Time to publication for publicly funded clinical trials in Australia: an observational study

Abstract

Objective: To examine the length of time between receiving funding and publishing the protocol and main paper for randomised controlled trials.

Design: An observational study using survival analysis.

Setting: Publicly funded health and medical research in Australia.

Participants: Randomised controlled trials funded by the National Health and Medical Research Council of Australia between 2008 and 2010.

Main outcome measures: Time from funding to the protocol paper and main results paper. Multiple variable survival models examining whether study characteristics predicted publication times.

Results: We found 77 studies with a total funding of $A59 million. The median time to publication of the protocol paper was 6.4 years after funding (95% CI 4.1 to 8.1). The proportion with a published protocol paper 8 years after funding was 0.61 (95% CI 0.48 to 0.74). The median time to publication of the main results paper was 7.1 years after funding (95% CI 6.3 to 7.6). The proportion with a published main results paper 8 years after funding was 0.72 (95% CI 0.56 to 0.87). The HRs for how study characteristics might influence timing were generally close to one with narrow CIs, the notable exception was that a longer study length lengthened the time to the main paper (HR=0.62 per extra study year, 95% CI 0.43 to 0.89).

Conclusions: Despite the widespread registration of clinical trials, there remain serious concerns of trial results not being published or being published with a long delay. We have found that these same concerns apply to protocol papers, which should be publishable soon after funding. Funding agencies could set a target of publishing the protocol paper within 18 months of funding.

Figure 1

Flow chart showing the data collection process. ANZCTR, Australian and New Zealand Clinical Trial Registry NHMRC, National Health and Medical Research Council; RCT, randomised controlled trial.

Figure 2

The three key events over time. Studies may go straight from funding to main paper publication or first publish a protocol paper, which is therefore a time-dependent variable. The illustration shows how ignoring the timing of the protocol lengthens the time between the protocol paper and the main paper which would bias the HR downwards. The thicker part of the arrow from protocol to main paper in the right panel is the arrow length in the left panel.

Figure 3

Flow chart showing publication status (protocol and main paper) of the 77 funded studies.

Figure 4

Kaplan-Meier survival curve (and 95% CIs as dashed lines) for time from funding to protocol paper published (n=77). Horizontal lines on the survival curve indicate censoring.

Figure 5

Kaplan-Meier survival curves (and 95% CIs as dashed lines) for time from funding to main paper published for all papers combined (left) and split into relatively long and short studies by median study length (right; n=77). Horizontal lines on the survival curves indicate censoring.