Development and preliminary validation of aculture-bound somatic symptom scale

Abstract

Background: Culture specific psychosomatic symptoms such as “internal heat” are a common manifestation of psychological distress among Nigerians. However, instruments that include them in diagnostic endeavour are scarce.
Aim: To develop and validate a new self-rating questionnaire based on psychosomatic symptoms peculiar in the local context, for the screening of Somatic Symptom Disorder (SSD) in Nigeria.
Method: A preliminary stage which involved a review of the Enugu somatization scale (ESS), focus group discussion with Consultant psychiatrists and pretesting with 25 patients yielded an eight-item scale which was then tested in a two stage study. In the first stage, 230 subjects were recruited from patients attending the general outpatient clinic of the University of Calabar Teaching hospital using systematic sampling. The 8-item scale as well as the 12-item General Health Questionnaire (GHQ-12) was then administered. One hundred and thirty one subjects comprising those with positive scores on the GHQ-12 and a fifth of those with negative scores underwent a clinical interview to determine a diagnosis of somatic symptom disorder (SSD) following Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM 5) criteria. Data was analysed using statistical package for social sciences (SPSS) version 22.
Results: The 8-item scale had a Cronbach's alpha of 0.78 with a sensitivity of 0.79, a specificity of 0.72 and a misclassification rate of 28% at an  optimized cut off of 3. Higher scorers on the scale were more likely to be cases at interview X²= 14.22 p < 0.001
Conclusions: The 8 item Culture Bound Somatic Symptoms scale can be a useful screen for somatic symptom disorder among patients with culture specific psychosomatic symptoms. Further validation studies are however needed to reassess its psychometric properties.

Key-words: Psychosomatic, culture bound, internal heat, validation, scale