Observational studies: going beyond the boundaries of randomized controlled trials

2010 ◽  
Vol 88 ◽  
pp. S3-S9 ◽  
Author(s):  
Wenying Yang ◽  
Alexey Zilov ◽  
Pradana Soewondo ◽  
Ole Molskov Bech ◽  
Fawzia Sekkal ◽  
...  
Keyword(s):  
Randomized Controlled Trials ◽  
Observational Studies ◽  
Controlled Trials ◽  
Randomized Controlled

scholarly journals High-cited favorable studies for COVID-19 treatments ineffective in large trials

2022 ◽  
Author(s):  
John P.A. Ioannidis
Keyword(s):  
Clinical Trials ◽  
Randomized Controlled Trials ◽  
Clinical Studies ◽  
Observational Studies ◽  
Randomized Trials ◽  
Controlled Trials ◽  
Randomized Controlled ◽  
Wide Dissemination ◽  
Highly Cited Articles ◽  
Highly Cited

Importance. COVID-19 has resulted in massive production, publication and wide dissemination of clinical studies trying to identify effective treatments. However, several widely touted treatments failed to show effectiveness in large well-done randomized controlled trials (RCTs). Objective. To evaluate for COVID-19 treatments that showed no benefits in subsequent large RCTs how many of their most-cited clinical studies had declared favorable results for these interventions. Methods. Scopus (last update December 23, 2021) identified articles on lopinavir-ritonavir, hydroxycholoroquine/azithromycin, remdesivir, convalescent plasma, colchicine or interferon (index interventions) that represented clinical trials and that had received >150 citations. Their conclusions were assessed and correlated with study design features. The ten most recent citations for the most-cited article on each index intervention were examined on whether they were critical to the highly-cited study. Altmetric scores were also obtained. Findings. 40 articles of clinical studies on these index interventions had received >150 citations (7 exceeded 1,000 citations). 20/40 (50%) had favorable conclusions and 4 were equivocal. Highly-cited articles with favorable conclusions were rarely RCTs while those without favorable conclusions were mostly RCTs (3/20 vs 15/20, p=0.0003). Only 1 RCT with favorable conclusions had sample size >160. Citation counts correlated strongly with Altmetric scores, in particular news items. Only 9 (15%) of 60 recent citations to the most highly-cited studies with favorable or equivocal conclusions were critical to the highly-cited study. Conclusion. Many clinical studies with favorable conclusions for largely ineffective COVID-19 treatments are uncritically heavily cited and disseminated. Early observational studies and small randomized trials may cause spurious claims of effectiveness that get perpetuated.

scholarly journals Impact of Ramadan Diurnal Intermittent Fasting on Hypoglycemic Events in Patients With Type 2 Diabetes: A Systematic Review of Randomized Controlled Trials and Observational Studies

2021 ◽  
Vol 12 ◽  
Author(s):  
Dana Abdelrahim ◽  
MoezAlIslam E. Faris ◽  
Mohamed Hassanein ◽  
Ayman Z. Shakir ◽  
Ayesha M. Yusuf ◽  
...  
Keyword(s):  
Systematic Review ◽  
Type 2 Diabetes ◽  
Randomized Controlled Trials ◽  
Observational Studies ◽  
Dietary Behaviors ◽  
Controlled Trials ◽  
Ramadan Fasting ◽  
Randomized Controlled ◽  
The Impact

Ramadan is the 9th month of the lunar calendar during which Muslims abstain from food and drink between dawn and sunset for 30 consecutive days. Ramadan fasting is observed by all healthy Muslim adults, as well many Muslims with type 2 diabetes (T2DM). Hypoglycemic events (HE) are a serious complication associated with diabetes management and are associated with increased cardiovascular disease risk. Conflicting results have been reported concerning the incidence of HE among people with T2DM observing Ramadan fasting. This review summarizes available scientific evidence on the occurrence of HE and the effects of different moderators on the incidence of HE among patients with T2DM during Ramadan. We conducted a systematic review of available observational studies and randomized controlled trials (RCTs) for patients with T2DM who fasted during Ramadan, with HE as the primary outcome. Ten databases were searched for relevant studies from inception until October 31, 2020. In total, 68 studies (35 RCTs and 33 observational studies) met the inclusion criteria. Non-sulfonylureas hypoglycemic medications showed superior effects in lowering the incidence of HE over sulfonylureas hypoglycemic medications. Variable moderators were associated with experiencing HE during Ramadan in both observational studies and RCTs, including sex, geographical location, body anthropometric indicators, season, dietary behaviors, fasting duration, time since diagnosis, and pre-fasting education. This comprehensive systematic review covered the largest number of observational and clinical studies investigating the impact of Ramadan on HE among patients with T2DM. The study highlights the significance of different moderators that influence the effect of Ramadan fasting on HE, including dietary behaviors, fasting time duration, sex, season, country, pre-fasting education, age, and time since diagnosis. The study also highlighted the impact of different hypoglycemic medications on HE and noted the superiority of non-sulfonylureas over sulfonylureas hypoglycemic medications in lowering the risk for hypoglycemia in people with T2DM during Ramadan fasting.

