Aims

The implications of geographical variation are unknown following adjustment for hospital length of stay (LOS) in heart failure (HF) trials that included patients whether or not they had systolic dysfunction. We investigated regional differences in an international acute HF trial.

Methods and results

The PROTECT trial investigated 2033 patients with acute HF and renal dysfunction hospitalized at 173 sites in 17 countries with randomization to rolofylline or placebo. We grouped enrolling countries into six regions. Baseline characteristics, in-hospital management, and outcomes were explored by region. The primary study outcome was 60-day mortality or cardiovascular/renal hospitalization. Secondary outcomes included 180-day mortality. Of 2033 patients, 33% were from Eastern Europe, 19% from Western Europe, 16% from Israel, 15% from North America, 14% from Russia, and 3% from Argentina. Marked differences in baseline characteristics, HF phenotype, in-hospital diuretic and vasodilator strategies, and LOS were observed by region. LOS was shortest in North America and Israel (median 5 days) and longest in Russia (median 15 days). Regional event rates varied significantly. Following multivariable adjustment, region was an independent predictor of the risk of mortality/hospitalization at 60 days, with the lowest risk in Russia (hazard ratio 0.39, 95% confidence interval 0.23-0.64 vs. Western Europe) due to lower rehospitalization; mortality differences were attenuated by 180 days.

Conclusions

In an international HF trial, there were differences in baseline characteristics, treatments, LOS, and rehospitalization amongst regions, but little difference in longer term mortality. Rehospitalization differences exist independent of LOS. This analysis may help inform future trial design and should be externally validated.

The ODYSSEY OUTCOMES trial, comprising over 47 000 patient-years of placebo-controlled observation, demonstrated important reductions in the risk of recurrent ischaemic cardiovascular events with the monoclonal antibody to proprotein convertase subtilisin/kexin type 9 alirocumab, as well as lower all-cause death. These benefits were observed in the context of substantial and persistent lowering of low-density lipoprotein cholesterol with alirocumab compared with that achieved with placebo. The safety profile of alirocumab was indistinguishable from matching placebo except for a ∼1.7% absolute increase in local injection site reactions. Further, the safety of alirocumab compared with placebo was evident in vulnerable groups identified before randomization, such as the elderly and those with diabetes mellitus, previous ischaemic stroke, or chronic kidney disease. The frequency of adverse events and laboratory-based abnormalities was generally similar to that in placebo-treated patients. Thus, alirocumab appears to be a safe and effective lipid-modifying treatment over a duration of at least 5 years.