Assessment of a Patient-based Pharmaceutical Care Scale

Shuvayu S. Sen and Joseph Thomas III


Am J Health Syst Pharm. 2000;57(17) 

In This Article

Abstract and Introduction

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.

Behaviors such as offering advice, information, and instruction and providing feedback on behaviors, thoughts, and feelings are a form of social support known as directive guidance. Directive guidance behaviors are among the most influential components of social support in increasing medication adherence. Efforts by health professionals to inform and encourage patients in the appropriate use of prescribed therapies have been shown to increase medication adherence.[1,2,3]

Many of the activities involved in pharmaceutical care -- providing patients with information about the proper use of medications, instructing them on how to deal with adverse effects, encouraging them to take their medications appropriately, and giving them feedback on how they are doing and how they can improve -- are forms of directive guidance and are essential to helping patients achieve desired therapeutic outcomes.[4] The level of directive guidance that patients receive from pharmacists can serve as an indicator of the quality of pharmaceutical care services. Measures of directive guidance might also prove useful in gauging the extent to which patients' perceptions of pharmaceutical services are linked to other measures of those services.

The Purdue Pharmacy Directive Guidance scale (PPDG) was developed to measure patients' perceptions of the directive guidance they receive from pharmacists.[5] The scale was found to be highly reliable, but the developers suggested further assessment of its reliability. Positing that patients receive different levels of directive guidance from different pharmacies, we decided to assess the validity of the PPDG by examining whether it captures differences in directive guidance received by patients who patronize different pharmacies. If pharmacists who differ in their perceptions of the level of pharmaceutical care they provide deliver different levels of directive guidance to patients, convergent validity of the PPDG can be assessed by evaluating the correlation between patients' PPDG scores and their pharmacists' views of the pharmaceutical care they deliver. Because pharmacists' services are expected to improve medication adherence and other outcomes, the validity of the PPDG could also be tested by examining whether PPDG scores are correlated with adherence to prescribed drug regimens, although this is a very high bar to meet.

The primary objective of this study was to evaluate the PPDG. Specifically, we sought (1) to examine whether the PPDG can detect significant differences in patients' perceptions of the level of directive guidance provided across different pharmacies, (2) to determine whether there is a significant correlation between patients' perceptions of the directive guidance they receive from pharmacists and patients' adherence to prescribed regimens, and (3) to determine whether there is a significant correlation between pharmacists' perceptions of pharmaceutical care they provide and patients' perceptions of directive guidance received as measured with the PPDG.


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