Predictors of Nonadherence in Multiple Sclerosis

Bret S. Stetka, MD


April 22, 2016

Editor's Note:
While on-site at the 2016 American Academy of Neurology Annual Meeting, Medscape spoke with Kyla McKay, a doctoral candidate in experimental medicine at the University of British Columbia, about her study looking at predicators of nonadherence in patients with multiple sclerosis (MS).[1]

Medscape: Can you give us some background on your study?

Kyla McKay: We were interested in exploring adherence rates to disease-modifying therapies in MS. We were specifically curious about what factors might be predictive of nonadherence to treatment. There are negative consequences to not adhering to drugs; studies have shown increased rates of hospitalization and relapse rates in MS as a result of nonadherence.

We set out using a large cross-Canada cohort of patients, 949 patients who we queried over 2 years at their annual clinic visits. We collected clinical and demographic information as well as data from self-reported questionnaires. We asked them about their symptoms of mental health, such as anxiety and depression, quality of life, alcohol dependence, cigarette smoking, etc. We also asked them if they were on an injectable disease-modifying therapy, and if so, how many doses they missed in the past 30 days.

Medscape: And what did you find?

Ms McKay: We found that over the full study period, about 22% of the 485 patients who were on a disease-modifying therapy were not adherent to their medication, which is fairly sizable. That's using the definition of adherence whereby anyone who took less than 80% of their injections was considered nonadherent within that month. We also did a supplementary analysis in which we looked at any missed doses as a definition of nonadherence. When we explored it this way, about 50% of people were considered not adherent.

In terms of characteristics that were associated with significantly increased odds of nonadherence, we didn't find any influence of age or sex. But those who had a longer disease duration were less likely to take their medications. Also, those with a low EDSS (Expanded Disability Status Scale) score or a milder disability status were less likely to be adherent.

Differences in disease-modifying therapy characteristics were also seen, which is probably related to the different dosing schedules. For example, glatiramer acetate is a daily injection, so in order to be considered nonadherent using our definition, a person would have to miss more than six doses in a month. Not a lot of people were missing that many doses.

When you look at glatiramer acetate adherence, patients appear to adhere to it better than to the interferons, but this is largely related to our definition of adherence. When we explored the same question using "any missed doses" as the definition of nonadherence, we found the opposite results. People appeared to be adhering better to the interferons relative to glatiramer acetate. Readers should be cognizant of this when they're interpreting the adherence literature.

Medscape: How did alcohol dependence influence adherence?

Ms McKay: Those with alcohol dependence were twice as likely to be nonadherent, which is a particular concern given the broader negative effects of alcohol use

Medscape: And how about cognitive difficulties?

Ms McKay: We used a very subjective measure of cognitive difficulties. This was part of the Health Utilities Index, which contains a cognition component and asks about forgetfulness and everyday problem-solving. These were people who self-identified as having cognitive difficulties, and we found higher odds of nonadherence among them.

Other research has shown that an important factor in nonadherence in MS is simply forgetting to take your medications, which is probably what we saw as well.

Medscape: What are the clinical implications of your findings?

Ms McKay: I think that these observational studies are an important addition to our understanding of drugs and how people take them. A lot of our understanding of these medications comes from the original clinical trials, but the reality is that these clinical trial patients are probably adhering better, and they're followed for a relatively short period of time. We found that it can be quite difficult for patients to adhere to their medications over a long period of time.

Perhaps doctors can make a point to check in with their patients by asking, "How many doses did you miss in the past 30 days?" A study came out recently that showed that this question is predictive of longer-term adherence. It's a really simple question you can ask your patients.

If they're not adherent, you can talk to them about nonadherence factors like alcohol dependence or cognition. They can also bring up the possibility of switching therapies. If a daily injection is too much for them, maybe consider an injectable with a less frequent dosing schedule or an oral therapy. These are conversations that can potentially be introduced into the doctor-patient relationship.


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