Diagnostic test accuracy of the walking impairment questionnaire in individuals with intermittent claudication

Background: The use of questionnaires in vascular rehabilitation has increased. The Walking Impairment Questionnaire (WIQ) can identify functional risk due to peripheral arterial disease (PAD). This study aimed to assess the accuracy of the WIQ for identifying individuals with PAD and intermittent claudication with low functional capacity. Patients and methods: A cross-sectional diagnostic test accuracy study was conducted. The Incremental Shuttle Walk Test (ISWT) assessed the distance walked, and the WIQ, the index test, evaluated the perception of functional capacity. Three reference values in the ISWT were defined: 380 m, 210 m (25th percentile), and 100 m. The accuracy, sensitivity, and specificity of the WIQ were tested using the Receiver Operating Characteristic curve and an alpha of 5% defined statistical significance. Results: One hundred and twenty-one volunteers participated in the study (64 ± 9.7 years, 65% men). The average distance in the ISWT was 270.6 ± 100.2 m. The WIQ scores were: mean 29.7 (14.0-50.2), distance (19; 6.3-47.8), walking speed (25; 13.0-43.5), and stairs (41.7; 12.5-75.0). The WIQ cut-off point for the ISWT references was 1) 37 for 380 m, with a sensitivity of 0.75 and specificity of 0.62 (AUC: 0.73, p=0.003; 95% CI 0.61 to 0.86); 2) 23 for 25th percentile (210 m), with a sensitivity of 0.75 and specificity of 0.70 (AUC: 0.77, p<.0001; 95% CI 0.68 to 0.86) and 3) 14 for 100 m, with a sensitivity of 0.78 and specificity of 0.83 (AUC: 0.77, p=.0001; 95% CI 0.64 to 0.91). Conclusions: The WIQ is helpful as a screening tool in research and clinical practice of PAD. The WIQ score with the best accuracy to identify individuals with low functional capacity was 14.