BACKGROUND: Randomized controlled trials (RCTs) may report outcomes different from those prespecified on trial-registration websites, protocols and statistical analysis plans (SAPs). This study sought to investigate the prevalence and characteristics of heart failure (HF) RCTs that report outcomes different from those prespecified. METHODS AND RESULTS: MEDLINE via PubMed was searched to include phase II-IV HF RCTs in 9 high-impact journals from 2010 to 2020. Outcomes reported in trial publications were compared with prespecified outcomes in protocols, registration websites and SAPs. We used the χ2 or Fisher exact test to analyze correlations between trial characteristics and inconsistencies. Among 216 trials, 32 inconsistencies were observed in 28 trials (13.0%). Among 32 inconsistencies, 2 (6.3%) pertained to omission of prespecified primary outcomes, 4 (12.5%) to omission of prespecified secondary outcomes, 2 (6.3%) to changing prespecified primary outcomes to secondary outcomes, and 2 (6.3%) to changing prespecified secondary outcomes to primary outcomes. Of the inconsistencies, 3 (9.4%) pertained to addition of new primary outcomes, 17 (53.1%) to addition of new secondary outcomes, and 2 (6.3%,) to changes in the timing of assessment of primary outcomes. The majority of the inconsistencies favored statistically significant findings; 78 (36.1%) were registered retrospectively. Single-center recruitment was associated with outcome inconsistencies (β = -0.14; 95% CI, -0.22 - -0.01; P = 0.035). CONCLUSIONS: More than 1 in 10 trials reported outcomes inconsistent with those specified in trial registration websites, SAPs and protocols. An action plan is warranted to minimize selective reporting and improve transparency.
