Measuring the burden of multimorbidity among Medicare beneficiaries via condition counts and cumulative duration

Objective The study's purpose was to describe the cumulative duration of 19 chronic conditions among Medicare fee-for-service (FFS) beneficiaries and examine variation in total expenditures explained by cumulative duration and condition counts. Design, Setting, Study Design, and Data Extraction In a retrospective cohort of FFS beneficiaries age >= 68, 2015 Medicare enrollment and claims data (N = 20 124 230) were used to identify the presence or absence of 19 diagnosed chronic conditions, and to construct MCC categories (0-1, 2-3, 4-5, 6+) and cumulative duration of each of 19 conditions from the date of first possible occurrence in claims (1/1/1999) to the end of follow-up (date of death or 12/31/2015). Total Medicare expenditures were estimated using linear models adjusted for demographic characteristics. Principal Findings Multimorbidity was common (71.7 percent with 2+ conditions). The mean cumulative duration of all 19 conditions was 23.6 person-years, which varied greatly by age and number of conditions. Condition counts were more predictive of Medicare expenditures than cumulative duration (R-squared for continuous measures = 0.461 vs 0.272; R-squared for quartiles = 0.408 vs 0.266). Conclusions The cumulative duration of chronic conditions varied widely for Medicare beneficiaries, especially for those with 6+ conditions, but was less predictive of total expenditures than condition counts.