Performance validity and outcome of treatment in patients with somatic symptom and related disorders (SSRD).

This study addresses the relationship between performance validity and treatment outcome in a sample of patients with somatic symptom and related disorders (SSRD). A retrospective analysis was performed in a sample of 337 patients with SSRD who received treatment. Interaction effects were determined between performance validity test (PVT) performance and raw change scores, reliable change index and clinical change of depression, anxiety and physical symptoms. Performance validity was measured by using the Test of Memory Malingering (TOMM). There was no significant difference between the PVT pass and PVT fail groups in change in depression, anxiety and physical symptoms after treatment. Both groups exhibited a comparable reduction in their symptoms of depression, anxiety and physical symptoms after treatment. There was also no association between PVT performance and raw change scores, reliable clinical changes and clinical changes on depression, anxiety, and physical symptoms. Performance validity was not related to treatment outcome in patients with SSRD, which is a clinically relevant finding. Further studies may want to look into other relevant aspects for determining the potential impact of performance (in)validity on treatment outcome in patients with SSRD, such as treatment drop-out or the number of missed/attended treatment sessions. Alternatively, as treatment outcome is usually determined based on patients' self-report, the impact that non-credible symptom reporting (i.e., symptom validity test failure) has on treatment outcomes is a logical next step for understating the impact of response bias beyond the testing session.