PROFSS: a screening tool for early identification of functional somatic symptoms

Abstract

Objective: To develop and validate a brief screening tool for predicting functional somatic symptoms (FSS) based on clinical and non-clinical information from the general practitioner referral letter, and to assess its inter-rater reliability.

Methods: The derivation sample consisted of 357 consecutive patients referred to an internal outpatient clinic by their general practitioner. Referral letters were scored for candidate predictors for the main outcome measure, which was a final diagnosis of FSS made by the internist. Logistic regression identified the following independent predictors: type of symptoms, somatic and psychiatric comorbidity, absence of abnormal physical findings by the general practitioner, previous specialist consultation, and the use of illness terminology. Temporal validation was performed in a cohort of 94 consecutive patients in whom predictors were scored by two independent raters.

Results: In both the derivation and validation sample, the discriminatory power of the model was good with areas under the receiver operating characteristic curves of 0.84 (95%confidence interval: 0.80-0.88) after bootstrapping and 0.82 (95%confidence interval: 0.73-0.91), respectively. Calibration of the models was excellent in both samples and the interobserver agreement in the validation sample was very good (intraclass coefficient: 0.82 (95%confidence interval: 0.75-0.88)). Based on this model, we constructed the brief screening tool PROFSS (Predicted Risk Of Functional Somatic Symptoms). PROFSS identified patient groups with risks of FSS ranging from 17% (95%CI: 10-26%) to 92% (95%CI:86-96%).

Conclusion: The presence of FSS can be predicted with the brief screening tool PROFSS, based on a limited set of items present in the general practitioner referral letter.

Keywords: Functional somatic symptoms; General practitioner; Medically unexplained symptoms; PROFSS; Prediction model; Referral letter.