Impact of comorbidity on mortality among older persons with advanced heart failure.

BACKGROUND: Care for patients with advanced heart failure (HF) has traditionally focused on managing HF alone; however, little is known about the prevalence and contribution of comorbidity to mortality among this population. We compared the impact of comorbidity on mortality in older adults with HF with high mortality risk and those with lower mortality risk, as defined by presence or absence of a prior hospitalization for HF, respectively.
METHODS: This was a retrospective cohort study (2002-2006) of 18,322 age-matched and gender-matched Medicare beneficiaries. We used the baseline year of 2002 to ascertain HF hospitalization history, in order to identify beneficiaries at either high or low risk of future HF mortality. We calculated the prevalence of 19 comorbidities and overall comorbidity burden, defined as a count of conditions, among both high and low risk beneficiaries, in 2002. Proportional hazards regressions were used to determine the effect of individual comorbidity and comorbidity burden on mortality between 2002 and 2006 among both groups.
RESULTS: Most comorbidities were significantly more prevalent among hospitalized versus non-hospitalized beneficiaries; myocardial infarction, atrial fibrillation, kidney disease (CKD), chronic obstructive pulmonary disease (COPD), and hip fracture were more than twice as prevalent in the hospitalized group. Among hospitalized beneficiaries, myocardial infarction, diabetes, COPD, CKD, dementia, depression, hip fracture, stroke, colorectal cancer and lung cancer were each significantly associated with increased hazard of dying (hazard ratios [HRs]: 1.16-1.93), adjusting for age, gender and race. The mortality risk associated with most comorbidities was higher among non-hospitalized beneficiaries (HRs: 1.32-3.78).
CONCLUSIONS: Comorbidity confers a significantly increased mortality risk even among older adults with an overall high mortality risk due to HF. Clinicians who routinely care for this population should consider the impact of comorbidity on outcomes in their overall management of HF. Such information may also be useful when considering the risks and benefits of aggressive, high-intensity life-prolonging interventions.