Development of a Patient-reported Outcome Measure for Adults with Lower Extremity Malignancies: The LIMB-Q ONC

Sarcomas are rare but aggressive cancers, and their treatment can have profound effects on quality of life. We sought to develop and establish the content validity of the LIMB-Q ONC, a novel patient-reported outcome measure (PROM) for adults with lower extremity malignancies, designed to reliably capture the impact of these cancers on patients.

Following international guidelines for the development of PROMs, we created a preliminary LIMB-Q ONC by adapting the LIMB-Q scales and incorporating 2 cancer-specific scales from the BREAST-Q. Content validity was evaluated through cognitive debriefing interviews with patients and feedback from subject experts. Comments were used to refine a final instrument.

We conducted 16 cognitive debriefing interviews with patients with soft-tissue sarcomas (n = 12), bone sarcomas (n = 3), and late effects of nonsarcoma cancer treatment (n = 1). Treatments included chemotherapy (75%), radiation therapy (69%), amputation (63%), and/or flap (50%) surgery. Revisions included replacing "injured lower limb" with "affected lower limb" and "uninjured lower limb" with "lower limb unaffected by cancer." Minor wording changes improved clarity, whereas no scales were added or removed. Content experts confirmed the instrument's comprehensiveness and relevance.

Content validity of the LIMB-Q ONC was established through qualitative patient interviews and expert review. The LIMB-Q ONC offers a valid tool for measuring the outcomes important to patients with primary lower extremity malignancies. This article demonstrates the content validity of the LIMB-Q ONC in this patient population and allows for future field testing of the PROM.