Depression May Lead You to Neglect Your Medicines

Summarized by Robert W. Griffith, MD
August 23, 2002 (Reviewed: August 20, 2004)

Introduction

As many as half of all people with high blood pressure don't take their antihypertensive medications as prescribed. There are many possible causes for this -- the obvious one being that high blood pressure doesn't usually have any symptoms. This is a serious situation, as failure to treat high blood pressure is likely to lead to a stroke, or some other cardiovascular event.

It's also been known for some time that people with depression are not good about taking their AIDS, asthma, or kidney transplant medications. So investigators from Brigham and Women's Hospital and Harvard Medical School decided to look at a possible relationship between failure to take antihypertensive medications and a variety of 'psychosocial' factors, including depression. Their results have just been published, and are summarized here.

What was done

The subjects were patients with high blood pressure at a large Health Maintenance Organization (HMO) and a Veterans Affairs Medical Center (VAMC), in the Boston area. People who were 40 or over, had been diagnosed with high blood pressure, had filled an antihypertensive prescription during 1996, and were enrolled for 6 months before and 1 year after their first prescription, were invited to take part. They were asked, by mail, to carry out a 45-minute telephone interview; roughly half of them agreed to this.

At the interview, the following mental and social areas were assessed, using well-tested questionnaires:

• depression symptoms - using items from the Brief Symptom Inventory depression subscale
• health beliefs -- e.g. "how important is it to take medications?"
• knowledge of high blood pressure and its treatment
• support of family, etc. regarding taking medication
• sense of being in control of one's life -- "how much influence do I have over the things that happen to me?"
• satisfaction as a patient -- doctor's explanations, clinic waiting times, etc.
• alcohol consumption
• tobacco use
• desirable but not necessarily true responses -- to what degree does the person give the "approved" or "desirable" response?

Compliance with taking blood pressure medicines was measured by analyzing the amount dispensed during one year after the initial prescription, and calculating the percent of days covered by the dispensed therapy.

Analyses were done to determine possible links between non-compliance and the psychosocial factors listed.

What was found

A total of 248 HMO and 248 VAMC patients took part in the study. For the most part, they were over 65, male, white, married, retired, high school education level or below, and not living alone.

The first analyses done didn't show any significant linkage between poor compliance and any of the factors studied. However, further analyses were done after adjusting for differences in age, sex, race, education, employment, and existing medical conditions, like cardiovascular disease. These showed that an increase in depression symptoms was significantly associated with lower compliance with medication. (For every one point increase on the 14-point depression symptom scale, the likelihood of drug compliance was 0.93 times less.)

There was one other factor that seemed to be linked to drug compliance: patients who believed that events were largely out of their own control were more likely to stick with taking their medications. Otherwise, no effects on medication compliance were found.

Comment

Although this is the first report of a relationship between depressive symptoms and poor compliance with blood pressure medication, other studies have shown this effect with different therapies. The present study, however, is more convincing than the previous ones, because of its size and good design.

The findings here mean that depressed patients should be checked frequently to make sure they are taking their medications as prescribed. Depression is often not diagnosed, and sometimes not treated adequately. It may be that, by recognizing and treating depression, doctors can help in the better management of high blood pressure and its hazardous consequences.

Source

• Noncompliance with antihypertensive medications. The impact of depressive symptoms and psychosocial factors. PS. Wang, RL. Bohn, E. Knight,  et al., J Gen Intern Med, 2002, vol. 17, pp. 504--511

Related Links
Risk of Stopping High Blood Pressure Medication
Depression: A Risk Factor for Heart Disease in Older People

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