[The impact of catastrophizing on the effect of depression on pain and functional ability : A longitudinal mediator analysis].

BACKGROUND: While the association between pain and depression is well proven, little is known about the mechanisms influencing this relationship. The cognitive distortion of catastrophizing plays a significant role in several concepts of both diseases.

OBJECTIVE: The aim of the study was to analyze the role of catastrophizing on the effect of depression on pain and functional ability.

MATERIAL AND METHODS: Participants were recruited from 11 outpatient rehabilitation centers in Germany at the beginning of orthopedic rehabilitation aftercare. Perceived functional ability (spinal function sort), pain intensity (rating scales) and physical functioning (36-item Short-Form Health Survey, SF-36) were assessed as dependent variables at the beginning of the aftercare (T1) as well as 6 months later (T2). The independent variable depression (Patient Health Questionnaire and Mental Health Index of the SF-36) as well as the mediator catastrophizing (Coping Strategies Questionnaire) were measured at T1. Pathway models were used to analyze the direct and indirect proportions of the total effect of an independent variable on a dependent variable and the role of catastrophizing as a mediator of this association.

RESULTS: A total of 241 patients were included in the analyses. Depression had a significant total effect on pain as well as functional capacity. Catastrophizing mediated substantial proportions of these effects (42.9-87.1%).

CONCLUSION: Catastrophizing mediates the relationship between depression and pain as well as functional capacity; therefore, the reduction of catastrophizing thoughts and attitudes should be a focus in rehabilitation programs.