REVIEW ARTICLE
UNDERSTANDING PATIENT MANAGEMENT: THE NEED FOR MEDICATION ADHERENCE AND PERSISTENCE
YC Chia MBBS (Mal), FRCP (Eng), University of Malaya, Kuala Lumpur, Malaysia
Address for correspondence: Professor Dr Chia Yook Chin, Department of Primary Care Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia. Tel: 603-79492620, HP: 6012-2739366, Fax: 603-79577941,
Email: chiayc@um.edu.my
Poor patient adherence to medication is one of the major factors contributing to poor disease control, in particular in chronic diseases. This has tremendous implications and poses both physical and economic burden on the patient, their families, the health care providers and the health care system.
DEFINITIONS
Various terminologies have been used interchangeable to describe the way patients take or do not take their prescribed medication. The word compliance suggests passivity on the patient’s part; that he is just passively following the doctor’s orders. It also suggests that the treatment plan is not based on a therapeutic relationship or on a contract established between the patient and the doctor.
Adherence on the other hand defines the extent to which a patient takes medication as prescribed by the health care professional. Adherence is measured in terms of the percentage of prescribed doses taken per defined period of time and conversely non-adherence is missing the medication.1
Persistence represents the accumulation of time from initiation to discontinuation of therapy and this is measured in terms of time. Consequently non-persistence is the premature discontinuation of treatment, i.e. not staying on the medication.
MAGNITUDE OF PROBLEM OF ADHERENCE AND PERSISTENCE
Poor adherence is probably more common in chronic conditions that are relatively asymptomatic for example hypertension. Many studies have shown that two-thirds of hypertensive patients do not achieve control.2,3 The WHO estimates that sub-optimal control of blood pressure causes 7.1 million deaths annually. And the major (and modifiable) reason for lack of control in most chronic disease management is failure of patients to take their medication.4 JNC 7 has identified poor medication taking behaviour (specifically non-adherence) as one of the main causes of failure to control blood pressure in hypertensive patients.5 In fact, studies on “refractory” hypertension showed that 20% had lapsed adherence and 30% became controlled as a result of monitoring by micro-electronic monitors.6
In an estimate of non-institutionalised Medicaid patients in the United States, non-adherence consumed US$873 more per patient in health care costs during the first year due to increased hospital expenditure.7 It also causes substantial worsening of disease and even death. 33-69% of medication related admissions were due to poor adherence. Studies have shown that those with poorer adherence have greater rates of stroke, heart failure and other cardiovascular complications.8
EPIDEMIOLOGY OF MEDICATION TAKING BEHAVIOUR
Adherence can vary from zero to greater than 100% where patients take more than the prescribed doses. Acceptable adherence rates are around 80% but it should be greater for other conditions like HIV drug treatment where one should aim for 95%. For obvious reasons adherence are higher for acute conditions. Unfortunately, for chronic conditions, even when under clinical trials conditions where supervision is much more closely monitored, adherence rates are only around 43-78%.9,10. A systematic review of adherence for hypertension treatment showed adherence rates of only 9-37%.11 Self-reported adherence rates also show that 35% are non-adherent. Even with dyslipidaemia, where the relationship to myocardial infarction is much better known to patients, half discontinue treatment within six months of starting medication.12Studies using electronic monitoring have shown 6 general patterns:13
- 1/6 are close to perfect adherence
- 1/6 take nearly all doses but with some timing irregularity
- 1/6 miss the occasional single day’s dose and some timing irregularity
- 1/6 take drug holidays 3-4 times per year with occasional omission of doses
- 1/6 take drug holiday monthly or more often and with frequent drug omissions
- 1/6 take few or no doses while giving impression of good adherence
Not unexpectedly, a systematic review of the association between dose regimens and medication compliance reported that adherence was inversely proportional to frequency of dosing.10
