Medication Supplies and Health Care Costs in Older Adults
abstract & commentary
Synopsis: More than one-half of older patients studied had either too much or too little of their prescribed medications when followed over a three-year period, with excess costs of $279,000 and missed costs of $602,121 out of a total cost of $1.96 million for the targeted medications. Both the over- and underusers had more hospital admissions and emergency department visits, with higher total costs for patients with oversupplies of medications.
Source: Stroupe KT, et al. J Am Geriatr Soc 2000;48:760-768.
Using records from an urban public health care system that provided care for a predominantly indigent population, patients older than age 60 were identified that had at least two ambulatory visits and/or one or more hospitalizations between 1993-1995, then further restricted to patients who had obtained at least one prescription and one refill. Their unique characteristics, pharmacy records, and costs of health care use were then tracked from 1994-1996. After patients were eliminated who had less than one year of data available, 4164 remained for the study. Higher total health care costs were predicted by three-year averages of body mass index more than 30 and serum albumin less than 3.5 g/dL of all the characteristics studied.
Although patients could use other sources of health care, internal audits demonstrated that the vast majority of their patients used only the single system from which the data was extracted, with 95% of adult general medicine patients obtaining their prescriptions from system pharmacies. Service sites included one hospital with an emergency department, and a network of neighborhood health care centers with pharmacies located both within the centers and at a central site. Patients were charged actual acquisition costs of drugs plus $4 for each prescription.
Prescribed medications were assigned to one of 12 drug categories of common medications used for chronic diseases commonly found in older adults. "Prn" and medications that did not fit into the categories were eliminated from the study. A ratio was calculated using the time interval between refills, which measured the amount of medication available to the patient for consumption. Ratios between 0.8 (80%) and 1.2 (120%) of prescribed medications were considered appropriate; less than 80% supply was tallied as an undersupply and more than 120% as an excess supply. These margins allowed for extra medications given to ensure supply before the next office visit (e.g., if a 2-month supply of drugs was refilled at a visit, the 30-day surplus would not count as excessive medications). The cost of oversupply was calculated as a comparison of hypothetical drug costs of 120% supply compared to actual costs. Multivariate analysis was also used to determine associations between medication supply, health care use costs, and other confounding variables such as age, race, gender, number of conditions, etc.
After three years of study, they found 47% of the patients had received an oversupply (> 120%) of the targeted prescribed medications and 16% an undersupply (< 80%). Only 37% received the appropriate supply. Greater comorbidities were statistically associated with oversupplies, and the categories most likely to be oversupplied were oral hypoglycemic drugs, ACE inhibitors, and digoxin. Most likely to be undersupplied were nitrates and inhaled respiratory medications.
Costs for inpatient and outpatient services were higher for patients with oversupplies of medications, and lower for those with undersupplies. However, both were associated with significantly higher probabilities of hospital admissions and emergency department visits, although the association for undersupplies disappeared when the analysis used 90% as the threshold rather than 80%. Total health care costs for the study population during the three-year period was more than $63 million, with $7.1 million for all outpatient pharmacy costs, and 28% of that for medications used for the targeted chronic conditions.
COMMENT BY MARY ELINA FERRIS, MD
With the advent of restricted pharmacy dispensing dictated by the patient’s payor source, it is now possible to track prescriptions filled and refilled with much more accuracy than ever before. The study group used by Stroupe and colleagues also had the advantage of a single hospital and emergency department as part of their closed health system, and they had access to ambulatory records to establish patients with chronic diseases and gather additional data. Over three years, they were able to follow the dispensing of selected medications and the use of health care services within their system with reasonable accuracy to establish their associations. Another advantage of their system was the low cost of medications and lack of prescription limits, which reduced cost and access variables that often contribute to inappropriate medication usage.
Since more than 40% of older adults have two or more chronic medical conditions, and 90% have at least one condition, the use of medications becomes a critical factor in their health care.1 Compliance with prescribed medications had long been acknowledged as a major problem, and this study documents a further widespread problem with simply obtaining the correct supply, further complicating the barriers to correct usage according to dosing directions.
As most clinicians already know by experience, the study found that patients who don’t fill their prescribed medications have worse outcomes. What may be surprising, however, is that they also found an association between oversupplies of medications and higher inpatient and outpatient costs. One might speculate that this later group of patients was either using too much medication or could have been confused about medication dosing. Another possible explanation could be that these patients had frequent medication changes and were more difficult to manage, although multiple dosing changes can also lead to compliance problems. It’s also conceivable that different physicians were giving patients overlapping prescriptions, which is a well-known problem when patients have complicated medical problems with multiple providers. In any event, the oversupply of medications identified a patient group at higher risk for hospital admissions, emergency department visits, and higher total health care costs.
Although this study only followed the supply of medications rather than actual patient compliance with dosing instructions, at least one published study has confirmed correlation between compliance and supply.2 Looking at the results from the reverse perspective, only 37% of the older patients had the correct supply of medications, indicating room for improvement in the areas of medication compliance, and giving prescribing physicians cause to consider the effectiveness of their intended therapies. These results should also provide support for adequate funding and monitoring of prescribed medications, since potentially unnecessary costs and hospital use were associated with inappropriate supplies.
References
1. Hoffman C, et al. JAMA 1996;276(18):1473-1479.
2. Choo PW, et al. Med Care 1999;37(9):846-857.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content