This study aimed to examine the impact of self-reported mental distress, assessed by the HADS, on the number of specific and non-specific DIW and medical costs in the two years following the testing. To address this aim, we conducted a longitudinal study, in which the HADS scores of 2,287 participants were used to predict their specific and non-specific DIW and medical costs in the first and second years after HADS assessment.
Our results revealed that self-reported mental distress (HADS scores) was significantly related to the number of non-specific DIW in the first and second years. Accordingly, the number of non-specific DIW increased continuously based on the level of mental distress. Compared to the reference group classified as no cases, severe cases had 5.1-times as many non-specific DIW in the first year and 3.7-times as many non-specific DIW in the second year. Not surprisingly, the increase of non-specific DIW was mainly driven by a significant increase of specific DIW. Compared to the no cases, severe cases showed 27.3-times as many specific DIW in the first year and 10.3-times as many specific DIW in the second year.
These results demonstrate that mental distress impacts a person’s life for several years by predicting their sickness absence rates even two years later. This increased sickness absence rate might be, in turn, related to a generally reduced social and occupational functioning levels and reduced well-being of individuals [33]. Furthermore, mental distress appears to be a central challenge for employers in terms of productivity loss. The financial consequences of specific DIW due to production loss can be calculated by multiplying the specific DIW by average income. Regarding average costs due to production loss in 2014 of 105 EUR per DIW [34], the averaged additional costs for an employee under severe mental distress due to absenteeism alone amount to 7,230 EUR in the first years and 4,163 EUR in the second year, compared to an employee without mental distress. According to prior empirical findings, the additional costs due to presenteeism can be estimated to be two to three times higher [31]. Our results revealed that 66% of participants classified as moderate cases and 42% of participants classified as severe cases, did not have any specific DIW in the two-year period that was analyzed. These results indicate that the percentage of people who go to work despite severe mental distress might be considerably high and illustrate the importance and spread of presenteeism. Given this high prevalence of presenteeism and the assumed adverse mental health outcomes, future studies should characterize this sub-sample's psychological and socio-demographic characteristics to better understand the risk factors for presenteeism. By doing so, a distinction should be made between whether work is perceived as a resource and thus contributes to the stabilization of mental health, or as a stressor that leads to the maintenance of high mental distress.
Both the anxiety and depression subscales of the HADS were predictive for specific and unspecific DIW. This is not surprising since 80% of all specific DIW in our sample were caused by the diagnostic groups’ affective disorders (42%, e.g., depression) and neurotic, stress and somatoform disorders (38%, e.g., anxiety disorders). This roughly corresponds to results from other studies in Germany, in which 88.6% of all specific DIW resulted from affective (41.4%) or neurotic, stress, and somatoform disorders (47.2%) [32]. Accordingly, it seems plausible that both the anxiety and depression subscale of the HADS predicted the number of specific DIW in our analyses. However, the impact of both HADS subscales for non-specific DIW is in contrast to the results of Schneider et al. [30], in which only the anxiety symptoms, but not the depressive symptoms, were found to be a significant predictor of the duration of absences due to non-specific DIW.
Beyond non-specific and specific DIW, our results demonstrated that mental distress is also significantly related to individuals’ specific and non-specific medical costs in the first and second year. Specific costs in the first year were 11.4-times higher for severe cases, compared to no cases. Even in the second year, severe cases showed 6.2-times as many specific costs as no cases. This amounts to an additional average specific cost of 2,073 EUR per person and year for severe cases in the first year and 1,106 EUR per person and year in the second year for the public health care system. The predictive effect of non-specific costs was considerably smaller, but also significant. Compared to no cases, severe cases averaged 2.7-times the costs in the first and 1.9-times the costs in the second year. This amounts to additional average non-specific costs of 3,513 EUR per person and year for severe cases in the first year and 2,922 EUR per person and year in the second year for the public health care system. These results underline the socio-economic burden of mental distress for public health care systems. However, they also show that this burden can be predicted by self-reported mental distress at an early stage, which opens the possibility for early interventions. Although these data represent costs from a German population, these results can be seen as an indicator for other industrialized countries, since both the prevalence of mental disorders (Germany 18%, EU 17.3%) and the percentage of direct and indirect medical costs due to mental illness in Germany (Germany 4.8%, EU 4.0%) are comparable to other EU countries [9].
Most demographic characteristics of our sample showed no consistent effects across the different dependent variables. However, these have been included mainly as control variables to control possible confounding variables. Future studies should specifically focus on these variables to draw reliable conclusions about socio-demographic variables' influence on absence days and medical costs. Only the participants' age showed a consistent pattern with increased non-specific DIW and non-specific medical costs for both years, but no differences in specific DIW and specific medical costs. Lower education in our sample was significantly related to non-specific DIW. However, on specific DIW, the increase by lower education yielded significance only in the second year. These results are in line with prior studies showing that mental distress (anxiety symptoms), higher age, and lower education emerged as significant predictors of non-specific DIW [30]. Given these findings, it seems likely that lower educational status and higher age can be considered a risk factor for non-specific DIW. However, their effect on specific DIW or medical costs remains uncertain. Future studies should include large and representative samples to investigate the differential effects of age and education on specific and non-specific DIW and specific and non-specific medical costs.