Mechanical Thromboprophylaxis in Critically Ill Patients: A Systematic Review and Meta-Analysis

2006 ◽  
Vol 15 (4) ◽  
pp. 402-412 ◽  
Author(s):  
Anthony Limpus ◽  
Wendy Chaboyer ◽  
Ellen McDonald ◽  
Lukman Thalib
Keyword(s):  
Intensive Care ◽  
Randomized Controlled Trials ◽  
Observational Studies ◽  
Meta Analysis ◽  
Controlled Trials ◽  
Trauma Patients ◽  
Intensive Care Patients ◽  
Randomized Controlled ◽  
Confounding Variables

• Objective To systematically review the randomized trials, observational studies, and survey evidence on compression and pneumatic devices for thromboprophylaxis in intensive care patients. • Methods Published studies on the use of compression and pneumatic devices in intensive care patients were assessed. A meta-analysis was conducted by using the randomized controlled trials. • Results A total of 21 relevant studies (5 randomized controlled trials, 13 observational studies, and 3 surveys) were found. A total of 811 patients were randomized in the 5 randomized controlled trials; 3421 patients participated in the observational studies. Trauma patients only were enrolled in 4 randomized controlled trials and 4 observational studies. Meta-analysis of 2 randomized controlled trials with similar populations and outcomes revealed that use of compression and pneumatic devices did not reduce the incidence of venous thromboembolism. The pooled risk ratio was 2.37, indicative of favoring the control over the intervention in reducing the deep venous thrombosis; however, the 95% CI of 0.57 to 9.90 indicated no significant differences between the intervention and the control. A range of methodological issues, including bias and confounding variables, make meaningful interpretation of the observational studies difficult. • Conclusions The limited evidence suggests that use of compressive and pneumatic devices yields results not significantly different from results obtained with no treatment or use of low-molecular-weight heparin. Until large randomized controlled trials are conducted, the role of mechanical approaches to thromboprophylaxis for intensive care patients remains uncertain.

scholarly journals Cardiovascular Effects of Androgen Deprivation Therapy in Prostate Cancer: Contemporary Meta-Analyses

2020 ◽  
Vol 40 (3) ◽  
Author(s):  
Jiun-Ruey Hu ◽  
Meredith S. Duncan ◽  
Alicia K. Morgans ◽  
Jonathan D. Brown ◽  
Wouter C. Meijers ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Randomized Controlled Trials ◽  
Androgen Deprivation Therapy ◽  
Observational Studies ◽  
Cardiovascular Effects ◽  
Androgen Deprivation ◽  
Controlled Trials ◽  
Cardiac Events ◽  
Randomized Controlled ◽  
Meta Analyses

Androgen deprivation therapy is a cornerstone of prostate cancer treatment. Pharmacological androgen deprivation includes gonadotropin-releasing hormone agonism and antagonism, androgen receptor inhibition, and CYP17 (cytochrome P450 17A1) inhibition. Studies in the past decade have raised concerns about the potential for androgen deprivation therapy to increase the risk of adverse cardiovascular events such as myocardial infarction, stroke, and cardiovascular mortality, possibly by exacerbating cardiovascular risk factors. In this review, we summarize existing data on the cardiovascular effects of androgen deprivation therapy. Among the therapies, abiraterone stands out for increasing risk of cardiac events in meta-analyses of both randomized controlled trials and observational studies. We find a divergence between observational studies, which show consistent positive associations between androgen deprivation therapy use and cardiovascular disease, and randomized controlled trials, which do not show these associations reproducibly.

scholarly journals PNS415 PUBLISHING OBSERVATIONAL STUDIES VS RANDOMIZED CONTROLLED TRIALS - A PUBMED REVIEW

2019 ◽  
Vol 22 ◽  
pp. S836
Author(s):  
L. Simoni ◽  
S. Rizzoli ◽  
P. Ciufici ◽  
A. Ori ◽  
G. Fiori
Keyword(s):  
Randomized Controlled Trials ◽  
Observational Studies ◽  
Controlled Trials ◽  
Randomized Controlled

scholarly journals Multidisciplinary Chronic Kidney Disease Clinic Practices: A Scoping Review

