Global implementation of the world health organization's International Classification of Diseases (ICD)-11: The allergic and hypersensitivity conditions model.

The International Classification of Diseases (ICD) provides a common language for use worldwide as a diagnostic and classification tool for epidemiology, clinical purposes and health management. Since its first edition, the ICD has maintained a framework distributing conditions according to topography, with the result that some complex conditions, such as allergies and hypersensitivity disorders (A/H) including anaphylaxis, have been poorly represented. The change in hierarchy in ICD-11 permitted the construction of the pioneer section addressed to A/H, which may result in more accurate mortality and morbidity statistics, including more accurate accounting for mortality due to anaphylaxis, strengthen classification, terminology and definitions. The ICD-11 was presented and adopted by the 72nd World Health Assembly in May 2019, and the implementation is ongoing worldwide. We here present the outcomes from an online survey undertaken to reach out the allergy community worldwide in order to peer review the terminology, classification and definitions of A/H introduced into ICD-11 and to support their global implementation. Data are presented here for 406 respondents from 74 countries. All of the subsections of the new A/H section of the ICD-11 had been considered with good accuracy by the majority of respondents. We believe that, in addition to help during the implementation phase, all the comments provided will help to improve the A/H classification and to increase awareness by different disciplines of what actions are needed to ensure more accurate epidemiological data and better clinical management of A/H patients.

Measurement of maternal functioning during pregnancy and postpartum: findings from the cross-sectional WHO pilot study in Jamaica, Kenya, and Malawi.

BACKGROUND: The World Health Organization's definition of maternal morbidity refers to "a negative impact on the woman's wellbeing and/or functioning". Many studies have documented the, mostly negative, effects of maternal ill-health on functioning. Although conceptually important, measurement of functioning remains underdeveloped, and the best way to measure functioning in pregnant and postpartum populations is unknown. METHODS: A cross-sectional study among women presenting for antenatal (N = 750) and postpartum (N = 740) care in Jamaica, Kenya and Malawi took place in 2015-2016. Functioning was measured through the World Health Organization Disability Assessment Schedule (WHODAS-12). Data on health conditions and socio-demographic characteristics were collected through structured interview, medical record review, and clinical examination. This paper presents descriptive data on the distribution of functioning status among pregnant and postpartum women and examines the relationship between functioning and health conditions. RESULTS: Women attending antenatal care had a lower level of functioning than those attending postpartum care. Women with a health condition or associated demographic risk factor were more likely to have a lower level of functioning than those with no health condition. However, the absolute difference in functioning scores typically remained modest. CONCLUSIONS: Functioning is an important concept which integrates a woman-centered approach to examining how a health condition affects her life, and ultimately her return to functioning after delivery. However, the WHODAS-12 may not be the optimal tool for use in this population and additional components to capture pregnancy-specific issues may be needed. Challenges remain in how to integrate functioning outcomes into routine maternal healthcare at-scale and across diverse settings.

[Quality of care analyses using ICD 11 : Detailed capture of treatment events]. / Analyse der Behandlungsqualität mittels ICD­11 : Differenzierte Kodierung von Behandlungsfehlern.

The identification of treatment errors, the so-called "undesirable" or "critical incidents", is crucial for improving and developing the quality of care. The new International Statistical Classification of Diseases and Related Health Problems-ICD-11-supports a structured data collection in the context of the quality of care and patient safety. Documentation conceptually relies on the multiple coding of the three dimensions of a critical incident: harm, cause, and mode. In this way, it is possible to capture the event in great detail, including the reasons for it and the effects it has. An evaluation of this concept in a field trial using 45 clinical case studies showed good concordance in coding across the documented participants.As the ICD-11 permits the detailed capture of near misses and their context, it could be used for structured documentation in incident reporting systems (databanks for the anonymous reporting of treatment errors). In this way, the error reports can be gathered in a more systematic way, so that they can be used for better quality improvement.In quality assessment, it is important to consider the time of diagnosis. Thus, the feature present on admission (POA) is a diagnosis qualifier that is of substantial importance for quality assessment and is widely used internationally. Up to now, it has not been permanently available in Germany. ICD-11 includes the relevant code.

