Multimorbidity Clusters Among People Aged 65 Years and Over in Australia: A Nationwide Cross-Sectional Data Linkage Study.

Abstract

To identify sex-specific multimorbidity patterns in Australia, using the Rx-Risk index (a medication-based measure), to: (i) estimate the prevalence of chronic treated conditions; (ii) map network-based multimorbidity clusters; and (iii) examine how these clusters vary by age, socio-economic status and geographic remoteness. Australian nationwide cross-sectional study using linked Pharmaceutical Benefits Scheme (PBS) and Medicare Benefits Schedule (MBS) data. Australian residents aged ≥ 65 years with at least one PBS and/or MBS claim between 1 July 2022 and 30 June 2023. Sex-specific network-based multimorbidity clusters and cluster profiles by age, socio-economic status and geographic remoteness. A total of 4,435,784 individuals (mean age, 74.8 years; 53.2% female) were included. Multimorbidity (≥ 2 conditions) was present in 76.1% of the cohort. Three consistent multimorbidity clusters were identified in both sexes: cardiovascular-metabolic, neuropsychiatric-functional decline and inflammatory-musculoskeletal-cancer. The prevalence of these clusters and their component conditions varied across sociodemographic groups, with higher prevalence observed in individuals aged ≥ 85 years and those living in socio-economically disadvantaged areas. Minimal differences were observed between metropolitan and non-metropolitan regions. Multimorbidity was highly prevalent among older Australians with at least one PBS and/or MBS claim during the study year, with multimorbidity clusters showing marked sociodemographic variation in prevalence. These findings highlight the heterogeneity in treated conditions captured in administrative claims and provide insights to inform future research and policy planning for prevention and management of multimorbidity in an ageing population.