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Shelly A. Vik
Colleen J. Maxwell
David B. Hogan
Scott B. Patten
Jeffrey A. Johnson
Lori Romonko- Slack


Medication adherence, measurement, pill count, self-report, elderly, home care



Medication adherence is an important public health issue. To better understand its relevance among vulnerable populations requires the availability of a valid, reliable and practical measurement approach. Researchers have proposed various competing methods, including pill counts and self-report measures.


To examine the utility of pill counts compared with self-report measures in the assessment of medication adherence among older home care clients.


The sample included 319 home care clients aged 65+ years randomly selected from urban and rural settings. During in-home assessments, nurses performed a medication review (including a pill count), administered the Morisky self-report scale, obtained supplemental information on medication use and completed the Resident Assessment Instrument for Home Care (RAI-HC). Responses to the Morisky scale and an open-ended question on nonadherence were combined to form a composite self-report measure of adherence.


Pill counts were either not feasible or considered inaccurate for 34.7% of subjects (47.5% of all eligible drugs). For the 205 subjects with available pill counts, estimates derived from the dispense date were found to underestimate adherence when compared with the actual start date reported by clients. The Morisky scale showed low reliability (Cronbach’s ?=0.42) and subjects’ responses to the scale were often in disagreement with their responses to the open-ended question on nonadherence. There was poor agreement between the pill count and self-report measures.


Our findings raise concerns about the feasibility and accuracy of pill counts as well as the validity of the Morisky self-report scale in the assessment of medication adherence among community-dwelling seniors.

