Chlamydia pneumonia serology, lung function decline, and treatment for respiratory disease

Associations have been reported between Chlamydia pneumoniae seropositivity and both acute and chronic obstructive airway diseases. Plasma specimens c ollected between 1979 and 1983 from 1,773 men 45 to 59 yr of age in Caerphi lly, South Wales, were tested for IgG and IgA antibodies to C. pneumoniae ( TW183) by microimmunofluorescence. Subsequent mortality and medication for obstructive airway disease were ascertained at 5-yr follow-up examinations. Spirometry was performed at the first and second examinations and analyzed both cross-sectionally and longitudinally; 642 men (36%) had IgG antibodie s at a titer of 1:16 or above, of whom 362 also had detectable IgA antibodi es. No statistically significant associations were found between either IgG titer or IgA titer and any of the outcome measures: inhaler therapy at ent ry; commencement of inhalers during follow-up; death from respiratory cause s; baseline FEV1, FVC, and FEV1/FVC ratio; and decline in FEV1 (p > 0.1 thr oughout). Men with high IgG titers (greater than or equal to 1:64) had a sl ower rate of decline of FEV1 than did seronegative subjects (adjusted mean difference in 5-yr change in FEV1: +22 ml, 95% confidence interval: -31 ml to +76 ml). Men with high IgA titers (greater than or equal to 1:16) had a slightly faster rate of decline (-12 ml, -96 ml to +71 ml). This first pros pective assessment suggests that chronic C. pneumoniae infection is not a m ajor risk factor for progressive airflow obstruction.