Patient Interpretation of Neuropathy (PIN) questionnaire: an instrument for assessment of cognitive and emotional factors associated with foot self-care.

OBJECTIVE Using the common-sense model of illness behavior, we developed and validated a self-report instrument for assessment of patients' cognitive and emotional representations of diabetic peripheral neuropathy (DPN) influencing foot self-care. RESEARCH DESIGN AND METHODS The Patient Interpretation of Neuropathy (PIN) questionnaire, generated from discussions with clinicians and interviews with patients with DPN, was administered to patients with DPN attending U.K. (n = 325) and U.S. (n = 170) diabetes centers. Psychometric tests of the PIN questionnaire comprised factor analysis, internal consistency, and test-retest reliability. Partial correlations and multivariate regressions established construct and criterion-related validity. The associations of PIN scales to past foot ulceration and foot self-care behaviors were compared with those using a generic measure of illness perception and emotion, the Revised Illness Perception Questionnaire (IPQ-R), which was adapted to neuropathy. RESULTS Factor analysis of the PIN questionnaire produced 11 scales, which explained 69% of item variance. Nine factors measured patients' common-sense beliefs about DPN and their levels of understanding of DPN-related medical information. Two factors assessed the emotions of worry about potential consequences and anger at practitioners. Most scales demonstrated adequate internal (Cronbach's alpha = 0.62-0.90) and test-retest reliability (Pearson's r = 0.51-0.64). Partial correlations between the PIN and IPQ-R scales in corresponding domains were significant but modest (rp = 0.15-0.26). Finally, PIN scales showed significant associations with past foot ulceration and foot self-care behaviors, thereby confirming criterion validity. CONCLUSIONS The 39-item PIN questionnaire is a reliable and valid measure of patients' cognitive and emotional representations of neuropathy affecting foot self-care.