Background and objective: To achieve a linguistic adaptation and psychometric validation into Spanish of the ID-Pain questionnaire for the screening of differential diagnosis of pain with a neuropathic component.
Material and method: Cross-sectional validation study carried out in 2 phases (cultural adaptation into Spanish language and validation study to test psychometric properties of the scale) in men and women > 18 years, with neuropathic (NP) and nociceptive (NNP) chronic pain for more than 6 months. Feasibility and reliability were explored. Criterion and convergent validity were studied by means of ID-Pain association with reference diagnosis and LANNS (Leeds Assessment of Neuropathic Symptoms and Signs) scale scores. Factor and ROC curves analysis, agreement with reference diagnosis and sensitivity and specificity values were assessed.
Results: A total of 283 subjects -64.4% women; mean age (standard deviation): 59.1 (14.9) years-, 145 (51.2%) with NP and 138 (48.8%) with NNP were included in the study. Administration time was 4.2 (3.0) min. Only 15% of participants required help for test completion. Factor analysis indicated a unifactorial solution accounting for 35.5% of the variance. The instrument was time-stable (test-retest r-Pearson = 0.98; p < 0.0005). Mean score differentiated NP from NNP patients; 3.5 (1.2) vs. 1.2 (1.4) (p < 0.0005). Optimum cut-off value was > or = 3 points, showing an area under the curve = 0.89; p < 0.0005, sensitivity value of 0.81, specificity of 0.84 and kappa coefficient of agreement with reference clinical diagnosis of 0.65. The scale also showed good concurrent validity with LANSS classification of subjects (kappa = 0.61; p < 0.0005).
Conclusions: The Spanish version of the ID-Pain questionnaire is feasible, reliable and appropriated as a self-administered screening tool for pain with a neuropathic component.