Of the 26 principal studies of emphysema, the out- come is based on visual comparison in 10 (38.5%), on diagnosis in seven (26.9%), on ICD codes in five (19.2%) and on other sources including self-report in four (15.4%). Asthmatics are excluded in two (7.7%) studies. The ...
Those who had made physician visits for traffic accidents (ICD-9 code: E800-E848) or acute gastroenteritis (ICD-9 code: 008.8; 009.1; 558.3; 558.9) the same year and who had never been diagnosed as having chronic bronchitis were considered potential study controls. Any case or control ...