Smoking is associated with greater pain intensity and pain-related occupational disability in Japanese workers

Purpose: Pain symptom, such as that caused by musculoskeletal disorders, is a major cause of occupational disability. As nicotine intake from smoking increases pain sensitivity, smokers may experience stronger pain and be more likely to experience pain-related disability than non-smokers. The study aim was to examine whether smoking was associated with pain-related occupational disability via pain intensity. Methods: Participants were 1189 workers with pain aged 20–74 years in Japan. Participants completed a self-report questionnaire, which included a question to measure pain-related occupational disability with ordinal-option: (1) without pain-related disability, (2) pain-related presenteeism, and (3) pain-related absenteeism. An ordinal logistic regression model was used to calculate multivariable-adjusted proportional odds ratios (OR) with 95% confidence intervals (CI) for the prevalence of pain-related occupational disability according to smoking status. A multiple mediation analysis was also conducted to assess whether pain sensitivity mediated the association between smoking and pain-related occupational disability. Adjusted variables were demographic variables, socioeconomic status, work-related psychosocial factors, general psychological factors, and pain duration. Results: Current smoking and pain were associated with pain-related occupational disability compared with non-smoking and pain (multivariable OR 1.78; 95% CI 1.26–2.52). Greater pain intensity partially mediated the association of current smoking and pain with pain-related occupational disability. The mediation rate (indirect/total effect) was 25%. Conclusion: Smoking and pain were associated with pain-related occupational disability, partially through greater pain intensity, among Japanese workers.