VALIDATION OF YORUBA ADAPTATION OF THE STROKE- SPECIFIC QUALITY OF LIFE SCALE

Abstract

The Stroke-Specific Quality of Life (SS-QoL) scale, a stroke patient-centred health-related quality of life measure was developed and validated in predominantly Caucasian population. It has been shown to have excellent internal consistency, validity and responsiveness. It enjoys wide utility and has been adapted to many cultures but not a Nigerian culture. The aims of this study were to cross-culturally adapt the scale into the Yoruba language and to conduct an initial investigation on its validity. The source (English) version of SS-QoL comprising twelve (12) domains was first adapted to the Yoruba culture by adding more examples that are Yoruba culture-specific to some items by the expert committee that was formed for the purpose of this study. The Adapted English Version (AEV) was independently translated into Yoruba by 2 Yoruba language experts, who later met to produce a consensus version. The consensus Yoruba translation was then taken through four rounds of back-translation and expert committee review to produce a Pre-final Yoruba Version (PFYV) equivalent of the AEV. The PFYV was pre-tested on thirty Yoruba-speaking stroke survivors. They were also involved in cognitive debriefing interview which indicated that participants understood the PFYV of SS-QoL and opined that no important areas had been omitted by the instrument. Most items were found to be relevant, except a few relating to household chores which were not applicable to most male participants from cultural point of view. Their comments were considered in another expert committee meeting to produce the Final Yoruba Version of the SS-QoL (FYV). The FYV was investigated for construct validity on thirty-five bilingual (23 males, 12 females) stroke survivors who were recruited purposively into a cross sectional correlation survey from secondary and tertiary health institutions in Ibadan. Each participant was assessed on the AEV and FYV within a two-hour interval. The order of administration of the versions was randomized. Data were analysed using Spearman’s correlation method and Wilcoxon signed ranks test at 95% level of significance. The mean age of participants was 58.5 ± 11.3 years while mean duration of stroke was 2.4 ± 2.3 years. All participants had at least secondary school education. The mean overall score on the AEV (170.9±34.9) did not differ significantly from that on FYV (167.7±30.9). On both AEV and FYV, participants’ mean domain score was highest (22.6 + 3.8 and 22.7 + 3.4) on language domain and lowest (9.0 + 2.3 and 8.0 + 2.4) on work domain respectively. Participants’ domain scores on the two versions did not differ significantly, except in work/productivity domain. There were significant correlations between the domain scores and overall score on the AEV and the corresponding domain scores (‘r’ ranged from 0.54 to 0.89) and overall score (r = 0.79) on FYV of the SS-QoL. There were significant correlations between participants’ ratings of their post-stroke and pre-stroke states on all domains (‘r’ ranged from 0.34 to 0.70), except energy and mood domains. The source version of SS-QoL was successfully adapted into Yoruba and the Yoruba version demonstrated evidence of adequate construct validity.