Global permutation tests for multivariate ordinal data: alternatives, test statistics, and the null dilemma

We discuss two-sample global permutation tests for sets of multivariate ordinal data in possibly high-dimensional setups, motivated by the analysis of data collected by means of the World Health Organisation's International Classification of Functioning, Disability and Health. The tests do not require any modelling of the multivariate dependence structure. Specifically, we consider testing for marginal inhomogeneity and direction-independent marginal order. Max-T test statistics are known to lead to good power against alternatives with few strong individual effects. We propose test statistics that can be seen as their counterparts for alternatives with many weak individual effects. Permutation tests are valid only if the two multivariate distributions are identical under the null hypothesis. By means of simulations, we examine the practical impact of violations of this exchangeability condition. Our simulations suggest that theoretically invalid permutation tests can still be 'practically valid'. In particular, they suggest that the degree of the permutation procedure's failure may be considered as a function of the difference in group-specific covariance matrices, the proportion between group sizes, the number of variables in the set, the test statistic used, and the number of levels per variable

The prospects for universal disability law and social policy

The worldwide disarray of disability social policy and law requires a new foundation to make it coherent and to remedy persistent contradictions, disincentives and other policy anomalies. In this paper we clarify and expand Irving Zola’s call for ‘universalized disability policy’ and develop his insight by drawing upon the well-known principles of Universal Design (UD), or Design for All, in architecture, product development and city planning to formulate analogous principles of universally designed disability social policy and law. Our objective is to show, by means of two examples - one in health care delivery and the other in welfare or social support policy - that ‘universalized’ policy for and on behalf of persons with disabilities is feasible. We find that there are some, albeit limited, examples of universalizing policy in these areas and suggests ways in which the full range of UD principles might be able to be implemented in these two policy areas. What we propose is merely a proof of concept rather than a complete proposal to restructure disability law and policy - which likely not be feasible, given the range of social and economic conditions of countries around the globe. We conclude with some tentative suggestions for areas of empirical research that would further the overall agenda of a universal disability social policy

Responsiveness of the International Classification of Functioning, Disability and Health (ICF) Core Set for rheumatoid arthritis

Background: The comprehensive International Classification of Functioning, Disability and Health (ICF) Core Set for rheumatoid arthritis (RA) is a selection of 96 categories from the ICF, representing relevant aspects in the functioning of patients with RA. Objectives: To study the responsiveness of the ICF Core Set for RA in rheumatological practice. Methods: A total of 46 patients with RA (72% women, mean (SD) age 53.6 (12.6) years, disease duration 6.3 (8.0) years) were interviewed at baseline and again after 6 months treatment with a disease-modifying antirheumatic drug (DMARD), applying the ICF Core Set for RA with qualifiers for problems on a modified three-point scale (no problem, mild/moderate, severe/complete). Patient-reported outcomes included Modified Health Assessment Questionnaire (MHAQ) and Short-Form 36 (SF-36) health survey, and disease activity was calculated. Responsiveness was measured as change in qualifiers in ICF categories, and was also compared with change in patient-reported outcomes. Results: After 6 months of DMARD treatment, improvement by at least one qualifier was seen in 20% of patients (averaged across all ICF categories), 71% experienced no change and 9% experienced worsening symptoms. Findings were similar across the different aspects of functioning. Mainly moderate effect sizes were seen for 6-month changes in the ICF Core Set for RA, especially in patients with improved health status, with similar effect size for disease activity. The components in the ICF Core Set for RA were only weakly associated with patient-reported outcomes and disease activity. Conclusions: The ICF Core Set for RA demonstrated moderate responsiveness in this real-life setting of patients where minor changes occurred during treatment with DMARDs

Individual interviews and focus groups in patients with rheumatoid arthritis: a comparison of two qualitative methods

Purpose: To compare two different approaches to performing focus groups and individual interviews, an open approach, and an approach based on the International Classification of Functioning, Disability and Health (ICF). Methods: Patients with rheumatoid arthritis attended focus groups (n=49) and individual interviews (n=21). Time, number of concepts, ICF categories identified, and sample size for reaching saturation of data were compared. Descriptive statistics, Chi-square tests, and independent t tests were performed. Results: With an overall time of 183h, focus groups were more time consuming than individual interviews (t=9.782; P<0.001). In the open approach, 188 categories in the focus groups and 102 categories in the interviews were identified compared to the 231 and 110 respective categories identified in the ICF-based approach. Saturation of data was reached after performing five focus groups and nine individual interviews in the open approach and five focus groups and 12 individual interviews in the ICF-based approach. Conclusion: The method chosen should depend on the objective of the study, issues related to the health condition, and the study's participants. We recommend performing focus groups if the objective of the study is to comprehensively explore the patient perspectiv

An International Expert Survey on Functioning in Vocational Rehabilitation Using the International Classification of Functioning, Disability and Health

