Commentary: Validation of the Somatic Symptom Disorder-B Criteria Scale for Adults in South Korea

Over the years, the diagnostic criteria for somatic symptoms and related disorders have evolved extensively. The most recent edition of the Diagnostic and Statistical Manual defines Somatoform Symptom Disorder (SSD) as the persistent occurrence of distressing somatic symptoms in association with abnormal thoughts, feelings, and behaviors, ultimately leading to substantial functional impediment.¹ It further clarifies the boundaries of rooting a diagnosis by deemphasizing the significance of medically unexplained symptoms while underscoring the prominence of psychobehavioural features of the illness.¹ This diagnostic reform aims to ease the conception and clinical implementation of somatoform diagnoses for non-mental healthcare professionals, especially since the first presentation is usually in a primary care setting.

Somatoform disorders constitute a substantial burden to the healthcare system. They are considered the third most prevalent mental health disorders, following anxiety and depression.² This significant healthcare utilization necessitates reliable diagnosis and management of these disorders. The reconceptualized criteria offer promising prospects especially given its liberal and broad nature. Nevertheless, a challenge remains in the variation of individual symptom presentation across different cultures. This is particularly relevant for people of Asian descent due to their higher propensity for somatic expression of mental health distress compared to their western counterparts.³ Furthermore, the cultural pathoplasticity of somatic disorders emphasizes the significance of culturally relevant diagnostic criteria. This has been demonstrated in a study examining the difference in somatic manifestations among Chinese Americans and Caucasian Americans, in which the former group mainly expressed cardiopulmonary and vestibular symptoms while the latter had DSM-4 aligned symptoms.⁴

Somatoform Symptom Disorders are typically diagnosed using the standard Structured Clinical Interview for DSM-Disorders (SCID). However, several standardized and validated self-reported tools are available to support physicians in the diagnostic process. Somatic Symptom Disorder–B Criteria Scale (SSD-12) is one such tool; it assesses the patient’s perspective of the cognitive, affective and behavioral aspects of their SSD. The instrument uses 12 items to operationalize the B-criteria described in the DSM-5, four items representing each of three psychological sub-domains. The original version has been psychometrically validated in clinical and non-clinical adult populations laying the foundation for further cross-cultural research.^5,6

In the current issue of Alpha Psychiatry, Young-Jin Lim investigated, in a cross-sectional study, the psychometric properties of the Korean Version of the Somatic Symptom Disorder-B Criteria Scale (K-SSD-12). The study assessed the validity and reliability of the translated instrument in a convenience sample of 349 adults. The scale demonstrated a certain degree of validity and reliability; however, the results varied slightly from previously published data.^5,6 Interestingly, the factorial analysis revealed a unidimensional model for the K-SSD-12; it did not substantiate the “three latent dimensions” model of the reconceptualized DSM-5 criteria. Furthermore, two items related to the cognitive subcriterion of the somatic disorder failed to load on the latent variable. On the other hand, the internal consistency and test-retest reliability results appeared to be within the acceptable range. Likewise, the correlation coefficient between the K-SSD-12 and the Illness Anxiety Scale (IAS) as well as the Somatosensory Amplification Scale (SSAS) were positive and significant, indicating optimal convergent validity.

The findings of the present study support the complex nature of cross-cultural research on somatoform disorders. As mentioned earlier, the pathoplasticity of these disorders is a significant contributor to variation in somatic presentation of emotional distress; however, this can be further complicated by the psycholinguistic equivalence of somatic expressions, particularly in the Asian culture.⁴ Information on the relationship between somatic metaphors and emotional states within the Korean culture is required to support the development of a valid and reliable tool for this population. In my view, including the gold standard, DSM-5 Structured Clinical Interview for DSM-Disorders to externally validate the K-SSD-12 is called for, especially since the tool has potential use for population-based screening. Although further research is required to ascertain the results of the current study and generate culturally relevant population-based norms for the K-SSD-12, Young-Jin Lim is to be acknowledged for stimulating the concept of ‘relativist’ research in diagnosing somatic symptom disorders within the Korean population.