[Web-based field studies on diagnostic classification and code assignment of mental disorders: comparison of ICD-11 and ICD-10]. / Internetbasierte Untersuchungen zur diagnostischen Klassifikation und Kodierung psychischer Störungen im Vergleich von ICD-11 und ICD-10.

The German Society for Psychiatry, Psychosomatics and Psychotherapy (DGPPN,) conducted a comprehensive field study (principal investigator WG) funded by the German Federal Ministry of Health in cooperation with 4 other German medical societies in the field of mental health (DGPM, DGPPR, DeGFS, DGfS) * to support WHO's development of the ICD-11 (Chapters 6 and 17). The objective of the web-based field study was to compare ICD-10 and ICD-11 (beta draft) for selected mental disorders, regarding consistency, accuracy and assessment of utility. The first study (TP1) focused on the diagnostic classification and the second (TP2) on assignment of diagnostic codes.In TP1, clinicians used either the ICD-10 Clinical Descriptions and Diagnostic Guidelines (CDDG) version or a draft version of the ICD-11 CDDG to evaluate 10 case vignettes in a randomized study implemented through the WHO GCPN **. As hypothesized, consistency was in favor of the ICD-11 (p = .02; n = 319 expert participants) though there was some variability across the different diagnostic categories. In addition, time for diagnosis was shorter (p = .01) and clinicians' judgment of utility (ease of use; goodness of fit) was better for ICD-11 (p = .047 and p < .001 respectively).TP2 focused on consistency of diagnostic code assignment for 25 short case descriptions (including explicit diagnosis and additional clinical information) using both ICD-10 and ICD-11 in a randomized web-based field study which was run on the WHO ICD-FiT *** platform. Based on 531 code assignments by120 expert clinicians, consistency for ICD-11 was significantly lower compared to ICD-10 (71 % vs. 82 %, p < .001) contrary to study hypothesis, and time required was significantly higher for ICD-11 (p < .001). Nevertheless, utility assessments were in favor of ICD-11 (p < .005).In summary, in TP1, given vignettes with more complex clinical descriptions more similar to clinical cases, ICD-11 showed advantages in the consistency of correct diagnoses among clinicians, time required to reach a diagnosis, and clinicians' ratings of clinical utility. These results provide evidence for quality improvement of the diagnostic process due to the revision of the more complete diagnostic guidelines for ICD-11. In the coding task of TP2, coding by clinicians using the ICD-10 was more consistent and faster than coding using the ICD-11. This may be a result of the greater complexity for coding use of the ICD-11 (e. g., due to 'post-coordination'), as well as greater familiarity with the ICD-10 system (which German clinicians currently use) and lack of practice with the new ICD-11 codes and tools. In spite of this, users assessed the ICD-11 system as more useful than the ICD-10, in part also because of ICD-11's more systematic and comprehensive coding tools. In addition, time needed for coding improved with practice, indicating need for intense education and training initiatives when ICD-11 is adopted and implemented into clinical practice.

Deriving ICD-10 Codes for Patient Safety Indicators for Large-scale Surveillance Using Administrative Hospital Data.

