JMIR Publications

ABSTRACT

Background:

Shift workers are at elevated risk of multiple chronic diseases due to circadian disruption, irregular schedules, and associated lifestyle factors. While prior research predominantly focused on individual chronic diseases, the clustering of diseases into distinct multimorbidity patterns among shift workers remains poorly understood. Furthermore, whether these patterns differentially predict relevant health outcomes such as sleep disturbance and job stress is not adequately examined.

Objective:

This study aimed to identify multimorbidity patterns among middle-aged shift workers and to examine their associations with occupational characteristics, health behaviors, sleep disturbance, and job stress.

Methods:

A cross-sectional nationwide survey was conducted among 897 shift workers aged ≥40 years in South Korea. Multimorbidity was defined as the presence of ≥2 physician-diagnosed chronic diseases. Latent class analysis was performed using 11 chronic diseases with prevalence ≥5% to identify multimorbidity patterns. Differences in sociodemographic, occupational, and behavioral characteristics across classes were examined using chi-square tests and analysis of variance. Multinomial logistic regression was used to identify predictors of class membership. Linear and logistic regression analyses were conducted to examine associations between latent class membership and distal outcomes, including insomnia severity and job stress.

Results:

Multimorbidity was present in 49.2% of participants. Four latent classes were identified: low morbidity (54.9%), cardiometabolic (35.8%), severe multimorbidity (5.5%), and musculoskeletal–depression (3.9%). Quick returns between shifts, hazardous drinking, and current smoking were significantly associated with cardiometabolic and severe multimorbidity classes. Female sex was strongly associated with the severe multimorbidity and musculoskeletal–depression classes. Compared with the low morbidity class, workers in the cardiometabolic and severe multimorbidity classes showed significantly higher insomnia severity and job stress. The severe multimorbidity class exhibited the highest levels of sleep disturbance and occupational stress.

Conclusions:

Multimorbidity is highly prevalent among middle-aged shift workers and manifests in distinct disease patterns with different occupational and behavioral risk profiles. These patterns are significantly associated with sleep disturbance and job stress. Occupational health strategies should adopt integrated approaches that address multimorbidity, sleep health, work-related stress, and modifiable lifestyle behaviors among shift workers.