Cross-cultural adaptation and validation of the Ukrainian version of the Standardized Evaluation of Pain (StEP) — a tool for assessing neuropathic pain in the lower back in patients with ankylosing spondylitis

Objective — to create a Ukrainian‑language version of the Standardized Evaluation of Pain (StEP) through translation and cross‑cultural adaptation with subsequent validation in patients with ankylosing spondylitis (AS). 
Methods and subjects. The translation and cross‑cultural adaptation of the StEP questionnaire was carried out in accordance with the standard recommendations of the Guidelines for the process of cross‑cultural adaptation of self‑report measures. 49 patients with a diagnosis of AS according to the modified New York criteria and duration of pain in the lower back ≥ 3 months and 31 persons of the control group were examined. AS activity in patients was assessed using the ASDAS (Ankylosing Spondylitis Disease Activity Score) and BASDAI (Bath Ankylosing Spondylitis Disease Activity Index), functional status — according to the BASFI (Bath Ankylosing Spondylitis Functional Index) and BASMI (Bath Ankylosing Spondylitis Metrology Index) indices. The ASQoL (Ankylosing Spondylitis Quality of Life Questionnaire) index was used to assess the quality of life of AS patients. The intensity of pain in AS patients was determined using a visual analog scale. The Leeds assessment of neuropathic symptoms and signs (LANSS) and the DN4 questionnaire (Douleur Neuropathique en 4 Questions) were used to compare the results of the StEP questionnaire. The statistical analysis of the results was carried out using the methods of variational statistics using the SPSS22 software package (SPSS Inc.). 
Results. According to disease activity indices, high and very high disease activity prevailed in patients with AS: the average value according to ASDAS was 3.8 ± 0.8, according to BASDAI — 5.5 ± 1.2. Functional disorders according to BASFI were 5.2 ± 1.8 on average, range of motion in the spine according to BASMI was 5.2 ± 2.3. The quality of life of patients with AS according to ASQoL was on average 8.3 ± 4.4. Pain intensity according to the visual analog scale — 6.1 ± 1.5. The reliability of the Ukrainian‑language version of the StEP questionnaire was assessed by the test‑retest method with an interval of 7 days in 22 patients with AS. The analysis of the received data proved the high reliability of the StEP questionnaire (intraclass correlation coefficient was 0.987). Cronbach’s alpha coefficient (0.987) confirmed the internal consistency of the Ukrainian version of the StEP questionnaire. The sensitivity of the StEP questionnaire showed a close pairwise correlation (Spearman’s correlation coefficient — 0.955). Testing of the StEP questionnaire in patients with AS revealed the presence of neuropathic pain in 55.1 % of cases. The average value of the StEP questionnaire in AS patients was 4.6 ± 5.3, in the control group it was 0.1 ± 0.4. The final values of the StEP questionnaire were statistically significantly correlated with LANSS and DN4 indicators (p < 0.01). 
Conclusions. The Ukrainian‑language version of the StEP questionnaire was created, and its cross‑cultural adaptation and validation was carried out. The Ukrainian‑language version of the StEP questionnaire showed a sufficient level of reliability and validity for further use in scientific and medical practice for the Ukrainian‑speaking population. In patients with AS, using the Ukrainian version of the StEP questionnaire, the presence of a neuropathic component of the pain syndrome is detected in 55 % of cases, which should be taken into account when treating this cohort of patients. 
 