Perceived Physical Activity Decline as a Mediator in the Relationship Between Pain Catastrophizing, Disability, and Quality of Life in Patients with Painful Diabetic Neuropathy

Background: To fully understand the burden of painful diabetic neuropathy (PDN), we investigated the relationship of pain catastrophizing with disability and quality of life in patients with PDN. Furthermore, we studied the mediating roles of physical activity and/or decline in physical activity. Methods: This questionnaire-based cross-sectional study included 154 patients with PDN. Linear regression analyses, adjusted for age, gender, pain intensity, and insulin treatment, were performed to assess the association of pain catastrophizing (Pain Catastrophizing Scale [PCS]) with the outcome variables disability (Pain Disability Index [PDI]) and quality of life (Norfolk Quality of Life Questionnaire Diabetic Neuropathy Version [QOL-DN]). The mediating roles of actual physical activity (Physical Activity Rating Scale [PARS]) and perceived Physical Activity Decline (PAD) were assessed using mediation analyses according to Baron and Kenny. Results: This study included 154 patients (62% male). Mean age was 65.7 years (SD = 6.6). PCS (M = 20.3, SD = 13.1) was significantly associatedwithPDI (M = 32.4, SD= 17.0; R-2 = 0.356, P < 0.001), QOL-DN (M = 52.6, SD = 26.1; R-2 = 0.437, P < 0.001), and PAD (M = 7.4, SD = 5.7; R-2 = 0.087, P = 0.045). PAD acted as a partial mediator in the associations of PCS with PDI and QOL-DN, respectively. There was no association of PCS with PARS. Conclusions: Pain catastrophizing was associated with increased disability and decreased quality of life in patients with PDN. Also, it was associated with a perceived decline in physical activity, which had a mediating role in the association between catastrophizing and disability and quality of life, respectively. This study emphasizes the role of catastrophic thinking about pain and the experienced loss in daily activities due to PDN.