The feasibility, repeatability, validity and responsiveness of the EQ-5D-3L in Krio for patients with stroke in Sierra Leone

Abstract

Abstract Objectives To assess the feasibility, repeatability, validity and responsiveness of the EQ-5D-3L in Krio for patients with stroke in Sierra Leone, the first psychometric assessment of the EQ-5D-3L to be conducted in patients with stroke in Sub Saharan Africa. Methods A prospective stroke register at two tertiary government hospitals recruited all patients with the WHO definition of stroke and followed patients up at seven days, 90 days and one year post stroke. The newly translated EQ-5D-3L, Barthel Index (BI), modified Rankin Scale (mRS) and National Institute of Health Stroke Scale (NIHSS), a measure of stroke severity, were collected by trained researchers, face to face during admission and via phone at follow up. Feasibility was assessed by completion rate and proportion of floor/ceiling effects. Internal consistency was assessed by inter item correlations (IIC) and Cronbach’s alpha. Repeatability of the EQ-5D-3L was examined using test–retest, EQ-5D-3L utility scores at 90 days were compared to EQ-5D-3L utility scores at one year in the same individuals, whose Barthel Index had remained within the minimally clinical important difference. Known group validity was assessed by stroke severity. Convergent validity was assessed against the BI, using Spearman’s rho. Responsiveness was assessed in patients whose BI improved or deteriorated from seven to 90 days. Sensitivity analyses were conducted using the UK and Zimbabwe value sets, to evaluate the effect of value set, in a subgroup of patients with no formal education to evaluate the influence of patient educational attainment, and using the mRS instead of the BI to evaluate the influence of utilising an alternative functional scale. Results The EQ-5D-3L was completed in 373/460 (81.1%), 360/367 (98.1%) and 299/308 (97.1%) eligible patients at seven days, 90 days and one year post stroke. Missing item data was low overall, but was highest in the anxiety/depression dimension 1.3% (5/373). Alpha was 0.81, 0.88 and 0.86 at seven days, 90 days and one year post stroke and IIC were within pre-specified ranges. Repeatability of the EQ-5D-3L was moderate to poor, weighted Kappa 0.23–0.49. EQ-5D-3L utility was significantly associated with stroke severity at all timepoints. Convergent validity with BI was strong overall and for shared subscales. EQ-5D-3L was moderately responsive to both improvement Cohen’s D 0.55 (95% CI:0.15—0.94) and deterioration 0.92 (95% CI:0.29—1.55). Completion rates were similar in patients with no formal education 148/185 (80.0%) vs those with any formal education 225/275 (81.8%), and known group validity for stroke severity in patients with no formal education was strong. Using the Zimbabwe value set instead of the UK value set, and using the mRS instead of the BI did not change the direction or significance of results. Conclusions The EQ-5D-3L for stroke in Sierra Leone was feasible, and responsive including in patients with no formal education. However, repeatability was moderate to poor, which may be due to the study design, but should add a degree of caution in the analysis of repeated measures of EQ-5D-3L over time in this population. Known group validity and convergent validity with BI and mRS were strong. Further research should assess the EQ-5D in the general population, examine test–retest reliability over a shorter time period and assess the acceptability and validity of the anxiety/depression dimension against other validated mental health instruments. Development of an EQ-5D value set for West Africa should be a research priority.