Evaluating Psychometric Properties of the International Knee Documentation Committee Subjective Knee Form in a Heterogeneous Sample of Post-Operative Patients

Abstract

Background The International Knee Document Committee Subjective Knee Form (IKDC-SKF) is a patient-reported outcome measure used in orthopedics and sports medicine. Further psychometric assessment is necessary to confirm measurement properties in a large, heterogenous sample. Purpose The purpose of the study was to assess the psychometric properties of the IKDC-SKF in a large, heterogenous sample. Study Design Cross-Sectional Study Methods An exploratory factor analysis (EFA) was conducted to identify a sound latent structure and to assess internal consistency in a large sample of patients who underwent knee arthroscopy. A confirmatory factor analysis (CFA) was conducted to confirm structural validity. Multi-group invariance was conducted to assess factorial stability across sex and age groups, while longitudinal invariance procedures were performed to assess stability over time. Results A 3-factor, 9-item IKDC-SKF short form was identified with EFA procedures. The model was confirmed with CFA (CFI = 0.983; TLI = 0.975; IFI = 0.983; RMSEA = 0.057), while a sound 2-factor, 6-item model was also identified (CFI = 1.0; TLI = 0.999; IFI = 1.0; RMSEA = 0.11). The 9-item IKDC-SKF short form was invariant across groups but not time; removal of a single item (i.e., 8-item IKDC-SKF short form) resulted in longitudinal invariance. The 6-item IKDC-SKF short form was invariant across groups and time. Conclusion The 6-item, 8-item, and 9-item short form versions of the IKDC-SKF exceed contemporary fit recommendations and present as plausible alternatives to the IKDC-SKF with improved measurement properties, reduced scale response burden, and evidence of multi-group and longitudinal invariance. Further, the 6- and 8-item IKDC-SKF short forms may be used to assess group differences or change across time. # Level of evidence here Level 3 ©The Author(s)

International Knee Documentation Committee Subjective Knee Form Latent Growth Model Analysis: Assessing Recovery Trajectories

“…The International Knee Documentation Committee Subjective Knee Form (IKDC-SKF), an internationally recognized PROM, is widely used by healthcare societies to assess knee pathologies in orthopedics and sports medicine [12][13][14][15][16] and has been translated for use in multiple languages [14,15,[17][18][19][20][21]. The IKDC-SKF was proposed as a 19-item model, assessing symptoms (e.g., pain, stiffness), sport activity (e.g., stair ambulation, knee movement), and function (e.g., daily activities); however, researchers have recently proposed the use of condensed versions of the scale due to improved model fit and decreased patient response burden [22,23]. For example, three short-form versions of the IKDC-SKF (six-, eight-, and nine-items) have been identified using Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) procedures on large (n > 1000) datasets [22].…”

“…The IKDC-SKF was proposed as a 19-item model, assessing symptoms (e.g., pain, stiffness), sport activity (e.g., stair ambulation, knee movement), and function (e.g., daily activities); however, researchers have recently proposed the use of condensed versions of the scale due to improved model fit and decreased patient response burden [22,23]. For example, three short-form versions of the IKDC-SKF (six-, eight-, and nine-items) have been identified using Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) procedures on large (n > 1000) datasets [22]. All three short-form versions have evidence of multigroup and longitudinal invariance, supporting their use to assess group differences and change over time [22]; however, the six-item IKDC-SKF (i.e., IKDC-6) was recommended due to greater model precision [22].…”

“…For example, three short-form versions of the IKDC-SKF (six-, eight-, and nine-items) have been identified using Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) procedures on large (n > 1000) datasets [22]. All three short-form versions have evidence of multigroup and longitudinal invariance, supporting their use to assess group differences and change over time [22]; however, the six-item IKDC-SKF (i.e., IKDC-6) was recommended due to greater model precision [22]. Because longitudinal invariance was established for the six-item IKDC-SKF [22], LGM can be used to guide assessment of patient recovery.…”

“…All three short-form versions have evidence of multigroup and longitudinal invariance, supporting their use to assess group differences and change over time [22]; however, the six-item IKDC-SKF (i.e., IKDC-6) was recommended due to greater model precision [22]. Because longitudinal invariance was established for the six-item IKDC-SKF [22], LGM can be used to guide assessment of patient recovery.…”

The Significance of Selecting an Appropriate Patient-Reported Outcome Measure (PROM): A Cross-Cultural Adaptation of the Specific Paediatric International Documentation Committee Subjective (Pedi-IKDC) Knee Form

“…Therefore, the International Knee Documentation Committee Subjective Knee Form (IKDC) is one of the most often used patient-reported outcome measures in orthopaedic sports injury research and is specifically developed for ligament, meniscal, and cartilage injuries [12]. The IKDC score has been validated several times for evidence of its relevance, even among adolescents [12][13][14][15][16]. So far, numerous countries have made translations and cultural adaptations of the IKDC score, with the overall goal of having many countries use the same scale for the same conclusions and communication [17][18][19].…”