Preventing work disability (WD), which presents as temporary (TWD) or permanent disability (PWD) is important for the individual and for society. Screening questionnaires are often used within the context of health surveillance to identify employees at WD risk at occupational health services (OHS) in Finland. Some of them, such as the Health Risk Appraisal (HRA) and the Subjective Cognitive Complaints (SCC) questionnaires, have indicated predictive value for identifying employees at an increased risk of TWD in smaller settings and selected occupational groups in earlier studies.
The objective of the thesis was to study whether the HRA and SCC questionnaire predict TWD, defined as sickness absence (SA), and PWD, defined as disability benefit (DB) that includes rehabilitation subsidy and disability pension, among employees in different industries like the HRA cohort and among knowledge- intensive sedentary occupations like the SCC cohort. TWD lasts under one year, while PWD is defined as work disability that lasts over one year.
In the study, the HRA and the SCC questionnaires were used. These were able in the earlier studies with smaller study sample sizes to identify employees with temporary WD risks. The HRA identifies "high risk" subgroups based on self- reported health problems and SCC based on cognitive complaints. In the present study with a larger study population than in the previous studies, we evaluated the predictive value of these classifications among employees from different industries. The data was collected from screening questionnaires from one national occupational OHS provider’s register. The study participants were working-age employees from different industry sectors.
The results of the HRA and SCC were combined with the registry data on SAs and DBs. A Hurdle model with a negative binomial response was used to analyze zero- inflated count data of SA. Cumulative incidence (CIF) function was used to illustrate the differences between the HRA risk groups and SCC categories in the accumulation of DBs, respectively. The Fine-Gray model was used to estimate the predictors for DB occurring over time.
Self-reported health problems within the “WD risk” category in the HRA predicted future SA in both genders, regardless of occupational grading among over 22,000 employees from different industries. Subjective cognitive complaints predicted a higher total count of SA days among employees from knowledge-intense occupations. Belonging to the “WD risk” category in the HRA and the “abnormal SCC score” category predicted permanent WD in both genders in both the unadjusted and adjusted models.
In the HRA cohort, the ratio of the means of SA days varied between 2.7 and 4.0, depending on gender and occupational group. The lower limit of the 95% confidence interval (CI) was 2.0 at the lowest. The most common primary reasons for permanent WD were musculoskeletal (39%) and mental disorders (21%). In addition to age and prior sick leave days, the “WD risk” category in the HRA predicted DB in the Fine-Gray Model. Hazard ratios (HR) were 10.9 or more, with the lower limit of the 95% confidence interval being 3.3 or more among those with two simultaneous WD risk factors.
In the SCC cohort, the ratio of the means of SA days in the abnormal SCC category was higher than 2.8 as compared to the reference group (no findings) with the lower limit of the 95% confidence interval being 2.2. The most common primary reasons for permanent WD were mental (36%) and musculoskeletal (20%) disorders. SCC predicted DB in both genders when controlling for age and prior SA in the Fine-Gray Model. Hazard ratios were 2.9 at the lowest, with a 95% confidence interval of 1.4–6.0. The overall annual DB incidence was 0.15%: 0.18% among the females and 0.12% among the males.
Belonging to the “WD risk” category as defined in the HRA or to the abnormal SCC score category predicted the number of accumulated SA days during the 12- month follow-up and DB during a follow-up of six and eight years, respectively, irrespective of the other predictors or confounding factors.
These findings have implications for targeting preventive occupational health care actions toward those in need to prevent SA and DB. The HRA and the SCC questionnaire are potential tools for recognizing employees who are at an increased risk of WD regardless of the occupational group, as in the case of the HRA, and among knowledge-intensive workers as in the case of the SCC questionnaire.
The doctoral dissertation of Med. Lic. Minna Pihlajamäki in the field of occupational health titled Identifying Temporary and Permanent Work Disabil ty Risk with Two Questionnaires in Occupational Health Services will be publicly examined at the Faculty of Medicine and Health Technology of Tampere University at 12 o'clock on Friday 12 February, 2021. Professor Kari Reijula from University of Helsinki will be the opponent while Professor emeritus Jukka Uitti will act as the custos.
The event can be followed via remote connection.
The dissertation is available online at
http://urn.fi/URN:ISBN:978-952-03-1836-9
Photo: Samuel Hoisko