KOOS score maps were externally validated to inform knee arthroplasty shared decision making.

Purpose: The Knee injury and Osteoarthritis Outcome Survey (KOOS) profile of outcome measures are among the most commonly used outcome measures in knee arthroplasty (KA). The purpose was to develop and externally validate "score maps" (one-page figural depictions of most likely scores) for KOOS Pain and Function subscales to facilitate a variety of clinical decisions related to shared decision making prior to KA.

Methods: Presurgical KA data collected within 1 year of surgery and obtained in two independent studies were used in this cross-sectional study. Score maps were designed to be easily understandable, single-page graphical depictions of predicted KOOS Pain, and KOOS Function, daily activity subscales. To create the score maps, individual item scores from one dataset were used to determine the most probable responses for each item for the entire range of possible scores. Predicted KOOS score maps were derived from Osteoarthritis Initiative (OAI) data and externally validated using an independent single site KA cohort study. Score map predicted scores from OAI were compared to actual presurgical KOOS subscale scores using Weighted Kappa (Κ) agreement coefficients and actual versus predicted differences in scores.

Results: The score maps derived from OAI and applied to actual scores in the validation sample demonstrated moderate to substantial chance-corrected agreement for both KOOS Pain and KOOS Function, daily activity subscale items. For example, KOOS Pain score map scores applied to the external validation dataset showed chance-corrected agreement with Κ ranging from 0.43 to 0.73. Score maps predicted actual item scores within ± 1 point at least 94% of the time. Findings for the KOOS Function, daily activity subscale items were similar.

Conclusions: Score maps derived from OAI data agreed with actual KOOS scores obtained on an independent dataset at an acceptable degree of precision. Easy-to-use KOOS Pain and Function, daily activity score maps have potential to facilitate a variety of important clinical decisions during discussions between patients and surgeons prior to KA.

Level Of Evidence: Level III prognostic study.