Risk factors for occupational acute mountain sickness

Abstract

BACKGROUND: Studies of occupational acute mountain sickness (AMS) have not focused on the more severe end of the spectrum to date. AIMS: To examine risk factors associated with the development of occupational AMS severe enough to receive treatment in a compression chamber. METHODS: A nested case referent study in a cohort of high-altitude (4000 m) mine workers, comparing cases of severe, chamber-treated AMS to matched referents. Using logistic regression, we tested potential risk factors based on premorbid surveillance examinations, including cigarette smoking (current smoking, smoking intensity and exhaled carbon monoxide [CO]). RESULTS: There were 15 cases and 30 controls. In multivariate analysis including age, sex and place of residence, current smoking was associated with increased risk of severe AMS (odds ratio [OR] 10.0; 95% confidence interval [CI] 1.5-67.4), taking into account any prior, less severe AMS event, which was also a potent risk factor (OR 33.3; 95% CI 2.8-390). Smoking intensity (cigarettes per day) and exhaled CO were also statistically significantly associated with severe AMS. CONCLUSIONS: Cigarette smoking is a strong, previously under-appreciated risk factor for severe AMS. Because this is a modifiable factor, these findings suggest that workplace-based smoking cessation should be tested as an intervention to prevent such morbidity.