Reliability and Validity of an Instrument for Assessing Patients' Perceptions about Medications for Diabetes: The PAM-D

Purpose To evaluate the reliability and validity of the Perceptions About Medications for Diabetes (PAM-D) instrument. Methods The item pool was generated from a literature review and 18 focus groups of Type 2 diabetes patients. Surveys were mailed to 1,000 low-income diabetes patients; 362 were returned; 65 of 100 re-test surveys were returned. Results This paper uses data from 343 Type 2 respondents. Mean age and age diagnosed were 59 and 48, respectively; 72% female; 52% African American; 51% were taking oral antihyperglycemic agents [OHA] monotherapy, 18% insulin monotherapy, and 28% insulin plus OHA. The initial 66 items were reduced to 37 across nine scales: scheduling flexibility, portability convenience, regimen inconvenience, medication effectiveness, difficulty remembering medications, gastrointestinal, hypoglycemia-related, and weight/edema physical side effects, and emotional side effects. Scale reliabilities ranged from 0.71 to 0.92 (coefficient alpha) and from 0.54 to 0.83 (test-retest coefficient, 37-81-day interval); factor loadings ranged from 0.35 to 0.86 (median, 0.67); significant scale differences across medication groups (insulin, OHA, insulin plus OHA) were consistent with a priori hypotheses. Conclusions The PAM-D has substantial reliability and validity in a low-income, inner-city population of Type 2 diabetes patients and may be valuable for understanding multidimensional perceptions driving patients' treatment preferences.