The Prevalence of Multimorbidity and Associations With Clinical Outcomes Among Middle Aged People in Golestan, Iran: A Longitudinal Cohort Study

Background: As the populations of lower- and middle-income countries (LMICs) age, multimorbidity is increasing. There is little research on epidemiology and consequences of multimorbidity in LMICs. Methods: The Golestan Cohort Study recruited participants aged 40-75 years free of any gastrointestinal cancer between January 2004 and June 2008. Baseline data were collected on demographics, medications, self-reported illness, tobacco and alcohol consumption, physical activity, and clinical measurements were taken. Participants were followed up annually and hospital admissions and deaths were recorded.  Multimorbidity was categorised as: count of conditions, or as two or more conditions, and the association with death within ten years of study entry was investigated using multivariable logistic regression. Further associations of multimorbidity with survival and hospitalisations were explored using Cox models and Poisson logistic regression models respectively. Findings: Of the original 50,045 individuals, 2,162 were removed because of missing baseline data or incorrect follow up date entered. A further 2,297 participants were removed from the complete case analysis due to loss to follow up; these participants were included in the survival analysis.During 10 years of follow up 5,411 participants died and 17,855 were hospitalised at least once. Odds of death increased with increasing number of conditions, after controlling for age, sex, education, wealth, physical activity, smoking history, and BMI. Compared to no conditions, the odds ratio (OR) for death for people with two or more conditions was 1.99 (95% CI 1.86 - 2.12, p<0.001) and even higher for people with four or more conditions (OR 3.57; 95% CI 3.12-4.08, p <0.001). Number of hospital admissions also significantly increased with number of conditions after adjustment for demographic and behavioural risk factors. Interpretation: This is one of the first studies to report on longitudinal effects of multimorbidity in a LMIC, and shows that the long terms effects of multimorbidity on mortality and hospitalisation, are just as detrimental as in high income countries. This should have major impact on health policy and planning in the years to come, and resources and global health funds need to be aimed at improving health system preparedness in LMICs to treat this patient group. Funding Statement: MDW acknowledges support from the NIHR Newcastle Biomedical Research Centre. TM is supported by the National Institute for Health Research (NIHR) Applied Research Collaboration (ARC) West Midlands. This report presents independent research funded by the National Institute for Health Research (NIHR). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: This was a secondary analysis of de-identified participant data. The initial study was approved by the ethics committee of the Digestive Diseases Research Institute, Tehran, University of Medical Sciences (OHRP-IRB-00001641). Before participation, a written informed consent was obtained from each participant, allowing investigators to use anonymised data for future analysis.