Assessment of a patient-based pharmaceutical care scale.

The Purdue Pharmacist Directive Guidance scale (PPDG), which is designed to measure patients' perceptions of the level of directive guidance received from pharmacists, was studied. Hypertension patients were interviewed by telephone between July 15 and August 15, 1998, with a survey including the PPDG, the Medication Adherence Scale (MAS), and the Friends and Family Support scale (FFS). The Behavioral Pharmaceutical Care Scale (BPCS) was mailed between May 15 and July 15, 1998, to pharmacies from which the patients obtained most of their prescriptions. The MAS measures patients' medication adherence, and the FFS measures their perceptions of the social support they receive from family and friends. Analysis of variance was used to assess whether there was significant variation in scale scores across pharmacies. Pearson correlation analysis was used to assess simple correlation among scales, and regression analysis was used to examine the association between scale scores while controlling for demographic variables, family support, and number of prescription drugs taken. Interviews with 163 patients were analyzed, and 64 pharmacists representing 32 pharmacies responded. The PPDG did not detect any difference across pharmacies in patients' perceptions of the level of directive guidance received. There was no significant correlation between PPDG scores and pharmacists' perceptions of the level of pharmaceutical care provided as measured with the BPCS or between PPDG scores and MAS scores. The findings reconfirmed the PPDG's reliability and factor structure and provided some evidence of convergent validity. The PPDG was reliable. Evidence of validity was not conclusive, although the high threshold for validity may have been responsible for this.