Factor structure and concurrent/convergent validity of the modified somatic perception questionnaire and pain beliefs instrument

Objective

Our goal was to create a parsimonious combination of the Modified Somatic Perception Questionnaire (MSPQ) and the Pain Beliefs Screening Instrument (PBSI) through factorial structural analysis and to investigate the associations of the new scale (if unique) to disability, health condition, and quality of life report in patients with neck and low back pain scheduled for spine fusion surgery.

Methods

Factor analysis was used to refine all items within the 2 scales to 4 distinct factors: (1) somatic complaints of the head/neck, (2) somatic complaints of the gastrointestinal symptom, (3) pain beliefs and fear, and (4) self perception of serious problems. Each factor was assessed for concurrent validity with other well-established tools including the Deyo comorbidity index, the Short Form (SF)-36 mental and physical component subscales, and the Oswestry and Neck Disability Indices (ODI/NDI).

Results

The PBSI was fairly to moderately correlated with assessment tools of quality of life (SF-36) and disability assessment (ODI/NDI). Some of the items in the factor 1 from the MSPQ were slightly associated with the Deyo comorbidity index but not with the ODI/NDI.

Conclusions

The items from the MSPQ failed to associate with measures of quality of life and disability and thus may provide only marginal value when assessing the multidimensional aspects associated with neck and low back pain. The PBSI has moderate correlation with disability assessments. Neither tool was found to strongly correlate with disability measures or with SF-36 scales (mental and physical component subscales). Additional tools may be needed to further identify the dimensions associated with chronic pain patients.