We performed a systematic review to assess whether we can quantify the underreporting of adverse events (AEs) in the published medical literature documenting the results of clinical trials as ...compared with other nonpublished sources, and whether we can measure the impact this underreporting has on systematic reviews of adverse events.
Studies were identified from 15 databases (including MEDLINE and Embase) and by handsearching, reference checking, internet searches, and contacting experts. The last database searches were conducted in July 2016. There were 28 methodological evaluations that met the inclusion criteria. Of these, 9 studies compared the proportion of trials reporting adverse events by publication status. The median percentage of published documents with adverse events information was 46% compared to 95% in the corresponding unpublished documents. There was a similar pattern with unmatched studies, for which 43% of published studies contained adverse events information compared to 83% of unpublished studies. A total of 11 studies compared the numbers of adverse events in matched published and unpublished documents. The percentage of adverse events that would have been missed had each analysis relied only on the published versions varied between 43% and 100%, with a median of 64%. Within these 11 studies, 24 comparisons of named adverse events such as death, suicide, or respiratory adverse events were undertaken. In 18 of the 24 comparisons, the number of named adverse events was higher in unpublished than published documents. Additionally, 2 other studies demonstrated that there are substantially more types of adverse events reported in matched unpublished than published documents. There were 20 meta-analyses that reported the odds ratios (ORs) and/or risk ratios (RRs) for adverse events with and without unpublished data. Inclusion of unpublished data increased the precision of the pooled estimates (narrower 95% confidence intervals) in 15 of the 20 pooled analyses, but did not markedly change the direction or statistical significance of the risk in most cases. The main limitations of this review are that the included case examples represent only a small number amongst thousands of meta-analyses of harms and that the included studies may suffer from publication bias, whereby substantial differences between published and unpublished data are more likely to be published.
There is strong evidence that much of the information on adverse events remains unpublished and that the number and range of adverse events is higher in unpublished than in published versions of the same study. The inclusion of unpublished data can also reduce the imprecision of pooled effect estimates during meta-analysis of adverse events.
There is considerable debate as to the relative merits of using randomised controlled trial (RCT) data as opposed to observational data in systematic reviews of adverse effects. This meta-analysis of ...meta-analyses aimed to assess the level of agreement or disagreement in the estimates of harm derived from meta-analysis of RCTs as compared to meta-analysis of observational studies.
Searches were carried out in ten databases in addition to reference checking, contacting experts, citation searches, and hand-searching key journals, conference proceedings, and Web sites. Studies were included where a pooled relative measure of an adverse effect (odds ratio or risk ratio) from RCTs could be directly compared, using the ratio of odds ratios, with the pooled estimate for the same adverse effect arising from observational studies. Nineteen studies, yielding 58 meta-analyses, were identified for inclusion. The pooled ratio of odds ratios of RCTs compared to observational studies was estimated to be 1.03 (95% confidence interval 0.93-1.15). There was less discrepancy with larger studies. The symmetric funnel plot suggests that there is no consistent difference between risk estimates from meta-analysis of RCT data and those from meta-analysis of observational studies. In almost all instances, the estimates of harm from meta-analyses of the different study designs had 95% confidence intervals that overlapped (54/58, 93%). In terms of statistical significance, in nearly two-thirds (37/58, 64%), the results agreed (both studies showing a significant increase or significant decrease or both showing no significant difference). In only one meta-analysis about one adverse effect was there opposing statistical significance.
Empirical evidence from this overview indicates that there is no difference on average in the risk estimate of adverse effects of an intervention derived from meta-analyses of RCTs and meta-analyses of observational studies. This suggests that systematic reviews of adverse effects should not be restricted to specific study types. Please see later in the article for the Editors' Summary.
