Spanish modified version of the palliative care outcome scale–symptoms renal: cross-cultural adaptation and validation

Daniel Gutiérrez-Sánchez, Juan P. Leiva-Santos, Rosa Sánchez-Hernández, Domingo Hernández-Marrero, Antonio I. Cuesta-Vargas

Patients with chronic kidney disease (CKD) have a high symptoms burden that is related to a poor health-related quality of life (HRQoL) and high costs of care. Validated instruments may be useful for assessing the symptoms and monitoring outcomes in these patients. The Palliative care Outcome Scale-Symptoms Renal (POS-S Renal) is a patient-reported outcome measure for assessing symptoms in CKD stage 4-5. This study is the first cross-cultural adaptation and psychometric analysis of this clinical tool. The purpose of this study is to carry out a cross-cultural adaptation of the POS-S Renal for Spanish-speaking patients, and to perform an analysis of the psychometric properties of this questionnaire. The English version of the POS-S Renal was culturally adapted and translated into Spanish using a double forward and backward method. An expert panel evaluated the content validity. The questionnaire was pilot-tested in 30 patients. A total of 200 patients with CKD stage 4-5 filled in a modified Spanish version of the POS-S Renal and the MSAS-SF. Statistical analysis to evaluate the psychometric properties of the questionnaire was carried out. The content validity index (CVI) was 0.97, which indicated that the content of the instrument is an adequate reflection of the symptoms in advanced CKD (ACKD). The factor analysis indicated a two-factor solution explaining 35.05% of total variance. The confirmatory factor analysis (CFA) demonstrated that the two factor model was well supported (comparative fit index = 0.98, root mean square error of approximation = 0.068). This assessment tool demonstrated a satisfactory test-retest reliability (r = 0.909 to factor 1, r = 0.695 to factor 2, r = 0.887 to total score), good internal consistency to factor 1 (α = 0.78) and moderate internal consistency to factor 2 (α = 0.56). Concurrent criterion-related validity with MSAS-SF was also demonstrated, with r = 0.860, which indicated a high degree of correlation with a validated instrument that has been used in patients with ACKD. The Spanish modified version of the POS-S Renal is a reliable and valid instrument that can be used to assess symptoms in Spanish patients with CKD stage 4-5.