Studying Antidepressant Nonadherence Using Discarded Blood Samples

Studies show that antidepressant nonadherence is very common. Published reports vary widely, placing the percentage of nonadherent antidepressant users somewhere between 25-50%. It is no secret that these medications work better when taken on a consistent basis. However, it is hard to measure actual adherence due to the fact that patients may become embarrassed or lie, appearing to be more adherent to their medications than they really are. Robertson and colleagues came up with a unique idea in order to measure adherence and bring light to the fact that more individuals may be nonadherent then we, as pharmacist, are led to believe. This team used discarded blood samples from routine clinical blood draws to measure antidepressant nonadherence. They surveyed the electronic health data and collected patients 14-90 days from treatment initiation who were prescribed sertraline, citalopram, bupropion, or venlafaxine. They examined the discarded blood samples from 109 such individuals with active and recently filled antidepressant prescriptions, and looked for detectable serum levels of that drug. Overall, 17% of the samples lacked a detectible level of antidepressants. I think this was a unique way to study nonadherence and although I do not think it could be used at the community level, I think there are areas of pharmacy in which this might one day play a role.

In what ways do you think this could work in our profession?


Roberson AM, Castro VM, Cagan A, Perlis RH. Antidepressant nonadherence in routine clinical settings determined from discarded blood samples. J Clin Psychiatry. (published 24 November 2015).

Adherence is Overrated

When a patient walks into a pharmacy and says they are having trouble remembering to take a medication, there are problems that arise when determining the degree of nonadherence. First of all, patients will undoubtedly underestimate the amount of times the have missed their medication. In addition, if a patient is not stating any issues with adherence, pharmacists can only truly observe refill behavior to monitor adherence. Only the date the prescription is filled can be recorded, so often monitoring adherence can be difficult.

But here is why Dr. Crowe, PharmD, is stating that adherence is “overrated” – patients can be perfectly adherent, never missing a single dose and still experience ineffective drug therapy. Dr. Crowe feels that the focus of pharmacists should lie on making sure the drug therapy regimen is efficacious, no matter the adherence of the patient. Because pharmacists see patients several times in between visits with their physician, they can be the one to monitor symptoms and side effects in between the visits. Dr. Crowe states that this is important because “when patients hold up their end of the adherence bargain, they [should be] doing so with an effective medication.” He uses the example of multiple sclerosis (MS) and how pharmacists can not only monitor the symptoms, but the relapse frequency. If this frequency becomes too high, they can recommend a switch in therapy.

This is a great concept that I have never thought of before in the way that was described by the article. It makes sense that if patients are doing everything they should be, they should be getting the best possible benefits from their medication. As far as monitoring symptoms to check for medication efficacy, I immediately thought of antidepressant medications. Because they take several weeks to work, it would be helpful for the pharmacist to check in on the patient when they are refilling a prescription to see how their mood has improved. If there is no improvement after one or two refills, they can contact the physician to recommend a change in therapy. I hope that this mentality is one that every pharmacist uses or is introduced to during their career, in addition to monitoring adherence.

Crowe, Michael. “Adherence is Overrated.” Pharmacy Today. 21.7 (1 July 2015). 63. Web. 17 February 2016.