and two studies had a non-significant association. For adults, two studies resulted in a positive association between high BMI and dental caries, and two studies had a non-significant association. These were rated as having low to moderate risk of bias.

CONCLUSION

As a result of this equivocal outcome within the systematic review, body mass index and dental caries present as a complex association. Further long-term studies are required to translate the findings into clinical practice.

Systematic review and meta-analysis of the provision of preventive care for modifiable chronic disease risk behaviours by mental health services

People with mental illness experience increased chronic disease burden, contributed to by a greater prevalence of modifiable chronic disease risk behaviours. Policies recommend mental health services provide preventive care for such risk behaviours. Provision of such care has not previously been synthesised. This review assessed the provision of preventive care for modifiable chronic disease risk behaviours by mental health services. Four databases were searched from 2006 to 2017. Eligible studies were observational quantitative study designs conducted in mental health services, where preventive care was provided to clients for tobacco smoking, harmful alcohol consumption, inadequate nutrition, or inadequate physical activity. Two reviewers independently screened studies, conducted data extraction and critical appraisal. Results were pooled as proportions of clients receiving or clinicians providing preventive care using random effects meta-analyses, by risk behaviour and preventive care element (ask/assess, advise, assist, arrange). Subgroup analyses were conducted by mental health service type (inpatient, outpatient, other/multiple). Narrative synthesis was used where meta-analysis was not possible. Thirty-eight studies were included with 26 amenable to meta-analyses. Analyses revealed that rates of assessment were highest for smoking (78%, 95% confidence interval [CI]:59%-96%) and lowest for nutrition (17%, 95% CI:1%-35%); with variable rates of care provision for all behaviours, care elements, and across service types, with substantial heterogeneity across analyses. Findings indicated suboptimal and variable provision of preventive care for modifiable chronic disease risk behaviours in mental health services, but should be considered with caution due to the very low quality of cumulative evidence. PROSPERO registration: CRD42016049889.

Accuracy of proton magnetic resonance for diagnosing non-alcoholic steatohepatitis: a meta-analysis

Liver biopsy is the reference standard test to differentiate between non-alcoholic steatohepatitis (NASH) and simple steatosis (SS) in non-alcoholic fatty liver disease (NAFLD), but noninvasive diagnostics are warranted. The diagnostic accuracy in NASH using MR imaging modality have not yet been clearly identified. This study was assessed the accuracy of magnetic resonance imaging (MRI) method for diagnosing NASH. Data were extracted from research articles obtained after a literature search from multiple electronic databases. Random-effects meta-analyses were performed to obtain overall effect size of the area under the receiver operating characteristic(ROC) curve, sensitivity, specificity, likelihood ratios(LR), diagnostic odds ratio(DOR) of MRI method in detecting histopathologically-proven SS(or non-NASH) and NASH. Seven studies were analyzed 485 patients, which included 207 SS and 278 NASH. The pooled sensitivity was 87.4% (95% CI, 76.4–95.3) and specificity was 74.3% (95% CI, 62.4–84.6). Pooled positive LR was 2.59 (95% CI, 1.96–3.42) and negative LR was 0.17 (95% CI, 0.07–0.38). DOR was 21.57 (95% CI, 7.27–63.99). The area under the curve of summary ROC was 0.89. Our meta-analysis shows that the MRI-based diagnostic methods are valuable additions in detecting NASH.

Early Enteral Nutrition Reduces Mortality and Improves Other Key Outcomes in Patients With Major Burn Injury: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

To identify, appraise, and synthesize current evidence to determine whether early enteral nutrition alters patient outcomes from major burn injury.

DATA SOURCES

Medline, Embase, and the China National Knowledge Infrastructure were searched. The close out date was May 1, 2018.

STUDY SELECTION

Early enteral nutrition was defined as a standard formula commenced within 24 hours of injury or admission to ICU or burn unit. Comparators included any form of nutrition support "except" early enteral nutrition. Only randomized controlled trials reporting patient-centered outcomes were eligible for inclusion.

DATA EXTRACTION

The primary outcome was mortality. Gastrointestinal hemorrhage, sepsis, pneumonia, renal failure, and hospital stay were evaluated as secondary outcomes.

