Adherence to DMTs: is it important?

“Another factor that affects treatment strategies in relation to DMTs is adherence, i.e. taking your medication. I was preparing a post on a recent study, but dug up this older one, which was better, to illustrate a point.”

Steinberg et al.  Impact of adherence to interferons in the treatment of multiple sclerosis: a non-experimental, retrospective, cohort study. Clin Drug Investig. 2010;30(2):89-100. doi: 10.2165/11533330-000000000-00000. 

BACKGROUND: RRMS is a chronic disease affecting about 400 000 people in the US characterized by increasing MSer disability and burden on society. While there is no cure for MS, pharmaceutical treatments exist that can limit the number of relapses a MSer experiences, and slow disease progression. One such class of agents used to treat RRMS are the interferons: interferon-beta-1a (Rebif and Avonex and interferon-beta-1b (Betaseron and Extavia). MSers must take these injectable medications regularly to achieve the optimal outcomes. However, MSer issues and potential adverse effects of the medication may prevent the patient from taking the medication as directed and lower adherence. To date, limited evidence exists regarding the effect of MSer adherence to interferon-beta therapies on clinical and economic outcomes.


OBJECTIVE: The purpose of this study was to explore the impact of MSer adherence to interferon-beta therapy on MS relapse rates and healthcare resource utilization.

METHODS: Using a non-experimental, retrospective cohort design, a sample population (n = 1606) was drawn from MSers identified in a database that includes both pharmacy and medical claims data. The study population was separated into two groups based on a measure of medication possession ratio (MPR*)-adherent and non-adherent patients, and adherence was defined as MPR > or =85% in a given year during the study period (2006-8). Key outcome variables included MS relapses and healthcare resource utilization. Data were analysed using parametric and non-parametric statistics, and regression modeling.


*Medication Possession Ratio (MPR) measures the percentage of time a patient has access to medication; i.e. takes the medication.
RESULTS:  During the study period, the average MPR for all MSers on interferon-beta therapy varied from 72% to 76%. Only 27-41% of MSers in each year were considered adherent (i.e. MPR > or =85%) and only 4% of MSers had an MPR of > or =85% throughout the 3-year study period (2006-8). MSers who were adherent tended to have a lower risk of relapses over 3 years than non-adherent MSers. A significantly lower risk of relapses was found in 2006 (risk ratio [RR] 0.89; 95% CI 0.81, 0.97). Furthermore, an increasingly larger effect emerged between adherence and relapses when comparing adherent patients (MPR > or =85%) with subgroups of non-adherent MSers (<80%, <75%, <70%, <65% and <60%). The impact of adherence on emergency room (ER) visits also tended to suggest a lower risk during 2006, 2007 and 2006-8. During 2008, the risk for an ER visit was significantly lower for MSers adherent in 2007 (RR 0.78; 95% CI 0.61, 0.99). Inpatient admissions followed the ER trends, as MSers considered adherent in 2006 and 2007 tended to have a lower risk over 3 years. This result was significant for MSers adherent in 2007 (RR 0.79; 95% CI 0.65, 0.98).


CONCLUSION: The findings of low MSer adherence and the impact of adherence on relapses and healthcare resource utilization strongly suggest opportunities to reduce healthcare resource utilization and healthcare costs among RRMSers taking interferon-beta therapy. Efforts should be undertaken to understand and improve medication-taking behaviour in this population so as to minimize the negative impacts of RRMS on MSers while reducing unnecessary direct and indirect costs to treat disease exacerbations.


“This study shows two things: (1) how common poor adherence is in relation to interferon beta therapy and (2) how it impacts on the effectiveness of the drug; the lower your MPR the higher your relapse rate.”

“It is clear that if you don’t take interferon-beta as prescribed and you miss injections it impacts on the average effectiveness of the medication. This is why induction therapies are so appealing in that once you have had an induction therapy you can’t undo the effects. Alemtuzumab, cladribine  and rituximab/ocrelizumab are induction type agents. In contrast maintenance drugs that require to be taken continuously require MSers to be adherent. In our experience, Natalizumab, that requires MSers to come in on a monthly basis is also good for adherence in that we, the healthcare providers, know when the MSers are having their infusion and make sure  they don’t miss injections. It is generally believed that oral therapies will improve adherence rates, but this is not necessarily true. Data from other areas of medicine show that patients on oral treatments rarely take their medications as prescribed.”

“Overall non or poor adherence is a major issue across disease areas and is something that has a major impact on outcomes, MS is no exception. This is why it is very important for MSers to know why they are taking DMTs, to understand the aims of the treatment and to manage expectations; i.e. what to expect on the drug.”

One thought on “Adherence to DMTs: is it important?”

  1. has anyone research the caused of poor adherence?I can think of a couple: 1) discomfort (particularly with daily/weekly injections)2) Forgetness: Why oh why in the era of a smart phone? easy to set up a reminder and a check-listG should design an iphone/android app to monitor adherence of his patience :)3)travelling: holidays, jet lags etc… disorganise once daily routine.4) a relapse: yep, one can perceive that the drug is not working and self prescribe a "holiday" (thinking that dieting or else is more effective)I guess the medical profession should approach the above (among others) one by one instead of lamenting. That's clearly a job for the MS nurses

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