Mortality Risk in a Birth Cohort of Commuter Air Carrier and Air Taxi Pilots

Does intermittent exposure to high altitude increase the risk of cardiovascular disease in workers? A systematic narrative review

OBJECTIVE

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.

PROSPERO REGISTRY NUMBER

CRD42020171301.

Body Mass Index and Cardiovascular Disease in a Birth Cohort of Commuter Air Carrier and Air Taxi Pilots

PURPOSE

Acute cardiovascular events such as heart attack and stroke in commercial pilots have been a concern to flight safety. The purpose of this study was to examine the association of body mass index (BMI) with cardiovascular disease in commercial pilots.

METHODS

We followed from 1987 to 1997 a cohort of 3019 male commuter and air taxi pilots who were born between 1933 and 1942 and who were certified by the US Federal Aviation Administration. The relationship between BMI and the risk of cardiovascular disease was assessed using Poisson regression modeling based on generalized estimation equations.

RESULTS

At baseline, 55% of the pilots were overweight (25 kg/m(2) BMI < 30 kg/m(2)) and 7% were obese (BMI >/= 30 kg/m(2)). The follow-up accumulated a total of 20,671 person-years and 1897 diagnoses of cardiovascular disease, yielding an incidence rate of 92 per 1000 person-years. The incidence rates of cardiovascular disease increased significantly with BMI. With adjustment for baseline history of cardiovascular disease and age, pilots who were overweight and obese had 6% and 22% higher risk of cardiovascular disease, respectively, than their counterparts with normal BMI.

CONCLUSIONS

The prevalence of overweight/obesity and the relationship between BMI and cardiovascular disease among commercial pilots parallel findings from the general population. Incorporating BMI into the current medical standards for commercial pilots merits serious consideration.