Trajectories of Chronic Disease and Multimorbidity Among Middle-aged and Older Patients at Community Health Centers.

Importance: Health-related consequences of multimorbidity (≥2 chronic diseases) are well documented. However, the extent and rate of accumulation of chronic diseases among US patients seeking care in safety-net clinics are not well understood. These insights are needed to enable clinicians, administrators, and policy makers to mobilize resources for prevention of disease escalations in this population. Objectives: To identify the patterns and rate of chronic disease accumulation among middle-aged and older patients seeking care in community health centers, as well as any sociodemographic differences. Design, Setting, and Participants: This cohort study used electronic health record data from January 1, 2012, to December 31, 2019, on 725 107 adults aged 45 years or older with 2 or more ambulatory care visits in 2 or more distinct years at 657 primary care clinics in the Advancing Data Value Across a National Community Health Center network in 26 US states. Statistical analysis was performed from September 2021 to February 2023. Exposures: Race and ethnicity, age, insurance coverage, and federal poverty level (FPL). Main Outcomes and Measures: Patient-level chronic disease burden, operationalized as the sum of 22 chronic diseases recommended by the Multiple Chronic Conditions Framework. Linear mixed models with patient-level random effects adjusted for demographic characteristics and ambulatory visit frequency with time interactions were estimated to compare accrual by race and ethnicity, age, income, and insurance coverage. Results: The analytic sample included 725 107 patients (417 067 women [57.5%]; 359 255 [49.5%] aged 45-54 years, 242 571 [33.5%] aged 55-64 years, and 123 281 [17.0%] aged ≥65 years). On average, patients started with a mean (SD) of 1.7 (1.7) morbidities and ended with 2.6 (2.0) morbidities over a mean (SD) of 4.2 (2.0) years of follow-up. Compared with non-Hispanic White patients, patients in racial and ethnic minoritized groups had marginally lower adjusted annual rates of accrual of conditions (-0.03 [95% CI, -0.03 to -0.03] for Spanish-preferring Hispanic patients; -0.02 [95% CI, -0.02 to -0.01] for English-preferring Hispanic patients; -0.01 [95% CI, -0.01 to -0.01] for non-Hispanic Black patients; and -0.04 [95% CI, -0.05 to -0.04] for non-Hispanic Asian patients). Older patients accrued conditions at higher annual rates compared with patients 45 to 50 years of age (0.03 [95% CI, 0.02-0.03] for 50-55 years; 0.03 [95% CI, 0.03-0.04] for 55-60 years; 0.04 [95% CI, 0.04-0.04] for 60-65 years; and 0.05 [95% CI, 0.05-0.05] for ≥65 years). Compared with those with higher income (always ≥138% of the FPL), patients with income less than 138% of the FPL (0.04 [95% CI, 0.04-0.05]), mixed income (0.01 [95% CI, 0.01-0.01]), or unknown income levels (0.04 [95% CI, 0.04-0.04]) had higher annual accrual rates. Compared with continuously insured patients, continuously uninsured and discontinuously insured patients had lower annual accrual rates (continuously uninsured, -0.003 [95% CI, -0.005 to -0.001]; discontinuously insured, -0.004 [95% CI, -0.005 to -0.003]). Conclusions and Relevance: This cohort study of middle-aged patients seeking care in community health centers suggests that disease accrued at high rates for patients' chronological age. Targeted efforts for chronic disease prevention are needed for patients near or below the poverty line.