Relationship between scores from the Knee Outcome Survey and a single assessment numerical rating in patients with patellofemoral pain.

Objective: To determine the relationship between patient-reported single numeric ratings and actual scores obtained from a validated instrument, the Knee Outcome Survey (KOS).

Background: Patient-reported outcome (PRO) measures are an important component of patient management. Information obtained from PRO measures can be used to prioritize goal setting, assist with clinical decision-making, provide evidence for effectiveness of interventions, monitor progress, and assess organizational or clinician performance.

Methods: Scores from the KOS activity of daily living (ADL) and Sports subscales completed at the time of initial examination of patients with patellofemoral pain (n = 29) were retrospectively analyzed and compared to a single assessment numerical rating.

Results: Bi-variate Pearson product correlation was used to determine association between the KOS-ADL and KOS-Sports with respective single assessment numerical ratings. A high correlation was observed between the KOS-ADL (0.85, p < 0.01) and KOS-Sports (0.88, p < 0.01) with a single assessment numerical rating.

Conclusions: Administration and scoring of standardized outcome measures such as the KOS-ADL and KOS-Sports require several minutes to administer but correlate well with a single assessment numerical ratings. The high correlation of single assessment numerical scores to actual KOS-ADL and KOS-Sports scores may provide support for discretionary use of single numerical ratings during interim patient care visits and/or in instances when time is limited. Additional studies are needed with larger patient populations and specific diagnostic subgroups to determine additional clinical relevance.