**3.4 Therapy-related factors**

This aspect included factors related to medication taking, such as medication class, side effects, dosing regimens, and polypharmacy [4]. The effects and complexity of the therapy might affect adherence.


#### **Table 1.**

*Patient-related factors that may influence medication adherence in CVD.*


#### **Table 2.**

*Socioeconomic-related factors that may influence medication adherence in CVD.*

Medication class consistently influenced adherence. Angiotensin II receptor blockers (ARBs) had the highest rate of adherence (~30–33% better than other classes), while diuretics showed the lowest rate [15]. Certain medications were reported to be hard to swallow [29]. Different packaging or brand names might cause some patients to dislike the medications, fearing fake medications [29]. Side effects might explain why different drug classes had different rates of adherence. At standard dose,

*Medication Adherence in Cardiovascular Diseases DOI: http://dx.doi.org/10.5772/intechopen.108181*

thiazides were more likely to cause a side effect compared with beta-blockers (BBs), calcium-channel blockers, and angiotensin-converting enzyme inhibitors (ACEIs), while ARBs were not associated with any side effects [15, 32].

Complex dosing regimens (e.g. a large number of daily doses) might negatively influence adherence [15]. The once-daily dosing regimen was associated with better adherence as opposed to twice-daily in patients with atrial fibrillation receiving oral anticoagulants [33]. Adherence was decreased in patients taking many medications to treat their comorbidities, contributing to the forgetfulness of taking medications [4]. Frequent changes in regimens also affected adherence negatively [29].

#### **3.5 Condition-related factors**

This aspect was related to the patient's illnesses and comorbidities [15]. Factors in this aspect influenced medication adherence differently; certain comorbidities increased adherence, while others decreased it [15]. Generally, comorbidities were associated with lower adherence [34].

Severe chronic illnesses with significant symptoms hampered adherence, as were chronic diseases with little to no symptoms [27]. Patients receiving primary prevention were less likely to adhere than patients receiving secondary prevention [15]. The impact of comorbidity on adherence varied. While diabetes was reported to improve adherence in CVD patients [15, 27], depression affected adherence negatively [15, 32, 35, 36]. Persistent depression decreased adherence more than remittent depression, and severe depression came with a 3.7 times higher risk of nonadherence than no depression [35].