2019 ◽  
Vol 6 ◽  
pp. 205435811988266 ◽  
Author(s):  
David Collister ◽  
Lonnie Pyne ◽  
Jessie Cunningham ◽  
Maoliosa Donald ◽  
Amber Molnar ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Randomized Controlled Trials ◽  
Glomerular Filtration ◽  
Scoping Review ◽  
Observational Studies ◽  
Controlled Trials ◽  
Team Composition ◽  
Randomized Controlled

Background: Multidisciplinary chronic kidney disease (CKD) clinics improve patient outcomes but their optimal design is unclear. Objective: To perform a scoping review to identify and describe current practices (structure, function) associated with multidisciplinary CKD clinics. Design: Scoping review. Setting: Databases included Medline, EMBASE, Cochrane, and CINAHL. Patients: Patients followed in multidisciplinary CKD clinics globally. Measurements: Multidisciplinary CKD clinic composition, entry criteria, follow-up, and outcomes. Methods: We systematically searched the literature to identify randomized controlled trials, non-randomized interventional studies, or observational studies of multidisciplinary CKD clinics defined by an outpatient setting where two or more allied health members (with or without a nephrologist) provided longitudinal care to 50 or more adult or pediatric patients with CKD. Included studies were from 2002 to present. Searches were completed on August 10, 2018. Title, abstracts, and full texts were screened independently by two reviewers with disagreements resolved by a third. We abstracted data from included studies to summarize multidisciplinary CKD clinic team composition, entry criteria, follow-up, and processes. Results: 40 studies (8 randomized controlled trials and 32 non-randomized interventional studies or observational studies) involving 23 230 individuals receiving multidisciplinary CKD care in 12 countries were included. Thirty-eight focused on adults (27 with CKD, 10 incident dialysis patients, one conservative therapy) while two studies focused on adolescents or children with CKD. The multidisciplinary team included a mean of 4.6 (SD 1.5) members consisting of a nephrologist, nurse, dietician, social worker, and pharmacist in 97.4%, 86.8%, 84.2%, 57.9%, and 42.1% of studies respectively. Entry criteria to multidisciplinary CKD clinics ranged from glomerular filtration rates of 20 to 70 mL/min/1.73m2 or CKD stages 1 to 5 without any proteinuria or risk equation-based criteria. Frequency of follow-up was variable by severity of kidney disease. Team member roles and standardized operating procedures were infrequently reported. Limitations: Unstandardized definition of multidisciplinary CKD care, studies limited to CKD defined by glomerular filtration rate, and lack of representation from countries other than Canada, Taiwan, the United States, and the United Kingdom. Conclusions: There is heterogeneity in multidisciplinary CKD team composition, entry criteria, follow-up, and processes with inadequate reporting of this complex intervention. Additional research is needed to determine the best model for multidisciplinary CKD clinics. Trial registration: Not applicable.

Dietary saturated fat and heart disease: a narrative review

2019 ◽  
Vol 78 (6) ◽  
pp. 474-485 ◽  
Author(s):  
Jeffery L Heileson
Keyword(s):  
Heart Disease ◽  
Randomized Controlled Trials ◽  
Observational Studies ◽  
Meta Analysis ◽  
Saturated Fat ◽  
Heart Association ◽  
Controlled Trials ◽  
Randomized Controlled ◽  
Disease Outcomes ◽  
Meta Analyses

Abstract The American Heart Association (AHA) recently published a meta-analysis that confirmed their 60-year-old recommendation to limit saturated fat (SFA, saturated fatty acid) and replace it with polyunsaturated fat to reduce the risk of heart disease based on the strength of 4 Core Trials. To assess the evidence for this recommendation, meta-analyses on the effect of SFA consumption on heart disease outcomes were reviewed. Nineteen meta-analyses addressing this topic were identified: 9 observational studies and 10 randomized controlled trials. Meta-analyses of observational studies found no association between SFA intake and heart disease, while meta-analyses of randomized controlled trials were inconsistent but tended to show a lack of an association. The inconsistency seems to have been mediated by the differing clinical trials included. For example, the AHA meta-analysis only included 4 trials (the Core Trials), and those trials contained design and methodological flaws and did not meet all the predefined inclusion criteria. The AHA stance regarding the strength of the evidence for the recommendation to limit SFAs for heart disease prevention may be overstated and in need of reevaluation.

Sign in / Sign up

Export Citation Format

Share Document