Five-year trajectories of symptom severity, physical and mental functioning in patients with persistent somatic symptoms: the PROSPECTS cohort study

Objectives Knowledge about the long-term course and prognosis of persistent somatic symptoms (PSS) is important to improve clinical decision-making and guidance for patients with PSS. Therefore, we aimed to: (1) identify distinct 5-year trajectories of symptom severity, physical and mental functioning in adult patients with PSS and (2) explore patient characteristics associated with these trajectories. Design We used longitudinal data (seven measurements over a 5-year period) of the PROSPECTS study: a prospective cohort of adult patients with PSS. We applied Latent Class Growth Mixture Modelling to identify distinct trajectories for the three outcomes. Setting and participants Patients were recruited in general practices and specialised treatment facilities for PSS throughout the Netherlands. The study population consisted of participants with three or more measurements available (n=297). Primary outcome measures Symptom severity (Patient Health Questionnaire 15), physical and mental functioning (RAND-36 Physical Component Summary and Mental Component Summary). Results For symptom severity, we identified two 'stable' trajectories: 'severe symptoms, stable' (15.8%) and 'moderate symptoms, stable' (84.2%). For physical functioning, we identified three trajectories: 'poor physical functioning, marked improvement' (8.5%); 'poor physical functioning, stable' (34.7%) and 'moderate physical functioning, slight improvement' (56.8%). For mental functioning, we identified three trajectories: 'poor mental functioning, marked improvement' (13.9%); 'moderate mental functioning, deterioration' (12.2%) and 'moderate mental functioning, slight improvement' (73.8%). Patients' characteristics such as personal, social and environmental background, illness stressors, comorbid diseases, cognitive, emotional and behavioural responses varied for the distinct trajectories. Conclusions We identified distinct 5-year trajectories for the three outcomes. Our findings suggest a high prevalence of persistence of symptoms and limited improvement in physical and mental functioning in the majority of patients with PSS. In a small proportion of patients, we identified trajectories that showed considerable physical or mental improvement or deterioration. Patient characteristics differed for the identified trajectories and may guide early recognition, although predictive studies are warranted.