Predictors of participation in primary care group-format back pain self-care interventions

The goal of this study was to explain how primary care back pain patients who volunteer for a group-format self-care intervention differ from nonvolunteers. This is relevant to the generalizability of studies that rely on volunteers as well as the characteristics of patients who do not seek out self-care interventions.

This study was conducted at a large health maintenance organization in western Washington state.

"Volunteers" (n = 481) were primary care back pain patients participating in randomized trials of a self-management intervention who were recruited through passive nonintensive means (a mailed invitation). "Nonvolunteers" (n = 967) consisted of a representative sample of consecutive back pain patients. We compared the baseline characteristics of these two groups.

The relatively small percentage (8%) of primary care back pain patients who volunteered for, and ultimately participated in, group self-management classes tended to be white, older, better educated, and more likely to be retired than nonvolunteers. The two groups did not differ significantly on most clinical measures, including pain intensity and persistence. Patients experiencing the highest (and lowest) levels of pain-related activity interference were less likely to volunteer than those with moderate activity limitations, however.

Those individuals volunteering to participate in a group-format self-care intervention in a primary care setting differed from nonvolunteers primarily on demographic measures as opposed to clinical measures. Back pain patients experiencing the highest levels of activity limitations were somewhat less likely to participate than those with moderate activity limitations. Recruitment for effective self-care interventions is an important issue in determining their impact on a population basis.