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© 2001 American Society for Clinical Oncology Lack of Adherence With the Analgesic Regimen: A Significant Barrier to Effective Cancer Pain ManagementByFrom the Schools of Nursing, Medicine, and Pharmacy, University of California, San Francisco, CA, and School of Nursing, University of Pennsylvania, Philadelphia, PA. Address reprint requests to Christine Miaskowski, RN, PhD, Department of Physiological Nursing, University of California, San Francisco, 2 Koret Way, Box 0610, Rm N 611Y, San Francisco, CA 94143-0610; email: chris.miaskowski{at}nursing.ucsf.edu
PURPOSE: To evaluate oncology outpatients’ level of adherence to their analgesic regimen during a 5-week period.
PATIENTS AND METHODS: A random sample of 65 adult oncology outpatients with a Karnofsky performance status score of RESULTS: Overall adherence rates for ATC opioid analgesics ranged from 84.5% to 90.8% and, for PRN analgesics, from 22.2% to 26.6%. No significant differences over time were found in either of these adherence rates. CONCLUSION: One factor that seems to contribute to ineffective cancer pain management is poor adherence to the analgesic regimen.
IN CHRONIC MEDICAL conditions like diabetes and hypertension, the patient’s level of adherence with the therapeutic regimen is the subject of intense investigations.1 Estimates of nonadherence rates range from 15% to 93%,2 with an average of one third of the patients failing to adhere to a recommended therapeutic regimen.3-6 With several chronic medical conditions, the consequences of poor adherence include treatment failure and increased health care costs. Only two studies7,8 have provided cross-sectional data on oncology patients’ level of adherence with their analgesic regimen. Du Pen et al7 reported that oncology patients adhered to their prescribed opioid therapy between 62% and 72% of the time. However, the methods used to calculate these adherence scores were not described. In a cross-sectional study of breakthrough pain,8 adherence rates for opioid analgesics ranged from 0% to 270% with a mean of 80%. In this study, both regularly scheduled and as-needed opioid analgesics were included in the analysis of adherence rates for routine analgesics. Neither of these studies included nonopioid analgesics in their calculation of adherence rates. Currently, no information is available on how well oncology outpatients who experience cancer-related pain adhere to their analgesic regimen on a long-term basis. In addition, little is known about differences in adherence rates for analgesics prescribed on an around-the-clock (ATC) basis compared with those prescribed on an as-needed (PRN) basis. Therefore, the purpose of this longitudinal study was to evaluate oncology outpatients’ level of adherence with their analgesic regimen during a 5-week period by comparing doses of analgesics prescribed versus taken on an ATC basis and on a PRN basis.
Sample and Settings This study is part of a large, ongoing, randomized clinical trial that is testing the effectiveness of a self-care intervention compared with standard care in improving the management of cancer pain. Only data from patients in the standard care arm of the randomized clinical trial were used in this analysis. Sixty-five patients were recruited from seven outpatient settings in Northern California. The participants were adult oncology outpatients (> 18 years of age) who were able to read, write, and understand English; had a Karnofsky performance status score9 of  50; had an average pain intensity score of 2.5; and had radiographic evidence of bone metastasis.
Instruments The daily pain medication diary provided information on opioid, nonopioid, and adjuvant analgesics prescribed and taken on an ATC and on a PRN basis. The research nurses recorded on a weekly basis the name, dose, and administration schedule for all of the analgesics that the patients’ physician had prescribed and any over-the-counter medications the patients were taking for pain. Patients recorded the times they took their analgesics on a daily basis. If a change in the pain medication prescription occurred, patients were instructed to make the change on their diary.
Data Collection Procedures
Data Analysis To account for the prescription and administration of all nonopioid, opioid, and adjuvant analgesics, a Medication Quantification Scale (MQS) score was calculated using the method described by Steedman et al.14 The MQS provides a method for quantifying analgesic use by calculating scores for each analgesic on the basis of weights assigned by medication class and dosage level. These individual scores were summed to create a quantitative index of total analgesic medication usage suitable for statistical analyses. MQS scores for analgesic medications that were prescribed and taken on an ATC basis as well as on a PRN basis were calculated daily. Daily scores were averaged to provide a weekly MQS score. One-way, repeated-measures analyses of variance were done to determine if pain intensity and pain duration scores changed during the 5 weeks of data collection and to determine if the amounts of analgesics prescribed and taken changed over time. Adherence rates (ie, dose taken divided by dose prescribed, multiplied by 100) were calculated for ATC opioid analgesics, PRN opioid analgesics, and MQS scores each week for the 5 weeks of data collection, and repeated-measures analyses of variance were performed to determine if scores changed over time. If the Mauchley criterion indicated that the subject’s assumption of sphericity was not met, Greenhouse-Geisser–corrected P values are reported. If the main effect of time was significant, orthogonal polynomial tests for a trend were calculated to determine the nature of the change. A P value of less than .05 was considered statistically significant.
