¶ … voluntary, collaborative and active involvement of the patient in a course of behaviour that is mutually accepted in order to gain therapeutic result (Michael, H. et al., 2009). According to this definition it can be clearly observed that the patient has a clear choice to follow the goal and that the patient and well as the providers agree to make a medical regimen and treatment goals (Delamater, 2006). There are two basic factors involved in the medical adherence, these are:

Whether the patients takes the medicine that has been prescribed to him/her.

Whether the patient keeps on taking the prescribed medicine or not.

Therefore, the adherence behaviour is divided into 2 main concepts which are: adherence and persistence. Although the concept of adherence and persistence is similar however, adherence means the intensity with which the drug was taken during the duration of the therapy while, persistence means the overall duration of the drug therapy (Caetano et al., 2006). This paper presents a Literature review (evidence based) on Interventions to improve medication adherence in people with multiple chronic conditions (cardiovascular).

Prevalence of Medication Nonadherence

It is very common for the patients suffering from cardiovascular diseases to be nonadherent to the medication. Jackevicius et al. (2008) after being hospitalized for acute myocardial infarction found out that the cardiac medications weren't even filled by one fourth of the patients by day 7 of discharge. This makes up to approximately 24% of the patients (Jackevicius et al., 2008).

It was shown by another study that about 34% of the patients at least 1 medication with 3 months of the discharge from hospital while, 12% stopped all 3 medications (Ho et al., 2006). Apart from the early discharge period there also seem to be an increasing decline in the adherence to the medication when it comes to the cardio protective medications (eg, statins, ?-blockers).

It was found by Newby et al. (2006) that the self-report of patients for the consistent use of medication over a period of 6-12 months was very low. About three fourths (71%) of the patients reported the persistent use of aspirin, the continuous use of ?-blockers was reported by less than half of the patients (46%), 44% took the lipid-lowering agents while 21% took all three of the medication after being diagnosed with the coronary artery disease.

Another study was conducted which showed that the percentage of patients who were still taking the statin medication 2 years after being hospitalized for the acute coronary syndrome was 40% while, the patients who were taking the statins for the treatment of coronary artery disease the adherence was even lower (Jackevicius and Mamdani, 2002).

The nonadherence to the medication for other cardiovascular diseases vary greatly according to the population that is being studied as well as the particular medicines that are studied such as; the medication event monitor (MEMS) data was used by Vrijens et al. (2008) and the result that he got clearly showed that the people who were prescribed antihypertensive medications stopped taking them within 1 year of the time that it was initially prescribed. It was also found that on any particular day a patient won't take ?10% of the doses of medication that were scheduled (Vrijens et al., 2008).

In contrast to the findings of Vrijens et al. (2008), Bramley et al. (2006) found that from among the patients who were on monotherapy for hypertension, 75% of those patients were adherent to the medication, which meant that the ratio of their possessing the medication was from 80-100%.

The medication adherence in the heart failure patients also vary widely such as; it was reported in a study that the persistence rates 5 years after an index heart failure for renin-angiotensin inhibitors was 79% while it was 56% for spironolactone, 65% for ?-blockers and 83% for statins (Gislason et al., 2007). The rate of nonadherence was to a large extent lower based on pill counts in the Candesartan in Heart Failure: Assessment of Reduction in Mortality and Morbidity (CHARM) randomized, controlled trial of the heart patients with heart failure was conducted which showed that the percentage of patients who were taking less than 80% of the pills that were prescribed to them was 11% (Granger et al., 2005).

Interventions to Improve Medication Adherence

Up till now the results that have been achieved through the interventions conducted for the sake of medication adherence have been modest. Generally speaking, the multimodal intervention have been a lot more successful than the unimodal, the reason behind this is the fact that there are multiple factorial reasons for nonadherence (Haynes et al., 2008; Heneghan et al., 2006; Schroeder et al., 2004; McDonald et al., 2004; Kripalani et al., 2007; Petrilla et al., 2005).

et al., 2009).
The most promising interventions have been the multimodal interventions which not only improved the adherence but the outcomes as well (Michael, H. et al., 2009). The stable outpatients that were diagnosed with heart failure were randomized clinically by Murray et al. (2001) to an intensive pharmacist-led intervention against usual care and an improvement of about 10.9% in adherence to the cardiovascular medications was found.

Although the opportunities to improve medication adherence through the observational studies has been highlighted but there are many hurdles towards implementing these interventions in the clinical practices such as; the successful interventions that took place before had included multiple components and most often than not these components have been heterogeneous therefore, implementing those components in the routine practices can be very difficult. The cost of implementing these procedures gets increased by the requirement f the staff or the clinical personnel to monitor the procedure. Also, presently, there aren't a lot of financial incentives available for the promotion of the medication adherence. Until and unless some of these problems are solved the implementation of these studies in the routine clinical practices is going to be very difficult (Michael, H. et al., 2009).

Patterns and Reasons for Medication Nonadherence

Most of the times the reasons for the poor medication adherence are multifactorial, these reasons can be intentional or unintentional. The intentional nonadherence is when a person deliberately deviates from the treatment plan; therefore, it is an active process (Lowry et al., 2005).

In unintentional nonadherence a person can careless or forget to take the medication and this is a passive process. Vrijens et al. (2008) referred to this as the execution of the prescribed regimen. There are six general patterns of execution based on the electronic monitoring data, these are:

(1) Close to perfect adherence;

(2) Taking almost all the doses with some irregularity in the timing;

(3) Occasionally miss a single day's dose

(4) Taking drug holidays 3-4 times a year

(5) Taking drug holidays each month and therefore, not taking a lot of medication doses

(6) Taking few or no doses at all (Urquhart et al., 1997).

There are 5 major groupings being made by the World Health Organization for medication nonadherence, these are: patient, therapy, health system -- related factors, socioeconomic and condition (World Health Organization, 2003).

Another important factor that needs to be kept in mind here is that although in most of the cases patients are the ones who are held responsible for the medication nonadherence however, the healthcare system factors can also play an important role when it comes to the patient's nonadherence to medications (Michael, H. et al., 2009).

It was found by Makaryus et al. (Makaryus and Friedman, 2005) that there are less than 50% of the patients who remember the names of all of their medications and even few who know the purpose of those medicines, this clearly suggests that the system factors can play an important role in the medication nonadherence by the patients after getting discharged from the hospital. This founding was supported by another study which suggested that the discharge counseling reduced the medication non-adherence (Jackevicius et al., 2008).

Some studies also suggest that the system-level factors for example the bureaucratic processes which are associated with insurance claims can also have an impact on the adherence (Michael, H. et al., 2009). Bokhour et al. (2006) conducted a qualitative study in which he found out that from among the hypertension-related visits to the hospitals which resulted in the uncontrolled blood pressure; one third of those patients weren't even asked by the care provider about the medication that they were taking. Therefore, there can be a lot of non-patient related factors that could lead to medication nonadherence.