Comparison of clinical features: somatoform disorder and somatic symptom disorder

Objective To explore the differences of clinical characteristics between the somatoform disorder (SFD) and somatic symptom disorder (SSD) in out-patient clinics of tertiary hospitals in China. Methods Patients in the out-patient waiting list of gastroenterology, neurology, traditional Chinese medicine and psychiatry departments were recruited by convenient sampling method, and screened by self-rating questionnaires, including Patient Health Questionnaire-15(PHQ-15), Patient Health Questionnare-9(PHQ-9), General Anxiey Disorder Scale (GAD-7), Somatic Symptom Disorder-B Criteria Scale (SSD-12), WHO Disability Assessment Schedule 2.0 (WHO DAS 2.0), etc, followed by structured interviews so that the diagnosis of SSD and SFD were finally confirmed. Various clinical features were compared between SSD and SFD patients by independent t-test. Results Among the 699 subjects, 236 cases (33.8%) were diagnosed with SSD, and 431 cases (61.7%) were diagnosed with SFD. The diagnostic consistency between SSD and SFD was low (Cohen kappa coefficient=0.291, P<0.01). The scores of PHQ-15 ((12.01±5.54) vs. (10.38±5.53), t=3.624), PHQ-9 ((11.84±6.76) vs. (9.40±6.57), t=4.546), GAD-7 ((9.70±6.08) vs. (7.34±5.92), t=4.871), SSD-12 ((23.60±11.43) vs. (16.52±12.64), t=7.154) and WHO DAS 2.0 ((22.65±8.52) vs. (19.96±7.77), t=4.128) in SSD patient group were significantly higher than those in SFD patient group (P<0.01). Conclusions The diagnostic consistency of SSD and SFD is low. Compared with SFD patients, SSD patients present with more somatic symptom load, anxiety and depression, symptom related emotions, thinking and behavior problems, and social function impairment, which might deserve more medical attention and appropriate interventions. Key words: Somatoform disorder; Somatic symptom disorder; Population characteristics; Consultation liaison psychiatry