DATA SYNTHESIS

Nine-hundred fifty-eight full-text articles were retrieved and screened. Seven randomized controlled trials enrolling 527 participants with major burn injury were included. Compared with all other types of nutrition support, early enteral nutrition significantly reduced mortality (odds ratio, 0.36; 95% CI, 0.18-0.72; p = 0.003; I = 0%). Early enteral nutrition also significantly reduced gastrointestinal hemorrhage (odds ratio, 0.21; 95% CI, 0.09-0.51; p = 0.0005; I = 0%), sepsis (odds ratio, 0.23; 95% CI, 0.11-0.48; p < 0.0001; I = 0%), pneumonia (odds ratio, 0.41; 95% CI, 0.21-0.81; p = 0.01; I = 63%), renal failure (odds ratio, 0.27; 95% CI, 0.09-0.82; p = 0.02; I = 32%), and duration of hospital stay (-15.31 d; 95% CI, -20.43 to -10.20; p < 0.00001; I = 0%).

CONCLUSIONS

The improvements in clinical outcomes demonstrated in this meta-analysis are consistent with the physiologic rationale cited to support clinical recommendations for early enteral nutrition made by major clinical practice guidelines: gut integrity is preserved leading to fewer gastrointestinal hemorrhages, less infectious complications, a reduction in consequent organ failures, and a reduction in the onset of sepsis. The cumulative benefit of these effects improves patient survival and reduces hospital length of stay.

Pharmacoepidemiology: Using randomised control trials and observational studies in clinical decision-making

Weighing up sources of evidence is a key skill for clinical decision-makers. Randomised controlled trials (RCTs) and observational studies each have advantages and disadvantages, and in both cases perceived weaknesses can be improved through modifications of design and analysis. In the field of pharmacoepidemiology, RCTs are the best way to determine whether an intervention modifies an outcome being studied, largely because randomisation reduces bias and confounding. Observational studies are useful to investigate whether benefits/harms of a treatment are seen in day-to-day clinical practice in a wider group of patients. Although observational studies, even in a small cohort, can provide very useful clinical evidence, they may also be misleading (as shown by subsequent RCTs), in part because of allocation bias. There is an unmet need for clinicians to become well versed in appraising the study design and statistical analysis of observational pharmacoepidemiology (OP) studies, rather like the medical training already offered for RCT evaluation. This is because OP studies are likely to become more common with the computerisation of healthcare records and increasingly contribute to the evidence base available for clinical decision-making. However, when the results of an RCT conflict with the results of an OP study, the findings of the RCT should be preferred, especially if its findings have been repeated elsewhere. Conversely, OP studies that align with the findings of RCTs can provide rich and useful information to complement that generated by RCTs.

Concussed athletes walk slower than non-concussed athletes during cognitive-motor dual-task assessments but not during single-task assessments 2 months after sports concussion: a systematic review and meta-analysis using individual participant data

Objectives

To determine whether individuals who sustained a sports concussion would exhibit persistent impairments in gait and quiet standing compared to non-injured controls during a dual-task assessment .

Design

Systematic review and meta-analysis using individual participant data (IPD).

Data sources

The search strategy was applied across seven electronic bibliographic and grey literature databases: MEDLINE, EMBASE, CINAHL, SportDISCUS, PsycINFO, PsycARTICLES and Web of Science, from database inception until June 2017.

Eligibility criteria for study selection

Studies were included if; individuals with a sports concussion and non-injured controls were included as participants; a steady-state walking or static postural balance task was used as the primary motor task; dual-task performance was assessed with the addition of a secondary cognitive task; spatiotemporal, kinematic or kinetic outcome variables were reported, and; included studies comprised an observational study design with case–control matching.

Data extraction and synthesis

Our review is reported in line with the Preferred Reporting Items for Systematic review and Meta-Analyses-IPD Statement. We implemented the Risk of Bias Assessment tool for Non-randomised Studies to undertake an outcome-level risk of bias assessment using a domain-based tool. Study-level data were synthesised in one of three tiers depending on the availability and quality of data: (1) homogeneous IPD; (2) heterogeneous IPD and (3) aggregate data for inclusion in a descriptive synthesis. IPD were aggregated using a ‘one-stage’, random-effects model.

