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AIDS:
Correspondence

The costs of antiretroviral drug wastage

Ostrop, Nikola J.a; Gill, M. Johnab

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aSouthern Alberta HIV Clinic, Foothills Medical Centre, Calgary, Alberta, Canada; and bDepartment of Medicine, University of Calgary, Calgary, Alberta, Canada.

Received: 11 November 1999; accepted 23 November 1999.

The cost of the antiretroviral medications used to treat HIV infection is significant, accounting for the majority of the care costs in our regional population living with HIV, and will probably increase further [1]. Difficulties arising from these complex therapies may lead to drug discontinuation, with the possible subsequent wastage of dispensed agents. In the light of the high cost of antiretroviral medications, an understanding of both the extent and the causes of this wastage would be helpful. Such information could then be used to modify practices to minimize the wastage and maximize the impact of the drug budget. Few published reports have focused exclusively on the issue of drug wastage [3–8]. All of those studies indicate a need for programmes to optimize the use of medication and reduce its cost without decreasing services [5].

The extent and costs of antiretroviral drug wastage was quantified over a 1 year period in order to benchmark wastage within the system and to identify possible interventions to minimize the issue. The care of all HIV-infected individuals is centralized in Southern Alberta, Canada. Access to provincially funded antiretroviral agents is provided at no charge through one pharmacy supporting the Southern Alberta HIV Clinic and its satellites. In an attempt to increase follow-up and communication with patients, antiretroviral agents have been routinely dispensed as a maximum of a 1 month supply. In addition, medications are usually dispensed in amounts that last only up until the patient's next appointment, if this is less than a month away.

All clinic patients between 1 April 1998 and 31 March 1999 (1 fiscal year), who had their antiretroviral regimen changed or discontinued, were asked to return any unused antiretroviral drugs. Clinical trial drugs were not included in the collection because of the different dispensing and care procedures dictated by the study protocols. An analysis compared the cost of all and individual antiretroviral agents returned with that of antiretroviral agents dispensed during that time period. In order to arrive at an estimate of the return rate and hence total antiretroviral wastage, pharmacy dispensing records were reviewed for those patients not returning any unused antiretroviral agents who had an antiretroviral drug discontinued in that time frame. All prescription fills for each particular drug were used to calculate an amount potentially remaining.

Two hundred and eleven patients stopped a specific non-clinical trial antiretroviral drug regimen between 1 April 1998 and 31 March 1999, either through treatment discontinuation, death or switch of regimen. Leftover medications were recovered from 47 patients (22%). For the 164 antiretroviral regimen discontinuations in which no drug was returned, a calculation from pharmacy dispensing records estimated that 127 patients (60%) should not have had any drug to return (assuming full adherence and no loss or sharing of drug). Fifty of these patients were in fact given less than a 1 month supply to last only up until the next doctor's appointment, whereas for others the script length was synchronized with appointments; a few had been asked to finish old medications before a switch, if that was determined to be non-urgent from both a medical and the patient's perspective. The remaining 37 patients (18%) were calculated to have a total of 627 patient-days of leftover antiretroviral therapy, amounting to a total of 1371 days of individual agents. With two exceptions, all were less than a 1 month supply. Both exceptions were caused by a 3 month supply dispensed to patients leaving the province, with an estimated wastage of 45 and 84 days supplies, equivalent to Can$1196 and Can$2972, respectively.

The total cost of all unused discontinued antiretroviral medications returned was Can$17 178.10. In addition, the calculated wastage of those drugs not returned was Can$15 291.94. The total cost of antiretroviral drugs dispensed during the same time frame was Can$3 630 280.90, resulting in a returned 0.47% wastage and a maximal potential wastage of 0.89%. The wastage of individual agents as a percentage of the total dispensed is shown in Table 1. Reasons for the drug discontinuations (either treatment discontinuation or a switch in regimen) resulting in the return of the above unused medications were as follows: gastrointestinal side-effects accounted for 35% of the wastage, followed by viral failure (30%), specific adverse events (6%), lack of housing/income (5%), discontinuation as a result of other drug(s) in the regimen being stopped for another specific reason (4%), simplification of regime (4%), patient decision (3%), death (3%), psychosocial reasons (2%), palliation (2%) and medication expiry (1%).

Table 1
Table 1
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The wastage found in our study is smaller than reported in earlier studies of wastage in HIV [7,8]. However, it still indicates room for improvement and for an ongoing approach to minimize significant costs. The results are difficult to compare, because the former studies probably do not reflect the current HIV population, the current potency of the medications or the dispensing and administrative practices. Previous studies have provided a number of valuable recommendations, which may also be reflected in the results of this study as they have guided these procedures. A number of reports emphasized the importance of adherence strategies, of patient and healthcare provider education and of tailoring a drug regimen to fit a patient's daily routine best [3,5]. The higher wastage seen with maintenance therapies may partly be caused by the larger quantities being dispensed. They also suggested that patient awareness of the cost may influence wastage. It would be interesting to know if wastage varies according to the source of funding.

These results suggest that limiting drug wastage is strongly associated with the intensity and support offered by pharmacy care. Emphasis on patient education and on adherence strategies, dispensing medications in smaller quantities as well as individualizing the length of prescription may limit wastage of antiretroviral therapy to less than 1%. It is also recommended that only a 2 week supply of an initial antiretroviral drug regimen should be provided, during which time the patient may be at high risk of experiencing possibly treatment-limiting side-effects. Patients can also be requested to bring all their antiretroviral drugs to each clinic and pharmacy visit to allow new quantities dispensed to balance those remaining.

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Acknowledgements

The authors wish to thank Kathryn Hull for her efforts with data collection, Bill Davidson for his assistance with data analysis and Kimberly Montgomery for her review of the manuscript.

Nikola J. Ostropa

M. John Gillab

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References

1. Albert T, Williams G. The economic burden of HIV/AIDS in Canada. Ottawa, Ontario: Canadian Policy Research Networks Inc.; 1998.

2. Kuspis DA, Krenzelok EP. What happens to expired medications? A survey of community medication disposal. Vet Hum Toxicol 1996, 38: 48 –49.

3. Cameron S. Study by Alberta pharmacists indicates drug wastage a `mammoth' problem. Can Med Assoc J 1996, 155: 1596 –1598.

4. Wong A, De Angelis C, Charbonneau F. Drug wastage in cancer [Letter]. Can J Hosp Pharm 1995, 48 (5): 263. 263.

5. Boivin M. The cost of medicine waste. Can Pharm J 1997, 130 (4): 32 –39.

6. Rosenbloom D, Scime J, Elviss OD. et al. Measurement of insulin wastage in five Ontario hospitals. Can J Hosp Pharm 1994, 47: 5 –7.

7. Steel S, George R. Wasted drugs in HIV infection and AIDS. BMJ 1992, 304: 123. 123.

8. Asboe D, Daniels D, Erskine D, Boag FC. Wasted drugs in HIV infection and AIDS. BMJ 1992, 304: 508 –509.

© 2000 Lippincott Williams & Wilkins, Inc.

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