hypertension v. compliance with antihypertensive therapy

HYPERTENSION V. COMPLIANCE WITH ANTIHYPERTENSIVE THERAPYAuthor(s): David L. SackettSource: Canadian Journal of Public Health / Revue Canadienne de Sante'e Publique, Vol. 71, No.3 (MAY/JUNE 1980), pp. 153-156Published by: Canadian Public Health AssociationStable URL: http://www.jstor.org/stable/41987817 .

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Editorial

HYPERTENSION V. COMPLIANCE WITH ANTIHYPERTENSIVE THERAPY*

If hypertensives drop out of a treatment program or fail to take their medicine, all previous effort expended in detection, linkage, work-up and treatment (as recommended by the Cana- dian hypertension task forces and committees*) is nullified. It is therefore important to answer four questions: (a) How regularly do hypertensives

remain under care and take their medicine (that is, what is their compliance with antihypertensive drug regimens?)

(b) Is low compliance interfering with the achievement of goal blood pressure? If so,

(c) Can anything be done to improve low compliance?

(d) How can this knowledge be applied in clinical practice?

How Regularly do Hypertensive Patients Remain Under Care and Take Their Medicine?

Most pertinent data are from outside Canada, although there are some useful recent data from Ontario. Caldwell et

*A Report from the Canadian Hypertension Task Force. This is the fifth part in this series of articles on hypertension. The first part was published in the September/ Oc- tober Journal, 1979, pp 295-99. The second part in the November/ December Journal, 1979 pp 386-7; the third part in the January/ February Journal, 1980, pp 12-18; and the fourth part in the March/ April Journal, 1980, pp 101-106.

al. ( 1 ) followed up 76 hypertensives who had been started on antihypertensive drugs at a Detroit hospital; they found that half had dropped out of the treatment program by eleven months, and that only 1 7% of these patients were still under care for their hypertension 5 years later. Two other studies found that it may be difficult to keep hypertensive patients under care long enough even to begin therapy. Finnerty et al. (2) found, during a Washington, D.C. population survéy, that only 50% of hypertensive patients kept a follow-up clinic appointment, and Fletcher et al. (3) found that at an emergency department in a Baltimore hospital, only 58% of hypertensive patients kept their sub- sequent appointments at the hospital's clinic.

More recent data have come from special hypertension care programs and are considerably more optimistic. Only 7% of a group of Hamilton steelworkers dropped out of care during the first six months of therapy (4) and only 3% of New York department store employees dropped out during the first year of care (5). On the other hand, 20% of Chicago employees dropped out of the first year of an antihypertensive care program, although only 3% dropped out the next year (6). Finally, of 224 new and old hypertensive patients in a Hamilton general practice 11% dropped out or

moved away within the first year (7). Several investigators have used the

control of blood pressure as an indirect measure of compliance. In most, hypertension was considered controlled if the treated patients' blood pressure fell suf- ficiently to no longer satisfy the entry criteria for hypertension. When defined in these terms, the results of eight studies performed in this decade are remarkably similar, regardless of where they were done and what criteria were used to define hypertension. After one year of treatment hypertension was controlled in two-thirds of the patients whether they were in general practice or in special hypertension care programs. Five hypertension studies have included pill-counts or the direct measurement of antihypertensive drugs in blood or urine, and these are summarized in Table I (4, 8-10). These data are in general agreement with compliance mea- surements obtained by other routes, and indicate that compliance with antihypertensive regimens warrants attention and concern.

Is Low Compliance Interfering with the Achievement of Goal Blood Pressure?

Lowenthal et al ( 1 1) tested urine from hypertensive patients in Chicago to see whether they were taking their prescribed thiazides and found that the two- thirds of patients who had positive urine

Canadian Journal of Public Health Vol. 71, May/June 1980 153



TABLE I. Pill-Counts and Biochemical Measures of Compliance

Site and Sample Measurement Compliance Rate

49 hypertensives in a Pill-Count Mean pill-count = 63% neighbourhood health Proportion or patients taking centre in Detroit 90% of prescribed regimen = 20%

240 hypertensive Pill-Count Proportion of patients taking steelworkers in ^ 80% of prescribed regimen in Hamilton the sixth month of Rx = 53%

100 hypertensives in a Pill-Count Proportion of patients taking university hypertension 95% of prescribed regimen = 47% clinic in Cincinnati, Ohio

35 dialysis patients Propranolol Proportion of patients with in Washington, D.C. blood levels detectable levels of propranolol

=51% 172 hypertensives in a Thiazide Proportion of patient visits university hypertension urine tests with positive tests = 65% clinic in Chicago, Illinois

TABLE II. Why Hypertensive Patients May Not Take Their Medicine

(A) The duration of treatment is very long. (B) The regimen is often complex, requiring several tablets per dose and several

doses per day. (C) Most hypertensive patients have no symptoms at the beginning of treatment.