Background Vocational rehabilitation (VR) is a key process in work disability (WD) management which aims to engage or re-engage individuals to work and employment. The International Classification of Functioning, Disability and Health (ICF) by the World Health Organization (WHO) can be interfaced with VR but there is a lack of evidence of what ICF contents experts in the field consider. The objective of this study is to survey the experts in the VR field with regard to what factors are considered important to patients participating in VR using the ICF as the language to summarize the results. Methods An internet-based survey was conducted with experts from six WHO Regions (Africa, the Americas, Eastern Mediterranean, Europe, South-East Asia, and Western Pacific). Experts were asked six open-ended questions on factors that are important in VR. Each question was related to a component of the ICF (body functions, body structures, activities and, environmental factors, and personal factors). Responses were linked to the ICF. Results Using a modified stratified randomized sampling, 201 experts were sent the survey and 151 experts responded (75% response rate). We identified 101 ICF categories: 22 (21.8%) for body functions, 13 (12.9%) for body structures, 36 (35.6%) for activities and participation, and 30 (29.7%) for environmental factors. Conclusions There was a multitude of ICF functioning domains according to the respondents which indicates the complexity of VR. This expert survey has provided a list of ICF categories which could be considered in V

Development of a metric for tracking and comparing population health based on the minimal generic set of domains of functioning and health

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Identification of candidate categories of the International Classification of Functioning Disability and Health (ICF) for a Generic ICF Core Set based on regression modelling

Background: The International Classification of Functioning, Disability and Health (ICF) is the framework developed by WHO to describe functioning and disability at both the individual and population levels. While condition-specific ICF Core Sets are useful, a Generic ICF Core Set is needed to describe and compare problems in functioning across health conditions. Methods: The aims of the multi-centre, cross-sectional study presented here were: a) to propose a method to select ICF categories when a large amount of ICF-based data have to be handled, and b) to identify candidate ICF categories for a Generic ICF Core Set by examining their explanatory power in relation to item one of the SF-36. The data were collected from 1039 patients using the ICF checklist, the SF-36 and a Comorbidity Questionnaire. ICF categories to be entered in an initial regression model were selected following systematic steps in accordance with the ICF structure. Based on an initial regression model, additional models were designed by systematically substituting the ICF categories included in it with ICF categories with which they were highly correlated. Results: Fourteen different regression models were performed. The variance the performed models account for ranged from 22.27% to 24.0%. The ICF category that explained the highest amount of variance in all the models was sensation of pain. In total, thirteen candidate ICF categories for a Generic ICF Core Set were proposed. Conclusion: The selection strategy based on the ICF structure and the examination of the best possible alternative models does not provide a final answer about which ICF categories must be considered, but leads to a selection of suitable candidates which needs further consideration and comparison with the results of other selection strategies in developing a Generic ICF Core Set

Rethinking Disability

Disability as a health outcome deserves more attention than it has so far received. With people living longer and the epidemiological transition from infectious to noncommunicable diseases as the major cause of health burden, we need to focus attention on disability - the non-fatal impact of heath conditions - over and above our concern for causes of mortality.With the first Global Burden of Disease study, WHO provided a metric that enabled the comparison of the impact of diseases, drawing on a model of disability that focused on decrements of health. This model has since been elaborated in the International Classification of Functioning, Disability and Health as being either a feature of the individual or arising out of the interaction between the individual's health condition and contextual factors. The basis of WHO's ongoing work is a set of principles: that disability is a universal human experience; that disability is not determined solely by the underlying health condition or predicated merely on the presence of specific health conditions; and finally, that disability lies on a continuum from no to complete disability. To determine whether interventions at individual or population levels are effective, an approach to disability measurement that allows for an appropriate and fair comparison across health conditions is needed. WHO has designed the Model Disability Survey (MDS)~to collect information relevant to understand the lived experience of disability, including the person's capacity to perform tasks actions in daily life, their actual performance, the barriers and facilitators in the environment they experience, and their health conditions. As disability gains prominence within the development agenda in the United Nations Sustainable Development Goals, and the implementation of the United Nations Convention on the Rights of Persons with Disabilities, the MDS will provide the data to monitor the progress of countries on meeting their obligations.The lesson learned from WHO's activities is that disability is a universal human experience, in the sense that everyone can be placed on a continuum of functioning and either currently experiences or is vulnerable to experiencing disability over the course of their lives. This understanding of disability is the key to mainstreaming disability within the public discourse

Which environmental factors are associated with lived health when controlling for biological health? - a multilevel analysis

Background: Lived health and biological health are two different perspectives of health introduced by the International Classification of Functioning, Disability and Health (ICF). Since in the concept of lived health the impact of the environment on biological health is inherently included, it seems intuitive that when identifying the environmental determinants of health, lived health is the appropriate outcome. The Multilevel Item Response Theory (MLIRT) model has proven to be a successful method when dealing with the relation between a latent variable and observed variables. The objective of this study was to identify environmental factors associated with lived health when controlling for biological health by using the MLIRT framework. Methods: We performed a psychometric study using cross-sectional data from the Spanish Survey on Disability, Independence and Dependency Situation. Data were collected from 17,303 adults living in 15,263 dwellings. The MLIRT model was used for each of the two steps of the analysis to: (1) calculate people's biological health abilities and (2) estimate the association between lived health and environmental factors when controlling for biological health. The hierarchical structure of individuals in dwellings was considered in both models. Results: Social support, being able to maintain one's job, the extent to which one's health needs are addressed and being discriminated against due to one's health problems were the environmental factors identified as associated with lived health. Biological health also had a strong positive association with lived health. Conclusions: This study identified environmental factors associated with people's lived health differences within and between dwellings according to the MLIRT-model approach. This study paves the way for the future implementation of the MLIRT model when analysing ICF-based data