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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 2, March/April 2019
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pain, colitis and heart failure.
44
The respondents use a five-item
Likert scale, from five (never) to one (always). The questionnaire
makes it possible to calculate total adherence scores and to
classify patients into two dichotomous groups: high (
>
23) and
low adherence (
<
22). The maximum score, 25 points, indicates
perfect adherence.
The Revised HF Compliance Scale evaluates adherence to
recommendations regarding dietary patterns, such as sodium
restriction and fluid restriction, physical activity and daily
weighting. Answers are provided using a five-point scale, with 0
signifying never; 1
=
seldom; 2
=
half of the time; 3
=
mostly; 4
=
always. Compliance is measured based on the patients’ answers
regarding the preceding week (sodium and fluid restriction,
medication and physical activity), the preceding month (daily
weighting), or the last three months (appointment keeping)
before index hospitalisation.
Compliant patients are those who answer ‘always’ or
‘mostly’ with regard to following particular recommendations
and perform daily weighing or monitor their weight at least
three times a week. If the patients successfully follow at least
four out of the six recommendations, they are regarded as
‘overall compliant’. The questionnaire has good psychometric
properties: Cronbach’s
α
=
0.768, average inter-item correlation:
0.362. In available studies, the questionnaire has been used both
for measuring overall compliance and for evaluating the specific
components. A Polish version is currently being developed.
In Cameron’s meta-analysis to identify instruments that
measure self-care in chronic heart failure (CHF) and to
demonstrate their psychometric properties, out of 14 scales
measuring self-care capabilities in HF, only two disease-
specific self-care instruments had been subjected to stringent
psychometric testing among patients with CHF [the Self-care
Heart Failure Index (SCHFI) and the European Heart Failure
Self-care Behavior Scale (EHFScBS)]. Therefore knowledge
about CHF self-care and CHF clinical practice can only be
advanced if researchers use these scales in their studies.
45
Authors studying adherence to HF treatment often use
the so-called Medication Event Monitoring System (MEMS).
The system consists of a micro-electronic monitoring device,
fitted in the caps of medication containers, which records the
number of container openings. Such data allow the calculation
of medication adherence. The number of days on which the
prescribed number of doses was taken during the monitoring
period is divided by the total number of days during the study
period and then multiplied by 100%. A result of a minimum
of 88% indicates that the patient adhered to the medication
regimen. Any patient with a result below this figure is considered
non-adherent. This figure was adopted based on a study that
showed that patients who displayed an adherence of over 88%
had higher chances of Edmonton Frailty Scale (EFS).
46
TheHeart FailureComplianceQuestionnaire byEvangelista
et
al
. measures compliance in six domains: follow-up appointments,
medication, diet, exercise, smoking and stopping alcohol
intake. The evaluation period for follow-up appointments is the
preceding three months, and for medication, diet restrictions
(fluids and sodium), and exercise, the preceding week. The
respondents use a five-item Likert scale, from 0 (never) to 4
(always). The total score for each domain is between 0 and 100
points. The total adherence score can also be calculated, with a
result of 75% indicating good adherence.
47
The Medication Adherence Scale (MAS) originally comprised
32 items and was developed for measuring three groups of
factors associated with adherence. The questionnaire was piloted
on a group of 10 patients with HF. The number of items was
due to the need to evaluate patients’ knowledge, attitudes and
barriers related to taking medication. A group of four experts
on HF verified the accuracy and completeness of the instrument,
and the respondents confirmed their understanding of the items.
The final questionnaire comprises 14 items, providing general
information about behaviour with regard to taking medication,
and 18 items related to knowledge (three items), attitudes (four
items) and barriers (11 items). Patients use an 11-item Likert
scale to answer, between 0 (strongly disagree) and 10 (strongly
agree). The 14 general items include questions about how many
prescriptions for pills the patients have, how many pills they take
per day, how many times they need to take pills on different time
schedules, how they keep track of the pill times, whether or not
they have anybody who helps make their medication schedule,
whether or not they use pills for their heart that healthcare
providers did not prescribe, whether or not they ever skip taking
some of their pills, how they take their pills when they go out,
and whether they have anybody to remind them to take their
medication. The above items only serve descriptive purposes and
were not part of the psychometric testing.
Regarding the psychometric evaluation, 63% of the variance
in medication adherence was explained by three factors, as
revealed in the principal component analysis, namely, knowledge,
attitudes and barriers to medication adherence. Internal
consistency at the sub-scale level was measured with Cronbach’s
α
, whose range was 0.75–0.94. The Spearman rho correlation
coefficients between the MEMS and Knowledge
,
Attitudes
and
Barriers scores ranged between 0.25 and 0.31 (
p
<
0.05).
Conclusion
Effective identification of patients at risk of non-adherence
can be particularly useful in planning interventions to improve
symptom control, prevent complications, enhance long-term
outcomes, and limit adverse effects of treatment. Unfortunately
there is no gold standard for adherence measurement. The
ideal measurement tool for adherence should be easy to apply,
practical, reliable, flexible, user friendly and low cost. Our study
should provide general directions to help healthcare professionals
choose the most common and suitable questionnaires for their
aims and subsequently deliver efficient, tailored interventions to
improve patients’ medication-taking behaviours.
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Tang KL, Quan H, Rabi DM. Measuring medication adherence in
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