There is
a need for tools to measure the information patients need in order
for healthcare professionals in general, and particularly pharmacists,
to communicate effectively and play an active part in the way
patients manage their medicines. Previous research has developed
and validated constructs to measure patients’ desires for information
and their perceptions of how useful their medicines are. It is
important to develop these tools for use in different settings
and countries so that best practice is shared and is based on
the best available evidence.
Objectives: this project sought to validate of a survey tool measuring
the “Extent of Information Desired” (EID), the “Perceived Utility
of Medicines” (PUM), and the “Anxiety about Illness” (AI) that
had been previously translated for use with Portuguese patients.
Methods: The scales were validated in a patient sample of 596:
construct validity was explored in Factor analysis (PCA) and internal
consistency analysed using Cronbach’s alpha. Criterion validity
was explored correlating scores to the AI scale and patients’
perceived health status. Discriminatory power was assessed using
ANOVA. Temporal stability was explored in a sub-sample of patients
who responded at two time points, using a T-test to compare their
mean scores.
Results: Construct validity results indicated the need to remove
1 item from the Perceived Harm of Medicines (PHM) and Perceived
Benefit of Medicines (PBM) for use in a Portuguese sample and
the abandon of the tolerance scale. The internal consistency was
high for the EID, PBM and AI scales (alpha>0.600) and acceptable
for the PHM scale (alpha=0.536). All scales, except the EID, were
consistent over time (p>0.05; p<0.01). All the scales tested
showed good discriminatory power. The comparison of the AI scale
with the SF-36 indicated good criterion validity (p<0.05).
Conclusion: The translated tool was valid and reliable in Portuguese
patients- excluding the Tolerance scale. Some of the scales may
benefit from further refinement, such as the PHM subscale.
