Construct validity of functional status scores of patients with lymphedema.

During treatment of lymphedema, routine use of patient-reported outcomes measures (PROMs) is recommended to monitor patient progress; however, the validity functional status (FS) PROMs in these patients is unknown. Our aims were to examine construct validity of the shoulder computerized adaptive testing (CAT) and the foot-and-ankle CAT, as a measure of FS for patients selecting the shoulder or the foot-and-ankle as their main body part affected by their lymphedema. We assessed the ability of the FS scores to distinguish between patient groups in clinically expected ways at admission and discharge from physical therapy. At admission (n=1600), patients who were younger and had more acute symptoms, less severe lymphedema, less co-morbidities, no relevant surgical history, did not use medications for chronic conditions, and exercised regularly, had higher FS. At discharge (n=611), patients who were younger and had less advanced lymphedema, fewer co-morbidities, no relevant surgical history, did not use medications for chronic conditions, exercised regularly, and had more acute symptoms had higher FS change, after controlling for their baseline FS score. Low participation rates in FS outcomes data collection could have biased results. Overall, the CAT-based FS PROMs used in this study discriminated between patient groups in clinically logical ways both at intake and at discharge from lymphedema treatment.