Assessing heterogeneity in meta-analysis: Q statistic or I2 index?

In meta-analysis, the usual way of assessing whether a set of single studies is homogeneous is by means of the Q test. However, the Q test only informs meta-analysts about the presence versus the absence of heterogeneity, but it does not report on the extent of such heterogeneity. Recently, the I² index has been proposed to quantify the degree of heterogeneity in a meta-analysis. In this article, the performances of the Q test and the confidence interval around the I² index are compared by means of a Monte Carlo simulation. The results show the utility of the I² index as a complement to the Q test, although it has the same problems of power with a small number of studies

Quantitative systematic review of the associations between short-term exposure to nitrogen dioxide and mortality and hospital admissions.

BACKGROUND: Short-term exposure to NO₂ has been associated with adverse health effects and there is increasing concern that NO₂ is causally related to health effects, not merely a marker of traffic-generated pollution. No comprehensive meta-analysis of the time-series evidence on NO₂ has been published since 2007. OBJECTIVE: To quantitatively assess the evidence from epidemiological time-series studies published worldwide to determine whether and to what extent short-term exposure to NO₂ is associated with increased numbers of daily deaths and hospital admissions. DESIGN: We conducted a quantitative systematic review of 204 time-series studies of NO₂ and daily mortality and hospital admissions for several diagnoses and ages, which were indexed in three bibliographic databases up to May 2011. We calculated random-effects estimates by different geographic regions and globally, and also tested for heterogeneity and small study bias. RESULTS: Sufficient estimates for meta-analysis were available for 43 cause-specific and age-specific combinations of mortality or hospital admissions (25 for 24 h NO₂ and 18 of the same combinations for 1 h measures). For the all-age group, a 10 µg/m(3) increase in 24 h NO₂ was associated with increases in all-cause, cardiovascular and respiratory mortality (0.71% (95% CI 0.43% to 1.00%), 0.88% (0.63% to 1.13%) and 1.09% (0.75% to 1.42%), respectively), and with hospital admissions for respiratory (0.57% (0.33% to 0.82%)) and cardiovascular (0.66% (0.32% to 1.01%)) diseases. Evidence of heterogeneity between geographical region-specific estimates was identified in more than half of the combinations analysed. CONCLUSIONS: Our review provides clear evidence of health effects associated with short-term exposure to NO₂ although further work is required to understand reasons for the regional heterogeneity observed. The growing literature, incorporating large multicentre studies and new evidence from less well-studied regions of the world, supports further quantitative review to assess the independence of NO₂ health effects from other air pollutants

How effective are Z-drug hypnotics for treatment of adult insomnia? Meta-analysis of data submitted to the Food and Drug Administration

The Problem: Z-drugs are the most commonly prescribed hypnotics worldwide. They are widely prescribed because general practitioners and patients believe that they are effective and superior to older hypnotics. Previous meta-analyses of Z-drugs suffer from publication or reporting bias and did not adequately examine study heterogeneity. We wanted to investigate the effectiveness of Z-drugs in adults using a data source that was less likely to be affected by publication bias. The approach: We examined clinical trials of currently approved Z-drugs submitted to the Food and Drug Administration (FDA) since pharmaceutical companies are required to provide information on all sponsored trials, whether published or not, when applying for new drug approvals. We included randomized double blind placebo controlled trials and excluded studies with a crossover design, those including healthy patients with normal sleep or single night studies with induced insomnia. We analysed drug efficacy as change score from baseline to posttest for drug and placebo groups, and the difference of both change scores for available outcomes. Weighted raw and standardized mean differences with their confidence intervals (CIs) under random-effects assumptions were calculated for polysomnographic (PSG) and subjective outcomes: wake after sleep onset, sleep latency, number of awakenings, total sleep time, sleep efficiency, subjective sleep quality, and morning sleepiness score. We performed weighted regression moderator analysis to explain heterogeneity of drug effects. Findings: We included 16 studies comprising 4973 subjects from different countries, varying drug dosages, treatment lengths and study years. Z-drugs showed significant but small improvements (reductions) only in PSG (d+ = -0.36, 95% CI = -0.57 to -0.16) and subjective sleep latency (d+ = -0.33, 95% CI = -0.62 to -0.041) compared with placebo. Analyses of weighted mean raw differences indicated that drugs decreased sleep latency by only 22 minutes (95% CI = -33 TO -11) with no evidence of change in other measures. Moderator analyses indicated that sleep latency was more likely to be reduced with larger drug doses, studies published earlier, including higher proportions of younger or women patients, and of longer treatment duration. Consequences: This study of FDA data shows that, despite being commonly prescribed, Z-drugs have limited benefit with small reductions in subjective and PSG sleep latency especially with larger dosages, but no improvement in other sleep measures compared to placebo. Placebo effects were moderate for sleep latency. Doctors and patients need to be aware of the relative benefits as well as harms of hypnotic drugs when deciding to use them in preference to psychological treatments

