To our knowledge, this is the largest study on workforce participation in PD to date. The primary finding is that the median workforce survival among workforce active persons receiving a PD diagnosis was about two years shorter than in age- and sex-matched controls (43 months compared to 66 months). Among persons diagnosed with PD during a ten-year period, 33.5% had stopped working at diagnosis, 76.7% within 5 years, and 90.9% within 10 years. We also found that, on the group level, persons that were male, with post-secondary education or higher, and an earlier age of PD diagnosis stayed at work longer.
Previous studies have found the time to loss of employment in workforce active persons with PD to be a median of 7 (95% CI: 4.8–9.2) years9, a median of 6 (95% CI: 5.4–6.6) years8, or a mean of 4.2 ± 4.4 years6. In our study, there were significant differences in median workforce survival depending on the age of diagnosis. For persons diagnosed before an age of 50 years, the median workforce survival was 147 months (Fig. 3A), while it was 19 months for those diagnosed after an age of 60 years (Fig. 3C). Although the prior studies are not dissimilar to our finding of a median survival of 43 months/3.6 years, the age of the study populations and national differences with regards to stipulated retirement age (65 years in Sweden at the time of the study) are likely to influence the time to loss of employment considerably. Nonetheless, for these reasons, comparisons of workforce survival in populations of persons with PD must be made with considerable caution and should preferably include references to matched non-PD populations.
We show that the workforce participation in the PD case group was reduced significantly already at the time of diagnosis in all age groups (Table 2). This is in line with previous studies showing increased prediagnostic morbidity16,17, unemployment, healthcare spending10, and sick-leave in persons later diagnosed with PD11. The established symptoms of prodromal PD—such as rapid eye movement (REM) sleep behavior disorder, autonomic dysfunction, depression, and mild motor signs18—can largely explain the increased prediagnostic risk for falls16,19, musculoskeletal disorders11, constipation, urinary dysfunction, and fatigue seen in previous studies17. The National Patient Register does not include primary care visits, but persons in Sweden seeking primary care with a suspected movement disorder are typically referred to a neurologist for diagnosis. We, therefore, think that the considerable majority of newly diagnosed PD patients in the studied age span were included in this study. However, due to the nature of both the healthcare system and the progression of PD, there can be a delay between the first appearances of clinical symptoms to a diagnosis. Together with the potential misclassification of other illness as PD, this may have contributed to the reduced workforce participation already at diagnosis in the PD case group.
We found that higher education is associated with longer workforce survival among persons with PD. Potential explanations for this finding are that education is a proxy for having a higher socioeconomic status and/or cognitive reserve20. Persons with higher socioeconomic status generally have more influence over their workday and a stronger connection between effort and reward, which may reduce the risk for job dissatisfaction. Furthermore, both declining health and job dissatisfaction increase the probability for job loss in workers: self-perceived healthy workers who are dissatisfied with their job have a six-fold increase in the risk for health-related job loss21. Persons who already rate their health as poor have a higher risk for disability pension, unemployment, and early retirement, while chronic disease and mental health problems increase the risk for disability pension and unemployment, but not early retirement22. Education, the type of occupation, and cognitively stimulating leisure activities are markers of a higher cognitive reserve23,24, which may help protect against a decline in executive and memory function that can be detrimental for the work ability20.
The finding that persons with PD receiving DAT during follow-up had significantly shorter workforce survival than those that did not (Fig. 6) contrasts previous studies indicating that DAT might help sustain working ability14,15 and performance of daily activities13 in PD. However, DATs are typically initiated during mid-to-advanced stages of PD, at which point a significant portion of working-age persons with PD have already left the workforce1. Our finding that the median time from diagnosis to initiation of DAT exceeds the median workforce survival in the DAT group (89 versus 57 months) underscores this problem.
The large number of workforce active persons with PD included is a unique strength of this study. However, the study has several limitations that need to be considered in the interpretation of the results. Firstly, the percentage of misclassified PD in the National Inpatient Register is not known, but it is likely that the case group included a minority of persons with atypical parkinsonism or other movement disorders. This is also supported by the surprisingly large proportion of deaths during follow-up in the case group, which could be the result of a misclassification of persons with more rapidly progressing movement disorders than PD. The overall positive predictive value of the Inpatient Register has been shown to be between 85–95% depending on the diagnosis25. Secondly, any misclassification of younger persons is likely to result in larger discrepancies as the expected workforce survival is long. Furthermore, the data we had access to lack information on many of the disease-specific characteristics that are likely to influence workforce survival in PD. This information could for example have improved the accuracy of the matching between persons with PD and either DAT or not.
Persons with young- or early-onset PD are typically progressing at a slower rate than those with later onset and have been shown to exhibit distinct biochemical features26,27,28. Although the time to loss of employment is longer in persons with earlier PD onset, so is the time of lost employment and the amount of lifetime earnings loss29. The slower disease progression and more future workforce participation and income at risk make persons with early-to-mid PD onset ideal for future interventions aiming to improve workforce participation after a PD diagnosis. However, the increased probability for underlying predisposing mutations in younger persons with PD must be considered as this may affect the generalizability of findings.
This study was based on the total Swedish population and just as for most previous studies on workforce participation in PD, the unique setup of a single country’s healthcare and social security system may affect the generalizability of the findings. Nevertheless, some of the findings are of particular interest. Workforce participation is reduced already at the time of a PD diagnosis and continues to decline during the course of the disease. The effect of DAT on working ability in PD is still not clear and, according to current routines, DATs are often introduced at a stage in the disease when many have already stopped working. Studies on the effect of DAT on the work ability of workforce active persons with PD are warranted. Supportive measures intended to facilitate workforce participation are needed shortly after the PD diagnosis has been established and structured interventions aiming to improve workforce participation for this population are warranted.