BACKGROUND: Existing administrative data patient safety indicators (PSIs) have been limited by uncertainty around the timing of onset of included diagnoses. OBJECTIVE: We undertook de novo PSI development through a data-driven approach that drew upon "diagnosis timing" information available in some countries' administrative hospital data. RESEARCH DESIGN: Administrative database analysis and modified Delphi rating process. SUBJECTS: All hospitalized adults in Canada in 2009. MEASURES: We queried all hospitalizations for ICD-10-CA diagnosis codes arising during hospital stay. We then undertook a modified Delphi panel process to rate the extent to which each of the identified diagnoses has a potential link to suboptimal quality of care. We grouped the identified quality/safety-related diagnoses into relevant clinical categories. Lastly, we queried Alberta hospital discharge data to assess the frequency of the newly defined PSI events. RESULTS: Among 2,416,413 national hospitalizations, we found 2590 unique ICD-10-CA codes flagged as having arisen after admission. Seven panelists evaluated these in a 2-round review process, and identified a listing of 640 ICD-10-CA diagnosis codes judged to be linked to suboptimal quality of care and thus appropriate for inclusion in PSIs. These were then grouped by patient safety experts into 18 clinically relevant PSI categories. We then analyzed data on 2,381,652 Alberta hospital discharges from 2005 through 2012, and found that 134,299 (5.2%) hospitalizations had at least 1 PSI diagnosis. CONCLUSION: The resulting work creates a foundation for a new set of PSIs for routine large-scale surveillance of hospital and health system performance.

Enhanced capture of healthcare-related harms and injuries in the 11th revision of the International Classification of Diseases (ICD-11).

The World Health Organization (WHO) plans to submit the 11th revision of the International Classification of Diseases (ICD) to the World Health Assembly in 2018. The WHO is working toward a revised classification system that has an enhanced ability to capture health concepts in a manner that reflects current scientific evidence and that is compatible with contemporary information systems. In this paper, we present recommendations made to the WHO by the ICD revision's Quality and Safety Topic Advisory Group (Q&S TAG) for a new conceptual approach to capturing healthcare-related harms and injuries in ICD-coded data. The Q&S TAG has grouped causes of healthcare-related harm and injuries into four categories that relate to the source of the event: (a) medications and substances, (b) procedures, (c) devices and (d) other aspects of care. Under the proposed multiple coding approach, one of these sources of harm must be coded as part of a cluster of three codes to depict, respectively, a healthcare activity as a 'source' of harm, a 'mode or mechanism' of harm and a consequence of the event summarized by these codes (i.e. injury or harm). Use of this framework depends on the implementation of a new and potentially powerful code-clustering mechanism in ICD-11. This new framework for coding healthcare-related harm has great potential to improve the clinical detail of adverse event descriptions, and the overall quality of coded health data.

Concept analysis of the patient reported outcomes measurement information system (PROMIS(®)) and the international classification of functioning, disability and health (ICF).

PURPOSE: The Patient Reported Outcomes Measurement Information System (PROMIS (®) ) is a US National Institutes of Health initiative that has produced self-report outcome measures, using a framework of physical, mental, and social health defined by the World Health Organization in 1948 (WHO, in Preamble to the Constitution of the World Health Organization as adopted by the International Health Conference, New York, 1948). The World Health Organization's International Classification of Functioning, Disability and Health (ICF) is a comprehensive classification system of health and health-related domains that was put forward in 2001. The purpose of this report is to compare and contrast PROMIS and ICF conceptual frameworks to support mapping of PROMIS instruments to the ICF classification system . METHODS: We assessed the objectives and the classification schema of the PROMIS and ICF frameworks, followed by content analysis to determine whether PROMIS domain and sub-domain level health concepts can be linked to the ICF classification. RESULTS: Both PROMIS and ICF are relevant to all individuals, irrespective of the presence of health conditions, person characteristics, or environmental factors in which persons live. PROMIS measures are intended to assess a person's experiences of his or her health, functional status, and well-being in multiple domains across physical, mental, and social dimensions. The ICF comprehensively describes human functioning from a biological, individual, and social perspective. The ICF supports classification of health and health-related states such as functioning, but is not a specific measure or assessment of health, per se. PROMIS domains and sub-domain concepts can be meaningfully mapped to ICF concepts. CONCLUSIONS: Theoretical and conceptual similarities support the use of PROMIS instruments to operationalize self-reported measurement for many body function, activity and participation ICF concepts, as well as several environmental factor concepts. Differences observed in PROMIS and ICF conceptual frameworks provide a stimulus for future research and development.

Mapping the content of the Patient-Reported Outcomes Measurement Information System (PROMIS®) using the International Classification of Functioning, Health and Disability.

