RESUMO
BACKGROUND: Indonesia ranks 7th highest in the world for the number of deaths caused by tobacco use including those caused by Chronic Obstructive Pulmonary Disease (COPD). The purpose of this study was to determine the influence of initial smoking age and habit on the incidence of COPD. METHODS: This research was a case-control study. The sampling in this research took a systematic random sampling method. The samples of this study were 56 respondents of a case group and 56 respondents of a control group. This study was conducted at Ngudi Waluyo Hospital, Wlingi, Blitar from October to November 2017. RESULTS: The factors that influenced the incidence of COPD were being male (p = 0.00; OR = 6.333; 95%CI = 2.776-14.450), a smoker (p = 0.00050; OR = 5.1318; 95%CI = 1.9004-13.8958), initially smoking at <15 years old (p = 0.00; OR = 11,769; 95%CI = 4.086-33.903), initially getting into a smoking habit at the age of <15 years old (OR = 12; CI = 1346-106,950), initially getting into a smoking habit at the age of ≥15 years old (OR = 3647; CI = 1625-8183) and having smoked for ≥30 years (OR = 8857; CI = 3298-23,787). CONCLUSION: There are three factors of smoking behavior that influence COPD: smoking habit, initial smoking age and smoking duration. Of all factors, forming a smoking habit at the age of <15 years old has the biggest risk (OR = 12; CI = 1346-106,950).