FARMERS LUNG-DISEASE - LONG-TERM CLINICAL AND PHYSIOLOGIC OUTCOME

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Abstract
To determine the long-term effects of farmer''s lung disease and the factors influencing the outcome, 141 patients with farmer''s lung disease were evaluated. At the time of the last follow up, 29 patients died and 92 (mean age, 54 yr) were studied clinically, physiologically and radiologically. The mean length of disease was 14.8 yr (range, 2.25-40 yr). Symptoms at the time of the last follow-up included complaints of cough (33% of the patients), breathlessness while walking on level ground (20%), breathlessness on minor exertion (14%), breathlessness while at rest (3%), chronic bronchitis (28%) and 39% (36 of 92 patients) had some evidence of interstitial changes on roentgenogram. Abnormal vital capacity was present in 11 patients (12%), abnormal total lung capacity in 11 (12%), and abnormal CO diffusing capacity in 27 (30%). The ratio of 1 s forced expiratory volume to forced vital capacity was abnormal in 23 patients (25%), and arterial PO2 [partial pressure of oxygen] was abnormal in 39 (40%). Patients with a history of 5 or more symptomatic recurrences had significantly smaller values (P < 0.05) for vital capacity, total lung capacity and CO diffusing capacity than did those patients with less than 5 recurrences. There was no significant relation between continued farming or length of disease and lung function. On the basis of several measurements of airway function, 34 of the patients (58%) had some abnormality. Symptomatic recurrences may be the most important factor in determining the danger of progressive disease. Persistently positive precipitins were correlated with decreased CO diffusing capacity. Airway disease is relatively uncommon but does occur, and in some cases it is a possible consequence of farmer''s lung disease.