Sample Demographics Patients (n = 65) were primarily white (87.5%) and middle aged (mean, 59.3 years) and had an average of 2 years of college education. The majority of the patients were female (67.2%) and married or partnered (57.8%), with 21.9% living alone. Additional demographic and disease-related characteristics of the patients are summarized in Table 1.
Baseline Characteristics of the Pain Problem The characteristics of the pain at the time of the patients’ enrollment onto the study are found in Table 2. The majority of the patients were experiencing moderate to severe pain that lasted almost half of each day and had been in pain for more than 6 months. In addition, more than 92% of the patients who were working reported that pain limited their work activities.
Pain Intensity and Duration Over Time No significant differences were found in average, worst, or least pain intensity scores or in the number of hours per day the patients experienced significant pain during the 5 weeks of data collection (Fig 1).
Pain Medication Data In this sample of 65 patients, nine (13.9%) were prescribed opioid analgesics on an ATC basis, 37 (56.9%) were prescribed opioid analgesics on a PRN basis, and 19 (29.2%) were prescribed both ATC and PRN analgesics. Analgesic prescriptions. No significant differences over time were found in the doses of opioid analgesics prescribed on an ATC basis or on a PRN basis. However, significant differences (F(4,256) = 7.87; P = .0008) were found in the prescription MQS scores over time. Tests for polynomial trends indicated a significant increasing linear trend in prescribed MQS scores. Analgesic administration. No significant differences over time were found in the doses of opioid analgesic taken on an ATC basis, on a PRN basis, or in the MQS score for the amount of analgesic taken.
Adherence Data
This study is the first to evaluate oncology outpatients’ level of adherence to their analgesic regimen on a long-term basis. Because more than 90% of oncology care is provided on an outpatient basis, it is critically important for clinicians to have knowledge of how patients adhere to their analgesic regimen after the physician writes the prescription. Our data indicate that one of the major factors that contributes to the undertreatment of cancer pain is the patients’ lack of adherence to the therapeutic regimen.
Of note, adherence rates were significantly higher when patients were prescribed opioid analgesics on an ATC basis. Over the 5 weeks of this study, patients took an average of 88.9% of their ATC dose. In sharp contrast to the extremely high adherence rate with the ATC dosing regimens, oncology outpatients who were prescribed PRN opioid analgesics took only 24.7% of the prescribed dose. One could speculate that the reason for the lower adherence rates for the PRN regimen is that these patients were experiencing less pain and, therefore, needed less analgesics. However, as shown in Fig 3, no significant differences were found during the 5 weeks of the study in the percentage of patients who reported severe pain (ie, worst pain intensity score of
Patients’ level of adherence to their overall analgesic regimen as measured by the MQS score was approximately 55%. This adherence rate is lower than the 66% quoted for other types of medication regimens3-6 and may explain the inadequate pain control. It is important to note that adherence rates using any of the measures of analgesic consumption did not change during the 5 weeks of the study. Equally important, worst, average, and least pain scores as well as hours per day in pain did not change. One approach to improving pain management in this patient population would be to encourage patients to increase their level of adherence with their pain medication regimen and to increase the dose to achieve optimal pain control. Besides the poor adherence rates, an examination of the types of pain management regimens these patients were prescribed provides another explanation for why pain scores and hours per day in pain were so high in this sample. Current practice guidelines for cancer pain management recommend that patients with chronic cancer pain, like pain from bone metastasis, receive an ATC long-acting opioid analgesic for their constant pain and a short-acting opioid analgesic on a PRN basis for breakthrough pain.15 Only 29.2% of our sample were prescribed an analgesic regimen on the basis of these recommended guidelines. One might argue that physicians prescribed analgesics on the basis of an assessment of the patient’s level of pain. However, no significant correlations were found between any of the scores for analgesic prescriptions and any of the pain measures (ie, worst, average, least, and hours per day). One of the major methodologic issues in evaluating adherence to any medication regimen is how to measure the actual amount of medication taken by the patient.1,16 A variety of approaches, including pill counts, electronic measurement devices, an evaluation of a specific outcome measure (eg, a reduction in blood pressure), or direct measurement of the drug in the urine or blood are recommended to evaluate adherence with a drug regimen.16-18 Although these approaches are more rigorous than diary data, they are expensive. In addition, on the basis of an analysis of patient interview data obtained during this study, the use of pain medications seems to involve a complex set of decisions that is different from taking, for example, an antihypertensive medication on a daily basis. On the basis of the design of this study, which included home visits by our research nurses, we decided to use a pain medication diary to assess patients’ level of adherence. This approach proved effective in that the research nurses verified the analgesic prescriptions and over-the-counter use three times during the 5-week period, and 98% of the patients completed the pain medication diary on a daily basis. Most of the studies that evaluated various methodologic approaches to document adherence with medication regimens found that patients tend to overreport the amount of medication they take when a diary format is used compared with an electronic monitoring device.19,20 In contrast, when patients’ self-reports were compared with some objective measure of medicine taking, studies showed that patients are accurate when they say that they have not taken their medication.21 Oncology outpatients in our study reported relatively low levels of adherence with their analgesic regimen. If anything, our data may be an overestimation of extremely poor levels of adherence with analgesics in oncology outpatients who are experiencing pain from bone metastasis. Further research is needed to determine what methods are the most appropriate for the determination of adherence with ATC and PRN dosing of analgesic medications, what factors contribute to patients’ decision-making processes regarding analgesic intake, and what additional factors influence patients’ level of adherence with an analgesic regimen.