AbstractObjectivesTo estimate the association between the duration and level of exposure to different classes of anticholinergic drugs and subsequent incident dementia.DesignCase-control ...study.SettingGeneral practices in the UK contributing to the Clinical Practice Research Datalink.Participants40 770 patients aged 65-99 with a diagnosis of dementia between April 2006 and July 2015, and 283 933 controls without dementia.InterventionsDaily defined doses of anticholinergic drugs coded using the Anticholinergic Cognitive Burden (ACB) scale, in total and grouped by subclass, prescribed 4-20 years before a diagnosis of dementia.Main outcome measuresOdds ratios for incident dementia, adjusted for a range of demographic and health related covariates.Results14 453 (35%) cases and 86 403 (30%) controls were prescribed at least one anticholinergic drug with an ACB score of 3 (definite anticholinergic activity) during the exposure period. The adjusted odds ratio for any anticholinergic drug with an ACB score of 3 was 1.11 (95% confidence interval 1.08 to 1.14). Dementia was associated with an increasing average ACB score. When considered by drug class, gastrointestinal drugs with an ACB score of 3 were not distinctively linked to dementia. The risk of dementia increased with greater exposure for antidepressant, urological, and antiparkinson drugs with an ACB score of 3. This result was also observed for exposure 15-20 years before a diagnosis.ConclusionsA robust association between some classes of anticholinergic drugs and future dementia incidence was observed. This could be caused by a class specific effect, or by drugs being used for very early symptoms of dementia. Future research should examine anticholinergic drug classes as opposed to anticholinergic effects intrinsically or summing scales for anticholinergic exposure.Trial registrationRegistered to the European Union electronic Register of Post-Authorisation Studies EUPAS8705.
Randomized controlled trials are the principal means of establishing the efficacy of drugs. However pre-marketing trials are limited in size and duration and exclude high-risk populations. They have ...limited statistical power to detect rare but potentially serious adverse events in real-world patients. We summarize the principal methodological challenges in the reporting, analysis and interpretation of safety data in clinical trials using recent examples from systematic reviews. These challenges include the lack of an evidentiary gold standard, the limited statistical power of randomized controlled trials and resulting type 2 error, the lack of adequate ascertainment of adverse events and limited generalizability of trials that exclude high risk patients. We discuss potential solutions to these challenges. Evaluation of drug safety requires careful examination of data from heterogeneous sources. Meta-analyses of drug safety should include appropriate statistical methods and assess the optimal information size to avoid type 2 errors. They should evaluate outcome reporting biases and missing data to ensure reliable and accurate interpretation of findings. Regulatory and academic partnerships should be fostered to provide an independent and transparent evaluation of drug safety.
Aim
The aim of this review was to summarize the prevalence, frequency and comparative value of information on the adverse events of healthcare interventions from user comments and videos in social ...media.
Methods
A systematic review of assessments of the prevalence or type of information on adverse events in social media was undertaken. Sixteen databases and two internet search engines were searched in addition to handsearching, reference checking and contacting experts. The results were sifted independently by two researchers. Data extraction and quality assessment were carried out by one researcher and checked by a second. The quality assessment tool was devised in‐house and a narrative synthesis of the results followed.
Results
From 3064 records, 51 studies met the inclusion criteria. The studies assessed over 174 social media sites with discussion forums (71%) being the most popular. The overall prevalence of adverse events reports in social media varied from 0.2% to 8% of posts.
Twenty‐nine studies compared the results from searching social media with using other data sources to identify adverse events. There was general agreement that a higher frequency of adverse events was found in social media and that this was particularly true for ‘symptom’ related and ‘mild’ adverse events.
Those adverse events that were under‐represented in social media were laboratory‐based and serious adverse events.
Conclusions
Reports of adverse events are identifiable within social media. However, there is considerable heterogeneity in the frequency and type of events reported, and the reliability or validity of the data has not been thoroughly evaluated.
We conducted a meta-analysis of serious adverse events (dementia, macro- and micro-vascular events, falls and fractures, and death) associated with hypoglycemia in older patients treated with glucose ...lowering drugs.
