Hypersensitivity pneumonitis in workers exposed to metalworking fluids.

BACKGROUND: This study used data from a large UK outbreak investigation, to develop and validate a new case definition for hypersensitivity pneumonitis due to metalworking fluid exposure (MWF-HP). METHODS: The clinical data from all workers with suspected MWF-HP were reviewed by an experienced panel of clinicians. A new MWF-HP Score was then developed to match the "gold standard" clinical opinion as closely as possible, using standard diagnostic criteria that were relatively weighted by their positive predictive value. RESULTS: The new case definition was reproducible, and agreed with expert panel opinion in 30/37 cases. This level of agreement was greater than with any of the three previously utilized case definitions (agreement in 16-24 cases). Where it was possible to calculate, the MWF-HP Score also performed well when applied to 50 unrelated MWF-HP cases. CONCLUSIONS: The MWF-HP Score offers a new case definition for use in future outbreaks.

Natural history and risk factors of early respiratory responses to exposure to cotton dust in newly exposed workers.

OBJECTIVE: A prospective study of newly exposed cotton workers was performed to investigate the natural history of respiratory symptoms and lung function changes. METHODS: A total of 157 workers naive to cotton dust exposure were investigated by questionnaire, spirometry, and skin tests. They were examined before employment (baseline) and at the end of the first week, and the first, third, sixth, and 12th month after starting work. Acute airway response was defined as either a cross-first-shift or a cross-week fall in forced expiratory volume in one second (FEV1). The longitudinal change of lung function over the year was also calculated. Five hundred seventy-two personal dust sampling and 191 endotoxin measurements were performed to assess the exposure. RESULTS: Forty percent of workers reported work-related symptoms in the first week of the study. Smoking, endotoxin, and dust concentrations were risk factors for all work-related symptoms. Acute airway responses were witnessed after immediate exposure. Female status was the only factor found to be predictive of acute airway response. The mean longitudinal fall in FEV1 at 1 year was 65.5 mL (standard error = 37.2). Age, early respiratory symptoms, and early fall in cross-week FEV1 were found to predict the 12-month fall in FEV1. Cross-first-shift and cross-week falls in FEV1 reduced in magnitude during the course of the study. CONCLUSIONS: This study of workers naive to cotton dust exposure has demonstrated that respiratory symptoms and acute airway responses develop early following first exposure, and a tolerance effect develops in those workers with the continued exposure. Current smoking and increasing exposure predicts the development of work-related lower respiratory tract symptoms, while early symptoms and acute airway changes across the working week predict the longitudinal loss of lung function at 1 year.