Supported by grant no. CA 64734 from the National Cancer Institute, Bethesda, MD, and unrestricted grants from Janssen Pharmaceutica, Titusville, NJ, and Purdue Pharma L.P., Stamford, CT. We acknowledge the support and assistance of all of the physicians and nurses at our study sites as well as our project staff, are especially grateful to all of the patients and family caregivers who participated in this study, and thank Julie Alden for technical assistance with the preparation of the manuscript.
1. Myers LB, Midence K: Concepts and issues in adherence, in Myers LB, Midence K (eds): Adherence to Treatment in Medical Conditions. Amsterdam, the Netherlands, Harwood Academic Publishers, 1998, pp 1-24 2. Kaplan RM, Simon HJ: Compliance in medical care: Reconsideration of self-predictions. Ann Behav Med 12: 66-71, 1990 3. Blackwell B: Patient compliance. N Engl J Med 289: 249-253, 1973 4. Davis MS: Variations in patients’ compliance with doctors’ advice: Analysis of congruence between survey responses and results of empirical observations. J Med Educ 41: 1037-1048, 1966[Medline] 5. Davis MS: Physiologic, psychological, and demographic factors in patients’ compliance to doctors orders. Med Care 6: 115-122, 1968 6. Stimson GV: Obeying doctor’s orders: A view from the other side. Soc Sci Med 8: 97-104, 1974
7.
Du Pen SL, Du Pen AR, Polissar N, et al: Implementing guidelines for cancer pain management: Results of a randomized controlled clinical trial. J Clin Oncol 17: 361-370, 1999 8. Ferrell BR, Juarez G, Borneman T: Use of routine and breakthrough analgesia in home care. Oncol Nurs Forum 26: 1655-1660, 1999[Medline] 9. Karnofsky D: Performance scale, in Kennealey GT, Mitchell MS (eds): Factors That Influence the Therapeutic Response in Cancer. New York, NY, Plenum Press, 1977, pp 97-101 10. Burrows M, Dibble SL, Miaskowski C: Differences in outcomes among patients experiencing different types of cancer-related pain. Oncol Nurs Forum 25: 735-741, 1998[Medline] 11. Glover J, Dibble SL, Dodd MJ, et al: Mood states of oncology outpatients: Does pain make a difference? J Pain Symptom Manage 10: 120-128, 1995[Medline] 12. Miaskowski C, Dibble SL: The problem of pain in outpatients with breast cancer. Oncol Nurs Forum 22: 791-797, 1995[Medline] 13. Miaskowski C, Zimmer EF, Barrett KM, et al: Differences in patients’ and family caregivers’ perceptions of the pain experience influence patient and caregiver outcomes. Pain 72: 217-226, 1997[Medline] 14. Steedman SM, Middaugh SJ, Kee WG, et al: Chronic pain medications: Equivalence levels and method of quantifying usage. Clin J Pain 8: 204-214, 1992[Medline] 15. Jacox A, Carr DB, Payne R, et al: Management of cancer pain: Clinical Practice Guideline No. 9—AHCPR Publication No. 94-0592. Rockville, MD, Agency for Health Care Policy and Research, U.S. Department of Health and Human Services, Public Health Service, 1994
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Stephenson BJ, Rowe BH, Haynes RB, et al: Is this patient taking the treatment as prescribed? JAMA 269: 2779-2781, 1993
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Cramer JA, Mattson RH, Prevey ML, et al: How often is medication taken as prescribed? A novel assessment technique. JAMA 261: 3273-3277, 1989 18. Lee JY, Kusek JW, Greene PG, et al: Assessing medication adherence by pill count and electronic monitoring in the African American Study of Kidney Disease and Hypertension (AASK) Pilot Study. Am J Hypertens 9: 719-725, 1996[Medline] 19. Straka RJ, Fish JT, Benson SR, et al: Patient self-report of compliance does not correspond with electronic monitoring: An evaluation using isosorbide dinitrate as a model drug. Pharmacotherapy 17: 126-132, 1997[Medline]
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Waterhouse DM, Calzone KA, Mele C, et al: Adherence to oral tamoxifen: A comparison of patient self-report, pill counts, and microelectronic monitoring. J Clin Oncol 11: 1189-1197, 1993 21. Fletcher RH: Patient compliance with therapeutic advice: A modern view. Mt Sinai J Med 56: 453-458, 1989.[Medline] Submitted December 5, 2000; accepted July 5, 2001.
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Copyright © 2001 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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ABSTRACT
INTRODUCTION
