Chronic disease management among people with serious mental illness across rural, small urban, and metropolitan settings

Context: People with serious mental illness (SMI) are at increased risk of complications and earlier death from comorbid chronic diseases, compared with patients without mental illness. Despite similar prevalence of mental illness across rural, small urban, and metropolitan settings, those living in a rural context experience disproportionately worse chronic disease related health outcomes. These disparities may be related to differences in access to recommended chronic disease management.

Objective: To describe patterns of chronic disease management across rural, small urban, and metropolitan settings, and explore variation by coinciding treatment for mental illness.

Study Design: Observational analysis of linked administrative data

Setting or Dataset: Physician billing records (including laboratory tests), prescriptions dispensed, and patient registry data in British Columbia, Canada, accessed via Population Data BC

Population Studied: All people ages 20-105 registered for provincial health insurance between April 1, 2022 and March 31, 2023 who were treated for diabetes or hypertension in the two preceding years

Instrument: Comparison across metropolitan, small urban, and rural contexts, among people treated for serious mental illness, common mental illness, or not treated for mental illness

Outcome Measures: Chronic disease management including primary care visits, billing premiums indicating responsibility for longitudinal care, lab tests, prescriptions, and referrals.

Results: The proportion of patients with a premium billed for diabetes or hypertension was highest in small urban areas, but lower amongst patients with SMI across all three geographic settings, with particularly low values in metro. The proportions of people with diabetes or hypertension-related blood testing were generally similar across the three geographic settings, but people treated for SMI and particularly living rurally had lower access overall. The proportions of people with any diabetes or anti-hypertensive drug were similar across settings, but with some variation in patterns for insulin and non-insulin diabetes drugs. Referral to and/or visit with an ophthalmologist was most common in metropolitan settings, with similarly lower values in small urban and rural.

Conclusions: This analysis highlights geographic variation in chronic disease management, and pronounced gaps in access among people treated for SMI, particularly in rural settings.