OBJECTIVES: To explore the perceived working mechanisms of psychosomatic therapy according to patients with persistent somatic symptoms (PSS) and their psychosomatic therapists.

DESIGN: Qualitative study using semistructured face-to-face interviews and focus groups. All interviews were audiorecorded, transcribed verbatim and analysed, by two researchers independently, based on the thematic analysis.

SETTING: Alongside a randomised controlled trial to establish the (cost-)effectiveness of psychosomatic therapy in patients with PSS in primary care, we conducted a process evaluation with a qualitative study. Patients were recruited in general practice in three regions in the Netherlands.

PARTICIPANTS: Interviews were conducted with twenty patients with PSS who received psychosomatic therapy and 25 psychosomatic therapists. In addition, two focus groups were conducted with six and seven psychosomatic therapists, respectively.

INTERVENTION: Psychosomatic therapy, delivered by specialised exercise and physical therapists, is a multimodal and tailored treatment based on the biopsychosocial model.

OUTCOME MEASURES: Experiences, opinions and views from patients' and therapists' perspective on psychosomatic therapy were identified.

RESULTS: A total of 37 interviews with patients, 25 interviews and two focus groups with therapists were analysed. Three main themes emerged from the data of the patients: (1) continuous alternation of psychosocial conversations and body-oriented exercises; (2) awareness of body-mind connection and (3) good relationship with therapist. Four main themes emerged from the data of the therapists (1) building rapport; (2) continuously searching for common ground; (3) making patients aware of the interaction between body and mind; and (4) continuous alternation between exploration and treatment.

CONCLUSION: According to patients as well as therapists, the continuous alternation of psychosocial conversations and body-oriented exercises to provide awareness of the interaction between body and mind are the perceived working mechanism of psychosomatic therapy. Therapeutic alliance and finding common ground between patient and therapist are prerequisites for the success of psychosomatic therapy.

TRIAL REGISTRATION NUMBER: NL7157 (NTR7356).