Incidence rate and determinants of multimorbidity in the community: A retrospective cohort study

Abstract Objective: This study aims to estimate the incidence of multimorbidity between 2009 and 2023 and to identify its key determinants. Methods: This retrospective cohort study was conducted using a sub-cohort derived from the 2009-Balçova’s Heart Study (2009-BAK), carried out in Balçova, İzmir. In the current study, the presence of multimorbidity was considered as the outcome variable, while age groups, gender, and education level were included as independent variables. The effect of independent variables on the dependent variable was analyzed using Cox regression analysis. The incidence rates of multimorbidity were calculated according to gender and age groups. Results: Among the participants, 66.7% were women and 8.2% were aged 70 years and older; hypertension was the most prevalent chronic condition, affecting 37.2% of the total sample. The incidence rate of multimorbidity was calculated as 27.3 per 1,000 person-years overall, with 27.6 observed in females and 41.4 among individuals aged 70 years and above. According to the results of multivariable Cox regression analysis, age was strongly associated with an increased risk of multimorbidity; individuals aged 70 and above had a 3.68-fold higher risk compared to those aged 30–39 (HR: 3.68, 95% CI: 2.63–5.16, p < 0.001). Conclusion: This study is the first cohort study conducted in our country on the epidemiology of multimorbidity. This study’s results highlight the importance of targeted preventive strategies for older populations to address the growing burden of multimorbidity. Keywords: multimorbidity, incidence, cohort study