Portuguese Version of the Intentional Non-Adherence Scale: Validation in a Population of Chronic Pain Patients

Autores da FMUP

• Rute Sofia Monteiro Sampaio

  Autor

• Claudia Camila Rodrigues Pereira Dias

  Autor

• José Manuel Pereira Dias De Castro Lopes

  Autor

Participantes de fora da FMUP

• Cruz, M
• Pinho, S
• Weinman, J

Unidades de investigação

• Biomedicina

• Laboratório Associado RISE- Rede de Investigação em Saúde

  

  Investigador

  Fernando Carlos De Landér Schmitt

• Recursos Comuns

  

  Investigador

  Guilhermina Maria Da Silva Rêgo

• RISE-Health

  

  Investigador

  Fernando Carlos De Landér Schmitt

Abstract

Objective: Despite the effectiveness of pain medicines, nonadherence to prescribed medication remains a major problem faced by healthcare systems. The aim of present study was to perform the translation, cultural adaptation, and validation of the Intentional Non-Adherence Scale (INAS) for the European Portuguese language in a sample of chronic pain patients. Methods: A Portuguese version of the INAS scale was constructed through a process of translation, back translation, and expert's panel evaluation. A total of 133 chronic pain patients were selected from two chronic pain clinics from tertiary hospitals in Porto, Portugal. The protocol interview included the assessment of pain beliefs (PBPI), beliefs about medicine (BMQ), medication adherence (MARS-P9), and two direct questions about adherence previously validated. Results: The internal consistency in all subscales was alpha = 0.902 for testing treatment; alpha = 0.930 for mistrust treatment; alpha = 0.917 for resisting treatment; and alpha = 0.889 for resisting illness. Exploratory and confirmatory factor analysis revealed a four-factor structure that explained 74% of the variance. The construct validity of the INAS was shown to be adequate, with the majority of the previously defined hypotheses regarding intercorrelations with other measures confirmed. Conclusion: The Portuguese version of INAS could be a valuable and available instrument for Portuguese researchers and clinicians to assess the intentional nonadherence determinants during the management of chronic pain.

Keywords

• medication adherence; chronic pain; reliability; validity; factor analysis