Veröffentlicht

July 25, 2021

WHODAS 2.0

The WHO Disability Assessment Schedule 2.0 (WHODAS 2.0) was developed from its predecessor, the WHODAS, to meet the specific demand and the need for a meaningful, standardized instrument that can be implemented across different disease areas to assess patients’ state of health.1

The WHODAS 2.0 is a Patient-Reported-Outcome (PRO) instrument that uses 36 questions to assess the global health status of patients across 6 health domains, independent of disease. They include:

  • Cognition – understanding, and communication: 6 questions.
  • Mobility – movement and locomotion: 5 questions
  • Self-care – personal hygiene, dressing, eating and coping alone: 4 questions
  • Social interaction – interacting with other people: 5 questions
  • Life activities – domestic duties, leisure, work and studies: 8 questions
  • Social participation – community activities, participation in society: 8 questions.

The questionnaire’s domains are based upon the conceptual framework of the WHO’s International Classification of Functioning, Disability and Health (ICF), which has been the international standard to describe and measure health and disability since 2001. All ICF domains are fully covered by WHODAS 2.0, making it unique as a generic, disease-independent PRO instrument.2

The WHODAS is available in 3 different survey forms:

  • administered and completed by the interviewer

  • administered and completed by the patient

  • administered and completed by a third party (e.g. relative, spouse) on behalf of the patient.

It is also available in at least 47 languages.11

WHODAS 2.0 Short Form - 12 items

Following on from the WHODAS 2.0, a short form with 12 questions was developed to enable shorter surveys. It also covers all 6 health domains and contains 2 questions per domain. In the study in which it was developed, the WHODAS 2.0 was capable of covering 81% of the variance of the WHODAS 2.0 and was able to identify over 90% of all patients with even mild limitations.1 It is also available in 3 different survey forms (see above).

WHODAS 2.0 12+24-item version - 12 to 36 items

The 12+24-item version of the WHODAS 2.0 is a hybrid of the 36-item full version and 12-item short form. It can only be administered by an interviewer or by Computer-Adaptive Testing (CAT). The 12-item short form is used first to screen for limitations in the 6 health domains. If limitations are identified in each domain, the patient is asked up to a maximum of 24 additional questions to describe all existing limitations in more detail. A perfectly healthy patient would be asked only 12 questions, whilst a more limited patient would be asked 30 or more questions.

WHODAS 2.0 evaluation

The WHODAS 2.0 evaluation takes into account the occupational status of the patient. For patients without a paid occupation, only 32 of the 36 questions are considered.

There is a simple and a complex scoring for the full and short version of the WHODAS 2.0 which are expanded upon below.

Simple scoring

Each answer is assigned its predefined score:
1 – “None”
2 – “Low”
3 – “Moderate
4 – “Strong”
5 – “Very strong/not possible”

All points are summed and the total score reflects the patient’s health status.

Based on feedback, scoring templates have been made available on the WHO website that use a point scale of 0-4 instead of 1-5 as above. This change does not appear to be compulsory, but it is important to note that the scoring scale used should be compared with the methodologically correct associated norms in order to assess patients adequately.3

Complex scoring

An Excel template and syntax for SPSS is available for complex scoring with each answer being assigned a predefined score.

All points within a domain are summed up so that 6 differently weighted domain scores are obtained.

The 6 domain scores are summed and converted into a summary score, which has a scale from 0 to 100 (0 = no restriction, 100 = greatest possible restriction).

The domain scores from 2 each represent the health status with regard to the respective health domain. The summary score from 3 represents the patient’s global health status with respect to all 6 health domains simultaneously.

There is normative data from several studies that can be used to classify patients into population percentiles using their summary scores.4 The corresponding tables can be found in the WHODAS 2.0 user manual.

Strengths

The WHODAS 2.0 is a validated and established questionnaire that can be used to assess the health status of patients irrespective of disease.1,5-11 Its validity and application is demonstrated by its use within many clinical studies that have been able to show large patient numbers.11-13

In addition, there is a short version, the WHODAS 2.0 Short Form, which, despite a considerable shortening of questions, still has a comparatively high informative value.1 This short version is particularly well suited for implementation in everyday clinical practice such as to follow the course of treatment of patients.

Limitations

The full version of the WHODAS 2.0 is very extensive with 36 questions, so that an implementation in clinical research is certainly practicable, but difficult to implement in everyday clinical practice.

License

The use and evaluation of all versions of the WHODAS 2.0 requires licensing. This is free of charge for non-commercial users and only requires online approval of a user agreement (from the WHO as rights holder) with details of the intended use.14 Our PRO consultants happily provide more in-detail information.

Conclusion

Overall, the WHODAS 2.0 is a meaningful and well-established questionnaire for disease-independent assessment of patients’ global health status. It is also flexible due to its different available forms. Depending on the version, it can be easily implemented in clinical research as well as in patient care.