ObjectivesTo examine the association of a high C-reactive protein (CRP) level at discharge from an acute decompensated heart failure (ADHF) hospitalisation with the 1-year clinical outcomes.DesignA post-hoc subanalysis of a prospective cohort study of patients hospitalised for ADHF (using the Kyoto Congestive Heart Failure (KCHF) registry) between October 2014 and March 2016 with a 1-year follow-up.SettingA physician-initiated multicentre registry enrolled consecutive hospitalised patients with ADHF for the first time at 19 secondary and tertiary hospitals in Japan.ParticipantsAmong the 4056 patients enrolled in the KCHF registry, the present study population consisted of 2618 patients with an available CRP value both on admission and at discharge and post-discharge clinical follow-up data. We divided the patients into two groups, those with a high CRP level (>10 mg/L) and those with a low CRP level (≤10 mg/L) at discharge from the index hospitalisation.Primary and secondary outcome measuresThe primary outcome measure was all-cause death after discharge from the index hospitalisation. The secondary outcome measures were heart failure hospitalisations, cardiovascular death and non-cardiovascular death.ResultsThe high CRP group and low CRP group included 622 patients (24%) and 1996 patients (76%), respectively. During a median follow-up period of 468 days, the cumulative 1-year incidence of the primary outcome was significantly higher in the high CRP group than low CRP group (24.1% vs 13.9%, log-rank p<0.001). Even after a multivariable analysis, the excess mortality risk in the high CRP group relative to the low CRP group remained significant (HR, 1.43; 95% CI, 1.19 to 1.71; p<0.001). The excess mortality risk was consistent regardless of the clinically relevant subgroup factors.ConclusionsA high CRP level (>10 mg/L) at discharge from an ADHF hospitalisation was associated with an excess mortality risk at 1 year.Trial registration detailshttps://clinicaltrials.gov/ct2/show/NCT02334891 (NCT02334891) https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000017241 (UMIN000015238).