Database on the Standardized mortality ratio (SMR all causes and SMR all cancer) for various professions (706 cohorts/groups): the maximum "health worker effect" for cosmonauts and doctors

Abstract

Researchers have formed a database for work on the evaluation of the indices of the "standardized mortality ratio" (SMR±95% confidence intervals — CI) in comparison with the general population for total mortality and mortality from all malignant neoplasms ("all cancers") for various professions and types of employment (mainly men). The database includes 689 publications (706 cohorts/groups, 67 professions and types of employment).
 Experts have conducted an assessment the presence of the "healthy worker effect" (HWE) in the studies included in the database based on the criterion of the upper 95% CI value of less than one.
 Among all professions and types of employment, scientists have identified HWE in total mortality only in 52%, and in mortality from all types of cancer — only in 28% of cohorts/groups.
 HWE for both indicators simultaneously and only for total mortality occurred in 26% of cases. For 2% of the studies, there is an inverse relationship (absence of HWE for total mortality in the presence of an effect on mortality from all types of cancer), which is most likely accidental.
 There were no strict dependencies between HWE and the carcinogenic potential of activity, although there was a definite trend. 
 The frequency of work with HWE for specific professions identified as the most "unprofitable" work with such heavy metals as Hg, Cd, Pb, Cu (the frequency of HWE is 0% for total mortality and 5% (mercury miners) for mortality from malignant neoplasms; one publication), followed by activities related to dust exposure (talc, quartz, various minerals, etc.; 5% and 6%) and asbestos (10% and 2%). Pilots (89% and 65%), oil and petrochemical industry workers (97% and 56%), as well as doctors (94% and 96%) and cosmonauts/astronauts (100% and 67%; the sample is small) occupied leading positions in the highest frequency of HWE.
 A complete sample of SMR studies of foreign doctors (1886–2017) demonstrated a strict linear decrease in the SMR value in total mortality compared with the population since the 1940s (r=–0.927; p<0.001), with SMR=0.38 (95% CI: 0.01; 0.76) achieved by the 2010s.
 At the same time, mortality from all cancers among doctors was reduced in comparison with the population almost equally for all time periods since 1926 (average SMR=0.6; 95% CI: 0.53; 0.66).
 Possible reasons for the reduced mortality among foreign doctors compared to the population are not only in prevention and professional skills, but probably in better access to medicine and specialists. In connection with professional solidarity, medical care and informing doctors is apparently distinguished by great attention.
 Earlier treatment of non-cancerous pathologies is also important, preventing their transformation into chronic ones, which can subsequently lead to carcinogenic consequences.