Long-term mortality in young and middle-aged adults hospitalised with chronic disease: a Danish cohort study

OBJECTIVES: To examine the long-term outcomes for patients hospitalised with chronic diseases at age 30, 40 or 50 years. DESIGN: Nationwide, population-based cohort study. SETTING: All Danish hospitals, 1979–1989, with follow-up through 2014. PARTICIPANTS: Patients hospitalised during the study period with one, two or three or more chronic diseases and age-matched and sex-matched persons from the general population without chronic disease leading to hospitalisation: age-30 group: 13 857 patients and 69 285 comparators; age-40 group: 24 129 patients and 120 645 comparators; and age-50 group, 37 807 patients and 189 035 comparators. MAIN OUTCOME MEASURES: Twenty-five-year mortality risks based on Kaplan-Meier estimates, years-of-life-lost (YLLs) and mortality rate ratios based on Cox regression analysis. YLLs were computed for each morbidity level, as well as in strata of income, employment, education and psychiatric conditions. RESULTS: Twenty-five-year mortality risks and YLLs increased steadily with increasing number of morbidities leading to hospitalisation and age, but the risk difference with general population comparators remained approximately constant across age cohorts. In the age-30 cohort, the risk differences for patients compared with comparators were 35.0% (95% CI 32.5 to 37.5) with two diseases and 62.5% (54.3% to 70.3%) with three or more diseases. In the age-50 cohort, these differences were, respectively, 48.4% (47.4 to 49.3) and 61.7% (60.1% to 63.0%). Increasing morbidity burden augmented YLLs resulting from low income, unemployment, low education level and psychiatric conditions. In the age-30 cohort, YYLs attributable to low income were 2.4 for patients with one disease, 6.2 for patients with two diseases and 11.5 for patients with three or more diseases. CONCLUSIONS: Among patients with multiple chronic diseases, the risk of death increases steadily with the number of chronic diseases and with age. Multimorbidity augments the already increased mortality among patients with low socioeconomic status.