BACKGROUND: The Patient-Reported Outcomes Measurement Information System (PROMIS (®) ) is a US National Institutes of Health initiative that has produced self-reported item banks for physical, mental and social health. OBJECTIVE: To describe the content of PROMIS at the item level using the World Health Organization's International Classification of Functioning, Disability and Health (ICF). METHODS: All PROMIS adult items (publicly available as of 2012) were assigned to relevant ICF concepts. The content of the PROMIS adult item banks was then described using the mapped ICF code descriptors. RESULTS: The 1,006 items in the PROMIS instruments could all be mapped to ICF concepts at the second level of classification, with the exception of three items of global or general health that mapped across the first-level classification of ICF activity and participation component (d categories). Individual PROMIS item banks mapped from 1 to 5 separate ICF codes indicating one-to-one, one-to-many and many-to-one mappings between PROMIS item banks and ICF second-level classification codes. PROMIS supports measurement of the majority of major concepts in the ICF body functions (b) and activity and participation (d) components using PROMIS item banks or subsets of PROMIS items that could, with care, be used to develop customized instruments. Given that the focus of PROMIS is on measurement of person health outcomes, concepts in body structures (s) and some body functions (b), as well as many ICF environmental factor, have minimal coverage in PROMIS. DISCUSSION: The PROMIS-ICF mapped items provide a basis for users to evaluate the ICF-related content of specific PROMIS instruments and to select PROMIS instruments in ICF-based measurement applications.

Socioeconomic inequality in disability among adults: a multicountry study using the World Health Survey.

OBJECTIVES: We compared national prevalence and wealth-related inequality in disability across a large number of countries from all income groups. METHODS: Data on 218,737 respondents participating in the World Health Survey 2002-2004 were analyzed. A composite disability score (0-100) identified respondents who experienced significant disability in physical, mental, and social functioning irrespective of their underlying health condition. Disabled persons had disability composite scores above 40. Wealth was evaluated using an index of economic status in households based on ownership of selected assets. Socioeconomic inequalities were measured using the slope index of inequality and the relative index of inequality. RESULTS: Median age-standardized disability prevalence was higher in the low- and lower middle-income countries. In all the study countries, disability was more prevalent in the poorest than in the richest wealth quintiles. Pro-rich inequality was statistically significant in 43 of 49 countries, with disability prevalence higher among populations with lower wealth. Median relative inequality was higher in the high- and upper middle-income countries. CONCLUSIONS: Integrating equity components into the monitoring of disability trends would help ensure that interventions reach and benefit populations with greatest need.

Harmonizing WHO's International Classification of Diseases (ICD) and International Classification of Functioning, Disability and Health (ICF): importance and methods to link disease and functioning.

BACKGROUND: To understand the full burden of a health condition, we need the information on the disease and the information on how that disease impacts the functioning of an individual. The ongoing revision of the International Classification of Diseases (ICD) provides an opportunity to integrate functioning information through the International Classification of Functioning, Disability and Health (ICF). DISCUSSION: Part of the ICD revision process includes adding information from the ICF by way of "functioning properties" to capture the impact of the disease on functioning. The ICD content model was developed to provide the structure of information required for each ICD-11 disease entity and one component of this content model is functioning properties. The activities and participation domains from ICF are to be included as the value set for functioning properties in the ICD revision process. SUMMARY: The joint use of ICD and ICF could create an integrated health information system that would benefit the implementation of a standard language-based electronic health record to better capture and understand disease and functioning in healthcare.

ICD-11 for quality and safety: overview of the WHO Quality and Safety Topic Advisory Group.

