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  • L E KleinCompliance and blood pressure control.

    Print ISSN: 0194-911X. Online ISSN: 1524-4563 Copyright 1988 American Heart Association, Inc. All rights reserved.

    is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231Hypertension doi: 10.1161/01.HYP.11.3_Pt_2.II61

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  • Compliance and Blood Pressure ControlLAWRENCE ELLIOT KLEIN

    SUMMARY Compliance with medical therapy in general is often low, and compliance with bloodpressure treatment is no better. Numerous studies have shown that patients frequently drop out oftreatment for hypertension. Furthermore, even when patients stay in treatment, they often take theirmedications in a way quite dissimilar from that prescribed. Identifying noncompliant patients isimportant but not always easy to accomplish. Pill counts, the "gold standard," are seldom practical inroutine clinical practice. Assessing compliance by its biological effect is compromised by physiologicaldiversity among patients. Assessing compliance from patient self-reports is limited hi its accuracy butis more useful than many researchers and clinicians appreciate. Compliance behavior is affected bymany factors. Complexity of medical regimen has some effect; the presence of drug side effects hassurprisingly little. Contrary to what many clinicians think, increased age is often accompanied byincreased medication compliance. Features of the doctor-patient relationship likely have an importanteffect on patient compliance, though our knowledge of these factors is still limited.(Hypertension 11 [Suppl II]: II-61-H-64, 1988)

    KEY WORDS ambulatory medicine patient education clinical assessment

    COMPLIANCE is a complex topic that becomesno simpler when viewed only in the frame-work of blood pressure control. Though nec-essarily limited, the following discussion highlightsseveral key aspects of compliance with hypertensiontherapy.

    How Much Compliance?A first issue, obviously, is the actual magnitude of

    patient compliance with hypertension therapy. As not-ed in Dr. German's review, compliance behavior ingeneral is often suboptimal. Unfortunately, compli-ance with hypertension therapy is no better. For exam-ple, Engelland et al.' reviewed records from a medicalpractice in an affluent section of Manhattan and report-ed that 51 % of a sample of hypertensive patients failedto reappear during the year following their initial visit.Similarly, Gillum et al. ,2 reviewing 2 years of recordsfrom a Boston teaching hospital's outpatient clinic,reported that 50% of newly and 30% of previouslydiagnosed hypertensive patients failed to return to theclinic within 6 months of their last scheduled appoint-ment. Johnson et al.,3 in a follow-up study of a com-munity population volunteering for a shopping-centerblood pressure screening program, found that 21% of

    From the Division of Internal Medicine and Health ServicesResearch and Development Center, The Johns Hopkins University,Baltimore, Maryland; and Division of Geriatric Medicine, George-town University, Washington, D.C.

    Address for reprints: Dr. Lawrence Elliot Klein, Suite 331, 3301New Mexico Avenue, N.W., Washington, D.C. 20016.

    patients had stopped treatment within 1 year. Like-wise, 19% of patients in The Australian Mild Hyper-tension Trial refused to continue with therapy withinthe first 2 years of the program, often discontinuingduring the first few months.4

    Thus, these and other studies5"7 confirm that manypatients drop out of treatment for hypertension. This isnot the only bad news, however, because it turns outthat compliance among those staying in treatment interms of how they actually consume their medicationsis poor also.

    For example, Johnson et al.,3 studying their shop-ping-center screening program, reported that only 60%of the patients remaining in treatment claimed to befully compliant with their drug regimen. Likewise,Sackett et al.,8 describing their landmark study ofCanadian steelworkers enrolled in a randomized trialof antihypertensive treatment, reported that only about50% of patients complied with at least 80% of theirprescribed drug regimen. Data from the MarylandStatewide Hypertension Survey9 revealed that amongpatients who were actively under treatment (defined ashaving medication bottles at home) when interviewed,only 60% scored high on a four-point compliancescale.

    Clinicians and Their Assessment ofPatient Compliance

    These and other studies10"12 document that evenwhen patients remain under treatment, compliance intaking medication is often poor. However, when pa-tients remain in treatment, clinicians, at least theoreti-

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  • n-62 ANTIHYPERTENSIVE DRUG EFFECTS SUPPL H HYPERTENSION, VOL 11, No 3, MARCH 1988

    cally, can target compliance-promoting measures atthose who fail to take their medications as prescribed.However, this assumes that clinicians can identifynoncompliant patients.

    Although there is little written specifically about theability of clinicians to recognize patients' noncom-pliance with antihypertensive therapy, several studiesdo show clinicians in general to be inaccurate in thisregard. For example, Muslin and Appel13 and Caronand Roth14 have reported that house staff physiciansare no better than 50% accurate in identifying whetherpatients are complying with prescribed medicationregimens. Interestingly, Davis13 has provided datasuggesting that senior physicians can be even moreinaccurate than junior clinicians in recognizingnoncompliance.

    Methods for Assessing Patient ComplianceAs these and other studies16' n demonstrate, personal

    assessments by clinicians of patients' compliance areof limited accuracy. Thus, the question is raised as towhether there exist other more accurate means of as-sessing compliance.

    It is easy, of course, to assess dropping out of treat-ment altogether since the patient is no longer there.However, much harder is the task of assessing howmuch medication a patient actually consumes relativeto how much was prescribed.

    Traditionally, the "gold standard" in assessingmedication compliance has been pill counts. Thoughthis can be an effective means of assessing compliancein carefully controlled prospective trials, it is of limitedutility in tine world of everyday practice. Obviously,the typical clinician cannot drop in on his patients athome to count pills. On the other hand, asking patientsto bring their pill bottles to the office is not an accept-able alternative since pill count accuracy is easily com-promised. For example, patients may forget to bringtheir pill bottles to the office. Or, if they bring pillbottles to the office, they may forget having dividedtheir medication among several bottles for conve-nience and bring in only some of the bottles. Of, if theydo bring in all bottles, they may first purposely emptyout some of the pills so as to not "disappoint" theirdoctor.

