[Validation of the "Conocimiento del Paciente sobre sus Medicamentos" (CPM-ES-ES) questionnaire].

This work cross-culturally adapted the Spanish questionnaire `Patients' knowledge about their medications ("Conocimiento del Paciente sobre sus Medicamentos" - CPM-ES-ES) for use in Brazil. It measures the level of medication knowledge by means of 11 questions. Eighty patients ≥ 80 years were investigated and in 39 cases the caregivers were interviewed. The evaluation of conceptual and item equivalences considered the concept of knowledge and the questions that assess it as pertinent. Semantic equivalence was obtained by the correspondence in the denotative and connotative meaning of items. The study of measurement equivalence included factorial analysis and the calculation of validity and reliability estimates. As with the original questionnaire, principal component analysis identified 4 components, however, in 2 of them there were differences regarding included items. One question was removed from this analysis due to its sample inadequacy. Medication knowledge was correlated with medication regimen complexity r = -.22, p = .046. Medication knowledge of antihypertensives was correlated with their adherence r = .70, p < .001, and blood pressure control rb = .46, p = .029. The adapted version revealed functional equivalence, therefore it can be used in the Brazilian context.