This paper outlines the approach that the WHO's Family of International Classifications (WHO-FIC) network is undertaking to create ICD-11. We also outline the more focused work of the Quality and Safety Topic Advisory Group, whose activities include the following: (i) cataloguing existing ICD-9 and ICD-10 quality and safety indicators; (ii) reviewing ICD morbidity coding rules for main condition, diagnosis timing, numbers of diagnosis fields and diagnosis clustering; (iii) substantial restructuring of the health-care related injury concepts coded in the ICD-10 chapters 19/20, (iv) mapping of ICD-11 quality and safety concepts to the information model of the WHO's International Classification for Patient Safety and the AHRQ Common Formats; (v) the review of vertical chapter content in all chapters of the ICD-11 beta version and (vi) downstream field testing of ICD-11 prior to its official 2015 release. The transition from ICD-10 to ICD-11 promises to produce an enhanced classification that will have better potential to capture important concepts relevant to measuring health system safety and quality-an important use case for the classification.

Development of the first disability index for inflammatory bowel disease based on the international classification of functioning, disability and health.

OBJECTIVE: The impact of inflammatory bowel disease (IBD) on disability remains poorly understood. The World Health Organization's integrative model of human functioning and disability in the International Classification of Functioning, Disability and Health (ICF) makes disability assessment possible. The ICF is a hierarchical coding system with four levels of details that includes over 1400 categories. The aim of this study was to develop the first disability index for IBD by selecting most relevant ICF categories that are affected by IBD. METHODS: Relevant ICF categories were identified through four preparatory studies (systematic literature review, qualitative study, expert survey and cross-sectional study), which were presented at a consensus conference. Based on the identified ICF categories, a questionnaire to be filled in by clinicians, called the 'IBD disability index', was developed. RESULTS: The four preparatory studies identified 138 second-level categories: 75 for systematic literature review (153 studies), 38 for qualitative studies (six focus groups; 27 patients), 108 for expert survey (125 experts; 37 countries; seven occupations) and 98 for cross-sectional study (192 patients; three centres). The consensus conference (20 experts; 17 countries) led to the selection of 19 ICF core set categories that were used to develop the IBD disability index: seven on body functions, two on body structures, five on activities and participation and five on environmental factors. CONCLUSIONS: The IBD disability index is now available. It will be used in studies to evaluate the long-term effect of IBD on patient functional status and will serve as a new endpoint in disease-modification trials.

Experiences in aligning WHO SMART guidelines to classification and terminology standards.

OBJECTIVES: Digital adaptation kits (DAKs) distill WHO guidelines for digital use by representing them as workflows, data dictionaries and decision support tables. This paper aims to highlight key lessons learnt in coding data elements of the antenatal care (ANC) and family planning DAKs to standardised classifications and terminologies (CATs). METHODS: We encoded data elements within the ANC and family planning DAKs to standardised CATs from the WHO CATs and other freely available CATs. RESULTS: The coding process demonstrated approaches to refine the data dictionaries and enhance alignment between data elements and CATs. DISCUSSION: Applying CATs to WHO clinical and public health guidelines can ensure that recommendations are operationalised in a digital system with appropriate consistency and clarity. This requires a multidisciplinary team and careful review to achieve conceptual equivalence between data elements and standardised terminologies. CONCLUSION: The systematic translation of guidelines into digital systems provides an opportunity for leveraging CATs; however, this approach needs further exploration into its implementation in country contexts and transition into machine-readable components.

ICD-11 Morbidity Pilot in Kuwait: Methodology and Lessons Learned for Future Implementation.

This paper reports on the first ICD-11 morbidity pilot for inpatient discharges in a public general hospital. We detail the pilot methodology, lessons learned in terms of facilitators and challenges, physician-reported opinion, and considerations for future implementation. The pilot included: engaging stakeholders; selecting the setting; building a common understanding of the discharge process; evaluating and preparing IT infrastructure; ICD-11 training; small-scale pre-pilot testing; implementing the pilot while providing on-site support and collecting data for analysis including a brief user-experience survey. Overall, physicians were satisfied with the experience. Facilitators for success included national health system influence, leadership commitment, a multidisciplinary team approach, physician-tailored training, using social media for training, and providing on-site support. Challenges included potential IT problems, and difficulties relating to training and engaging physicians. Issues to consider include DRG system requirements, and comparability of ICD-11 pilot results from different countries. In conclusion, ICD-11 can be successfully implemented for documenting diagnoses by physicians in a public hospital by installing the coding tool on the electronic hospital information system. Pilots can improve ICD-11 content by using the online proposal mechanism. Implementing ICD-11 requires effective change management, stakeholder-tailored communication, and innovative ideas for training to match the electronic nature of ICD-11 and its potential new users, physicians.