    A second means of evaluating medication compli-ance used at times by both researchers and practicingclinicians has been the measurement of drug levels andthe assessment of biological effects of treatment. How-ever, both of these means of assessing compliance arelimited. For one thing, drug levels of antihypertensivemedications are not routinely available and, even ifthey were, would not likely be very useful because ofphysiological variation among individuals in theirclearance of these drugs. Similarly, assessing drugcompliance by looking at biological effects is limitedby physiological variability among patients. For exam-ple, although thiazides tend to depress serum potas-sium levels and raise serum uric acid levels, the magni-tude of these effects if too variable for serum levels tobe useful in assessing medication compliance. Blood

    pressure control itself is neither a sensitive nor specificmeasure of compliance since it is possible for a patientto be compliant but hypertensive (if his medicationregimen is inadequate) or, conversely, to be noncom-pliant but normotensive (if he did not actually need allthe medication prescribed).

    Self-Report and the Recognition of NoncomplianceAsking patients whether they are compliant with

    their antihypertensive regimen is another way to assesscompliance behavior, though it is a method so simplis-tic that it has generated little enthusiasm among re-searchers. However, in light of the fact that it is clini-cally easy to do and since other means of assessingcompliance have shown limited utility, this means ofevaluating compliance has recently received increasedattention.

    For example, Levine et al.18 reported on a four-itemcompliance scale used in studying three educationalinterventions aimed at hypertensive ambulatory pa-tients. They found a high degree of consistency inresponses among the four items and adequate predic-tive validity with blood pressure control. Furthermore,Morisky et al.,19 studying these patients at year two,reported 75% of those scoring high on the scale to haveadequate blood pressure control compared with 47%scoring low (p

  • COMPLIANCE AND BLOOD PRESSURE/ATem n-63

    ance (90% or greater compliance) was found to be 70%predictive of a pill count indicating 80 to 100% com-pliance. Conversely, a self-report of low compliance(less than 90% compliance) was 91% predictive of 0 to79% compliance. These figures, though admittedlyless than perfect, do suggest that questioning patientsabout their compliance can give useful information.

    Predicting NoncomplianceSuccessful recognition of noncompliance after it has

    occurred (whether through pill counts, self-report,etc.) is valuable bdth so that researchers can take com-pliance into consideration in assessing new therapiesand so that clinicians can understand poor medicaloutcomes. However, even more useful would be theability to predict noncompliance ahead of time, there-by giving researchers and clinicians an opportunity toattempt to prevent it in the first place.

    For example, it has been suggested that we coulddevelop a profile of the type of individual who is likelyto be noncompliant by considering some combinationof characteristics of the patient, the treating physician,and the medication regimen itself.22 If we were silc-cessful in this regard, then we could concentrate ontargeting compliance promotion programs at those in-dividuals most likely to be noncompliant. Additional-ly, if one could identify specific aspects of the doctor-patient interaction or specific features of treatmentitself that correlate with noncompliance, then we couldpotentially work to modify these elements and, there-by, increase compliance.

    Age and ComplianceOne potential determinant of compliance behavior

    that has been widely discussed in the medical literatureover the years has been that of patient age. In particu-lar, much has been written about how there is an espe-cially great problem of medication noncomplianceamong the elderly. Interestingly, however, when onebegins to look closely at these pronouncements, it be-comes clear that much of what is referenced is eitheranecdotal or limited in its applicability.23 In fact, care-ful review of the literature suggests that elderly pa-tients on average try especially hard to be compliant,despite some clinicians' perceptions to the contrary.This seems true for medication use in general as well asfor antihypertensive medications specifically.

    For example, Haines and Ward,24 summarizing datafrom two national surveys sponsored by the NationalHeart, Lung, and Blood Institute, report that "Youngerhypertensives were more likely to discontinue theirmedication than were older ones." Similarly, datafrom the most recent of the Maryland Statewide Hy-pertension Surveys demonstrate that among those pa-tients who reported in the past being prescribed antihy-pertensive medications, the most likely (p

  • H-64 ANTfflYPERTENSIVE DRUG EFFECTS SUPPL II HYPERTENSION, VOL 11, No 3, MARCH 1988

    one would not expect patients to be more compliantwith their medications because they experience sideeffects. However, although there is some data support-ing such an inverse relationship, a review of data over-all actually suggests that this inverse relationship isrelatively weak (and, in fact, may actually be of limit-ed clinical importance). For example, a study of 299randomly selected outpatients from a teaching hospitalmedical practice revealed very few patients stoppingtheir medications in general because of side effects,which was similar to what was found in the MarylandStatewide Hypertension Survey that concentrated onantihypertensive medications.28

    Compliance and the Doctor-Patient RelationshipAs the preceding brief discussion has attempted to

    demonstrate, the issue of compliance and blood pres-sure control is complex and incompletely understooddespite the publication of numerous papers exploringmedical compliance in general. Dr. German in herreview has highlighted aspects of the doctor-patientrelationship affecting compliance in general, stressingher belief in their importance. Similarly, it would seemprobable that these factors affect compliance withblood pressure therapy specifically. Unfortunately,relatively few studies have addressed this particularissue, thereby limiting our ability to intercede in thedoctor-patient relationship to maximize compliance.

    ConclusionThe preceding discussion has summarized our

    knowledge of compliance in the treatment of hyperten-sion. In part, the data are discouraging, revealing largenumbers of patients dropping out of treatment as wellas low compliance among patients staying in treat-ment. On the other hand, we have seen that clinicianscan use patie...