Serum IgD in subjects with and without chronic obstructive pulmonary disease: a previous finding restudied.

A previous study of matched pairs of subjects with and without COPD showed higher geometric mean values of serum IgD among the affected subjects. In an attempt to replicate this finding in another sample a cooperative study was undertaken to measure IgD in subjects from an epidemiologic study of airway obstructive disease from a different geographic region. The relationship between serum IgD (Ine scale) and % FEV1, was identical in the 2 samples. The lack of statistical significance when analyzing the Arizona sample in a matched pair fashion is attributed to an underrepresentation of subjects with very low % FEV1, and smaller sample size.