Generating comprehensive functioning and disability data worldwide: development process, data analyses strategy and reliability of the WHO and World Bank Model Disability Survey.

BACKGROUND: Data on functioning and disability collected at population level is essential to complement mortality and morbidity, to estimate rehabilitation needs of countries and regions and to monitor the Convention on the Rights of Persons with Disabilities (CRPD) and the Sustainable Development Goals (SDGs). The objective of this paper is to briefly report the development process of the WHO Model Disability Survey, its data analysis strategy as well as its reliability and ability to measure low to high levels of functioning and disability across countries. METHODS: The development process is described in detail, and a secondary analysis using Rasch methods is conducted to report reliability and targeting using data from eight national and two regional implementations of the survey. RESULTS: The currently available versions of the Model Disability Survey are presented. The survey has good to very good internal reliability and good targeting in all included countries. CONCLUSION: The participatory and evidence-based development, consideration of the expertise of stakeholders, the availability of previously developed ICF-based surveys, and WHO tools targeting functioning and disability are reflected in its good to very good psychometric properties. The survey has been implemented to date in Afghanistan, Cameroon, Chile, Costa Rica, India, Laos, Pakistan, Philippines, Sri Lanka, and Tajikistan, and is used to inform policy-making, to monitor the CRPD and SDGs and to plan the delivery of rehabilitation services.

20 Years of ICF-International Classification of Functioning, Disability and Health: Uses and Applications around the World.

The International Classification of Functioning Disability and Health (ICF) was approved in 2001 and, since then, several studies reported the increased interest about its use in different sectors. A recent overview that summarizes its applications is lacking. This study aims to provide an updated overview about 20 years of ICF application through an international online questionnaire, developed by the byline authors, and sent to each World Health Organization Collaborating Centers of the Family of International Classifications (WHO-FIC CCs). Data was collected during October 2020 and December 2021 and descriptive content analyses were used to report main results. Results show how, in most of the respondent countries represented by WHO-FIC CCs, ICF was mainly used in clinical practice, policy development and social policy, and in education areas. Despite its applications in different sectors, ICF use is not mandatory in most countries but, where used, it provides a biopsychosocial framework for policy development in health, functioning and disability. The study provides information about the needs related to ICF applications, that can be useful to organize targeted intervention plans. Furthermore, this survey methodology can be re-proposed periodically to monitor the use of the ICF in the future.

Use of The International Classification of Functioning, Disability and Health (ICF) as a conceptual framework and common language for disability statistics and health information systems.

A common framework for describing functional status information is needed in order to make this information comparable and of value. The World Health Organization's International Classification of Functioning, Disability and Health (ICF), which has been approved by all its member states, provides this common language and framework. The article provides an overview of ICF taxonomy, introduces the conceptual model which underpins ICF and elaborates on how ICF is used at population and clinical level. Furthermore, the article presents key features of the ICF tooling environment and outlines current and future developments of the classification.

Measuring functioning and disability using household surveys: metric properties of the brief version of the WHO and World Bank model disability survey.

BACKGROUND: The Model Disability Survey (MDS) is the current standard recommended by WHO to collect functioning and disability data. Answering calls from countries requesting a version to be implemented as a module that could be integrated into existing surveys and be used for monitoring disability trends and for data disaggregation, WHO developed the brief MDS. The objectives of this paper are to evaluate the metric properties of the disability metrics generated with the Brief MDS and the precision of the Brief MDS in comparison with the full MDS. RESULTS: The partial credit model, a unidimensional model for polytomous data from the Rasch family, was applied to evaluate psychometric properties using data from national MDS implementations in Chile (N = 12,265) and in Sri Lanka (N = 3000). The Brief MDS generates valid metrics for measuring disability, from the perspectives of capacity and performance, thereby achieving good levels of measurement precision in comparison with its full counterpart. CONCLUSION: Given the scarcity of valid functioning and disability modules for household surveys, the Brief MDS represents a milestone in disability measurement. The Brief MDS is currently used by countries to monitor disability trends over time, which is especially important to evaluate the impact of health policies and public health interventions, to disaggregate indicators of the Sustainable Development Goals, and to monitor the implementation of the UN Convention on the Rights of Persons with Disabilities (CRPD).