Prevalence, impact and treatment of generalised anxiety disorder in bipolar disorder : A systematic review and meta-analysis

Publisher Copyright: © 2016, BMJ Publishing Group. All rights reserved.Question Recent data suggest that anxiety disorders are as often comorbid with bipolar disorder (BD) as with unipolar depression; however, less attention has been paid to comorbidity of anxiety disorders with BD. Generalised anxiety disorder (GAD) is one of the most prevalent anxiety disorders that is highly comorbid with other mental disorders. We carried out a systematic review and meta-analysis to assess the degree of comorbidity between GAD and BD. Study selection and analysis We searched for all studies, which included primary data concerning the existence of GAD in patients with BD. The literature search strategy, selection of publications and the reporting of results have been conducted with PRISMA guidelines. The meta-analysis calculated prevalence estimates using the variance-stabilising Freeman-Tukey double arcsine transformation. We applied the inverse variance method using both fixed-effects and random-effects models to estimate summary effects for all combined studies. Heterogeneity was assessed and measured with Cochran’s Q and I2 statistics, respectively. Findings The current meta-analysis analysed data from 28 independent studies and a total of 2975 patients from point prevalence studies and 4919 patients from lifetime studies. The overall random-effects point prevalence of GAD in patients with BD was 12.2% (95% CI 10.9% to 13.5%) and the overall random-effects lifetime estimate was 15.1% (95% CI 9.7% to 21.5%). Both estimates reported significant heterogeneity (94.0% and 94.7%, respectively). Conclusions Published studies report prevalence rates with high heterogeneity and consistently higher than those typically reported in the general population. It is believed that comorbid GAD might be associated with a more severe BD course and increased suicidality, and it is unknown how best to treat such conditions. The current meta-analysis confirms that GAD is highly prevalent in BD and the rate is higher in comparison to those in the general population.publishersversionPeer reviewe

Analysis of the Diferential Efcacy of the Reduced Version Over the Extended Version of an Afective‑Sexual Education Program for Adults with Intellectual Disabilities

Recently, with the increase in demand, multiple intervention proposals aimed at improving the sexual health of people with intellectual disabilities have emerged. Among them is the SALUDIVERSEX program, which takes a positive approach to sexuality. It has an extended version, consisting of 16 sessions and whose efcacy has already been proven, and a reduced version of 10 sessions. Thus, the present study aimed to test the diferential efcacy of the two versions. A total of 208 participants (103 women and 105 men) aged between 19 and 67 years (M=37.23, SD=10.66) completed a battery of instruments before and after the intervention. Statistical analyses showed that users who participated in the reduced version of the program presented a signifcantly higher rate of improvement in their sexual behaviors compared to those who participated in the extended version (Sexual response: β10=− 0.46±0.19, p=.034; Sex practices: β10=− 0.52±0.23, p=.037; Use condoms: β10=− 1.56±0.59, p=.017), as well as a signifcantly higher decrease in the risk of sufering sexual abuse (β10=3.95±0.64, p<.001). However, no statistically signifcant diferences in sexuality knowledge were obtained with respect to the improvement between the two versions (β10=− 0.09±1.21, p=.94). Meanwhile, the professionals who applied the program found that those who participated in the reduced version, although they presented a signifcantly greater increase in their knowledge about privacy (β10=− 0.48±0.08, p<.001), did not improve their concerns about their inappropriate sexual behaviors as much as the users of the extended version (β10=− 1.35±0.21, p<.001). Thus, although both versions were efective, the reduced version seems to do so to a greater extent and in a shorter time, which makes it the more recommendable option

