Abstract
Aim: To evaluate the properties of the measurement of the
Global Evaluation of Medication Adherence Instrument (GEMA) among
patients with chronic diseases.
Methods: A methodological study was conducted in public
hospital of the state of São Paulo, Brazil. The adherence to
anticoagulants as well as the International Normalized Ratio (INR) was
assessed on 127 patients. Besides GEMA, two other instruments were used
to assess adherence: the Morisky Medication Adherence Scale–8 (MMAS-8)
and the Measurement of Adhesion to Treatments (MAT).
Results: The GEMA presented a satisfactory level of specificity
(0.76) to identify adherents among those with a stable INR, low
sensitivity (0.43) for the identification of non-adherents among those
with an unstable INR, and a Positive Predictive Value of 0.70. Positive
and weak to moderate correlations were observed between the proportion
of doses assessed with GEMA and the scores on the MMAS-8 (r=0.26 and
r=0.22, respectively) and the MAT (r=0.22 and r=0.30, respectively).
Conclusion: The GEMA presented good practicality,
acceptability, and evidence of specificity regarding the stability of
the INR. The validity of the construct was partially supported by the
relationship with self - reported measures of adherence.
KEYWORDS: anticoagulants, medication adherence, nursing,
self-care, validity