Contrary to prior studies, in which female gender was found to be a significant predictor of specific DIW [31, 32], our analyses showed no differences of specific DIW between male and female participants. However, a closer look at the descriptive factors shows that the factors from our study (1.57) are comparable to those from previous studies (1.6) [31, 32]. Therefore, the non-significant differences in DIW depending on the sample characteristics in our study could result from a too-small sample size in the different subgroups, thus limiting the power for individual comparisons. With 89%, the proportion of female participants was considerably high. Interestingly, female participants showed higher specific medical costs in both years. This finding is in line with prior research, indicating a higher prevalence of anxiety and affective mental disorders in female populations [9, 35].
Strengths, Limitations, And Recommendations For Future Research
Our study's major strengths relate to its longitudinal research design and the analysis of real DIW and medical cost data from a health insurance company in conjunction with psychometrically assessed mental distress from individuals. By including DIW and medical costs in the first and second year, we were able to show that self-reported mental distress was predictive for DIW and medical costs regardless of the DIW and medical costs occurring immediately after the HADS assessment, and this enabled us to show the long-term consequences of severe mental distress. By including specific and non-specific DIW and specific and non-specific costs as dependent variables, we were able to show the importance of mental health for general, occupational functioning and point to the consequences of mental distress for companies and the public health care systems. Furthermore, the available cut-off scores of the HADS to distinguish between no, mild, moderate, and severe cases allowed us to demonstrate clear, practical implications for the consequences of severe mental distress in applied settings. However, this study has some limitations, which should be considered when interpreting the results.
First, we only investigated the main effects of the sample characteristics and mental distress. However, more complex interaction effects between the independent variables are conceivable and should be investigated in future studies using larger sample sizes. Second, although our overall sample size was reasonably large, it does not signify a representative sample of the German population. Thus, some socio-demographic subgroups might be too small, resulting in limited power for examining the relationship between different sample characteristics and DIW and medical costs, respectively (e.g., n = 11 participants in the unemployment group). Third, in addition to the sample characteristics analyzed in this study, other variables might impact the relationship between mental distress and DIW, such as the quality of health management in organizations [36], subjectively perceived workplace characteristics (e.g., social support, leadership quality; [37, 38]), or inter-individual differences in psychological conditions, such as self-efficacy or work attitude [39]). In addition, variables should be investigated, influencing the relationship between mental distress and medical costs, such as access to psychotherapy or stigmatization. Finally, we analyzed DIW and medical costs independently of each other. Future studies should investigate how medical costs and DIW are related to each other over time (e.g., whether increased specific medical costs help reduce DIW). Future studies should also systematically investigate how prevention programs for distressed individuals and evidence-based treatments for individuals with mental disorders contribute to saving money by restoring occupational and social functioning.
Implications For Practice
This study shows the extent to which self-reported mental distress is related to the subsequent inability to work and to medical costs. On an individual level, our results indicate that mental distress affects a person’s life after a span of two years by reducing occupational and social functioning. Our results demonstrate the high socio-economic costs of mental distress through productivity losses due to reduced functional levels at the societal level. The results, therefore, suggest that joint efforts should be made to effectively reduce mental distress. Individuals with mild and moderate mental distress who do not yet suffer from a manifested mental illness should be given access to preventive services. Preventive structures should be established within peoples’ everyday lives (e.g., at the workplace) to enable low-threshold access [15–16]. Not recognizing mental distress, ignoring it, or not taking effective countermeasures might exacerbate the problem and result in significant negative financial impact. A preventive commitment from employers to the workforce's mental health should ultimately lead to a better working atmosphere, a better quality of life for employees, and an increase in productivity [11].
Individuals with severe mental distress or those with manifested mental disorders should be given rapid access to specialized help in the form of evidence-based psychotherapeutic or psychiatric treatments. Prior studies from the UK have shown that increasing access to psychological therapies would largely pay for itself by reducing other depression and anxiety-related public costs (e.g., medical costs and productivity loss) and increasing revenues (e.g., paying taxes [16]). Rapid access to mental health services should be enabled, since the time spent waiting to start psychological treatments was negatively associated with treatment outcome [15]. One best-practice example of how access to psychotherapy can be improved is the English Improving Access to Psychological Therapies (IAPT) service, which delivers psychological therapies recommended by the National Institute for Health and Care Excellence for depression and anxiety disorders to more than 537,000 patients in the UK each year [15]. Evaluation by the IAPT approach has shown that 40.3% of patients showed reliable recovery, 63.7% showed a reliable improvement, and 6.6% showed reliable deterioration [40].
The short processing time of the HADS and the simultaneously good predictive validity regarding the DIW allow for an efficient, cost-effective, and early assessment of the mental distress across different settings. Therefore, it could be used as a suitable screening tool for mental distress to effectively allocate prevention measures in the context of selected or indicated prevention. To improve access to specialized treatments, general practitioners in private practice could use the HADS as a risk-assessment parameter for mental disorders. Since the HADS is suitable for identifying specific mental disorders in physical health settings, it might be advisable to consult an expert (i.e., a psychiatrist or psychotherapist) if conspicuous values of the HADS appear [27].