The psychological features of distinct somatic syndromes: A cluster analysis according to population-based somatic symptom profiles in Taiwan

Abstract

Functional somatic syndromes (such as chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome) are often comorbid. Whether these syndromes are distinct constructs and whether they have different psychological features are interesting questions. We perform a cluster analysis based on a nationwide survey in Taiwan to answer these questions. A score of at least 5 on the Patient Health Questionnaire-15 (PHQ-15, measuring somatic symptoms) indicated somatic syndromes and the data of 550 subjects were included. According to the gastrointestinal, pain-fatigue and cardiovascular subdimension scores of the PHQ-15, we performed a two-step cluster analysis. The demographic data and the cluster scores of the Health Anxiety Questionnaire and the Patient Health Questionnaire-4 (measuring depression and anxiety) were compared. Multinomial logistic and multiple linear regression analyses were used to clarify the associations between clusters/somatic symptoms and demographics/psychological features. Four clusters were generated and named according to their somatic features: "high gastrointestinal symptoms", "high pain-fatigue and comorbid somatic symptoms", "middle to high pain-fatigue symptoms" and "high cardiovascular symptoms". The high pain-fatigue and comorbid somatic symptom cluster had the highest levels of extent to which symptoms interfere with a person's life, depression and anxiety. The high cardiovascular symptom cluster was featured by high excessive worry over health and illness and low educational level. The high gastrointestinal symptom cluster had relatively low psychopathologies. The results of this population-based analysis supported the existence of distinct somatic syndromes that are not parts of a single whole somatic syndrome and have different psychological features.