Meta-analysis of studies reporting on hypoglycemia and adverse events. The search included studies from two previously published systematic reviews, and an updated search of MEDLINE and EMBASE from April 2014 to November 2019. We assessed study validity based on ascertainment of hypoglycemia, adverse events and adjustment for confounders, and conducted a random effects meta-analyses, assessing heterogeneity using the I
statistic.
We included 44 studies involving 2,507,434 participants. Most of the studies used adjusted analysis for confounders and hypoglycaemic events were typically identified based on healthcare databases (severe events). Hypoglycemia was associated with increased likelihood of death in a meta-analysis of eighteen studies, pooled OR 2.02 (95% Confidence Interval 1.75-2.32). Studies assessing mortality signal a time-response relationship with a higher risk of adverse events occurring within the first 90 days after hypoglycemia. Our meta-analysis of nine studies demonstrated that hypoglycaemic episodes were associated with dementia - pooled OR 1.50 (95% CI 1.29-1.74). Our meta-analysis of nineteen studies demonstrated associations between hypoglycaemia and macrovascular complications, pooled OR 1.81 (95% CI 1.70-1.94), and microvascular complications (two studies) pooled OR 1.77 (95% CI 1.49-2.10). There is also an association between hypoglycemia and cardiovascular death (six studies) - pooled OR 2.11 (95% CI 1.55 to 2.87). Similarly, our meta-analysis of six studies demonstrated an association between hypoglycemia and falls and fractures, pooled OR 1.78 (95% CI 1.44-2.21) and 1.68 (95% CI 1.37-2.07) respectively.
This meta-analysis confirms previously reported concerns of serious harm following hypoglycemia, especially in the immediate time period after a hypoglycaemic event. Avoidance of hypoglycaemic episodes should be a priority in this vulnerable population.
BackgroundThe effect of inhaled corticosteroids (ICS) on fracture risk in patients with chronic obstructive pulmonary disease (COPD) remains uncertain. The aim of this study was to evaluate the ...association between ICS and fractures in COPD.MethodsMEDLINE, EMBASE, regulatory documents and company registries were searched up to August 2010. Randomised controlled trials (RCTs) of budesonide or fluticasone versus control treatment for COPD (≥24 weeks duration) and controlled observational studies reporting on fracture risk with ICS exposure vs no exposure in COPD were included. Peto OR meta-analysis was used for fracture risk from RCTs while ORs from observational studies were pooled using the fixed effect inverse variance method. Dose–response analysis was conducted using variance-weighted least squares regression in the observational studies. Heterogeneity was assessed using the I2 statistic.ResultsSixteen RCTs (14 fluticasone, 2 budesonide) with 17 513 participants, and seven observational studies (n=69 000 participants) were included in the meta-analysis. ICSs were associated with a significantly increased risk of fractures (Peto OR 1.27; 95% CI 1.01 to 1.58; p=0.04; I2=0%) in the RCTs. In the observational studies, ICS exposure was associated with a significantly increased risk of fractures (OR 1.21; 95% CI 1.12 to 1.32; p<0.001; I2=37%), with each 500 μg increase in beclomethasone dose equivalents associated with a 9% increased risk of fractures, OR 1.09 (95% CI 1.06 to 1.12; p<0.001).ConclusionAmong patients with COPD, long-term exposure to fluticasone and budesonide is consistently associated with a modest but statistically significant increased likelihood of fractures.
