Discrepancies between Registered and Published Primary and Secondary Outcomes in Randomized Controlled Trials within the Plastic Surgery Literature

Background: Recent studies have identified an alarmingly high incidence of discrepancy between registered and published outcomes in registered medical and surgical randomized controlled trials. This has not yet been studied in the plastic surgery literature.

Methods: The authors systematically assessed plastic surgery randomized controlled trials (RCTs) published between 2012-2016, in seven high impact plastic surgery journals. Data was collected from the registration website and published manuscript using a standardized data extraction form.

Results: 145 RCTs were identified, of which fifty-seven RCTs were registered (39%). Forty-nine RCTs were included in the final analysis. Forty-three of trials (88%) had a discrepancy between registered and published outcomes - 23 trials (47%) for primary outcome(s), and 37 trials (76%) for secondary outcome(s). The prevalence of unreported registered outcomes was 13% (primary) and 38% (secondary). Registered primary outcomes were published as secondary outcomes in 30% of trials. Publishing new non-registered secondary outcomes (65%) and changing the assessment timing of published primary outcomes (61%) were the most common types of discrepancies. Discrepancies favored a statistically significant positive outcome in nineteen of the forty-three trials (44%) with an outcome discrepancy.

Conclusions: Similar to studies of trials in other medical and surgical areas of the literature, the field of plastic surgery has high rates of discrepancies between registered and published trial outcomes. Outcome reporting discrepancy is even more problematic secondary outcomes, an area of analysis that has previously been poorly studied in other areas. This study also identified biasing practices such as outcome discrepancies favoring a statistically significant result.