Comorbidity-adjusted life expectancy using comprehensive summary measures of medical history: nationwide, population-based study in Sweden

A multidimensional diagnosis-based comorbidity index (MDCI) and a drug comorbidity index (DCI) have demonstrated superior discrimination of mortality risk compared to the Charlson Comorbidity Index (CCI) in smaller specific populations. We aimed to evaluate performance of these indices in an entire population according to age, sex, and to estimate comorbidity-adjusted life expectancy (CALE), i.e. life expectancy conditional on age and comorbidity. Open cohort study of all adults residing in Sweden in 2006-2022. Discrimination of mortality risk at one year of follow-up was assessed through the C-index. CALE was estimated using parametric survival models based on age and comorbidity. 10 079 529 individuals were included. The MDCI (C-index 0.882 [95% CI 0.882-0.882]) and DCI (C-index 0.871 [95% CI 0.870-0.871]) improved discrimination of mortality risk compared to the CCI (C-index 0.811 [95% CI 0.811-0.812]). For each age above 40 the combination of MDCI and DCI clearly separated risk of death within levels of CCI and identified a wider range of CALE than CCI. At age 70 CALE based on the combination of MDCI and DCI varied from 7.0 to 17.9 years at the 5th and 95th percentile in men, and from 8.9 to 20.2 years in women. CALE based on CCI varied from 11.0 to 16.1 years in men and 11.7 to 18.4 years in women. Comprehensive comorbidity indices improved discrimination of mortality risk over the CCI in all age groups in men and women and identified a wider range of comorbidity-adjusted life expectancy in individuals of the same age.