Recent U.S. data suggest an increased risk of work-related asthma among healthcare workers. However, results have been inconsistent and lacking in detail. To assess the magnitude of asthma risk, evaluate associations with occupational exposures, and estimate the burden of work-related asthma in healthcare professionals, a new survey instrument for work-related asthma among health care workers was developed, validated and administered in a field study. The project was conducted in two separate and consecutive phases. In Phase I, the survey instrument was developed, validated and refined. In Phase II the validated questionnaire was administered to a population-based sample of selected groups of health care workers in Texas. Phase I resulted in an eleven page questionnaire which required approximately 13 to 25 minutes to complete. Test-retest reliability of asthma and allergy items ranged from 75% to 94%, and internal consistency for these items was excellent (Cronbach's alpha greater than or equal to 0.86). Against methacholine challenge, an 8-item combination of asthma symptom items had a sensitivity of 72% and specificity of 71 %; against a physician diagnosis of asthma, this same combination showed a sensitivity of 89% and specificity of 98%. In Phase II, using the questionnaire validated in Phase I, a cross-sectional statewide survey of 5600 Texas healthcare professionals (physicians, nurses, respiratory therapists and occupational therapists) was conducted. A simple random sample of 1400 persons was drawn from each of the four populations of professionals (physicians, nurses, respiratory therapists and occupational therapists) with active licenses in 2003. Information on asthma symptoms and nonoccupational asthma risk factors obtained from the survey was then linked to occupational exposures derived from an external asthma risk factor job-exposure matrix (also developed for this study). Overall response rate was 66%. The final study population consisted of 862 physicians, 941 nurses, 968 occupational therapists and 879 respiratory therapists (n=3650). There were two a priori defined outcomes: a) physician-diagnosed asthma with onset after entry into healthcare ('reported asthma'), and b) 'bronchial hyperresponsiveness-related symptoms', defined through the 8-item symptom-based predictor. Reported asthma was associated with medical instrument cleaning (OR, 2.22; 95% CI, 1.34-3.67), general cleaning (OR, 2.02; 95% CI, 1.20-3.40), use of powdered latex gloves between the years 1992 and 2000 (OR, 2.17; 95% CI, 1.27 to 3.73) and administration of aerosolized medications (OR, 1.72; 95% CI, 1.05 to 2.83). The risk associated with latex gloves disappeared after 2000. Bronchial hyperresponsiveness-related symptoms were associated with general cleaning (OR, 1.63; 95% CI, 1.21-2.19), aerosolized medication administration (OR, 1.40; 95% CI, 1.06-1.84), use of adhesives on patients (OR, 1.65; 95% CI, 1.22-2.24) and exposure to a chemical spill (OR, 2.02; 95% CI, 1.28-3.21). Occupational exposures contribute importantly to asthma in healthcare professionals, meriting both further study and implementation of appropriate controls.
Dr G L Delclos, The University of Texas-Houston, School of Public Health, 1200 Herman Pressler St, Suite 1004, Houston, TX 77030, USA