Validation of the psychometrics properties of a French quality of life questionnaire among a cohort of renal transplant recipients less than one year.

ABSTRACT

BACKGROUND: Renal transplantation is considered as the treatment of choice for patients with end-stage renal disease. Health-related quality of life (HRQoL) of renal transplant recipients (RTR) is very important to assess, especially during the first year after transplantation. To provide new evidence about the suitability of HRQoL measures in RTR during the first post-transplant year, we explored the internal structure, reliability and external validity of a French specific HRQoL instrument, the Renal Transplant Quality of life Questionnaire Second Version (RTQ V2). METHODS: The data were issued from the French multicenter cohort of renal transplant patients followed during 4 years (EPIGREN). The HRQoL of RTR was assessed five times (at 1, 3, 6, 9 and 12 months after transplantation) with the RTQ V2, a specific instrument consisting of 32 items describing five dimensions. Socio-demographic information, clinical characteristics and HRQoL (i.e., RTQ V2 and SF-36) were collected. For the five times, psychometric properties of the RTQ V2 were compared to those reported from the reference population assessed in the validation study. RESULTS: Three hundred and thirty-four patients were enrolled. The proportions of well-projected items, item-internal consistency, item-discriminant validity, floor and ceiling effects, Cronbach's alpha coefficients and item goodness-of-fit statistics were satisfactory for each dimension at the five times of the study. The suitability indices of construct validity were higher than 90 % for each time (minimum-maximum 90.8-97.4 %). The external validity was less satisfactory, with a suitability indices ranged from 46.7 % at M1 to 66.7 % at M12. However, the discrepancies with the reference population (mainly for the gender) appeared logical considering the scientific literature on HRQoL of RTR during the first post-transplant year and may not compromise the external validity. CONCLUSION: These results support the validity and reliability of the RTQ V2 for evaluating HRQoL in RTR during the first post-transplant year, and confirm that the RTQ V2 is a useful tool to assess the HRQoL precociously after transplant.