Reliability and validity of the Bowel Function Index for evaluating opioid-induced constipation: translation, cultural adaptation and validation of the Portuguese version (BFI-P)

1. Dueñas, M.
2. Mendonça, L.
3. Sampaio, R.
4. Gouvinhas, C.
5. Oliveira, D.
6. Castro-Lopes, J.M.
7. Azevedo, L.F.