Reliability and validity of an instrument for assessing patients’ perceptions about medications for diabetes: the PAM-D
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To evaluate the reliability and validity of the Perceptions About Medications for Diabetes (PAM-D) instrument.
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.
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.
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.
KeywordsDiabetes Medication perceptions Patient satisfaction Patient-reported outcomes Psychometrics Validation studies
This research was funded with support from Eli Lilly & Company. Dr. Hayes is a full-time employee of and owns stock in Eli Lilly & Company, maker of diabetes treatments. This work was initially led by Dr. McHorney when she was Professor of Medicine at the Indiana University School of Medicine. Dr. McHorney is now a Senior Director in U.S. Outcomes Research, Merck & Company Inc. Dr. McHorney is a full-time employee of and owns stock in Merck & Co., Inc., maker of diabetes treatments. We thank the IU Medical Group (IUMG); ResNet, IUMG’s Primary Care Practice-Based Research Network, their staff for creating our data base and mailing the survey; staff of the Regenstrief Medical Record System; and Jackie Baker for coordinating returned surveys. Portions of this manuscript were presented as posters at the annual meetings of International Society of Quality of Life (2006) and International Diabetes Foundation (2006).
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