Measuring the activity of older people with chronic pain

Objective: A variety of instruments have been applied to the measurement of activity, yet few, if any, have been validated specifically for older people with chronic pain. This study has sought to examine the utility of the Human Activity Profile (HAP) for describing activity in a sample drawn from a pain clinic for older people. Design: The HAP was administered to 193 older pain clinic patients, 72 of whom completed the profile on a second occasion. A further 55 responses were collected from a group of community-dwelling volunteers. The factor structure of the HAP was tested using these 320 responses. The factors subsequently derived were compared with the Sickness Impact Profile (SIP) and the Barthel Index (BI). The discriminant validity of the HAP was examined by comparing factor scores for groups determined by gender, diagnosis, and status in the pain clinic. Results: The 94 items of the HAP loaded onto 10 factors, which explained 63.7% of the variance. These factors demonstrated moderate associations with the BI and the subscales of the SIP. The factors discriminated between men and women (F[12,180] = 9.85, p < 0.000). Differences were also present between subjects with a musculoskeletal pain problem, postherpetic neuralgia, and pain-free volunteers (F[24,340] = 4.7, p < 0.000). Factor scores increased between pre- and postclinic assessments (F[12,60] = 4.79, p < 0.000). Conclusions: The HAP has demonstrated qualities which favor its adoption as an activity measure for older pain clinic patients.