BACKGROUND: Temporomandibular disorders (TMD) are associated with musculoskeletal diseases (MSD), mental and behavioural disorders (MBD), and patients with TMD have been shown to have 2-3 times more days of sick leave (SL) and disability pension (DP) than the general population. MSD and MBD are two of the most common causes for SL and DP, and the association between TMD and the influence of comorbidities on the need for SL and DP among TMD patients need further clarification. This study investigates the impact of MSD and MBD comorbidity on SL and DP among TMD patients diagnosed in a hospital setting and/or surgically treated.

METHODS: All incident TMD patients diagnosed or treated in a hospital setting between 1998 and 2016 and aged 23-59 were included. A non-exposed comparison cohort was collected from the general population. The cohorts were grouped based on the presence of comorbidity: No comorbidity (Group I); MSD comorbidity (Group II); MBD comorbidity (Group III); and combined MSD and MBD comorbidity (Group IV). Main outcomes were mean annual days of SL and DP, and statistical analysis was conducted using generalized estimated equations.

RESULTS: TMD subjects with no comorbidities (Group I) and with MSD/MBD comorbidity (Group II and III) were 2-3 times more often on SL and DP than the corresponding groups from the general population. However, in the group with both MSD and MBD comorbidity (Group IV), the difference between the TMD subjects and the general population was diminishing, suggesting an additive effect.

CONCLUSION: TMD patients are more dependent on SL and DP benefits compared to general population and the difference remains even after considering MSD and MBD comorbidity. In individuals with combined MSD and MBD comorbidity, concurrent TMD has less impact on the need for social insurance benefits. The results accentuate the impact TMD has on the patients' impaired ability to return to work and why TMD should be recognized as having a substantial impact on individual and economic suffering as well as on societal costs, with emphasis on the influence of comorbidities on patient suffering.