Characteristics of Current Smokers in the PLCO Study, by COPD Status.

COPD cases responded affirmatively to question(s) regarding diagnosis of emphysema (on study baseline questionnaire, follow-up questionnaire in 2006, or both), chronic bronchitis (on study baseline questionnaire), or both. Baseline data were substituted for missing follow-up questionnaire data for the following variables (number of participants) for race (218), age at smoking initiation (108), pack-years (299), cigarettes per day (65), smoking duration (262). PLCO, Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Some values do not sum to 100 due to missing data. a Report prior to PLCO follow-up questionnaire in 2006 b Self-report of emphysema and chronic bronchitis was not mutually exclusive; 201 participants reported a diagnosis of both emphysema and chronic bronchitis, thus the sum of reports of emphysema and chronic bronchitis are greater than the total 1,136 COPD cases. Characteristics of Current Smokers in the PLCO Study, by COPD Status.