Validation of a single-factor structure and the scoring protocol for the Health Assessment Questionnaire-Disability Index (HAQ-DI)

University of California, Los Angeles, Los Ángeles, California, United States
Arthritis & Rheumatology (Impact Factor: 7.76). 08/2005; 53(4):536-42. DOI: 10.1002/art.21325
Source: PubMed


The extensively used Health Assessment Questionnaire Disability Index (HAQ-DI) has been well received by the research and clinical community, notably because of its measurement strengths including reliability and stability of scores over time, utility in observational studies and clinical trials, predictive relationship with morbidity and mortality in rheumatoid arthritis (RA), and its translation for use in different countries. However, HAQ-DI scoring has not been validated. The purpose of this study was to examine the structural validity of the HAQ-DI and evaluate the latent factors underlying HAQ-DI scoring.
This study used a cross-validation approach on a total of 278 patients with RA. Exploratory and confirmatory factor analyses were performed.
Results yielded a single-factor HAQ-DI score, which favored the current scoring system of the HAQ-DI. Additionally, modification indices suggested improved model fit with the secondary inclusion of correlated residual scores from a motor skills subdomain.
The current study provides the first validation of the HAQ-DI scoring system as determined by its latent factor structure. In addition, the findings suggest some benefit from a secondary interpretation of the scores based on domains that measure motor skills.

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Available from: Michael R Irwin, Oct 30, 2014
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    • "Rheumatoid arthritis (RA) is a chronic inflammatory joint disorder characterised by joint stiffness, swelling, and pain, and can have a profound impact on a patient’s health related quality of life [1,2]. As such, the goals of treatment of RA are not only symptom relief, reduction in disease activity, and reduction in the rate of joint damage, but also improvement in physical functioning and well-being from the patient’s perspective [3,4]. "
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    ABSTRACT: Objective To compare biologics as monotherapy or in combination with methotrexate (MTX) in terms of patient reported outcomes (PROs) in RA patients with an inadequate response to conventional DMARDs (DMARD-IR). Methods With a systematic literature review 17 RCTs were identified that evaluated adalimumab, certolizumab pegol, etanercept, golimumab, infliximab, abatacept, anakinra or tocilizumab. Treatment effects in terms of pain (0-100 mm), patient’s global assessment of disease activity (PGA; 0-100 mm), Health Assessment-Questionnaire (HAQ) disability index (DI; 0–3), and the physical component summary (PCS) of the SF36 Health Survey (0–100) at 24 weeks were combined by means of Bayesian network meta-analyses. Results With tocilizumab monotherapy, greater improvements in pain (difference = -11.1; (95% Credible Interval -21.3, -0.1)) and PGA (-10.3 (-20.4, 0.8)) were observed than with aTNF monotherapy. Tocilizumab was at least as efficacious as aTNF in HAQ-DI improvements (-0.16; (-0.37, 0.05)). aTNF + MTX (-17.9 (-23.1, -13.0) & -19.1 (-24.2, -14.4)), abatacept + MTX (-23.0 (-47.3, 1. 5) & -13.6 (-28.4, 2.0)) and tocilizumab + MTX (-16.0 (-26.3, -6.3) & -15.1 (-25.1, -5.7)) showed comparable reductions in pain and PGA relative to MTX. Efficacy of anakinra + MTX was much smaller as compared to other biologics. The greatest improvements in HAQ-DI relative to MTX were observed with aTNF + MTX (-0.30 (-0.37, -0.22)) and tocilizumab + MTX (-0.27 (-0.42, -0.12)), followed by abatacept + MTX (-0.21 (-0.37, -0.05)) and anakinra + MTX (-0.11 (-0.26, 0.05)). The improvements in SF36-PCS with abatacept + MTX, aTNF + MTX and tocilizumab + MTX were comparable. There is a >90% probability that aTNF + MTX results in a greater improvement in pain (-12.4), PGA (-16.1) and HAQ-DI (-0.21) than aTNF as monotherapy. Efficacy of tocilizumab + MTX showed comparable improvements in PROs as tocilizumab monotherapy. Conclusions Based on a network meta-analysis involving indirect comparison of trial findings, the following observations were made for DMARD-IR patients. In monotherapy, tocilizumab was associated with a greater improvement in pain and self-reported disease activity than aTNF, and was at least as efficacious regarding functional ability. The improvements in PROs with aTNF, abatacept and tocilizumab in combination with MTX were comparable. Improvements in PROs with tocilizumab as monotherapy were similar to that of tocilizumab + MTX, whereas aTNF as monotherapy was likely to be less efficacious than aTNF + MTX.
    Full-text · Article · Jul 2014 · Health and Quality of Life Outcomes
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    ABSTRACT: Structural validity for the Health Assessment Questionnaire-Disability Index (HAQ-DI) has recently been provided for patients with rheumatoid arthritis (RA). The goal of the current study was to examine the structural validity of the HAQ-DI in patients with systemic sclerosis (SSc, scleroderma) and to compare its performance with that in patients with RA. The HAQ-DI structural validity was first assessed in a sample of 100 scleroderma patients using confirmatory factor analysis. Second, the similarity of factor structures between SSc patients (n = 291) and RA patients (n = 278) was tested using a multigroup structural validity model to assure that comparison of scores between these two diagnostic groups is appropriate. Results yielded a single-factor HAQ-DI score which favored the current scoring system of the HAQ-DI (model fit was CFI = 0.99 and RMSEA = 0.04). Moreover, even the most stringent model of multigroup structural validity affirmed the similarity between SSc and RA patients on the HAQ-DI (model fit was CFI = 0.99 and RMSEA = 0.04) nor was it different from a model without any demands on group similarity: CFI difference = 0.007; chi(2) = 4.29, df = 26, p=0.99. The current results indicate that a single-factor HAQ-DI is appropriate for future clinical trials in scleroderma and, in addition, HAQ-DI scores among patients with SSc and early RA can be compared legitimately with one another.
    No preview · Article · Nov 2006 · Quality of Life Research
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    ABSTRACT: Rheumatoid arthritis (RA) patients who have inadequate response to anti-tumour necrosis factor (TNF) therapy currently have treatment options that are limited and less than optimal in their risk-to-benefit ratio. Abatacept provides a new generation of RA medications that has previously been demonstrated to have positive clinical outcomes with this population. The current study sought to demonstrate the efficacy of abatacept on quality of life (QoL) for RA patients with inadequate response to anti-TNF therapy. Patients were entered into a double-blind, placebo-controlled, multicentre randomized clinical trial, with 258 patients randomized to abatacept + disease-modifying anti-rheumatic drugs (DMARDs) and 133 patients randomized to placebo + DMARDS. The QoL was measured with the Short Form Health Survey (SF-36), Health Assessment Questionnaire (HAQ) and fatigue visual analogue scale, and was analysed with basic (ANOVA, chi-square) and multigroup growth curve techniques to assess differential change over time. Treatment group QoL improved significantly more than placebo on the HAQ and fatigue indices, as well as seven of the eight SF-36 scales and SF-36 physical and mental summary scores. Improvement rate was faster for abatacept than for placebo on the QoL measures, and the improvements from abatacept related to normal levels of QoL on many domains. Clinically relevant benefits of abatacept over placebo are discussed regarding improving QoL. Importantly, the larger rate of change for abatacept over placebo provides clinicians with a medication that can lead to meaningful changes in a patient's life within a few weeks, even when the patient previously failed anti-TNF therapy.
    Full-text · Article · Nov 2006 · Rheumatology
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