CONTEXT Recent reports of serious adverse events with rosiglitazone use have raised questions about whether the evidence of harm justifies its use for treatment of type 2 diabetes. OBJECTIVE To ...systematically review the long-term cardiovascular risks of rosiglitazone, including myocardial infarction, heart failure, and cardiovascular mortality. DATA SOURCES We searched MEDLINE, the GlaxoSmithKline clinical trials register, the US Food and Drug Administration Web site, and product information sheets for randomized controlled trials, systematic reviews, and meta-analyses published in English through May 2007. STUDY SELECTION Studies were selected for inclusion if they were randomized controlled trials of rosiglitazone for prevention or treatment of type 2 diabetes, had at least 12 months of follow-up, and monitored cardiovascular adverse events and provided numerical data on all adverse events. Four studies were included after detailed screening of 140 trials for cardiovascular events. DATA EXTRACTION Relative risks (RRs) of myocardial infarction, heart failure, and cardiovascular mortality were estimated using a fixed-effects meta-analysis of 4 randomized controlled trials (n = 14 291, including 6421 receiving rosiglitazone and 7870 receiving control therapy, with a duration of follow-up of 1-4 years). RESULTS Rosiglitazone significantly increased the risk of myocardial infarction (n = 94/6421 vs 83/7870; RR, 1.42; 95% confidence interval CI, 1.06-1.91; P = .02) and heart failure (n = 102/6421 vs 62/7870; RR, 2.09; 95% CI, 1.52-2.88; P < .001) without a significant increase in risk of cardiovascular mortality (n = 59/6421 vs 72/7870; RR, 0.90; 95% CI, 0.63-1.26; P = .53). There was no evidence of substantial heterogeneity among the trials for these end points (I2 = 0% for myocardial infarction, 18% for heart failure, and 0% for cardiovascular mortality). CONCLUSION Among patients with impaired glucose tolerance or type 2 diabetes, rosiglitazone use for at least 12 months is associated with a significantly increased risk of myocardial infarction and heart failure, without a significantly increased risk of cardiovascular mortality.
CONTEXT Inhaled anticholinergics (ipratropium bromide or tiotropium bromide) are widely used in patients with chronic obstructive pulmonary disease (COPD) but their effect on the risk of ...cardiovascular outcomes is unknown. OBJECTIVE To ascertain the cardiovascular risks of inhaled anticholinergics, including cardiovascular death, myocardial infarction (MI), and stroke. DATA SOURCES Systematic searches were conducted on March 19, 2008, of relevant articles in MEDLINE, the Cochrane Database of systematic reviews, regulatory authority Web sites in the United States and the United Kingdom, and manufacturers' trial registries with no date restrictions. STUDY SELECTION Randomized controlled trials of any inhaled anticholinergic for treatment of COPD that had at least 30 days of treatment and reported on cardiovascular events. DATA EXTRACTION The primary outcome was a composite of cardiovascular death, MI, or stroke. The secondary outcome was all-cause mortality. Relative risks (RRs) were estimated using fixed-effects models and statistical heterogeneity was estimated with the I2 statistic. DATA SYNTHESIS After a detailed screening of 103 articles, 17 trials enrolling 14 783 patients were analyzed. Follow-up duration ranged from 6 weeks to 5 years. Cardiovascular death, MI, or stroke occurred in 135 of 7472 patients (1.8%) receiving inhaled anticholinergics and 86 of 7311 patients (1.2%) receiving control therapy (RR, 1.58 95% confidence interval {CI}, 1.21-2.06; P < .001, I2 = 0%). Among individual components of the primary end point, inhaled anticholinergics significantly increased the risk of MI (RR, 1.53 95% CI 1.05-2.23; P = .03, I2 = 0%) and cardiovascular death (RR, 1.80 95% CI, 1.17-2.77; P = .008, I2 = 0%) without a statistically significant increase in the risk of stroke (RR, 1.46 95% CI, 0.81-2.62; P = .20, I2 = 0%). All-cause mortality was reported in 149 of the patients treated with inhaled anticholinergics (2.0%) and 115 of the control patients (1.6%) (RR, 1.26 95% CI, 0.99-1.61; P = .06, I2 = 2%). A sensitivity analysis restricted to 5 long-term trials (>6 months) confirmed the significantly increased risk of cardiovascular death, MI, or stroke (2.9% of patients treated with anticholinergics vs 1.8% of the control patients; RR, 1.73 95%CI, 1.27-2.36; P < .001, I2 = 0%). CONCLUSION Inhaled anticholinergics are associated with a significantly increased risk of cardiovascular death, MI, or stroke among patients with COPD.
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