Development of a Core Set for Knee Dysfunction Based on the International Classification of Functioning, Disability and Health: A Cross-sectional Study

Using a measurement type-independent metric to compare patterns of determinants between patient-reported versus performance-based physical function in hemodialysis patients

PURPOSE

We applied a previously established common T-score metric for patient-reported and performance-based physical function (PF), offering the unique opportunity to directly compare measurement type-specific patterns of associations with potential laboratory-based, psychosocial, sociodemographic, and health-related determinants in hemodialysis patients.

METHODS

We analyzed baseline data from the CONVINCE trial (N = 1,360), a multinational randomized controlled trial comparing high-flux hemodialysis with high-dose hemodiafiltration. To explore the associations of potential determinants with performance-based versus patient-reported PF, we conducted multiple linear regression (backward elimination with cross-validation and Lasso regression). We used standardized T-scores as estimated from the PROMIS PF short-form 4a (patient-reported PF) and the Physical Performance Test (performance-based PF) as dependent variables.

RESULTS

Performance-based and patient-reported PF were both significantly associated with a laboratory marker-based indicator of muscle mass (simplified creatinine index), although the effects were relatively small (partial f2 = 0.04). Age was negatively associated with PF; the effect size was larger for performance-based (partial f2 = 0.12) than for patient-reported PF (partial f2 = 0.08). Compared to performance-based PF, patient-reported PF showed a stronger association with self-reported health domains, particularly pain interference and fatigue. When using the individual difference between patient-reported and performance-based T-scores as outcome, we found that younger age and more fatigue were associated with lower patient-reported PF compared to performance-based PF (small effect size).

CONCLUSION

Patient-reported and performance-based assessments were similarly associated with an objective marker of physical impairment in hemodialysis patients. Age and fatigue may result in discrepancies when comparing performance-based and patient-reported scores on the common PF scale. Trial Registration CONVINCE is registered in the Dutch Trial Register (Register ID: NL64750.041.18). The registration can be accessed at: https://onderzoekmetmensen.nl/en/trial/52958 .

Development of a brief core set for knee dysfunction based on the International Classification of Functioning, Disability and Health: assessing construct validity and measurement potential

BACKGROUND

The comprehensive core set for knee dysfunction was developed to classify the functioning of people with any knee dysfunction. To be used as a clinical instrument to measure the functioning of people with knee dysfunction, the construct validity of the core set still needs to be assessed. The purpose of this study was to analyze the construct validity of the comprehensive core set for knee dysfunction as an instrument to measure functioning.

METHODS

A cross-sectional study with 200 participants with knee dysfunction with or without clinical diagnosis of knee pathology, with or without complaint of pain, with or without instability, and/or with or without knee movement restriction of any type. Participants were assessed using the comprehensive core set for knee dysfunction with 25 categories, the subjective form from the International Knee Documentation Committee scale, and measures of self-perceived general health and functioning. The construct validity of the core set was assessed by Rasch analysis, and the external construct validity was assessed by correlation between the score of the brief core set for knee dysfunction with the subjective form from the International Knee Documentation Committee scale, and scores of self-perception of health and functioning.

RESULTS

Twelve categories were consistent with a unidimensional construct, with no difference in the response pattern for age, sex, educational level, and time of complaint. These categories were included in the brief core set for knee dysfunction. The mean score of the brief core set was 37 ± 21 points, a value classified as moderate impairment regarding functioning. Correlations with the subjective form from the International Knee Documentation Committee scale and scores of self-perception were adequate (p < 0.01; r > 0.5).

CONCLUSION

The brief core set for knee dysfunction, a set with 12 categories, can be used as a clinical instrument to measure and score the functioning of people with knee dysfunction, aged between 18 and 89 years, with adequate construct validity.

Content validity of the International Classification of Functioning, Disability and Health core set for knee dysfunction: a Delphi study

OBJECTIVE

To assess the content validity of the preliminary core set for knee dysfunction based on the opinion of experts.

DESIGN

A panel of 180 experts in knee disorders or on the use of the International Classification of Functioning, Disability, and Health for musculoskeletal conditions was invited for this Delphi study. The experts gave their opinion on whether to include the categories of the preliminary core set for knee dysfunction in a more comprehensive core set, using a six-item Likert scale. Kappa coefficient was used to analyze the agreement between the experts, and a consensus of 75% among responses was considered acceptable.

RESULTS

Nineteen experts participated in all rounds. Of the 24 categories from the preliminary core set for knee dysfunction, 15 remained in the comprehensive core set and one category was further detailed into three new categories. Seven new categories were included. Thus, the comprehensive core set for knee dysfunction was composed of 25 categories with an agreement of 81.5% among responses and a Kappa value of 0.63.

CONCLUSION

After validation by experts, the comprehensive core set for knee dysfunction was composed of 25 categories that can be used to assess the functioning of patients with knee dysfunction.