Early identification of functional somatic disorders in an internal medicine diagnostic clinic: The DISTRESS trial

Abstract

Background: Functional Somatic Disorders (FSDs) affect approximately 10 % of the general population (1) and often lead to reduced quality of life, extensive diagnostic evaluations and increased healthcare costs. The DISTRESS (Diagnostic Intervention in Secondary care Targeting patients Referred for Evaluation of bodily Stress Symptoms) trial protocol describes a randomised clinical trial evaluating a novel FSD Diagnostic Clinic, with the aim of providing early diagnosis and thereby helping patients and clinicians bring the diagnostic odyssey to a definitive and meaningful conclusion.

Methods/design: This pragmatic, randomised trial employs allocation concealment and blinded outcome assessment, although the randomisation allocation is unavoidably unmasked to patients and clinicians due to the nature of the intervention. Patients with suspected FSD are randomised 1:1 to either the FSD Diagnostic Clinic, where internal medicine specialists (internists) undertake the FSD diagnostic process, or to usual diagnostic assessment. The two co-primary outcomes evaluate (a) healthcare utilization and (b) costs-effectiveness, assessed alongside health-related quality of life measured by the SF-36 survey at 12 months post-intervention. Secondary outcomes include relevant clinical outcomes and overall public expenses.

Discussion: The DISTRESS trial addresses challenges in diagnosing FSDs by evaluating a novel Diagnostic Clinic model and its impact on patient outcomes, cost-effectiveness, and healthcare utilization. Insights from separately conducted qualitative studies will complement the trial by assessing the clinic's acceptability and integration within the healthcare system. By training internists to diagnose and manage FSDs using approaches typically employed by FSD specialists, the FSD Diagnostic Clinic expands access to timely care within a stepped care model.

Trial registration: ClinicalTrials.gov Identifier: NCT06025617.

Keywords: Bodily distress syndrome (BDS); Cost-effectiveness; Diagnostic clinic; Functional somatic disorder (FSD); Randomised clinical trial (RCT); Somatic symptom disorder (SSD).