Validity of Activity-Based Checks (ABCs) of Pain, A Functional Pain Scale.

PURPOSE: The Activity-Based Checks of Pain (ABCs) is a pain assessment tool incorporating activities of daily living and instrumental activities of daily living. This instrument is designed to focus on functional capabilities and limitations due to pain. This study was designed to validate the factorial structure of the ABCs and assess its use in participants with chronic pain.

METHODS

Participants were recruited in two phases. Phase one optimized the design of the ABCs, with 297 subjects selecting their preferred icon for each function and rating its understandability. The most preferred and understandable icons were then used in phase two, where 304 participants with chronic pain completed the ABCs, the Patient-Reported Outcomes Measurement Information System (PROMIS) with additional PROMIS items that were analogous to the ABCs functions but not represented in the PROMIS-29, and the Brief Pain Inventory (BPI). Data were analyzed using exploratory factor analysis and confirmatory factor analysis.

RESULTS

Four factor loadings resulted in: multiplanar activities, sitting and/or hip flexor pain, walking and/or ambulation, and pain interference with lightweight unilateral activities. High internal consistency was demonstrated for all four factor loadings (0.623-0.879, 0.577-0.824, 0.512-0.841, 0.519-0.817, respectively). Correlations between items in the ABCs, PROMIS, and BPI resulted in moderate to strong correlations. Test-retest reliability was moderate to strong (intraclass correlation coefficient: 0.74).

CONCLUSIONS

The results confirm the ABCs as a valid and reliable tool for assessing the impact of pain on function in patients with chronic pain.