Prevalence and associated factors of asthma and COPD among adults in Iran based on the 2021 STEPS survey.

OBJECTIVE: This study aimed to estimate the prevalence of diagnosed asthma and Chronic Obstructive Pulmonary Disease (COPD) among Iranian adults aged 18 years and older using data from the STEPS 2021 survey. METHODS: We conducted a cross-sectional analysis using data from the nationally and sub-nationally representative world health organization (WHO) STEPS 2021 survey in Iran. Adults aged ≥ 18 years were selected through systematic cluster random sampling method. Self-reported lifetime physician-diagnosed chronic respiratory diseases (CRDs), including asthma or COPD was recorded using a standardized questionnaire. Data on demographics, socioeconomic status, smoking, physical activity (PA), anthropometric and biochemical indicators were collected. Logistic regression models were used to identify factors associated with CRDs. RESULTS: Among 27,794 adults, the overall weighted prevalence of self-reported CRDs was 4.39% (95% CI: 4.13,4.67), with slightly higher prevalences in females (4.61% [4.25,4.99]) and older adults (6.67% [6.00,7.41]). Multivariable analysis showed that older age (adjusted odds ratio (aOR): 2.30, 95% CI: [1.54,3.43]), obesity (1.56 [1.30,1.88]), and smoking (1.44 [1.18,1.78]), cardiovascular disease (1.41 [1.14,1.73]), hypertension (1.17 [1.01,1.36]), and cancer (2.50 [1.68,3.71]) were associated with CRDs. Twelve or more years of schooling was associated with lower odds (0.68 [0.53,0.87]) of CRDs compared to individuals with illiteracy education, while dyslipidemia showed a negative association (0.76 [0.64,0.90]). No significant difference in prevalence was observed between urban and rural residents. CONCLUSION: CRDs affect a substantial proportion of Iranian adults, with higher prevalence observed among older individuals, females, smokers, and those with cardiometabolic comorbidities. These findings highlight the need for targeted prevention strategies, enhanced disease surveillance, and integrated management approaches within Iran's primary healthcare system. Given the cross-sectional design and shared upstream exposures, associations should not be interpreted causally; observed co-morbidities may largely reflect common determinants.