Results

26 studies were included. IPD were available for 20 included studies. Consistently high and unclear risk of bias was identified for selection, detection, attrition, and reporting biases across studies. Individuals with a recent sports concussion walked with slower average walking speed (χ2=51.7; df=4; p<0.001; mean difference=0.06 m/s; 95% CI: 0.004 to 0.11) and greater frontal plane centre of mass displacement (χ2=10.3; df=4; p=0.036; mean difference −0.0039 m; 95% CI: −0.0075 to −0.0004) than controls when evaluated using a dual-task assessment up to 2 months following concussion.

Summary/conclusions

Our IPD evidence synthesis identifies that, when evaluated using a dual-task assessment, individuals who had incurred a sports concussion exhibited impairments in gait that persisted beyond reported standard clinical recovery timelines of 7–10 days. Dual-task assessment (with motion capture) may be a useful clinical assessment to evaluate recovery after sports concussion.

Protocol pre-registration

This systematic review was prospectively registered in PROSPERO CRD42017064861.

The Impact of Psychological Interventions on Posttraumatic Stress Disorder and Pain Symptoms: A Systematic Review and Meta-Analysis

OBJECTIVES

Posttraumatic stress disorder (PTSD) and pain often co-occur, introducing clinical challenges and economic burden. Psychological treatments are considered effective for each condition, yet it is not known which therapies have the potential to concurrently address PTSD and pain-related symptoms.

MATERIALS AND METHODS

To conduct a systematic review and meta-analysis, databases were searched for articles published between January 2007 and December 2017 describing results from clinical trials of interventions addressing PTSD and pain-related symptoms in adults. Two independent reviewers finalized data extraction and risk of bias assessments. A random-effects model was used for meta-analysis and to calculate pooled and subgroup effect sizes (ESs) of psychological-only (single modality) and multimodal interventions.

RESULTS

Eighteen trials (7 uncontrolled, 11 randomized controlled trials, RCTs), totaling 1583 participants, were included in the systematic review. RCT intervention types included exposure-based, cognitive-behavioral, and mindfulness-based therapies. Data from 10 RCTs (N=1, 35) were available for meta-analysis, which demonstrated moderate effect for reduced PTSD severity (ES=-0.55, confidence interval [CI]: -0.83, -0.26) and nonsignificant effect for pain intensity (ES=-0.14, CI: -0.43, 0.15) and pain interference (ES=-0.07, CI: -0.35, 0.20) outcomes. Findings from uncontrolled trials supported meta-analytic results from RCTs. Using GRADE assessment, the quality of evidence was deemed as moderate for RCTs and low for non-RCTs.

DISCUSSION

Findings indicated that the majority of the interventions appeared to have a greater impact on reducing PTSD rather than pain-related symptoms. There remains a need to further develop interventions that consistently impact PTSD and pain-related outcomes when these 2 conditions co-occur.

Efficacy of Chondroitin Sulfate in Patients with Knee Osteoarthritis: A Comprehensive Meta-Analysis Exploring Inconsistencies in Randomized, Placebo-Controlled Trials

INTRODUCTION

There are some controversies about treatment modalities in osteoarthritis (OA), including chondroitin sulfate (CS). The objective of this study was to determine whether CS is effective at alleviating pain and improving function in patients with knee OA and to identify the factors that explain inconsistencies in clinical trial results.

METHODS

We conducted a systematic review of randomized, placebo-controlled trials, searching the databases Medline, Cochrane central register for controlled trials and Scopus. Random effects meta-analysis was then performed, using tau2 and I2 statistics to assess heterogeneity. The pain and Lequesne index (LI) scores were expressed as standardized mean differences (SMDs), with a 95% confidence interval (CI). Heterogeneity was explored by stratifying the analyses according to pre-specified study-level characteristics and assessing the sources of funnel plot asymmetry.

