COPD incidence and OR (95% CI) by characteristic.

Logistic regression was used, and variables such as baseline FEV1/FVC, age, sex, education, self-reported economic status, smoking intensity, use of clean fuel and improved ventilation, and the number of hours spent cooking each day were entered in the model. Baseline FEV1/FVC was entered in the model as a continuous variable with an OR of 0.73 (95% CI, 0.68 to 0.79), and the OR of V-only versus CF-only was 0.69 (95% CI, 0.23 to 2.08).aEntered in the model instead of the variable “use of clean fuel and improved ventilation.”