Adherence to Disease Modifying Therapies

Poor adherence to medication regimens is a significant problem. According the World Health Organization, only 50 percent of patients worldwide who have chronic illnesses take their medication as it is prescribed, without skipping doses or allowing too much time to lapse between doses.

Why people fail to follow treatment recommendations is a complex problem and many different factors -- including cost, side effects, and psychological issues -- contribute to it. For people living with multiple sclerosis (MS), the complexity of actually taking the medication can also interfere with adherence because some of disease modifying therapies (DMTs) prescribed for MS require daily or weekly self-injections. Below we discuss the importance of adherence to disease modifying therapies, some of the reasons why compliance may be difficult for MS patients, and new treatments seeking to address one of those reasons. 

Importance of Adhering to DMTs There are 11 FDA-approved DMTs for MS and they all -- to varying degrees -- reduce the number of new MRI lesions, the number of exacerbations, and development of disability. The impact of non-adherence to MS therapies has not been widely assessed; however, studies have shown that long interruption in DMTs results in higher risk of severe relapse and that for maximum effectiveness DMTs need to be taken consistently. 

Factors Influencing Adherence

While there has been little data to characterize factors that influence adherence to all DMTs, studies of the injectable MS drugs suggest some factors that improve adherence:

  • A perception that the treating physician strongly supports the use of the prescribed medication;
  • A belief that using medication provides more control over the disease;
  • No previous use of a DMT;
  • Higher levels of hope, self-efficacy and self esteem; and
  • Lower levels of disability.

Factors that may increase non-adherence or poor adherence:

  • Side effects from therapy;
  • Inconvenience and difficulty with administering medicine via injection;
  • Simply not wanting to take an injection;
  • Depression and anxiety; and
  • Forgetting to take medication

New Drugs Seek to Address Difficulty with Injections

One factor that can reduce adherence is the difficulty with the injections themselves, so there has been a push to make injectable drugs easier to use. New formulations of two of the original DMTs – Copaxone and Avonex – have been developed to decrease the number of injections required to obtain a therapeutic effect from each drug.

In January this year, Teva released a 40 mg dose of Copaxone to complement the 20 mg dose that has been available since the 1990s. The larger dose formulation decreases the number of weekly injections from seven to three. The side effects per injection appear to be the same but because injections occur less frequently, the side effects are less frequent as well. In clinical trials the newer formulation appears to have the same effectiveness as the original daily dose.

This month, a new formulation of Avonex will also become available. Plegridy (peginterferon beta-1a, Biogen Idec) has the same active ingredient as Avonex, but it is pegylated, which means that it has another molecule attached to it that allows it to remain in the body longer and be absorbed more slowly. It’s injected under the skin every two weeks, which reduces of the number of monthly injections from four to two. It seems to cause the same types of side effects as the original drug, but again less often because it is injected less often. In clinical trials Plegridy was as effective as Avonex.

Problems with injections are just one factor that complicates adherence. We also know that people who take oral DMTs for MS don’t always take their medication, either, but for different reasons. The issue of treatment adherence is a complicated one and it extends beyond DMTs. We will explore the other aspects of treatment adherence, including lifestyle, diet and exercise in the next issue of InforMS magazine.