Examining Acuity Adjustment Metrics and Which Is Best for Monitoring Long-term Medication Expense

This article examined and compared two acuity adjustment metrics for monitoring medication expense over time in a health system.  The health system used for the study was the Ohio State University Wexner Medical Center.  The two metrics evaluated were case-mix index (CIS) and pharmacy intensity score (PIS) based on the markers relative weight (RW) and pharmacy intensity weight (PIW) respectively.  These acuity adjustment metrics are used to estimate the cost of medications for different diagnosis-related groups within a health system.  CIS and PIS provide guidelines for budgeting for medication within a health system, based on what diagnosis-related groups are present in the health system and how large those groups are.  It has long been debated which metric is better for predicting accurate medication expenses over time, and the differences between and accuracy of the two metrics have not been well-studied.  Determining which metric is more accurate is important because a large portion of a health system’s budget often goes towards medication, and even a small percentile difference in cost of medication expenses over time can mean a large difference in dollars for a health system.  The study was only conducted at one center, but the researchers attempted to make the results more generalizable by focusing on the data of medication expenses over time for only the top ten diagnosis-related groups nationally.  This way, the results were not skewed towards the diagnosis-related groups that the Wexner Medical Center sees more of than other health systems, such as cancer patients.  The results of the study indicated that the pharmacy intensity score (PIS) provided on average a more accurate estimate of medication expenses over time for all the diagnosis-related groups included in the nine-month study.  The article detailed that for some diagnosis-related groups with high variability in medication expense on an individual patient basis, neither metric was very good for estimating average medication expense over time.  However, overall, the conclusion was that PIW correlated more strongly with true medication expense than did RW, meaning that PIS is overall a better acuity adjustment metric, keeping in mind that there is still much research to be done in this area.

This article is not an article I would normally read based purely on the dryness of the title, but after reading it I have a greater understanding of and appreciation for the business aspect of managing medications in a health system.  Personally as a student pharmacist I find it easy to get wrapped up in the patient care aspect of pharmacy, and to forget that everything has a price.  With medications in particular, that price can be quite large, and can quickly multiply when the total medication expenditure of a health system is analyzed as a whole.  I am glad I read this article because I learned something new about how health systems can better budget for medications, which is a topic I had never considered before.

Brink HL, Naseman RW, Porter K, et al. An evaluation of acuity adjustment metrics to track medication expense over time. Am J Health-Syst Pharm. 2015;72:2157-65.

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