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How often do US-based human subjects research studies register on time, and how often do they post their results? A statistical analysis of the Clinicaltrials.gov database

Abstract

Context The Food and Drug Administration Modernization Act of 1997 (FDAMA) and the FDA Amendment Act of 2007 (FDAAA), respectively, established mandates for registration of interventional human research studies on the website clinicaltrials.gov (CTG) and for posting of results of completed studies.

Objective To characterise, contrast and explain rates of compliance with ontime registration of new studies and posting of results for completed studies on CTG.

Design Statistical analysis of publically available data downloaded from the CTG website.

Participants US studies registered on CTG since 1 November 1999, the date when the CTG website became operational, through 24 June 2011, the date the data set was downloaded for analysis.

Main outcome measures Ontime registration (within 21 days of study start); average delay from study start to registration; proportion of studies posting their results from within the group of studies listed as completed on CTG.

Results As of 24 June 2011, CTG contained 54 890 studies registered in the USA. Prior to 2005, an estimated 80% of US studies were not being registered. Among registered studies, only 55.7% registered within the 21-day reporting window. The average delay on CTG was 322 days. Between 28 September 2007 and June 23 2010, 28% of intervention studies at Phase II or beyond posted their study results on CTG, compared with 8.4% for studies without industry funding (RR 4.2, 95% CI 3.7 to 4.8). Factors associated with posting of results included exclusively paediatric studies (adjusted OR (AOR) 2.9, 95% CI 2.1 to 4.0), and later phase clinical trials (relative to Phase II studies, AOR for Phase III was 3.4, 95% CI 2.8 to 4.1; AOR for Phase IV was 6.0, 95% CI 4.8 to 7.6).

Conclusions Non-compliance with FDAMA and FDAAA appears to be very common, although compliance is higher for studies sponsored by industry. Further oversight may be required to improve compliance.

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