Validation of U.S. mortality prediction models for hospitalized heart failure in the United Kingdom and Japan

Aims: Prognostic models for hospitalized heart failure (HHF) were developed predominantly for patients of European origin in the United States of America; it is unclear whether they perform similarly in other health care systems or for different ethnicities. We sought to validate published prediction models for HHF in the United Kingdom (UK) and Japan. Methods and results: Patients in the UK (n =894) and Japan (n =3158) were prospectively enrolled and were similar in terms of sex (∼60% men) and median age (∼77 years). Models predicted that British patients would have a higher mortality than Japanese, which was indeed true both for in-hospital (4.8% vs. 2.5%) and 180-day (20.7% vs. 9.5%) mortality. The model c-statistics for the published/derivation (range 0.70–0.76) and Japanese (range 0.75–0.77) cohorts were similar and higher than for the UK (0.62–0.75) but models consistently overestimated mortality in Japan. For in-hospital mortality, the OPTIMIZE-HF model performed best, providing similar discrimination in published/derivation, UK and Japanese cohorts [c-indices: 0.75 (0.74–0.77); 0.75 (0.68–0.81); and 0.77 (0.70–0.83), respectively], and least overestimated mortality in Japan. For 180-day mortality, the c-statistics for the ASCEND-HF model were similar in published/derivation (0.70) and UK [0.69 (0.64–0.74)] cohorts but higher in Japan [0.75 (0.71–0.79)]; calibration was good in the UK but again overestimated mortality in Japan. Conclusion: Calibration of published prediction models appears moderately accurate and unbiased when applied to British patients but consistently overestimates mortality in Japan. Identifying the reason why patients in Japan have a better than predicted prognosis is of great interest.