Prevalence and risk factors for COPD in farmers: a cross-sectional controlled study

Abstract

There are conflicting data regarding the magnitude and determinants of chronic obstructive pulmonary disease (COPD) risk in farmers.In a cross-sectional study of 917 nonfarming working controls and 3787 farmers aged 40-75 years, we assessed respiratory symptoms, tobacco exposure, job history (without direct exposure measurement) and lung function. COPD was defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criterion ( post-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <0.70) and by the Quanjer reference equation ( post-bronchodilator FEV1/FVC <lower limit of normal (LLN)).The prevalence (95% CI) of COPD according to the GOLD criterion was 5.1% (4.4-5.8%) and 2.9% (1.8-4.0%) in farmers and controls, respectively ( p=0.005), and 3.1% (2.5-3.6%) and 1.5% (0.7-2.3%), respectively, for the LLN criterion ( p<0.01). For both COPD criteria after adjustment for age, sex and smoking status, COPD prevalence was similar in controls and crop farmers. Compared to controls, four job categories had a higher prevalence of COPD according to the GOLD criterion, namely, cattle breeders, swine breeders, poultry breeders and breeders of two or more livestock types. Among cattle breeders, only those from Franche-Comté had higher prevalence of COPD according to both GOLD and LLN criteria.The prevalence of COPD in farmers is higher than in nonfarming working controls, and depends on the farming activity, the region and the criterion used to define COPD. @ERSpublications Prevalence of COPD is higher in agricultural workers than in nonfarming working control subjects http://ow.ly/RUYe8

COPD in farmers: what have we learnt?

“…COPD prevalence estimates, then, often reflect either inclusion or exclusion of individuals whose respiratory conditions lie along the spectrum of illness between asthma and COPD. However, one would expect higher COPD prevalence in this population of French farmers, since GUILLIEN et al [11] evidently did not account for previously diagnosed asthma, including these persons in analyses.…”

“…In this issue of the European Respiratory Journal, GUILLIEN et al [11] report findings on the prevalence of COPD in farmers from two regions in France. Comparing the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and lower limit of normal (LLN) criteria, two commonly used methods for diagnosing COPD, they estimated prevalence in agricultural workers across five different farming activities, categorised through the use of complete occupational histories.…”

“…For example, individuals near the 0.70 cut-point could be classified as either having or not having COPD depending on the use of pre-or post-bronchodilator values [11], and different prevalences of obstructive disease can be measured in the same population depending on the reference population chosen for spirometry comparison. For example, the European Community for Steel and Coal equations [21], used in this study, yield lower prevalence than other equations, such as those from the National Health and Nutrition Examination Survey and the Global Lungs Initiative 2012 [22].…”

“…Therefore, the identification of COPD cases depends on the age of the population, the choice of spirometry-based criteria, the use of pre-or post-bronchodilator spirometry, and the choice of a reference population. GUILLIEN et al [11] acknowledged several of these methodological issues by using post-bronchodilator values and comparing the GOLD and LLN criteria. Interestingly, this population is older than the comparison European farming populations and therefore would be expected to have higher prevalence based on age structure alone.…”

“…crop farming, livestock farming, swine and poultry farming). GUILLIEN et al [11] used thorough job histories to categorise farmers into mutually exclusive categories, ensuring that individuals assigned to a farming activity had spent ⩾10 years in that activity. However, can these broad job titles give us a true idea of the exposures encountered by farmers, considering the differences in farming practices across geographical, cultural and time boundaries?…”