Multimorbidity combinations among older adults in Singapore: A cross-sectional study using polyclinic data

Background: Multimorbidity, the co-occurrence of multiple chronic conditions, is commonly managed in primary care and increasingly prevalent. Researchers are increasingly studying the unique combinations of chronic conditions and their associations with health service utilisation. However, published studies largely focus on common dyads and triads of chronic conditions. This study aims to determine the prevalence and combinations of multimorbidity among older adults managed in Singapore's primary care. Methods: A cross-sectional analysis of all Singapore citizens and permanent residents aged ≥50 years who visited any polyclinic between July 2017 to June 2018 was conducted. Patient diagnoses up to year 2012 were reviewed using 23 chronic condition categories to define multimorbidity. All multimorbidity combinations and their prevalence were analysed. Results: Among 502,036 polyclinic patients aged ≥50 years, 59.9% had multimorbidity. Of 4,194,050 possible multimorbidity combinations, 13,959 were observed. Combinations comprised between three to 13 chronic conditions. The most prevalent and costly combinations consisted three to four chronic conditions: (1) hyperlidaemia/hypertension/diabetes; (2) hyperlidaemia/hypertension/diabetes/functional limitation; (3) hyperlidaemia/hypertension/functional limitation; (4) hyperlipidaemia/hypertension/diabetes/cardiovascular disease; (5) hyperlipidaemia/hypertension/diabetes/arthritis; (6) hyperlipidaemia/hypertension/arthritis; (7) hyperlipidaemia/hypertension/cardiovascular disease; (8) hyperlipidaemia/hypertension/diabetes/obesity; (9) hyperlipidaemia/hypertension/diabetes/stroke; (10) hyperlipidaemia/hypertension/arthritis/functional limitation; (11) hyperlipidaemia/hypertension/diabetes/kidney. Conclusion: Although a wide variety of combinations were observed, hyperlipidaemia and hypertension were common in the most prevalent and costly combinations. As current management of chronic conditions focusses on disease-specific clinical outcomes, findings from this study suggest a need to optimise clinical outcomes for common multimorbidity combinations rather than simply aggregating outcomes for all conditions within the combination.