scholarly journals Methodological issues in observational studies and non-randomized controlled trials in oncology in the era of big data

2015 ◽  
Vol 45 (4) ◽  
pp. 323-327 ◽  
Author(s):  
S. Tanaka ◽  
S. Tanaka ◽  
K. Kawakami
Keyword(s):  
Big Data ◽  
Randomized Controlled Trials ◽  
Observational Studies ◽  
Controlled Trials ◽  
Methodological Issues ◽  
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.

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

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
Sign in / Sign up

Export Citation Format

Share Document