Aragón-Vela, JerónimoBejder, JacobR. Huertas, JesúsPlaza-Diaz, JulioNordsborg, Nikolai B.2022-09-272022-09-272020-11-20Aragón-Vela J, Bejder J, R Huertas J, Plaza-Diaz J, Nordsborg NB. Does intermittent exposure to high altitude increase the risk of cardiovascular disease in workers? A systematic narrative review. BMJ Open. 2020 Nov 20;10(11):e041532http://hdl.handle.net/10668/4154Objective: Several working groups (eg, miners, flight crews and soldiers) are subjected to chronic intermittent hypoxic exposure. The cardiovascular implications have been studied but not systematically reviewed with focus on possible negative health implications. The aim of the present review was to systematically evaluate the hypothesis that intermittent hypoxic exposure causes cardiovascular stress detrimental to health in workers. Design: Systematic review. Data sources: Electronic database search of PubMed, Scopus and Web of Science up to April 2020. Eligibility criteria: Studies of workers ≥18 years repeatedly subjected to months to years of irregular intermittent hypoxia, lasting from a few hours (eg, flight crews), one or a few days (eg, soldiers), or several days to weeks (eg, miners working at high altitude), written in English and evaluating the effect of intermittent hypoxia on cardiovascular disease were included. Animal studies, books, book chapters, personal communication and abstracts were excluded. The primary outcome measure was changes in standardised mortality ratio. Data extraction and synthesis: Two independent reviewers extracted data and assessed risk of bias using the Cochrane Collaboration’s tool. Results: 119 articles were identified initially, 31 of which met the inclusion criteria. Of these, 17 were retrospective cohort mortality studies (irregular short-term intermittent hypoxia), and 14 studies were observational (long-term intermittent hypoxia). The population of irregular short-term intermittent hypoxia users (flight crew) showed a lower mortality by cardiovascular disease. Long-term intermittent hypoxia over several years such as in miners or soldiers may produce increased levels of cardiac disorders (12 studies), though this is probably confounded by factors such as obesity and socioeconomic status. Conclusion: This systematic narrative review found that cardiovascular disease mortality in flight crews is lower than average, whereas miners and soldiers exposed to intermittent hypoxia experience increased risks of cardiovascular diseases. The impact of socioeconomic status and lifestyle appears of importance.enAtribución-NoComercial 4.0 Internacionalhttp://creativecommons.org/licenses/by-nc/4.0/Coronary heart diseaseOccupational & industrial medicinePhysiologyPublic healthRetrospective studiesAltitudeSystematic reviewEnfermedad coronariaMedicina del trabajoFisiologíaSalud públicaEstudios retrospectivosAltitudRevisión sistemáticaMedical Subject Headings::Phenomena and Processes::Biological Phenomena::Ecological and Environmental Phenomena::Environment::AltitudeMedical Subject Headings::Check Tags::FemaleMedical Subject Headings::Organisms::Eukaryota::Animals::Chordata::Vertebrates::Mammals::Primates::Haplorhini::Catarrhini::Hominidae::HumansMedical Subject Headings::Diseases::Cardiovascular Diseases::Vascular Diseases::Cerebrovascular Disorders::Brain Ischemia::Hypoxia-Ischemia, BrainMedical Subject Headings::Check Tags::MaleMedical Subject Headings::Analytical, Diagnostic and Therapeutic Techniques and Equipment::Investigative Techniques::Epidemiologic Methods::Epidemiologic Study Characteristics as Topic::Epidemiologic Studies::Case-Control Studies::Retrospective StudiesMedical Subject Headings::Diseases::Cardiovascular DiseasesMedical Subject Headings::Organisms::Eukaryota::AnimalsMedical Subject Headings::Anthropology, Education, Sociology and Social Phenomena::Social Sciences::Sociology::Social ClassMedical Subject Headings::Diseases::Cardiovascular Diseases::Heart DiseasesMedical Subject Headings::Disciplines and Occupations::Natural Science Disciplines::Science::Research::Biomedical Research::Outcome Assessment (Health Care)Medical Subject Headings::Psychiatry and Psychology::Behavior and Behavior Mechanisms::Psychology, Social::Life StyleMedical Subject Headings::Information Science::Information Science::Communications Media::Publications::Bibliography as Topic::Bibliometricsresearch article33444211open access10.1136/bmjopen-2020-0415322044-6055PMC7682469