Patients' Preferences About Medication Dosing Regimens

To the Editor: In the context of psychiatric treatment, compliance often means the extent to which patients take medication as prescribed (1). Cramer and Rosenheck (2) recently pointed out that with the growing fiscal pressure to reduce the intensity of outpatient and other treatments, contact between physicians and patients may become more restricted. As a result, encouraging patients to comply with their medication regimen may be more important than ever. Physicians must become more effective in encouraging compliance. To do so, they need information about factors that influence compliance.

Clinicians believe that patients' compliance worsens as the dosing frequency increases and as medication regimens become more complex (3). Therefore, they prefer once-a-day dosing or long-acting medication given weekly or monthly by injection or skin patch. However, little is known about patients' preferences regarding dosing schedules.

In 1997 we administered a 12-item questionnaire about compliance and preferred dosing schedules to 106 consecutive patients at two mental health clinics in southeastern Michigan. Patients' identities were unknown to the investigators; each patient's chart diagnosis was added to the questionnaire form by clerical personnel who were otherwise not involved in the study.

A total of 106 patients answered the questionnaire. Sixty-four percent were women, 66 percent were white, and 56 percent had a college education. Their mean±SD age was 43± 10.8 years. Major depression was the most frequent diagnosis, for 34 percent of the patients, and an antidepressant had been prescribed as primary medication for 64 percent of all patients. The majority of patients, 71 percent, reported being compliant with their medication regimen during the previous week and had not missed a single dose.

Fifty-one percent of patients preferred once-a-day dosing, 36 percent twice a day, 6 percent three times a day, and 2 percent four times a day. Interestingly, 4 percent preferred injections, and 1 percent preferred patches. Forty percent of patients on the four-times-a-day regimen would miss one of their daily doses, as would 21 percent of patients on a once-a-day regimen, 10 percent of patients on a twice-a-day regimen, and 25 percent of patients on a three-times-a-day regimen. In addition, 4 percent of patients receiving once-a-month injections would miss one dose.

Thirty-three percent of patients missed their medication during short-term use (up to four weeks), 33 percent during long-term use (four weeks to a year), and 35 percent during lifelong use. The majority of patients (67 percent) did not feel that having to take several different medications at a time would cause them to miss a dose.

Our sample was not large enough to perform separate analyses with different diagnoses and medications. However, the compliance rates between patients with different diagnoses and medications may not differ very much (2). Results of our study demonstrate that patients believe they may be more noncompliant with an increased number of daily doses, but generally they do not feel that polypharmacy affects their compliance. Thus the commonly held belief that a simpler dosing strategy leads to better compliance seems to be confirmed by patients' preferences. However, it is not clear how much the patients' preferences reflect the extent of their factual compliance. Further studies addressing this issue are needed.