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1. Col N, Fanale JE, Kronholm P. The role of medication noncompliance and adverse drug reactions in hospitalizations of the elderly. Arch Intern Med 1990;150(4):841-5.
2. Grymonpre RE, Mitenko PA, Sitar DS, Aoki FY, Montgomery PR. Drug-associated hospital admissions in older medical patients. J Am Geriatr Soc 1988;36(12):1092-8.
3. McKenney JM, Harrison WL. Drug-related hospital admissions. Am J Hosp Pharm 1976;33(8):792-5.
4. Haynes RB, McKibbon KA, Kanani R. Systematic review of randomised trials of interventions to assist patients to follow prescriptions for medications. [erratum appears in Lancet 1997 Apr 19;349(9059):1180.]. Lancet 1996;348(9024):383-6.
5. Craig HM. Accuracy of indirect measures of medication compliance in hypertension. Res Nurs Health 1985;8(1):61-6.
6. Fletcher SW, Pappius EM, Harper SJ.Measurement of medication compliance in a clinical setting. Comparison of three methods in patients prescribed digoxin. Arch Intern Med 1979;139(6):635-8.
7. Pullar T, Kumar S, Tindall H, Feely M. Time to stop counting the tablets? [see comments.]. Clin Pharmacol Ther 1989;46(2):163-8.
8. Steiner JF, Koepsell TD, Fihn SD, Inui TS. A general method of compliance assessment using centralized pharmacy records. Description and validation. Med Care 1988;26(8):814-23.
9. Gilmore JE, Temple DJ, Taggart HM. A study of drug compliance, including the effect of a treatment card, in elderly patients following discharge home from hospital. Aging (Milano) 1989;1(2):153-8.
10. Blenkiron P. The elderly and their medication: understanding and compliance in a family practice. Postgrad Med J 1996;72(853):671-6.
11. Gurwitz JH, Glynn RJ, Monane M, et al. Treatment for glaucoma: adherence by the elderly. Am J Public Health 1993;83(5):711-6.
12. Monane M, Bohn RL, Gurwitz JH, Glynn RJ, Avorn J. Noncompliance with congestive heart failure therapy in the elderly. [see comments.]. Arch Intern Med 1994;154(4):433-7.
13. Monane M, Bohn RL, Gurwitz JH, Glynn RJ, Levin R, Avorn J. The effects of initial drug choice and comorbidity on antihypertensive therapy compliance: results from a population- based study in the elderly. Am J Hypertens 1997;10(7 Pt 1):697-704.
14. Botelho RJ, Dudrak R, 2nd. Home assessment of adherence to long-term medication in the elderly. J Fam Pract 1992;35(1):61-5.
15. Kendrick R, Bayne JR. Compliance with prescribed medication by elderly patients. CMAJ 1982;127(10):961-2.
16. Okuno J, Yanagi H, Tomura S, et al. Compliance and medication knowledge among elderly Japanese home-care recipients. Eur J Clin
Pharmacol 1999;55(2):145-9.
17. Gray SL, Mahoney JE, Blough DK. Medication adherence in elderly patients receiving home health services following hospital discharge. Ann
Pharmacother 2001;35(5):539-45.
18. Roberts J, Tumer N. Pharmacodynamic basis for altered drug action in the elderly. Clin Geriatr Med 1988;4(1):127-49.
19. Smith NL, Psaty BM, Heckbert SR, Tracy RP, Cornell ES. The reliability of medication inventory methods compared to serum levels of
cardiovascular drugs in the elderly. J Clin Epidemiol 1999;52(2):143-6.
20. Rang HP DM, Ritter JM, Gardner P. Pharmacology. New York: Churchill Livingstone Inc., 1995.
21. Maronde RF, Chan LS, Larsen FJ, Strandberg LR, Laventurier MF, Sullivan SR. Underutilization of antihypertensive drugs and associated
hospitalization. Med Care 1989;27(12):1159-66.
22. Haynes RB, Taylor DW, Sackett DL, Gibson ES, Bernholz CD, Mukherjee J. Can simple clinical measurements detect patient noncompliance? Hypertension 1980;2(6):757-64.
23. Guerrero D, Rudd P, Bryant-Kosling C, Middleton B, Middleton BF. Antihypertensive medication- taking. Investigation of a simple regimen. [erratum appears in Am J Hypertens 1993 Nov;6(11 Pt 1):982.]. Am J Hypertens 1993;6(7 Pt 1):586-92.
24. Cramer JA. Microelectronic systems for monitoring and enhancing patient compliance with medication regimens. Drugs 1995;49(3):321-7.
25. Choo PW, Rand CS, Inui TS, et al. Validation of patient reports, automated pharmacy records, and pill counts with electronic monitoring of adherence to antihypertensive therapy. Med Care 1999;37(9):846-57.
26. Coons SJ, Sheahan SL, Martin SS, Hendricks J, Robbins CA, Johnson JA. Predictors of medication noncompliance in a sample of older adults. Clin Ther 1994;16(1):110-7.
27. Cooper JK, Love DW, Raffoul PR. Intentional prescription nonadherence (noncompliance) by the elderly. J Am Geriatr Soc 1982;30(5):329-33.
28. Hemminki E, Heikkila. Elderly people's compliance with prescriptions, and quality of medication. Scand J Soc Med 1975;3(2):87-92.
29. McElnay JC, McCallion CR, al-Deagi F, Scott M. Self-reported medication non-compliance in the elderly. Eur J Clin Pharmacol 1997;53(3-4):171-8.
30. McLane CG, Zyzanski SJ, Flocke SA. Factors associated with medication noncompliance in rural elderly hypertensive patients. Am J Hypertens
31. Spagnoli A, Ostino G, Borga AD, et al. Drug compliance and unreported drugs in the elderly. J Am Geriatr Soc 1989;37(7):619-24.
32. Gordis L, Markowitz M, Lilienfeld AM. The inaccuracy in using interviews to estimate patient reliability in taking medications at home. Med Care 1969;7(1):49-54.
33. Park LC, Lipman RS. A comparison of patient dosage deviation reports with pill counts. Psychopharmacology 1964;6(4):299-302.
34. Rickels K, Briscoe E. Assessment of dosage deviation in outpatient drug research. J Clin Pharm New Drugs 1970;10(3):153-60.
35. Grymonpre RE, Didur CD, Montgomery PR, Sitar DS. Pill count, self-report, and pharmacy claims data to measure medication adherence in the elderly. Ann Pharmacother 1998;32(7-8):749-54.
36. Morisky DE, Green LW, Levine DM. Concurrent and predictive validity of a self-reported measure of medication adherence. Medical Care 1986;24(1):67-74.
37. Vik SA, Maxwell CJ, Hogan DB, et al. Determinants and health related outcomes associated with nonadherence to prescribed drug regimens: a comparison of rural and urban home care clients (Working Paper #03-02) ear=2003. Edmonton: Institute of Health Economics, 2003.
38. RAI-Home Care (RAI-HC) Assessment Manual for Version 2.0. Marblehead, MA: Opus Communications, 2001.
39. Hirdes JP, Carpenter GI. Health outcomes among the frail elderly in communities and institutions: Use of the Minimum Data Set (MDS) to create effective linkages between research and policy. Canadian Journal of Aging 1997;S:53-69.
40. Morris JN, Fries BE, Steel K, et al. Comprehensive clinical assessment in community setting: applicability of the MDS-HC. J Am Geriatr Soc 1997;45(8):1017-24.
41. Streiner DL, Norman GR. Health Measurement Scales: A Practical Guide to Their Development and Use. 2nd Edition ed. Oxford: Oxford University Press, 2001.
42. Rich MW, Gray DB, Beckham V, Wittenberg C, Luther P. Effect of a multidisciplinary intervention on medication compliance in elderly patients with congestive heart failure. Am J Med 1996;101(3):270-6.
43. Morris JN, Fries BE, Mehr DR, et al. MDS Cognitive Performance Scale. J Gerontol 1994;49(4):M174-82.
44. Conn VS, Taylor SG, Kelley S. Medication regimen complexity and adherence among older adults. Image - J Nurs Scholarship 1991;23(4):231-5.
45. Gilbert JR, Evans CE, Haynes RB, Tugwell P. Predicting compliance with a regimen of digoxin therapy in family practice. CMAJ
46. Bender B, Wamboldt FS, O'Connor SL, et al. Measurement of children's asthma medication adherence by self report, mother report, canister weight, and Doser CT. Ann Allergy Asthma Immunol 2000;85(5):416-21.
47. Inui TS, Carter WB, Pecoraro RE. Screening for noncompliance among patients with hypertension: is self-report the best available measure? Med Care
48. Roth HP, Caron HS. Accuracy of doctors' estimates and patients' statements on adherence to a drug regimen. Clin Pharmacol Ther
49. Conrad P. The meaning of medications: another look at compliance. Soc Sci Med 1985;20(1):29-37.
50. Trostle JA. Medical compliance as an ideology. Soc Sci Med 1988;27(12):1299-308.
51. Weintraub M. Compliance in the elderly. Clin Geriatric Med 1990;6(2):445-52.