We performed a cross-sectional, multi-level study. In this study, MetS was defined based on American Heart Association (AHA) criteria. According to AHA, any patient who has 3 or more conditions of high levels of triglycerides, hypertension, hyperglycaemia, low levels of HDL, and waist circumference more than > 102 cm in men, and > 89 cm in women is considered as a MetS patient [21, 22]. In this study, due to lack of data regarding patients’ waist circumference, this item was not considered in defining criteria.
In current study, according to European view, patients whose prescriptions included 5 or more drugs were considered in the polypharmacy group [5–7]. We only included the drugs which have been repeated 3 times or more in the prescriptions of one year [23]. Only the patients who had blood sugar lowering agents in their prescriptions were considered as patients with diabetes.
Data was gathered from 102 million prescriptions related to Iranians Health Insurance Service records in 2015 and 2016, which was then overlapped with STEPS Iran 2016 project data. STEPS is a national, large scale cross sectional study which assessed risk factors of 4 non-communicable diseases (cardiovascular, diabetes, cancers, chronic respiratory diseases) in Iran in 389 districts. About 31,000 patients were enrolled in STEPS 2016 study and all their demographic and epidemiologic data as well as risky behaviours were recorded in the form of laboratory data, physical examinations, and questionnaire [24]. At first, approximately 16,000 patients, whose prescriptions overlapped with STEPS data were selected from insurance data and 2075 patients, 25 year olds and above with MetS were chosen according to AHA criteria (Fig. 1). All patients have been categorized based on gender, and area of living (urban and rural). Also we defined 4 age groups; 25 to 39 years, 40 to 59 years, 60 to 80 years and over 80 years old. Also based on their education level; we had illiterate, one to 6 years of education, 7 to 12 years of education and more than 12 years. Furthermore, Principle Component Analysis (PCA) was used to define the wealth index of the patients [25]. The data regarding asset ownership and housing characteristics information are collected which are then combined into a proxy indicator such as the wealth index, which is created using PCA. Patients were accordingly divided into 5 groups; 0-<20% as poorest, 20-<40% as poor, 40-<60% as average, 60-<80% as rich and 80–100% as richest [26]. All drugs in the prescriptions were recorded as ATC codes [27]. Then, we assessed polypharmacy among the prescriptions of patients with diabetes. In this step, we separated the patients who consumed blood sugar lowering drugs three times or more during one year and evaluated HbA1c levels and polypharmacy amongst them. According to American Diabetes Association (ADA), 7% is the standard cut off for HbA1c [28]. Patients with HbA1c level equal or less than 7% were placed in controlled group and those with HbA1c higher than 7% were considered uncontrolled. Then we calculated the cost of prescribed drugs used at least once a year in 2015 and 2016, and subsequently assessed whether polypharmacy is effective among these patients in controlling their blood sugar levels based on HbA1c levels. Cost was defined as the actual price of the prescribed medications at least one time in a period of one year.
Analysis was done based on both individual factors (gender and age) and sociodemographic factors (education level, area of living, and wealth index). Correlation of HbA1c levels was evaluated with these factors and polypharmacy using adjusted and unadjusted logistic regression models. In one approach HbA1c was considered as a dependent variable and individual and socio-demographic factors and polypharmacy were all considered independent variables and regression was performed. In another approach, cumulative cost of drugs was calculated in 2015 and 2016 amongst prescriptions of patients with diabetes and then the cumulative cost was considered as dependant variable and individual and sociodemographic factors as well as polypharmacy, were all considered independent variables and linear regression was applied. Since the cost did not have normal distribution, we calculated the logarithm of the cost in our assessments. SPSS version 22 software was used for analysis of data. P value ≤ 0.05 was considered as statistically significant.