The Cancer Pain Inventory: preliminary development and validation

The purpose of this study was to develop a Cancer Pain Inventory (CPI) that measures cancer patients' beliefs and concerns about pain. This paper describes development and pilot testing of a preliminary version of the CPI and describes its psychometric properties including its reliability and validity relative to established pain measures.

Subjects were recruited from inpatient and outpatient oncology services of an NCI-designated comprehensive cancer center. Participants completed the 50 potential CPI items and these standard measures-Orientation-Memory-Concentration Test, Survey of Pain Attitudes, Brief Pain Inventory, Pain Disability Index, and Center for Epidemiological Studies-Depression Scale. The magnitude and significance of associations between the CPI and the other measures were examined.

Of 366 patients who were eligible and agreed to participate in the study, 262 completed the questionnaires. Principal components analyses were used to select items most appropriate for retention in the preliminary version of the CPI and to describe its factor structure. Based on the content of items that loaded on each factor, the five factors were labeled as Catastrophizing, Interference with Functioning, Stoicism, Social Aspects, and Concerns about Pain Medication. Correlations between the CPI and other measures supported construct validity of the five CPI factors.

The results supported the validity of the CPI as a measure of five constructs relevant to the experience of pain in the cancer setting. The results also underscored the presence of unique features of cancer-related pain that clearly differ from commonly recognized dimensions of chronic, non-cancer-related pain.