(D) Antihypertensive drugs produce side-effects.

(E) Patients' "health beliefs" may contravene taking their medications.

tests were 3.2 times as likely to be at goal blood pressure than were the two-third of patients with negative urine tests. Canadian investigators performed unobtrusive pill-counts in the homes of hypertensive steelworkers in Hamilton and found that the men who were taking four-fifths or more of their antihypertensive drugs were also 3.3. times as likely to be at goal blood pressure than were men taking less medication (12). These studies confirm that, although blood pressure is an unsatisfactory index of compliance, low compliance interferes with the achievement and maintenance of blood pressure control; low compliance is responsible for as many as three-fourths of the failures to achieve goal blood pressure in these patients. This situation warrants action.

Can Anything be Done to Improve Low Compliance?

A number of compliance-improving strategies have been suggested in journal editorials, drug advertisements and task force reports; these suggestions range from patient education programs through negotiated treatment "contracts" to calendar packs of medications. All of these recommendations are plausible and some are feasible, but almost none have undergone any experimental evaluation in randomized trials.

In the event that a better understanding of compliance as a phenomenon would provide ideas for compliance- improving strategies, much effort has gone to identifying the predicators or determinants of compliance, which have been discussed in detail elsewhere

(13); those determinants most pertinent to hypertension are listed in Table II.

Medication compliance diminishes markedly with the passage of time, and most antihypertensive regimens must be life-long. Compliance is low when regimens are complex, and some hypertensive patients require several tablets per dose and multiple doses per day in order to achieve or approach goal blood pressure. Most hypertensive patients are symptom-free at the time that treatment is started, another feature which appar- ently discourages compliance. Furth- ermore, hypertensive patients with no symptoms who feel worse on treatment than they did before treatment began must overcome a considerable urge to quit taking their medication. Finally, if clinicians' advocacy of therapy runs contrary to patients' perceptions of the barriers they will have to overcome in complying with the regimen, they are unlikely to take all, or even some, of the medicine. In summary, most features of most antihypertensive drug regimens actively discourage compliance.

It is obvious that most of these determinants cannot be altered for antihypertensive regimens in present use. Those who wish to improve low compliance have had to look elsewhere for ideas for compliance-improving strategies.

Fortunately, testing of potential strategies has often been done by means of proper randomized clinical trials which have heeded essential principles of research design. In these trials, two groups of hypertensive patients under- going drug treatment have been ran- domly allocated to receive, or not receive, a potential compliance- improving strategy, and both groups closely followed with serial measure- ments of compliance and blood pressure control.

Using this strategy, it has been possible to identify those strategies which do and do not work. Haynes et al. (14) identified steelworkers who were neither compliant (pill-counts <80%) nor controlled (diastolic pressures ^90 mm Hg) after six months of treatment with antihypertensive drugs and

154 Canadian Journal of Public Health Vol. 71



allocated them to a control group or to an experimental group who were taught how to measure their own pressures, asked to record their blood pressure and medication-taking daily, shown how to "tailor" medication-taking to the per- formance of daily habits and rituals, and reinforced by bi-weekly visits and rewards for improved compliance and lowered blood pressure. Six months later, compliance had fallen 1.5% among control patients but rose 21.3% among experimental patients, 30% of whom achieved goal blood pressure. This same research group later applied a subset of these successful strategies (this tie restricted to self-home blood pressure measurement and recording or monthly home visits by a trained lay interviewer for blood pressure checks) in a randomized trial among hypertensive screenees detected in shopping pla- zas who remained uncontrolled one year later despite treatment. The strategy was successful in lowering the blood pressures of that subset of the experimental group who admitted at the outset that they had a compliance problem, but had no effect among experimental patients who denied that they had difficulty remembering to take their medications. Thus, self-home blood pressure measurement and recording appears useful as a compliance-improving strategy among uncontrolled hypertensive patients who admit that they have trouble remembering to take their medications (15).

