Cai Xu1,2, Joani M Christensen3, Tareck Haykal3, Malke Asaad3, Chris Sidey-Gibbons1,2, Mark Schaverien3. 1. MD Anderson Center for INSPiRED Cancer Care (Integrated Systems for Patient-Reported Data), The University of Texas MD Anderson Cancer Center, Houston, Texas, USA. 2. Department of Symptom Research, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA. 3. Department of Plastic Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Abstract
Background: The updated Lymphedema Life Impact Scale (LLIS, version 2) has been widely used to evaluate the effect of lymphedema from the patient's perspective. We sought to assess its ability to accurately and efficiently measure lymphedema-related impact using modern psychometric techniques. Methods and Results: We collected a total of 1054 patient-reported outcome measure scores from 285 patients with upper extremity lymphedema and 65 patients with lower extremity lymphedema between 2016 and 2020. We first evaluated the relationship between the LLIS score, L-Dex score, and limb volume difference (LVD), and used classical test and item response theories to assess its psychometric performance. The LLIS score was only very weakly associated with LVD (r = 0.17, p < 0.001) and L-Dex score (r = 0.22, p < 0.001). The LLIS had acceptable dimensionality. Items 7 (affects body image) and 16 (affects proper fit of clothing/shoes) were locally dependent (Yen's Q3 = 0.45). Eight of the 17 items was interpreted differently between upper and lower limb lymphedema patients (pseudo R2 ≥ 0.01). The scoring structure required correction for items 9 (affects intimate relations) and 12 (manages lymphedema). Removing items 18 (infection occurrence) and 7 resulted in substantially improved item response theory model fit (Tucker-Lewis index = 0.93, comparative fix index = 0.95, root mean square error of approximation = 0.07, and root means square of the residual = 0.06). The relationships between the LLIS and objective measures of lymphedema remained weak following modification (LVD; r = 0.13, p = 0.01, L-Dex; r = 0.26, p < 0.001). Conclusion: We were able to slightly improve the psychometric properties of the LLIS. However, these improvements did not rectify apparent issues with construct validity and both versions of the LLIS displayed a weak relationship with objective measures of lymphedema severity.
Background: The updated Lymphedema Life Impact Scale (LLIS, version 2) has been widely used to evaluate the effect of lymphedema from the patient's perspective. We sought to assess its ability to accurately and efficiently measure lymphedema-related impact using modern psychometric techniques. Methods and Results: We collected a total of 1054 patient-reported outcome measure scores from 285 patients with upper extremity lymphedema and 65 patients with lower extremity lymphedema between 2016 and 2020. We first evaluated the relationship between the LLIS score, L-Dex score, and limb volume difference (LVD), and used classical test and item response theories to assess its psychometric performance. The LLIS score was only very weakly associated with LVD (r = 0.17, p < 0.001) and L-Dex score (r = 0.22, p < 0.001). The LLIS had acceptable dimensionality. Items 7 (affects body image) and 16 (affects proper fit of clothing/shoes) were locally dependent (Yen's Q3 = 0.45). Eight of the 17 items was interpreted differently between upper and lower limb lymphedema patients (pseudo R2 ≥ 0.01). The scoring structure required correction for items 9 (affects intimate relations) and 12 (manages lymphedema). Removing items 18 (infection occurrence) and 7 resulted in substantially improved item response theory model fit (Tucker-Lewis index = 0.93, comparative fix index = 0.95, root mean square error of approximation = 0.07, and root means square of the residual = 0.06). The relationships between the LLIS and objective measures of lymphedema remained weak following modification (LVD; r = 0.13, p = 0.01, L-Dex; r = 0.26, p < 0.001). Conclusion: We were able to slightly improve the psychometric properties of the LLIS. However, these improvements did not rectify apparent issues with construct validity and both versions of the LLIS displayed a weak relationship with objective measures of lymphedema severity.
Authors: Cai Xu; Grace L Smith; Ying-Shiuan Chen; Cristina M Checka; Sharon H Giordano; Kelsey Kaiser; Lisa M Lowenstein; Hilary Ma; Tito R Mendoza; Susan K Peterson; Ya-Chen T Shih; Sanjay Shete; Chad Tang; Robert J Volk; Chris Sidey-Gibbons Journal: PLoS One Date: 2022-08-25 Impact factor: 3.752