The present study was conducted as part of Isfahan Healthy Heart Program (IHHP). Details of this program including sample size, data entry and data analysis have been published in a publication by Sarrafzadegan and colleagues.9
Multi-stage cluster randomization method was used for sampling and the population under study in the three cities of Isfahan, Najafabad and Arak were divided into urban and rural areas according to a general census conducted in 2008. These three cities were selected as intervention and control cities, due to their consistent populations and smaller number of migrants compared to the capital and other Iranian cities. Nearly 5-10% of this population were included in the study. Sample size was 9572 people who were classified based on age, sex, place of residence, marital status and level of education. Only participants who had lived in their respective areas for at least 10 years were included. Exclusion criteria include pregnancy, mental retardation and physical disabilities. Written informed consent was obtained from all participants after thoroughly briefing them about the stages of the study. Relevant information was obtained by trained health technicians by calling on the subjects at their homes.
Demographic factors; The demographic characteristics of participants was obtained in categories of age groups (19-24, 25-34, 35-44 years, 45-54, and above 55 years), sex (male, female), marital status (married and unmarried: single, divorced, separated), education level (0-5, 6-12, and above 12 years) and place of residence (urban, rural).
Indicators; One of the indicators studied was the subjects' smoking status. The subjects were placed in 3 groups, namely current smokers, non-smokers and ex-smokers.
Individuals smoking at least one cigarette per day were considered as current smokers, those who had quit smoking prior to the study were considered as ex-smokers, and those who did not smoke were considered as non-smokers.10
The standard GHQ12 for assessment of general health is completed by the respondents themselves. We used this questionnaire to assess the level of stress. This questionnaire consists of twelve 4-choice questions. To determine an individual's stress score in the preceding month based on the GHQ scoring method, those who chose (a) or (b) were given a score of 0, and those who chose (c) and (d) were given a score of 1. Scores of 4 and higher were considered as high GHQ, i.e. high stress.11
It must be noted that this questionnaire has been designed for subjects aged 12 years and higher and its reliability and validity has been assessed in an Iranian study.12
Statistical Analysis; The data were analyzed with SPSS15 and P values under the 0.05 were considered statistically significant. The data, including age, sex, place of residence, level of education and smoking status were depicted in percentages and compared using the chi square test. Logistic regression analysis was used to assess relative risk and confidence interval for stress level according to smoking status. Independent variables included smokers, non-smokers, ex-smokers, age groups, sex, place of residence, marital status and level of education. Stress level was the dependent variable.