Cross-cultural adaptation and validation of the Vietnamese version of the Knee Injury and Osteoarthritis Outcome Score (KOOS) in patients with knee osteoarthritis.

Abstract

Knee osteoarthritis (KOA) is common in Vietnam, affecting about 34 % of individuals over 40 years of age. The Knee Injury and Osteoarthritis Outcome Score (KOOS) is an internationally recognized patient-reported outcome used to assess the impact of KOA but it is not yet available in Vietnamese. This study aimed to translate the KOOS into Vietnamese and assess the psychometric properties of the translation (KOOS-V). The translation process involved forward/back translation, expert review and cognitive interviews for pretesting. Content validity was assessed by seven experts using the Content validity Index (CVI). A sample of 133 Vietnamese KOA patients (mean age: 63.7 years, 83 % female) completed the KOOS-V, Short Form 36 Health Survey (SF-36) and Numeric Pain Rating Scale (NPRS), and 67 of them were re-assessed after 5-8 days. Psychometric analyses included internal consistency, test-retest reliability, construct validity and cross-cultural comparison of KOOS-V subscales. KOOS-V exhibited excellent content validity (CVI = 0.86-1.00), satisfactory internal consistency (Cronbach's α = 0.70-0.98) and good to excellent test-retest reliability (ICC = 0.77-0.90). Construct validity was confirmed by moderate to strong correlations with SF-36 Physical Functioning (Spearman's ρ = 0.66 to 0.82) and moderate correlations with NPRS (ρ = -0.49 to -0.62). The cross-cultural comparison showed that the KOOS subscales in Vietnam presents the same challenge as in other cultures. The KOOS-V is a reliable, valid tool for assessing the functional impact of KOA in Vietnamese patients, contributing to its broader use worldwide in clinical and research settings.