Clinical Trials

Pre-planned studies of the safety, efficacy, or optimum dosage schedule (if appropriate) of one or more diagnostic, therapeutic, or prophylactic drugs, devices, or techniques selected according to predetermined criteria of eligibility and observed for predefined evidence of favorable and unfavorable effects. This concept includes clinical trials conducted both in the U.S. and in other countries.

Appraisal of: Banno, M et al (2019) Studies registered in non-ClinicalTrials.gov accounted for an increasing proportion of protocol registrations in medical research. J Clin Epidemiol 2019;116:106.

Reviewer(s): 
Short description: 

The objective of the study was to identify the proportion of registered studies in WHO ICTRP not included in ClinicalTrials.gov (described as non-ClinicalTrials.gov studies). The study also compares the characteristics of studies identified as non-ClinicalTrials.gov with those registered in ClinicalTrials.gov.

A total of 235,830 studies were identified as being on the ICTRP website between 2014-2018. The proportion of studies registered as non-ClinicalTrials.gov increased during that time from 38.3% to 53.3%. The proportion of non-ClinicalTrials.gov studies with a randomised design (among all studies with a randomised design registered on ICTRP) increased during that time from 43.9% to 56.7%. Non-ClinicalTrials.gov studies were more often retrospectively registered and lacked key information. Systematic review searches should include a search of ICTRP in addition to ClinicalTrials.gov.

Limitations stated by the author(s): 

The data included only studies registered in the ICTRP, other sources were not examined. The post hoc sensitivity analysis restricting to randomised controlled trials might be misclassified due to the keywords used.

Limitations stated by the reviewer(s): 
No additional limitations detected by the reviewers.
Study Type: 
Single study

Appraisal of: Wieseler B, Wolfram N, McGauran N et al. Completeness of reporting of patient-relevant clinical trial outcomes: comparison of unpublished clinical study reports with publicly available data. PLoS Med 2013;10(10):e1001526.

Reviewer(s): 
Short description: 
The authors compared the information available in clinical study reports and in publicly accessible sources (journal articles, registry reports) included in 16 HTA reports for drugs prepared in IQWiG. They assessed the completeness of information on patient-relevant benefit (e.g. symptom relief, health related quality of life) and harm (adverse effects) outcomes reported in each document type. Clinical study reports provided complete information of all outcomes on a higher proportion (86%) than publicly accessible sources (39%). They also provided more information on harms (87% versus 43 %). The authors conclude that clinical study reports should be made publicly available for the benefit of unbiased trial evaluation and informed decision-making in health care.
Limitations stated by the author(s): 
The main limitation was that the authors could only study those clinical study reports that were provided voluntarily upon request by the pharmaceutical companies. Also, the sample of clinical study reports was restricted on studies investigating drugs.
Limitations stated by the reviewer(s): 
No additional limitations detected by the reviewer.
Study Type: 
Single study
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