Patient compliance with antihypertensive regimens

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PATIENT COMPLIANCE WITH ANTIHYPERTENSIVE REGIMENS

DAVID L. SACKETI', M.D., M.Sc. Epid., R. BRIAN HAYNES, M.D., M.Sc., Ph.D., EDWARD S. GIBSON, M.D., D. WAYNE TAYLOR, M.Sc., ROBIN S. ROBERTS, M.Tech. and ARNOLD L. JOHNSON, M.D., C.M., M.Sc.

Departments of Clinical Epidemiology and Biostatistics and Medicine, McMaster University Health Sciences Center; and Dominion Foundries and Steel Limited, Hamilton, Ontario, Canada

ABSTRACT

Low compliance with antihypertensive drug regimens is a major cause of failure to achieve adequate blood pressure control. A simple clinical interview can identify the noncompliant patient who is most likely to benefit from compliance-improving strategies. These strategies, many of which require a minimal amount of additional clinical effort, can be applied in sequence to help a substantial portion of uncontrolled hypertensives achieve goal blood pressures.

INTRODUCTION

This essay will answer three questions: 1) How regularly do hypertensives take their medicine (that is, what is their compliance with antihypertensive drug regimens)? 2) Is low compliance interfering with the achievement of goal blood pressure? and 3) Can we do anything to improve low compliance? The answers, in short, are these: 1) about half of the time; 2) yes, it is; and 3) yes, we can.

Our group from the Health Sciences Center at McMaster University has had the privilege and en- joyment of working with nearly a hundred community and industrial physicians. These physicians look after 250 hypertensive men whose high blood pressure was discovered through screening at the steel mill where they work. In collaboration with them we studied the treatment of primary hypertension in ambulatory

patients?, 2 This essay is one of the results of that collaboration.

HOW REGULARLY DO HYPERTENSIVES TAKE THEIR MEDICINE?

Our studies from the community revealed that these middle-aged men, when prescribed a common Canadian antihypertensive regimen (a thiazide di- uretic, occasionally supplemented by a second drug like propranolol or methyldopa), had to take 80% or more of their prescribed pills each month before their blood pressure would show a substantial fall towards normal. 2 However, by the sixth month after starting treatment, only about half of these hypertensive men were taking this much (80% or more) of their antihypertensive drugs. This is shown graphi- cally in Figure 1.

Why don't hypertensives take their medicine? The reasons are many, and are discussed in detail else- where 3; those determinants most pertinent to hypertension are listed in Table I. Medication compliance diminishes markedly with the passage of time, and most antihypertensive regimens must be lifelong. Com- pliance is low when regimens are complex, but some hypertensives require several pills per dose and multi- ple doses per day in order to approach proper control. Most hypertensives are symptom-free at the time of

aA~Jto,

1 0 % . m

_ _ I [

o .lo -. .~ ~ .& .~ .~ .7o .so ./o I.oo COMPLIANCE IN THE SIXTH MONTH OF R x

Figure 1. Compliance (by pill count) of hypertensive men in their 6th month of treatment.

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Table I. Why hypertensives don't take their medicine.

(a) The duration of treatment is very long. (b) The regimen is often complex, requiring several pills

per dose and several doses per day. (c) Most hypertensives are symptomless at the beginning

of treatment. (d) Antihypertensive drugs produce side effects. (e) Patients' "health beliefs" may contravene taking their

pills.

�9 diagn~ another feature which apparently discour- ages compliance. Furthermore, the symptomless hypertensive who feels worse on treatment than he did before treatment must overcome a considerable urge to quit taking his medications. Finally, if the clinician's advocacy of therapy runs contrary to the patient's perceptions of the seriousness of hypertension as an illness, of his own susceptibility to its complica- tions, of the effectiveness of the treatment being pro- posed, and of the barriers he will have to overcome in complying with the regimen, he is unlikely to take all, or even some, of his medicine.*

In summary, many features of most antihyperten- sire drug regimens actively discourage compliance.

IS LOW COMPLIANCE WITH ANTI HYP ER TENSIVE REGIMENS INTER F ER ING WITH T H E A C H I E V E M E N T OF DESIRED BLOOD PRESSURE?

