Study says one-third of antidepressant dose increases result from poor patient adherence | Behavioral Healthcare Executive Skip to content Skip to navigation

Study says one-third of antidepressant dose increases result from poor patient adherence

November 9, 2010
by News release
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Boston - Nearly a third of all patients who are prescribed an increased dosage of antidepressants were not taking their original prescriptions regularly, according to new research conducted by the Medco Research Institute, the research subsidiary of Medco Health Solutions, Inc. (NYSE: MHS). The study was presented at the American Psychiatric Association's 62nd Institute on Psychiatric Services in Boston.

The study suggests that doctors should examine a patient's adherence to their antidepressant medications - meaning whether the patient is taking their medication consistently as directed - before raising the strength of the medication. The research found sub-optimal medication adherence is a contributing factor to disease relapse and may lead to unnecessary increases in dosing. Higher doses of antidepressants can worsen side-effects and also raise medication costs.

"A physician usually increases a dose when a patient is not responding to the current dosage. But this analysis shows that the reason the dose may not be effective is that many patients are not taking their antidepressants as directed. In this case, upping the dose may not remedy that issue," said Dr. David J. Muzina, National Practice Leader of the Medco Neuroscience Therapeutic Resource Center (TRC) and lead author of the studies. "Our data is showing us that lack of medication adherence is very common among patients. It's important that these adherence problems be identified and addressed to enable patients with depression to fully benefit from their medications."

The Medco Research Institute conducted this research through the Medco Neuroscience TRC, where pharmacists specialize in helping patients with behavioral health and neurological conditions. Medco's specialist pharmacists aim to optimize drug therapy effectiveness, maximize health outcomes by improving medication adherence, and help the patient avoid adverse effects from their medications.

Using Medco's database of medical and pharmacy claims for 13 million individuals, the study identified patients who were taking a specific dose of an antidepressant medication for at least 6 months before their doctor ordered an increased dose of that antidepressant, presumably due to clinical worsening of the condition being treated. By examining pharmacy claims records over the 6-18 months prior to the increased dose order, investigators found that 29.7 percent of patients had been poorly adherent with the antidepressant.

Poor adherence was defined by a medication possession ratio of less than 0.80, which suggests that a patient had been taking the antidepressant less than 80 percent of the time, judging by the frequency of prescription refills. The study also showed a significantly higher medication adherence among patients filling their prescriptions through the Medco Pharmacy, where they have the opportunity to receive counseling from a Medco Neuroscience specialist pharmacist.

More information about this study can be found at