Exploratory and confirmatory factor analysis of the PROMIS pain quality item bank

The assessment of pain sensation and quality is a key component in understanding the experience of individuals with chronic pain. This study evaluated the factor structure of the patient-reported outcome measurement information system (PROMIS) pain quality item bank. As part of the PROMIS project, we developed a pool of 37 pain quality items, based on a review of existing pain questionnaires and development of new items. A web-based survey was designed and completed by 845 members of the general population and 967 individuals with different types of chronic pain. Exploratory factor analysis (EFA) was conducted on a random split-half sample of the data to examine the factor structure of the 37 PROMIS pain quality items in the general population and in a chronic pain sample. A confirmatory factor analysis was conducted in the holdout sample. The EFA of the pain quality items resulted in comparable six-factor solutions for the general and chronic pain samples: (1) pulling/tugging pain; (2) tingling/numbness pain; (3) sharp/stabbing pain; (4) dull/aching pain; (5) pounding/pulsing pain; and (6) affective pain. The confirmatory factor analysis in the holdout sample supported this factor structure. Further research is needed to evaluate the psychometric characteristics of the derived scales based on their factor scores.