Background: Time-lag bias is a form of reporting bias resulting from the delayed publication of studies with ‘negative’ findings. If imaging diagnostic test accuracy (DTA) studies with negative conclusions have a delayed publication course, this may impede the ability to evaluate all evidence on a topic (e.g. in a systematic review)—potentially leading to the misallocation of healthcare resources towards diagnostic tests and detrimental downstream effects on patient outcomes.
Objective: To evaluate whether imaging DTA studies with positive conclusions or titles have a shorter time to publication than those with non-positive (i.e. negative or neutral) conclusions or titles.
Methods: We included primary imaging DTA studies from systematic reviews published in 2015. Conclusion and title positivity were extracted independently in duplicate for each study, based on a previously published classification scheme. Time from study completion to publication was extracted and calculated. A Cox regression model was used to evaluate associations of conclusion and title positivity with time to publication, adjusting for potentially confounding variables.
Results: 774 imaging DTA studies were included; time from study completion to publication could be calculated for 516 studies. Median time from completion to publication was 18 months (interquartile range [IQR]:13-26; 413 studies) for studies with positive conclusions, 23 months (IQR:16-33; 63 studies) for those with neutral conclusions, and 25 months (IQR:15-38; 40 studies) for those with negative conclusions (as seen in Table 1). Conclusion positivity was associated with a shorter time from completion to publication for studies with positive conclusions, compared to those with non-positive conclusions (hazard ratio [HR] 1.31; 95% confidence interval [CI]: 1.02-1.68), as seen in Figure 1. Positive titles were not significantly associated with a shorter time to publication (HR 1.12; 95% confidence interval: 0.75-1.69). When subdividing time from study completion to publication, conclusion positivity was associated with shorter time from study completion to submission (HR 1.31; 95% CI:1.00-1.74), but no association was identified between conclusion positivity and time from submission to publication (HR 0.95; 95% CI: 0.61-1.48).
Conclusions: Positive author conclusions (but not titles) were associated with a shorter time to publication. Imaging DTA studies with positive conclusions may be over-represented in the literature, potentially leading to overly-optimistic perceptions of the performance of diagnostic imaging tests.
Patient or healthcare consumer involvement: There were no patients or healthcare consumers involved in this project.