When we divide these hypertensive men in their sixth month of treatment into those whose compliance is "high" (that is, they took 80% or more of their prescribed pills) or "low" (less than 8 0 % ) , and see whether these high and low compilers have achieved desired blood pressure (say, 90 mm Hg diastolic or less), as shown in Table II, two conclusions become clear. First, these patients are much more likely to be controlled if they are highly compliant with their drug ~egimens. Second,'of the two thirds of the hypertensives who remain uncontrolled after six months of treatment, half are low compliers (cell d of Table II) ; (we shall return to the additional finding that many clinicians appear to set less ambitious treatment goals or are cautious about prescribing more powerful regimens (cell b) ).

* The determinants of compliance include many paradoxes. For example, perceptions are more powerful determinants of compliance than are either factual knowledge or actual disease severity; patients with quite high diastolic pressures are no more likely to take their medicine than patients with only slight blood pressure elevations.

Table 1I. The relation between compliance and the achievement of desired blood pressure.

Goal blood pressure Not

Compliance Achieved

High 23% a

achieved

34% b

Totals

57%

c d Low 12% 31% 43% Totals 35% 65% 100%

Thus the answer to the question is clear: outside the clinic, low compliance with antihypertensive drug regimens definitely interferes with the achievement of desired blood pressure.

CAN WE DO A N Y TH IN G TO IMPROVE LOW COMPLIANCE?

Journal editorials, drug advertisements and task force reports alike abound in recommendations of what the front-line clinician should do to improve the compliance of hypertensive patients. Suggestions range from patient-education programs through negotiated treatment "contracts" to calendar packs of pills. All of these recommendations are plausible and some are even feasible, but almost none have undergone any rigorous evaluation to see whether they work.

Accordingly, and in collaboration with our col- leagues in industrial and community practice, we have performed a series of randomized clinical trials of compliance-improving strategies among working men with newly treated primary hypertension. 1. 2 As shown in Table III, the results have been surprising.

First, we determined whether teaching patients about their disease and its treatment would improve their compliance. Hypertensive men were randomly allocated to a control group who received no instruc- tion or to an experimental group who underwent mastery learning of facts about hypertension. They learned its definition; what it did to target organs, health and life-expectancy; the benefits of antihypertensive drugs; why high compliance was essential; and some simple reminders for pill-taking. Testing showed that over 85% of these men mastered these facts about hypertension, whereas less than 20% of men in the control group knew this same information. This mastery learning had, nonetheless, no effect on these men's compliance. In the mastery teaming group 56% of the men were high compilers in the sixth month of treatment, compared with 59% of the controls.-" Thus the transfer of facts about hypertension and its treatment, although justifiable on other

FIRST QUARTER/1978

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Table IIL Results of clinical trials of compliance-improving strategies.

Strategy Sample Experimental group Control group Result

Teaching facts about hypertension

Augmenting the convenience of care

Men with primary hypertension who were just starting on drug treatment

Mastery learning of facts about hypertension

No mastery learning No effect upon compliance

Care at work on Care in the com- No effect upon corn- "company time" munity pliance

A "package" of be- havioral strategies

Hypertensive men who were neither compliant nor at goal after 6 months of

(a) Home blood pressures

(b) B.P. and medication recording

(e) Tailoring (d) Reinforcement

No further inter- vention

Compliance up <20%

Blood pressure down

grounds, cannot be expected--all by i tself-- to improve compliance.

We also found out whether increasing the convenience of long-term care and follow-up would improve compliance. These same hypertensive men were also randomly allocated to receive their hypertensive care with either the normal degree of convenience (in community physicians' offices throughout the city, outside of the patients' working hours) or with augmented convenience (from industrial physicians at the worksite, and on "company t ime") . To make a long story short, this failed as well. Of the normal convenience group 55% were high compliers, compared with 59% of the augmented convenience group. Thus augmenting the convenience of care and follow-up for hypertension over that which already exists in a city such as ours * cannot be expected to improve compliance. -~

Faced with these results, and confronted with a sizeable number of men (cell d of Table I I ) who were neither compliant nor at goal blood pressure in the sixth month of treatment, we decided to determine whether a more behaviorally oriented set of strategies

' could "salvage" any of this group. Accordingly, they were allocated to a control group (who received only routine care) or to an experimental group who, in addition to receiving their routine care, were followed by a "coordinator" . t This coordinator encouraged the experimental group 1) to learn how to measure their

* Readers who are unfamiliar with the Canadian system should note that patients make no direct payments for clinical or laboratory services there, and that the general level of primary medical care is excellent.

t The "coordinator" was a young woman with no prior health-professlonal training, who followed a predetermined protocol. She was not permitted any direct contact with the treating physicians (save in potential emergencies which, fortunately, never arose during the study).

own blood pressure with an aneroid cuff and separate s tethoscope; 2) to measure and record their own blood pressures at home once daily, using charts with clearly defined diastolic blood pressure goals (_<90 mmHg fifth phase); 3) to record all antihypertensive medications taken and missed each day; 4) to link their pill-taking to the execution of daily habits and rituals ("tai loring"); and 5) to come in to see the "coordinator" at the worksite every two weeks.