In another randomized trial, Black- well et al (9) found that a dispenser which displayed four daily doses for each of seven days, when coupled with interactive counselling by a pharmacist about hypertension, its treatment, spe- cific drugs and their side-effects, led to a doubling of the portion of patients taking more than 95% of their medication three months later and a statistically significant fall in diastlic blood pressures (the latter rose slightly among controls. This approach thus appears useful for patients on complex regimens.

Randomized trials have also demon- strated the futility of other approaches

to the compliance problem. Sacket et al (4) successfully instructed hypertensive patients about their illness, its treatment and the need for high compliance, but the mastery of this information had no effect upon their compliance. This team of investigators also found no difference in compliance when these men received follow-up care at the work-site on com- pany time as opposed to care in private physicians' offices.

Several randomized trials of other potential compliance-improving strategies are underway, and the usefulness of these manoeuvres will soon be known. Several of these trials deal with aspects of patient-therapist interaction and the organization of clinical services for hypertensive patients and are based upon promising results from sub- experimental research among patients with hypertension and both experimental and sub-experimental studies of a series of other health problems. Promis- ing strategies include expanded roles for pharmacists, nurses and public health nurses, patient contracts, reduction of major sources of inconvenience, simpli- fied dosing schedules, drug monitoring and feedback, and physician tutorials.

How Can This Knowledge be Applied in Clinical Practice?

Our understanding of compliance, its maintenance and modification is chang- ing rapidly. Accordingly, the recommendations of the task force will reflect this rapid change and the need for an informed group of clinicians.

These recommendations will also take the following findings into account: (1) Compliance problems are of real

concern only among patients who have failed to achieve goal blood pressures. Less attention need be given to patients who are well- controlled; their compliance can be sorted out during the "stepping- down" of their antihypertensive drug regimens.

(2) Clinicians must assure themselves that the prescribed regimen is strong enough to do the job. Up to half of uncontrolled hypertensive

patients are compliant and may simply be undertreated. Accord- ingly, clinicians must decide whether a patient's present regimen can be expected to bring the patient to goal or whether it needs to be "stepped up".

(3) Simply asking patients whether they are taking their blood pressure medicine may be a useful way of identifying those with low compliance. If the patient says "yes", he may or may not be telling the truth; if he says "no", he is virtually always telling the truth. Indeed, studies of Hamilton steelworkers found that 40 percent of the non-compliant, uncontrolled hypertensive men, when asked in a non-threatening, non-judgmental way, admitted that they were taking less than 80 percent of their prescribed antihypertensive drugs (14). Moreover, it is precisely that group of hypertensive patients who admit low compliance who show the greatest blood pressure responses to compliance- improving strategies. Thus, it may be possible to identify a substantial portion of those patients who would benefit from compliance-improving strategies without resorting to pill counts, drug analysis or other detec- tive work.

(4) Compliance-improving strategies are therapeutic manoeuvres, and should only be applied to informed and willing patients.

Summary and Recommendations Several features of antihypertensive

drug regimens discourage continued medication adherence, and low compliance with these regimens is common. Furthermore, low compliance interferes with the achievement of goal blood pressure. Commonly recommended strategies for maintaining and improving compliance have been shown to be inef- fectual when tested in randomized trials, but these same trials are also identifying effective strategies at a rapid rate. It is important that consenting patients benefit from this new knowledge.

May/June 1980 155



Recommendation 17: Treating clinicians should be encour- aged to identify uncontrolled, non- compliant hypertensive patients in their care by: (a) focusing on the patients who have

failed to reach goal blood pressure; (b) confirming that the prescribed reg-

imen is potent enough to reduce blood pressure to goal;

(c) asking patients in a non- threatening fashion about their compliance with the antihypertensive regimen;

(d) offering patients with compliance problems the opportunity to receive additional assistance.

Recommendation 18: Treating clinicians should receive up- to-date results of randomized trials and other investigations of other compliance-improving strategies so that they may apply these results to the benefit of uncontrolled hypertensive patients who will accept help for their medication compliance problems.

Recommendation 19: Priority should be given to determining the usefulness and feasibility of the identification and management of low compliance by pharmacists and other health professionals.

David L. Sackett, M.D., M.Sc. Epid.

