Long-term outcome of pulmonary function in farmer's lung: a 14 year follow-up with matched controls

Abstract

The long-term outcome of pulmonary function was evaluated in farmer's lung (FL) patients compared to representative control farmers. This is, to our knowledge, the first such study which has included a control group. Clinical examinations were conducted in 89 FL patients and 84 control farmers, matched by age, sex, and smoking habits. The mean time after the first diagnosed episode of FL was 14 yrs.The mean transfer factor of the lung for carbon monoxide (TL,CO) was on average 12% lower (p<0.001) in FL patients compared to control farmers. In spirometry, the mean maximum expiratory flow at 50% of vital capacity (MEF50) was lower (p=0.08) in FL patients but there were no differences in mean vital capacity (VC) or forced expiratory volume in one second (FEV1) between FL patients and control farmers. However, airway obstruction, defined as an FEV1/VC less than 88% of predicted, was more common in FL patients than in control farmers (33 versus 17%; p=0.02). Patients who had had recurrent episodes of FL had a significantly lower mean TL,CO compared to those FL patients who had experienced only a single episode.In conclusion, impairment of the pulmonary transfer factor is the most important long-term consequence of farmer's lung. However, farmer's lung may also lead to development of airway obstruction.

Hypersensitivity pneumonitis in a cluster of sawmill workers: a 10-year follow-up of exposure, symptoms, and lung function

“…16,24,25 An impaired pulmonary gas transfer and a tendency toward airway obstruction over time are the most common defects reported in exposed farmers. 27 This study has several strengths and limitations. The homogeneous and well-defined study group, precise and comprehensive measurements of exposure, and longitudinal design are all strengths.…”

Hypersensitivity pneumonia: the role of lung biopsy in diagnosis and management

“…26,27 Lung function improves over a period of months and years, but abnormalities may persist in nearly half of patients. [26][27][28] Diseasespecific mortality rates in chronic hypersensitivity pneumonia range from 10 to nearly 30%. Repeated symptomatic attacks, older age, cigarette smoking, and the presence of established fibrosis and honeycomb change at the time of diagnosis, are associated with a more aggressive course.…”

Pneumonia de hipersensibilidade crônica: análise de oito casos e revisão da literatura

“…O aspecto funcional típico da PH crônica é o distúrbio ventilatório restritivo (1,2,5) , o que foi encontrado em cinco dos sete pacientes estudados. Distúrbio ventilatório obstrutivo pode ser descrito e é explicado pelo comprometimento das vias aéreas pelo processo inflamatório granulomatoso (bronquiolite) e/ou pela fibrose (1,5,16) , sendo encontrado em dois casos desta série. Este achado também é descrito em outras doenças pulmonares intersticiais crô-nicas, tais como a sarcoidose e a fibrose pulmonar idiopática (FPI) (17) .…”

“…A espirografia normal vista num dos pacientes, contrastando com os sintomas e as alterações radiológicas, mostra que na PH crônica, tal como ocorre na FPI, nem sempre existe correlação absoluta entre os achados clínicos, radiológicos e funcionais (14,17) . A capacidade de difusão do monóxido de carbono e a complacência pulmonar não foram avaliados nesta série, mas em geral encontram-se reduzidas (1,5,16) . A hipoxemia constitui aspecto freqüente na PH crônica (1,5) e foi constatada em cinco de sete pacientes desta casuística.…”