Developing the World Health Organization Disability Assessment Schedule 2.0.

OBJECTIVE: To describe the development of the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) for measuring functioning and disability in accordance with the International Classification of Functioning, Disability and Health. WHODAS 2.0 is a standard metric for ensuring scientific comparability across different populations. METHODS: A series of studies was carried out globally. Over 65,000 respondents drawn from the general population and from specific patient populations were interviewed by trained interviewers who applied the WHODAS 2.0 (with 36 items in its full version and 12 items in a shortened version). FINDINGS: The WHODAS 2.0 was found to have high internal consistency (Cronbach's alpha, α: 0.86), a stable factor structure; high test-retest reliability (intraclass correlation coefficient: 0.98); good concurrent validity in patient classification when compared with other recognized disability measurement instruments; conformity to Rasch scaling properties across populations, and good responsiveness (i.e. sensitivity to change). Effect sizes ranged from 0.44 to 1.38 for different health interventions targeting various health conditions. CONCLUSION: The WHODAS 2.0 meets the need for a robust instrument that can be easily administered to measure the impact of health conditions, monitor the effectiveness of interventions and estimate the burden of both mental and physical disorders across different populations.

Validation of the "World Health Organization Disability Assessment Schedule, WHODAS-2" in patients with chronic diseases.

BACKGROUND: The WHODAS-2 is a disability assessment instrument based on the conceptual framework of the International Classification of Functioning, Disability, and Health (ICF). It provides a global measure of disability and 7 domain-specific scores. The aim of this study was to assess WHODAS-2 conceptual model and metric properties in a set of chronic and prevalent clinical conditions accounting for a wide scope of disability in Europe. METHODS: 1,119 patients with one of 13 chronic conditions were recruited in 7 European centres. Participants were clinically evaluated and administered the WHODAS-2 and the SF-36 at baseline, 6 weeks and 3 months of follow-up. The latent structure was explored and confirmed by factor analysis (FA). Reliability was assessed in terms of internal consistency (Cronbach's alpha) and reproducibility (intra-class correlation coefficients, ICC). Construct validity was evaluated by correlating the WHODAS-2 and SF-36 domains, and comparing known groups based on the clinical-severity and work status. Effect size (ES) coefficient was used to assess responsiveness. To assess reproducibility and responsiveness, subsamples of stable (at 6 weeks) and improved (after 3 moths) patients were defined, respectively, according to changes in their clinical-severity. RESULTS: The satisfactory FA goodness of fit indexes confirmed a second order factor structure with 7 dimensions, and a global score for the WHODAS-2. Cronbach's alpha ranged from 0.77 (self care) to 0.98 (life activities: work or school), and the ICC was lower, but achieved the recommended standard of 0.7 for four domains. Correlations between global WHODAS-2 score and the different domains of the SF-36 ranged from -0.29 to -0.65. Most of the WHODAS-2 scores showed statistically significant differences among clinical-severity groups for all pathologies, and between working patients and those not working due to ill health (p < 0.001). Among the subsample of patients who had improved, responsiveness coefficients were small to moderate (ES = 0.3-0.7), but higher than those of the SF-36. CONCLUSIONS: The latent structure originally designed by WHODAS-2 developers has been confirmed for the first time, and it has shown good metric properties in clinic and rehabilitation samples. Therefore, considerable support is provided to the WHODAS-2 utilization as an international instrument to measure disability based on the ICF model.