A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial
Abstract Background The International Knee Documentation Committee Subjective Knee Form (IKDC) is the most highly recommended patient reported outcome measure for assessing patients with anterior cruciate ligament (ACL) injuries and those undergoing ACL reconstruction (ACLR) surgery. The IKDC was de...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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BMC
2023-09-01
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| Series: | Health and Quality of Life Outcomes |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s12955-023-02186-y |
| _version_ | 1797556292205674496 |
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| author | Hana Marmura Paul F. Tremblay Alan M. J. Getgood Dianne M. Bryant |
| author_facet | Hana Marmura Paul F. Tremblay Alan M. J. Getgood Dianne M. Bryant |
| author_sort | Hana Marmura |
| collection | DOAJ |
| description | Abstract Background The International Knee Documentation Committee Subjective Knee Form (IKDC) is the most highly recommended patient reported outcome measure for assessing patients with anterior cruciate ligament (ACL) injuries and those undergoing ACL reconstruction (ACLR) surgery. The IKDC was developed as a unidimensional instrument for a variety of knee conditions. Structural validity, which determines how an instrument is scored, has not been definitively confirmed for the IKDC in respondents with ACL injuries, and in fact an alternative two-factor/subscale structure has been proposed in this population. The purpose of this study was to determine the most appropriate structure and scoring system for the IKDC in young active patients following ACL injury. Methods In total, 618 young patients deemed at high risk of graft rupture were randomized into the Stability 1 trial. Of the trial participants, 606 patients (98%) completed a baseline IKDC questionnaire used for this analysis. A cross sectional retrospective secondary data analysis of the Stability 1 baseline IKDC data was completed to assess the structural validity of the IKDC using exploratory and confirmatory factor analyses. Factor analyses were used to test model fit of the intended one-factor structure, a two-factor structure, and alternative four-factor and bifactor structures (i.e., a combination of a unidimensional factor with additional specific factors) of the IKDC, in a dataset of young active ACL patients. Results The simple one-factor and two-factor structures of the IKDC displayed inadequate fit in our dataset of young ACL patients. A bifactor model provided the best fit. This model contains one general factor that is substantially associated with all items, plus four secondary, more specific content factors (symptoms, activity level, activities of daily living, and sport) with generally weaker associations to subsets of items. Although the single-factor model did not provide unambiguous support to unidimensionality of the IKDC based on fit indices, the bifactor model supports unidimensionality of the IKDC when covariance between items with similar linguistic structure, response options, or content are acknowledged. Conclusions Overall, findings of a bifactor model with evidence of a reliable general factor well defined by all items lends support to continue interpreting and scoring this instrument as unidimensional. This should be confirmed in other samples. Clinically, based on these findings, the IKDC can be represented by a single score for young active patients with ACL tears. A more nuanced interpretation would also consider secondary factors such as sport and activity level. Trial registration The Stability 1 trial for which these data were collected was registered on ClinicalTrial.gov (NCT02018354). |
| first_indexed | 2024-03-10T16:59:49Z |
| format | Article |
| id | doaj.art-54c07c10156047029f7cb59460ef82b5 |
| institution | Directory Open Access Journal |
| issn | 1477-7525 |
| language | English |
| last_indexed | 2024-03-10T16:59:49Z |
| publishDate | 2023-09-01 |
| publisher | BMC |
| record_format | Article |
| series | Health and Quality of Life Outcomes |
| spelling | doaj.art-54c07c10156047029f7cb59460ef82b52023-11-20T11:00:05ZengBMCHealth and Quality of Life Outcomes1477-75252023-09-012111910.1186/s12955-023-02186-yA bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trialHana Marmura0Paul F. Tremblay1Alan M. J. Getgood2Dianne M. Bryant3School of Physical Therapy, Faculty of Health Sciences, Western UniversityDepartment of Psychology, Faculty of Social Science, Western UniversityFowler Kennedy Sport Medicine ClinicSchool of Physical Therapy, Faculty of Health Sciences, Western UniversityAbstract Background The International Knee Documentation Committee Subjective Knee Form (IKDC) is the most highly recommended patient reported outcome measure for assessing patients with anterior cruciate ligament (ACL) injuries and those undergoing ACL reconstruction (ACLR) surgery. The IKDC was developed as a unidimensional instrument for a variety of knee conditions. Structural validity, which determines how an instrument is scored, has not been definitively confirmed for the IKDC in respondents with ACL injuries, and in fact an alternative two-factor/subscale structure has been proposed in this population. The purpose of this study was to determine the most appropriate structure and scoring system for the IKDC in young active patients following ACL injury. Methods In total, 618 young patients deemed at high risk of graft rupture were randomized into the Stability 1 trial. Of the trial participants, 606 patients (98%) completed a baseline IKDC questionnaire used for this analysis. A cross sectional retrospective secondary data analysis of the Stability 1 baseline IKDC data was completed to assess the structural validity of the IKDC using exploratory and confirmatory factor analyses. Factor analyses were used to test model fit of the intended one-factor structure, a two-factor structure, and alternative four-factor and bifactor structures (i.e., a combination of a unidimensional factor with additional specific factors) of the IKDC, in a dataset of young active ACL patients. Results The simple one-factor and two-factor structures of the IKDC displayed inadequate fit in our dataset of young ACL patients. A bifactor model provided the best fit. This model contains one general factor that is substantially associated with all items, plus four secondary, more specific content factors (symptoms, activity level, activities of daily living, and sport) with generally weaker associations to subsets of items. Although the single-factor model did not provide unambiguous support to unidimensionality of the IKDC based on fit indices, the bifactor model supports unidimensionality of the IKDC when covariance between items with similar linguistic structure, response options, or content are acknowledged. Conclusions Overall, findings of a bifactor model with evidence of a reliable general factor well defined by all items lends support to continue interpreting and scoring this instrument as unidimensional. This should be confirmed in other samples. Clinically, based on these findings, the IKDC can be represented by a single score for young active patients with ACL tears. A more nuanced interpretation would also consider secondary factors such as sport and activity level. Trial registration The Stability 1 trial for which these data were collected was registered on ClinicalTrial.gov (NCT02018354).https://doi.org/10.1186/s12955-023-02186-yKneeAnterior cruciate ligamentOrthopaedic surgeryYouthPatient reported outcome measuresStructural validity |
| spellingShingle | Hana Marmura Paul F. Tremblay Alan M. J. Getgood Dianne M. Bryant A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial Health and Quality of Life Outcomes Knee Anterior cruciate ligament Orthopaedic surgery Youth Patient reported outcome measures Structural validity |
| title | A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial |
| title_full | A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial |
| title_fullStr | A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial |
| title_full_unstemmed | A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial |
| title_short | A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial |
| title_sort | bifactor model supports unidimensionality of the international knee documentation committee subjective knee form in young active patients with anterior cruciate ligament tears a retrospective analysis of a randomized controlled trial |
| topic | Knee Anterior cruciate ligament Orthopaedic surgery Youth Patient reported outcome measures Structural validity |
| url | https://doi.org/10.1186/s12955-023-02186-y |
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