Pharmacists as drug prescribers: validation of certification exams and evaluation instruments

The purpose of this article is to discuss the validity and reliability of certification tests and evaluation instruments for pharmacists as drug prescribers. Under California Law AB 717, the University of Southern California is operating one of two pilot programs to train and evaluate prescribing pharmacists. Various instruments have been created and administered, and validity results are presented. The presentation is organized into two areas dealing with the development of the examination instrument and then the assessment of the prescriptions written by pharmacists. The reliability of the three sections of the certification examination as measured by internal consistency was as follows: clinical therapeutics (KR 20=.84), physical assessment (KR 20=.88), and law (KR 20=.84). The exam was given to a group of physicians (N=14) to establish a cutting score. Thirty pharmacists who took the exam did slightly better than the physicians on clinical therapeutics, but the physicians performed better than pharmacists on physical assessment (p less than .01). A prescription evaluation form was constructed to evaluate the performance of the pharmacists as prescribers. The reliability of the form as measured by coefficient alpha was .84. Concurrent validity was explored by assessing the relationship between performance on the certification exam and judges' appropriateness scored on prescriptions for ambulatory hypertensive patients. These results indicate that the pharmacists, who passed the exam, can prescribe as appropriately as physicians.