Copyright © 2017 American College of Occupational and Environmental Medicine. Unauthorized reproduction of this article is prohibited Occupation and Obstructive Sleep Apnea: A Meta-Analysis Daniel A. Schwartz, MA, Denis Vinnikov, MD, PhD, MPH, and Paul D. Blanc, MD, MSPH Objective: Obstructive sleep apnea (OSA) remains a prevalent condition, but its occupational burden is unclear. We carried out a systematic review to characterize the consistency and magnitude of occupational associations with OSA. Methods: We studied OSA within three occupational categories: commercial drivers, organic solvent-exposed workers, other selected occu- pations. We performed a meta-analysis on the prevalence of OSA among drivers and the risk of OSA associated with solvent exposure. Results: The pooled OSA prevalence in drivers was 41% (95% confidence interval [CI] 26% to 56%) for apnea hypopnea-index (AHI) is greater than 5, and 15% (95% CI 12% to 19%) for AHI is greater than 15. Exposure to solvents was associated with increased but non-statistically significant risk of OSA: summary relative risk, 2.38 (95% CI 0.89 to 6.32). Evidence of occupational association was inconsistent for other factors. Conclusions: OSA is com- mon among commercial drivers and potentially associated with occupations involving likely solvent exposure. S everal risk factors have been associated with the development and progression of obstructive sleep apnea (OSA), including excess body weight, smoking, and alcohol consumption. Each of these risk factors, in turn, can have occupational associations. Health care costs, accident causation, and work-associated lifestyle risk factors have made occupation in association with OSA a topic of clinical and public health policy interest. 1 The potential link between OSA and employment as a commercial driver has gener- ated particular attention in this regard. 2,3 Moreover, the potential association between selected workplace inhalational exposures and OSA has also been the subject of multiple studies. Despite the potential importance of such work-related factors in the prevalence of and risk for OSA, there has been only limited systematic review of this topic. To address this knowledge gap, we undertook an assessment of the biomedical literature addressing occupational factors in the development of OSA, particularly focusing on commercial driving and work-related organic solvent exposure. We also reviewed studies relevant to other potential occupational factors, such as particulate inhalation, military service, and other discrete occupational risks. METHODS Overview We carried out a systematic review of occupational factors associated with increased OSA prevalence within an occupational group or increased risk compared with referents. A preliminary search revealed three occupational areas of interest with relevant data: commercial driving; work involving likely exposure to organic solvents; and a remaining heterogeneous group including exposure to particulates, military service, and miscellaneous professions. Based on this initial assessment, we designed a topic area specific, three-part search strategy to identify publications eligible for inclusion. We applied consistent study inclusion criteria for studies within categories of exposure, with allowance for differing criteria across topics depending on the nature of the available data sets. For OSA prevalence data among drivers, we required that sleep studies had been carried out among a cohort not preselected on the basis of symptoms suggestive of OSA, and that reported polysomnographic data included discrete apnea hypopnea-index (AHI) cut points. As a preliminary search showed no available case-control data, only cross-sectional data were used for the driver topic. For solvent exposure and miscellaneous exposures where risk relative to refer- ent group was estimated, we required that whatever the definition of OSA used (which could include various sleep laboratory criteria or diagnostic coding), the same one had been applied to both exposed and referent groups. For limited data beyond drivers and occu- pations with solvent exposure, we allowed either polysomnography- defined prevalence or risk estimation compared with a referent group. Where the data allowed, we employed a formal meta-analytic approach for a pooled prevalence estimate (OSA among drivers). For the study of OSA risk, we required use of an appropriate referent group and used meta-analysis to estimate pooled risk (OSA associ- ated with solvents). For the remaining studies of dust-exposure, military service, and miscellaneous occupations, we performed a narrative review only. Data Search and Studies Identification We used the updated PRISMA protocol 4 for our search and study identification process. We relied upon PubMed and Embase as the primary source for epidemiologic studies. Searches were inclus- ive of publications up to June 30, 2016. The search strategy for the driver topic area included the following search phrases: ‘‘drivers AND sleep AND apnea’’ and ‘‘commercial AND driver AND sleep AND apnea.’’ For other work-related factors including solvent exposures, the following search phrases were used: ‘‘occupational Learning Objectives  Discuss the unique approach followed in the present review and meta-analysis of research on occupation as a risk factor for obstructive sleep apnea (OSA).  Summarize the findings on the prevalence of OSA among commercial drivers.  Summarize the findings on solvent exposure as a risk factor for OSA, as well as in other occupational groups with studies including polysomnographic data. From the UC Berkeley-UCSF Joint Medical Program, School of Public Health, University of California, Berkeley, Berkeley (Mr Schwartz); Department of Internal Medicine, Occupational Disease and Hematology, Kyrgyz State Medical Academy, Bishkek, Kyrgyzstan, and School of Public Health, Al- Farabi Kazakh National University, Almaty, Kazakhstan (Dr Vinnikov); Division of Occupational and Environmental Medicine, Department of Medicine, University of California San Francisco, San Francisco (Dr Blanc), California. Funding sources: None declared. Authors Schwartz, Vinnikov, and Blanc have no relationships/conditions/circum- stances that present potential conflict of interest. The JOEM editorial board and planners have no financial interest related to this research. Supplemental digital contents are available for this article. Direct URL citation appears in the printed text and is provided in the HTML and PDF versions of this article on the journal’s Web site (www.joem.org). Address correspondence to: Daniel A. Schwartz, MA, School of Public Health, University of California, Berkeley, 50 University Hall #7360, Berkeley, CA 94720-7360 (dan.schwartz@berkeley.edu). Copyright ß 2017 American College of Occupational and Environmental Medicine DOI: 10.1097/JOM.0000000000001008 502 JOEM  Volume 59, Number 6, June 2017 CME A VAILABLE FOR THIS ARTICLE AT ACOEM.ORG