Can MMPI-2-RF confirm the structural validity of the somatoform spectrum of the Hierarchical Taxonomy of Psychopathology (HiTOP) in patients with chronic low back pain.

OBJECTIVES

This study aimed to evaluate the structural validity of the somatoform spectrum within the context of the Hierarchical Taxonomy of Psychopathology (HiTOP) model in patients with chronic low back pain.

METHODS

233 patients who were diagnosed with chronic low back pain (77.3 % female) completed the Oswestry Disability Index (ODI), the Health Anxiety Inventory-18 (HAI-18), the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF), and the Patient Health Questionnaire (PHQ-15). Confirmatory factor analyses were conducted at two levels: spectra and symptom levels. Competing models were tested-one modeling somatoform as an independent spectrum, and the other integrating it under the internalizing spectrum.

RESULTS

The distinct somatoform spectrum model showed superior fit at both the spectra (χ2 = 1.60, df = 12, p = .083) and symptom levels (χ2 = 1.12, df = 118, p = .161), compared to the nested internalizing model, which had weaker fit indices (spectra: χ2 = 2.05, df = 12, p = .016; symptom: χ2 = 1.73, df = 127, p < .001). In the correlation analysis (all p < .01), emotional and internalizing dysfunction was strongly linked to low positive emotions (r = 0.60), dysfunctional negative emotions (r = 59), and negative emotionality/neuroticism (r = 0.60), and moderately to thought dysfunction (r = 0.27); thought dysfunction showed powerful associations with psychoticism (r = 0.94), aberrant experiences (r = 0.84), and ideas of persecution (r = 0.79); behavioral and externalizing dysfunction correlated highly with disconstraint (r = 0.85) and antisocial behavior (r = 0.73); health anxiety was moderately related to negative emotionality/neuroticism (r = 0.21), cynicism (r = 0.22), and dysfunctional negative emotions (r = 26); somatic symptom severity (phq-15) was associated with somatic complaints (r = 0.41), ideas of persecution (r = 0.22), and negative emotionality/neuroticism (r = 0.24); and disability (ODI) correlated with somatic complaints (r = 0.25), ideas of persecution (r = 0.17), and negative emotionality/neuroticism (r = 0.19).

CONCLUSION

These findings support the structural independence of the somatoform spectrum within the HiTOP framework, especially in medical samples, and encourage further cross-cultural validation.