A Multilevel Model to Assess the Effectiveness of an Affective-Sexual Education Program for People with Intellectual Disabilities: the Influence of Participants’ Characteristics

Introduction Personal characteristics have been shown to influence the psychosexual development of people with intellectual disabilities. This study aims to evaluate the effectiveness of the SALUDIVERSEX program about affective-sexual education depending on gender, age, relationship status, and degree of autonomy. Methods Two hundred fifty-four participants, clustered within 28 daytime support services, completed a battery of instru- ments before and after the intervention. The data was collected between January 2021 and April 2022. Results Multilevel analyses, controlling for participant’s dependence within the same center, confirm that the program is equally effective regardless of gender. Likewise, younger participants, who have greater autonomy and who have a partner, seem to benefit more from the intervention. Conclusions This suggests that the SALUDIVERSEX program is a useful tool for educating adults with intellectual dis- abilities on sexuality, when they possess a high degree of autonomy. Policy Implications The present study contributes to the successful replication of the intervention being tested, providing information on the aspects that may be more difficult to learn depending on the personal characteristics of the individuals

Initial Severity and Antidepressant Benefits: A Meta-Analysis of Data Submitted to the Food and Drug Administration

Kirsch and colleagues show that, in antidepressant trials, there is a greater difference in efficacy between drug and placebo amongst more severely depressed patients. However, this difference seems to result from a poorer response to placebo amongst more depressed patients

Primary care hypnotic and anxiolytic prescription:Reviewing prescribing practice over 8 years

Introduction: Over the last few years, hypnotic and anxiolytic medications have had their clinical efficacy questioned in the context of concerns regarding dependence, tolerance alongside other adverse effects. It remains unclear how these concerns have impacted clinical prescribing practice. Materials and Methods: This is a study reviewing community-dispensed prescribing data for patients on the East Practice Medical Center list in Arbroath, Scotland, in 2007, 2011 and 2015. Anxiolytic and hypnotic medications were defined in accordance with the British National Formulary chapter 4.1.1 and chapter 4.1.2. All patients receiving a drug within this class in any of the study years were collated and anonymized using primary care prescribing data. The patients′ age, gender, name of the prescribed drug(s), and total number of prescriptions in this class over the year were extracted. Results: The proportion of patients prescribed a benzodiazepine medication decreased between 2007 and 2015: 83.8% (n = 109) in 2007, 70.5% (n = 122) in 2011, and 51.7% (n = 138) in 2015 (P = 0.006). The proportion of these patients prescribed a nonbenzodiazepine drug increased between 2007 and 2015: 30% (n = 39) in 2007, 46.2% (n = 80) in 2011, and 52.4% (n = 140) in 2015 (P = 0.001). There was a significant increase in the number of patients prescribed melatonin (P = 0.020). Discussion: This study reports a reduction in benzodiazepine prescriptions in primary care alongside increases in nonbenzodiazepine and melatonin prescribing, with an increase in prescribing rates of this drug class overall. Conclusion: Changes in this prescribing practice may reflect the medicalization of insomnia, local changes in prescribing practice and alongside national recommendations

An analysis of early insulin glargine added to metformin with or without sulfonylurea: impact on glycaemic control and hypoglycaemia

Aim: To evaluate the benefits of initiating insulin at an earlier versus later treatment stage, and regimens with/without sulfonylurea (SU)