Predicting work disability among people with chronic conditions: a large prospective cohort study

Few risk prediction scores are available to identify people at increased risk of work disability, particularly for those with an existing morbidity. We examined the predictive performance of disability risk scores for employees with chronic disease. We used prospective data from 88,521 employed participants (mean age 43.1) in the Finnish Public Sector Study which included people with chronic disorders: musculoskeletal disorder, depression, migraine, respiratory disease, hypertension, cancer, coronary heart disease, diabetes and comorbid depression and cardiometabolic disease. 105 predictors were assessed at baseline and participants were linked to a national disability pension register. During a mean follow-up of 8.6 years, 6836 (7.7%) participants got a disability pension, the incidence varying between 9.9% among participants with migraine and 27.7% in those with comorbid depression and cardiometabolic disease. C-statistics for an 8-item risk score, comprising age, self-rated health, number of sickness absences, socioeconomic position, number of chronic illnesses, sleep problems, BMI, and smoking at baseline, was 0.80 (95%CI: 0.80-0.81) for musculoskeletal disorders (N=33,601), 0.83 (0.82-0.84) for migraine (N=22,065), 0.82 (0.81-0.83) for respiratory disease (N=15,372) and exceeded 0.72 for other disease groups. With 30% estimated risk as a threshold, a positive test detection rate and false positive rate ranged from 42.2% and 18.8% (cancer) to 79.8% and 45.2% (comorbid depression and cardiometabolic disease). Predictive performance was not improved in models with a new set of predictors or re-estimated coefficients. In conclusion, the 8-item work disability risk score may serve as a scalable screening tool in identifying individuals with increased risk for work disability.