Departments of Clinical Epidemiolgy and Biostatistics, and of Medicine

McMaster University, Hamilton, Ontario

The reports and common recommendations of the Hypertension Task Force of the Ontario Council of Health and the Committee on Hypertension of the Canadian Heart Foundation and Canadian Cardiovascular Society were identical and the Group of Experts on Hypertension endorsed the Hyperten- sion Task Force report. Copies of the full report can be obtained by writing to the Government of Ontario Bookstore , 880 Bay Street , Toronto , Ontario M5S 1Z8 ($2.00).

REFERENCES

1. Caldwell JR, Cobb S, Dowling MD, deJohngh D. The dropout problem in antihypertensive treatment: A pilot study of social and emotional factors influence a patient's ability to follow antihypertensive treatment. J Chron Dis 1970; 22: 579-595.

2. Finnerty FA Jr, Mattie EC, Finnerty FA. I. Hypertension in the inner City: 1 , Analysis of clinic dropouts. Circulation 1973; 47: 73-75.

3. Fletcher SW, Appel FA, Bourgois M. Improving emergency room patient follow- up in a Metropolitan teaching hospital: Effect of a follow-up clerk. N Engl J Med 1 974; 29 1 : 385-8.

4. Sackett DL, Haynes RB, Gibson ES, Hackett BC, Taylor DW, Roberts RS, Johnson AL. Randomized clinical trial of strategies for improving medication compliance in primary hypertension. Lancet 1975; 1: 1205-7.

5. Alderman MH, Schoenbaum EE. Detection and treatment of hypertension at the work site. N Engl J Med 1975; 293: 65-8.

6. Stamler, R, Gosch RC, Stamler J, Ticho S, Civinelli J, Restivo B, Pritchard D, Fine D. Adherence and blood pressure response to hypertension treatment. Lancet 1975; 2: 1227-31.

7. Rudnick KV, Sackett DL, Hirst S, Holmes C. Hypertension in family practice. Can Med Assoc J 1977; 117: 492-7.

8. McKenney JM, Slining JM, Henderson HR, Devins D, Barr M. The effect of clinical pharmacy services on patients with essential hypertension. Circulation 1973; 48: 1104-11.

9. Blackwell B. Treatment adherence in hypertension. Amer J Pharm 1976; 148: 75-85.

10. Briggs WA, iíowenthal DT, Cirksena WH, Price WE, Gibson TP, Flamenbaum W. Pro- pranolol in hypertensive dialysis patients: Efficacy and compliance. Clin Pharm Ther 1975; 18: 606-12.

11. Lowenthal DT, Briggs WA, Mutterperl R, Adelman B, Creditor MA. Patient compliance for antihypertensive medication: The

usefulness or urine essays. Current Ther Pes 1976; 19: 405-9.

1 2. Sackett DL, T aylor D W, Haynes RB, Gibson ES, Johnson AL. Communication to the Hypertension Task Force, 1976.

13. Haynes RB, Taylor DW, Sackett DL, eds. Compliance in Health Care. Baltimore, Johns Hopkins University Press, 1979.

14. Haynes RB, Sackett DL, Gibson ES, Taylor DW, Hackett BC, Roberts RS, and Johnston AL. Improvement of medication compliance in uncontrolled hypertension. Lancet 1976; 1: 1265-8.

15. Johnson AL, Taylor DW, Sackett DL, Dun- nett CW, Shimizu AG. Self-recording of blood pressure in the management of hypertension. Can Med Assoc J 1978; 1 19: 1034-9.

HYPERTENSION V: LE RESPECT DE LA THERAPIE ANTI-HYPERTENSIVE*

Si le patient souffrant d'hypertension abandonne un programme de traitement ou oublie de prendre ses médica- ments, tous les efforts conscrés à la détection, à l'analyse des corrélations, aux exercices et au traitement tels que recommandés par le groupe de travail et les comités sur l'hypertension au Ca- nada*, sont anéantis. Il est dès lors

essentiel de répondre à quatre questions de base:

a) Dans quelle mesure les patients souffrant d'hypertension suivent-ils leur traitement et prennent-ils leurs médi- caments (en d'autres mots, quelle est leur observation des régimes de drogues contre l'hypertension)?

b) Est-ce qu'une observation limitée affecte la réalisation de la tension artérielle désirée? Si c'est le cas,

c) Est-ce que l'on peut faire quelque chose pour améliorer l'observation des ordonnances?

d) Comment applique-t-on une telle connaissance à la pratique clinique?

156 Canadian Journal of Public Health Vol. 71



hypertension v. compliance with antihypertensive therapy

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