A comparative performance analysis of the International Classification of Functioning, Disability and Health and the Item-Perspective Classification framework for classifying the content of patient reported outcome measures

Characterization of functioning in breast cancer survivors: an interpretive descriptive analysis study based on the International Classification of Functioning, Disability, and Health (ICF) and the Item-Perspective Classification Framework

PURPOSE

Breast cancer survivors may experience a variety of disabilities that could potentially compromise their independent functioning. This study aimed to examine their perspectives and experts on their functioning and interpret concepts with the International Classification of Functioning, Disability, and Health (ICF) and the Item-Perspective Classification Framework (IPF).

METHODS

Interpretive descriptive methods were used with in-depth interviewing with 16 breast cancer survivors and 22 experts using a semi-structured interview guide. The interviews were recorded, transcribed, and qualitatively analyzed using thematic analysis. The extracted data were linked to the ICF Core Set for Breast cancer and were interpreted by the IPF.

RESULTS

Four main themes emerged to define the functioning of breast cancer survivors: body functioning, physical functioning, social functioning, and mental functioning. Three other factors were also categorized as modifiers of functioning personal, emotional, and environmental. The 592 extracted meaningful concepts were linked to 38 (47%) categories from the ICF: 16 Body Functions, 14 Activities and Participation, and 8 Environmental Factors. The IPF classified all the extracted concepts, and most rational appraisals fell in the biological (B) domain. The concepts that required emotional appraisal were classified in Psychology (P).

CONCLUSION

Psychological and emotional factors were pivotal in defining functioning in patients with BC.

Development and validation of the ND10 to measure neck-related functional disability

BACKGROUND

Previous neck-specific patient-reported outcome measures (PROMs) have tended to measure both symptoms and disability. This multi-staged study developed and evaluated a neck-specific PROM focusing on functional disability.

METHODS

This study integrated findings from systematic reviews on neck-specific outcome measures, patient interviews, qualitative studies on neck disability, and iterative item testing to develop a 10-item measure of neck-related disability (ND10). Content validity was assessed by classifying items using the International Classification of Functioning, Disability and Health (ICF) and perspective linking. Patients (n = 78) with neck pain completed cognitive interviews, exploring items of the Neck Disability Index (NDI) and ND10, and completed structured questions related to literacy and relevance. Test-retest reliability and internal consistency were evaluated using intraclass correlation coefficients, Bland Altman graphs, and Cronbach's alpha. Concurrent convergent validity was evaluated by comparing the ND10 to the NDI, Single Assessment Numeric Evaluation (SANE), and Disabilities of the Arm, Shoulder and Hand (DASH). Known group validity was determined by comparing ND10 scores from patients, who rated their neck as more or less than 1/2 of "normal" on the SANE, using t-tests.

RESULTS

The ND10 requires respondents to make rational judgements about their neck-related body function and disability. It has high internal consistency (0.94) and re-test reliability (0.87; SEM = 3.2/100; MDC = 7.5); and no re-test bias (mean re-test difference of 0.6). It followed expected correlation patterns, being highly correlated with related multi-item PROMs (r = 0.85-0.91), and moderately correlated to the single-item SANE. More patients agreed that the ND10 was easily readable than did so for the NDI (84% vs 68%; p < 0.05). All the PROMs distinguished the patients who perceived themselves as being abnormal/normal defined by a dichotomized SANE (p < 0.01).

CONCLUSION

The ND10 is reliable and valid for measuring neck-related functional disability. Longitudinal and cross-cultural translation studies are needed to support future use.

ICF Linking and Cognitive Interviewing Are Complementary Methods for Optimizing Content Validity of Outcome Measures: An Integrated Methods Review

Content validity is a fundamental requirement of outcome measures. After reviewing operational needs and existing definitions, content validity we as defined as: the extent to which a measure provides a comprehensive and true assessment of the key relevant elements of a specified construct or attribute across a defined range, clearly and equitably for a stated target audience and context. ICF linkage rules from 2002, 2005, and 2019 have provide increasingly clear processes for describing and evaluating content of outcome measures. ICF Core Sets provide international reference standards of the core constructs of importance for different health conditions. Both are important as reference standards during content validation. To summarize their use as reference standards, the following summary indicators were proposed: (1) Measure to ICF linkage, (2) Measure to (Brief or Comprehensive) Core Set Absolute Linkage, (3) Measure to (Brief or Comprehensive) Core Set Unique Linkage, (4) Core Set Representation, and (5) Core Set Unique Disability Representation. Methods to assess how respondents engage with content are needed to complement ICF-linking. Cognitive interviewing is an ideal method since it used to explore how respondents interpret and calibrate response to individual items on an outcome measure. We proposed a framework for classifying these responses: Clarity/Comprehension, Relevance, Inadequate response definition, Reference Point, Perspective modification, and Calibration Across Items. Our analysis of 24 manuscripts that used ICF linking for content validation since updated linking rules were published found that authors typically used linking to validate existing measures, involved multiple raters, used 2005 linking rules, summarized content at a concept level (e.g., impairment, activity, participation) and/or use core sets as a reference standard. Infrequently, ICF linking was used to create item pools/conceptual frameworks for new measures, applied the full scope of the 2019 linking rules, used summary indicators, or integrated ICF-linking with qualitative methods like cognitive interviews. We conclude that ICF linkage is a powerful tool for content validity during development or validation of PROM. Best practices include use of updated ICF linking rules, triangulation of ICF linking with participant assessments of clarity and relevance preferably obtained using cognitive interview methods, and application of defined summary indicators.