Epidemiology of multimorbidity in Iran: An investigation of a large pharmacy claims database

Multimorbidity (MM) (presence of more than one chronic condition within a same patient) imposes a heavy burden on patients and health care systems. In contrast to high-income countries, the epidemiology of this phenomenon is unclear in low- and middle-income countries, particularly among Iranian population.

This was a retrospective cohort study using Iranian Health Insurance Organization claims database. A framework was developed for identifying a set of 18 chronic conditions from the pharmacy claims data in Iran. All 2013 outpatient utilizers (aged 18 years or older) were included. Data were analyzed according to number of chronic conditions, gender, and age. The association between MM and utilizations of health services was examined for 2013 to 2016.

In total, 481 733 people were included. Cardiovascular diseases (including hypertension) (19.1%), depression/anxiety/sleep disorders (13.7%), and acid-related disorders (10.3%) were the three most prevalent conditions. MM was present in 21.1%. Although prevalence of MM is higher in older age groups and was present in 40% of individuals aged 65 and older, the absolute number of multimorbid patients was higher in those younger than 65 years (66 271 vs 35 386). MM was more prevalent among women (22.1%) compared with men (19.5). After multivariate adjustment for age group and sex, each additional chronic condition was associated with an increase of 2.23 physician visits, 2.86 drugs dispensed, 2.32 laboratory tests, and 1.6 medical imaging.

Our findings challenge the current single-disease-based assumption implicit in Iranian health care system. To take account of MM, complementary strategies should be designed and implement in health care system.