Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort study
OBJECTIVES Long working hours have been reported to cause various health problems, but are currently practiced in many countries. Building upon a previous cross-sectional study, the authors aimed to elucidate the causal relationship between long working hours and hypothyroidism through a longitudina...
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| Format: | Article |
| Language: | English |
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Korean Society of Epidemiology
2022-11-01
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| Series: | Epidemiology and Health |
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| Online Access: | http://www.e-epih.org/upload/epih-44-e2022104.pdf |
| _version_ | 1797768354838085632 |
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| author | Yesung Lee Woncheol Lee Hyoung-Ryoul Kim |
| author_facet | Yesung Lee Woncheol Lee Hyoung-Ryoul Kim |
| author_sort | Yesung Lee |
| collection | DOAJ |
| description | OBJECTIVES Long working hours have been reported to cause various health problems, but are currently practiced in many countries. Building upon a previous cross-sectional study, the authors aimed to elucidate the causal relationship between long working hours and hypothyroidism through a longitudinal study. METHODS Data were collected at baseline from 45,259 participants without thyroid disease and with consistent weekly working hours (36–40, 41–52, 53–60, and >60 hours) during the follow-up period. Hypothyroidism was defined using the reference limits of serum thyroid-stimulating hormone and free thyroxine levels. By estimating hazard ratios (HRs) and 95% confidence intervals (CIs) using Cox proportional hazards regression analysis, the risk of incident hypothyroidism was evaluated with 36–40 hours of work per week as the reference. RESULTS During 138,261.7 person-years of follow-up, 2,914 participants developed hypothyroidism (incidence density, 2.11/102 person-years). The multivariable-adjusted HRs of incident hypothyroidism for 41–52 hours, 53–60 hours, and >60 hours of work per week were 1.13 (95% CI, 1.03 to 1.24), 2.53 (95% CI, 2.17 to 2.95), and 2.57 (95% CI, 2.09 to 3.15), respectively. In dose-response analyses, long working hours had an approximately linear relationship with hypothyroidism incidence. The risk of incident hypothyroidism in those who worked 53–60 hours and >60 hours per week compared with the reference group was significantly higher among the older age group (≥36 years, stratified by median age), men, and daytime workers. CONCLUSIONS This large-scale cohort study demonstrated the association between long working hours and an increased risk of incident hypothyroidism with a dose-response relationship. |
| first_indexed | 2024-03-12T20:53:17Z |
| format | Article |
| id | doaj.art-8b2e58bf8af84c9ba19e70831b2a7e81 |
| institution | Directory Open Access Journal |
| issn | 2092-7193 |
| language | English |
| last_indexed | 2024-03-12T20:53:17Z |
| publishDate | 2022-11-01 |
| publisher | Korean Society of Epidemiology |
| record_format | Article |
| series | Epidemiology and Health |
| spelling | doaj.art-8b2e58bf8af84c9ba19e70831b2a7e812023-08-01T00:41:58ZengKorean Society of EpidemiologyEpidemiology and Health2092-71932022-11-014410.4178/epih.e20221041352Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort studyYesung LeeWoncheol LeeHyoung-Ryoul KimOBJECTIVES Long working hours have been reported to cause various health problems, but are currently practiced in many countries. Building upon a previous cross-sectional study, the authors aimed to elucidate the causal relationship between long working hours and hypothyroidism through a longitudinal study. METHODS Data were collected at baseline from 45,259 participants without thyroid disease and with consistent weekly working hours (36–40, 41–52, 53–60, and >60 hours) during the follow-up period. Hypothyroidism was defined using the reference limits of serum thyroid-stimulating hormone and free thyroxine levels. By estimating hazard ratios (HRs) and 95% confidence intervals (CIs) using Cox proportional hazards regression analysis, the risk of incident hypothyroidism was evaluated with 36–40 hours of work per week as the reference. RESULTS During 138,261.7 person-years of follow-up, 2,914 participants developed hypothyroidism (incidence density, 2.11/102 person-years). The multivariable-adjusted HRs of incident hypothyroidism for 41–52 hours, 53–60 hours, and >60 hours of work per week were 1.13 (95% CI, 1.03 to 1.24), 2.53 (95% CI, 2.17 to 2.95), and 2.57 (95% CI, 2.09 to 3.15), respectively. In dose-response analyses, long working hours had an approximately linear relationship with hypothyroidism incidence. The risk of incident hypothyroidism in those who worked 53–60 hours and >60 hours per week compared with the reference group was significantly higher among the older age group (≥36 years, stratified by median age), men, and daytime workers. CONCLUSIONS This large-scale cohort study demonstrated the association between long working hours and an increased risk of incident hypothyroidism with a dose-response relationship.http://www.e-epih.org/upload/epih-44-e2022104.pdfhypothyroidismlong working hoursoverworkthyroidlongitudinal studiescohort studies |
| spellingShingle | Yesung Lee Woncheol Lee Hyoung-Ryoul Kim Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort study Epidemiology and Health hypothyroidism long working hours overwork thyroid longitudinal studies cohort studies |
| title | Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort study |
| title_full | Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort study |
| title_fullStr | Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort study |
| title_full_unstemmed | Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort study |
| title_short | Long working hours and the risk of hypothyroidism in healthy Korean workers: a cohort study |
| title_sort | long working hours and the risk of hypothyroidism in healthy korean workers a cohort study |
| topic | hypothyroidism long working hours overwork thyroid longitudinal studies cohort studies |
| url | http://www.e-epih.org/upload/epih-44-e2022104.pdf |
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