During each visit to the coordinator, the home records were reviewed and the blood pressure was checked. If compliance was high and if the diastolic blood pressure was as desired or had fallen by 4 mm Hg or more, the patient was praised and received a $4.00 credit toward ownership of the cuff and stetho- scope. If progress had not been made, the patient was encouraged to do better.

At the end of the experimental period (an additional six months) , compliance had fallen further in the control group. In the experimental group, however, it rose by over 20%, and one third of these previously uncontrolled men had now reached desired blood pressure, a These exciting results indicate that behaviorally oriented strategies can improve low compliance and bring previously uncontrolled hypertensives to desired blood pressure; additional studies are underway to isolate from this compound maneuver its most active ingredient.

HOW DO I APPLY THIS E M E R G I N G K N O W L E D G E A B O U T COMPLIANCE IN MY CLINICAL PRACTICE?

As our understanding of compliance improves, recommendations about practical applications will become more precise. At the moment, we believe that the following approach (summarized in Table IV) com- bines optimism with prudence:

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Table IV. How to apply compfiance-improvlng strategies in the management of hypertension.

(1) (2)

(3) (4)

Focus on patients who remain uncontrolled. Be sure that the current drug regimen is strong enough to do the job. Ask the patient! Introduce the compliance-improving strategies in a practical sequence: (a) tailoring (b) medication recording (e) more frequent visits (d) home blood pressures

1) Concentrate on patients who, despite your at- tempts to reduce their blood pressure, remain uncontrolled; depending on their clinical condition, you may elect to administer a compliance-impioving strategy

early in the course of therapy. Less attention need be given to patients who are well controlled; their compliance is of secondary importance.

2) Be sure that the drug regimen you have prescribed is strong enough to work adequately. A glance at cell b of Table II will remind you that up to half of the uncontrolled hypertensives are compliant and may simply be undertreated. Accordingly, you must decide whether the present regimen can be expected to bring the patient to goal or whether it needs to be increased.

3) Ask the patient whether he is taking his blood pressure pills. If he says "yes" he may or may not be telling the truth; if he says "no" he is virtually always telling the truth. Indeed, we have found that half of the noncompliant, uncontrolled hypertensive men (cell d of Table II) , when asked in a non-threatening, non-judgmental way, will admit that they are taking less than 80% of their prescribed antihypertensive

drugs. Moreover, it is precisely that group of men who admit low compliance who show the greatest blood- pressure responses to the strategies outlined below. Thus it is possible to identify a substantial portion of those patients who would benefit from compliance- improving strategies without resorting to pill counts, drug analyses or other detective work.

4) Introduce the compliance-improving strategies in a sequence which best suits your own practice. This usually means the introduction of simple strategies first, reserving those which consume more of your time and effort for those patients who do not respond. We list some of the strategies:

(a) "Tailorhzg": See whether you and your patient can identify his daily habits or rituals. If so, and if his antihypertensive regimen permits superimposing a dose-schedule upon these, strike a bargain with him to keep his medications at the sites of these rituals and to take his medicine just before he carries them out.

(b) Medication Recording: Ask your patient to begin to record each day the doses taken and doses missed of his antihypertensive drugs. This can be done on a pocket calendar or similar record.

(e) More Frequent Visits: Increase the degree of support and supervision by scheduling more frequent visits. In addition to closer blood pressure monitoring, these visits provide an opportunity to review the patient's medication record and to reinforce the tailoring of the regimen to daily habits and rituals.

(d) Home Blood Pressures: Finally, if the progres- sive introduction of the foregoing steps is not success- ful in achieving better blood-pressure control, teach the patient how to measure his own blood pressure and ask him to keep daily records of his blood pressure as well as his medication-taking.

REFERENCES

1. Haynes, R. B. et al. (1976): Lancet 1, 1265-1268. 2. Sackett, D. L. et al. (1975): Lancet 2, 1205-1208.

3. Sackett, D. L., Haynes, R. B., eds. (1976): In: Compliance with Therapeutic Regimens. The Johns Hopkins Press, Baltimore.

FIRST OUARTER/1978

Documents

Patient compliance with antihypertensive regimens