0.97 for both dimensions). On average, 19 and 14 items were needed to estimate the precise disability levels using the initial CAT for the first and second dimension. However, a marginal increase in the standard error of the estimate across successive iterations substantially reduced the number of items required to make an estimate. Conclusion Using a combination approach of EFA and Rasch analysis this study has shown that it is possible to calibrate items onto a single metric in a way that can be used to provide the basis of a CAT application. Thus there is an opportunity to obtain a wide variety of information to evaluate the biopsychosocial model in its more complex forms, without necessarily increasing the burden of information collection for patients."/>
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Table 3 Convergent validity between θR-CAT and subscale and total scores of the four original questionnaires.

From: An initial application of computerized adaptive testing (CAT) for measuring disability in patients with low back pain

Total/section scores θR-CAT Body Functions θR-CAT Activity-Participation
WHODAS II – Understanding and communicating 0.587** 0.396**
WHODAS II – Getting around 0.437** 0.801**
WHODAS II – Self care 0.391** 0.642**
WHODAS II – Getting along with people 0.382** 0.321**
WHODAS II – Getting along with people (without sexual activities item) 0.260* 0.071
WHODAS II – Life activities (without work items) 0.423** 0.647**
WHODAS II – Participation in society 0.549** 0.697**
WHODAS II – Total (without work and sexual items) 0.667 ** 0.820**
ODI 0.531** 0.724**
RDQ 0.639** 0.748**
NHP Energy 0.595** 0.424*
NHP Pain 0.659** 0.547**
NHP Emotional 0.892** 0.422**
NHP Sleep 0.737** 0.424**
NHP Social Isolation 0.809** 0.422**
NHP Physical Mobility 0.510** 0.708**
  1. *: ≤ 0.01, **: ≤ 0.001
  2. WHODAS II: World Health Organization Disability Assessment Schedule II, ODI: Oswestry Disability Index, RDQ: Roland Morris Low Back Pain Disability Questionnaire, NHP: Nottingham Health Profile.
  3. Expressed as Spearman's correlation (n = 91).
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BMC Musculoskeletal Disorders

ISSN: 1471-2474

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