RESULTS

The inclusion criteria yielded 18 trials. Overall, CS significantly but inconsistently reduced pain (SMD: - 0.63; 95% CI: - 0.91, - 0.35; I2 = 94%) and improved function (SMD: - 0.82; 95% CI: - 1.31, - 0.33; I2 = 95%). When limiting the analysis to studies with a low risk of bias, the pharmaceutical grade CS of IBSA origin showed a greater reduction in pain (SMD: - 0.25; 95% CI: - 0.34, - 0.16; I2 = 75%) and function (SMD: - 0.33; 95% CI: - 0.47, - 0.20; I2 = 53%, p = 0.07) compared with the other preparations (SMDPain: - 0.08; 95% CI: - 0.19, + 0.02; I2 = 20%; SMDFunction: - 0.18; 95% CI: - 0.36, +0.01; I2 = 0%). Assessing funnel plot asymmetry in the studies with a low risk of bias, we found strong correlations between the treatment effects and study size (pain: rS = 0.93; LI: rS = 0.86; p < 0.05). Ultimately, there was no residual heterogeneity in the CS effects when the smallest studies were removed from the analyses.

CONCLUSION

This new meta-analysis suggests that CS provides a moderate benefit for pain and has a large effect on function in knee OA, however with large inconsistency. The risks of bias, brand and study size were the factors explaining heterogeneity among the clinical trial results.

Meta-analysis of long-term survival after elective endovascular or open repair of abdominal aortic aneurysm

BACKGROUND

Endovascular aneurysm repair (EVAR) has become the preferred strategy for elective repair of abdominal aortic aneurysm (AAA) for many patients. However, the superiority of the endovascular procedure has recently been challenged by reports of impaired long-term survival in patients who underwent EVAR. A systematic review of long-term survival following AAA repair was therefore undertaken.

METHODS

A systematic review was performed according to PRISMA guidelines. Articles reporting short- and/or long-term mortality of EVAR and open surgical repair (OSR) of AAA were identified. Pooled overall survival estimates (hazard ratios (HRs) with corresponding 95 per cent c.i. for EVAR versus OSR) were calculated using a random-effects model. Possible confounding owing to age differences between patients receiving EVAR or OSR was addressed by estimating relative survival.

RESULTS

Some 53 studies were identified. The 30-day mortality rate was lower for EVAR compared with OSR: 1·16 (95 per cent c.i. 0·92 to 1·39) versus 3·27 (2·71 to 3·83) per cent. Long-term survival rates were similar for EVAR versus OSR (HRs 1·01, 1·00 and 0·98 for 3, 5 and 10 years respectively; P = 0·721, P = 0·912 and P = 0·777). Correction of age inequality by means of relative survival analysis showed equal long-term survival: 0·94, 0·91 and 0·76 at 3, 5 and 10 years for EVAR, and 0·96, 0·91 and 0·76 respectively for OSR.

CONCLUSION

Long-term overall survival rates were similar for EVAR and OSR. Available data do not allow extension beyond the 10-year survival window or analysis of specific subgroups.

Primary versus secondary source of data in observational studies and heterogeneity in meta-analyses of drug effects: a survey of major medical journals

Background

The data from individual observational studies included in meta-analyses of drug effects are collected either from ad hoc methods (i.e. “primary data”) or databases that were established for non-research purposes (i.e. “secondary data”). The use of secondary sources may be prone to measurement bias and confounding due to over-the-counter and out-of-pocket drug consumption, or non-adherence to treatment. In fact, it has been noted that failing to consider the origin of the data as a potential cause of heterogeneity may change the conclusions of a meta-analysis. We aimed to assess to what extent the origin of data is explored as a source of heterogeneity in meta-analyses of observational studies.

Methods

We searched for meta-analyses of drugs effects published between 2012 and 2018 in general and internal medicine journals with an impact factor > 15. We evaluated, when reported, the type of data source (primary vs secondary) used in the individual observational studies included in each meta-analysis, and the exposure- and outcome-related variables included in sensitivity, subgroup or meta-regression analyses.

Results

We found 217 articles, 23 of which fulfilled our eligibility criteria. Eight meta-analyses (8/23, 34.8%) reported the source of data. Three meta-analyses (3/23, 13.0%) included the method of outcome assessment as a variable in the analysis of heterogeneity, and only one compared and discussed the results considering the different sources of data (primary vs secondary).

Conclusions

In meta-analyses of drug effects published in seven high impact general medicine journals, the origin of the data, either primary or secondary, is underexplored as a source of heterogeneity.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0561-3) contains supplementary material, which is available to authorized users.