Asymptomatic population reference values for three knee patient-reported outcomes measures: evaluation of an electronic data collection system and implications for future international, multi-centre cohort studies.

OBJECTIVES: The aim was to assess whether the Knee Society Score, Oxford Knee Score (OKS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) were comparable in asymptomatic, healthy, individuals of different age, gender and ethnicity, across two remote continents. The purpose of this study was to establish normal population values for these scores using an electronic data collection system.

HYPOTHESIS: There is no difference in clinical knee scores in an asymptomatic population when comparing age, gender and ethnicity, across two remote continents.

METHODS: 312 Australian and 314 Canadian citizens, aged 18-94 years, with no active knee pain, injury or pathology in the ipsilateral knee corresponding to their dominant arm, were evaluated. A knee examination was performed and participants completed an electronically administered questionnaire covering the subjective components of the knee scores. The cohorts were age- and gender-matched. Chi-square tests, Fisher's exact test and Poisson regression models were used where appropriate, to investigate the association between knee scores, age, gender, ethnicity and nationality.

RESULTS: There was a significant inverse relationship between age and all assessment tools. OKS recorded a significant difference between gender with females scoring on average 1% lower score. There was no significant difference between international cohorts when comparing all assessment tools.

CONCLUSIONS: An electronic, multi-centre data collection system can be effectively utilized to assess remote international cohorts. Differences in gender, age, ethnicity and nationality should be taken into consideration when using knee scores to compare to pathological patient scores. This study has established an electronic, normal control group for future studies using the Knee society, Oxford, and KOOS knee scores.

LEVEL OF EVIDENCE: Diagnostic Level II.