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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12882-016-0402-8) contains supplementary material, which is available to authorized users.