Validity of a one-item drawing-based instrument to assess trunk deformity perception in kyphotic deformities

Introduction Body image and trunk appearance perception are two crucial attributes in determining the quality of life of individuals with spinal deformities. The Trunk Appearance Perception Scale (TAPS) is a drawing-based instrument used to evaluate this feature. The TAPS does not include a sagittal view of the trunk so it is never been used to assess trunk deformity perception in hyperkyphotic patients. This study aims to analyze the effect of introducing a new drawing on the TAPS scale representing the trunk view in the sagittal plane. Patients 170 non-surgical patients were included (mean age 16.9 years and 77.4% women) distributed in three groups. CONTROL group (no deformity): 22 cases; KYPHOSIS group (sagittal deformity): 49 cases and SCOLIOSIS group (coronal deformity): 99 cases (mean Cobb 42.4º). Method Cross-sectional study. A new drawing (TAPS4) was designed to represent the deformity in the sagittal plane with five response options. Clinical (SRS-22 and TAPS 4-items) and radiological (kyphosis T4-T12) data were collected in all patients. The statistical analysis consisted in determining for each group the internal consistency of the 3-items TAPS vs 4-items TAPS, as well as the discriminant validity (correlation with kyphosis magnitude) and convergent validity (correlation with the SRS-22 image subscale). In addition, test–retest reliability of new item 4 was determined in a subgroup of 30 kyphotic patients. During control visit, the patients received a complete physical examination and a full-spine AP and lateral X-ray in standing position using a low-radiation technique and fulfilled instruments TAPS 4 items and SRS-22r. Results The three groups were found to have statistically significant differences in the magnitude of kyphosis, quality of life, body image perception, the 3-items TAPS, 4-items TAPS and new item 4 score. The addition of the item 4 to TAPS 3 items did not cause a significant change in the internal consistency of the scales (Cronbach's alpha) (TAPS 3-items 0.8 vs. TAPS 4-items 0.8). Kyphosis magnitude was not correlated with the 3-items TAPS and 4-items TAPS scores; however, in the KYPHOSIS group, a significant negative correlation was observed between kyphosis and item 4 (Rho = − 0.4, p = 0.0001). A significant correlation was found in all groups between TAPS 3-items and TAPS 4-items and SRS-22 image domain; the correlation between item 4 and SRS-22 body image domain was 0.3 in the Scoliosis group and 0.7 in the Kyphosis group.