Comprehensibility, reliability, validity, and responsiveness of the Thai version of the Health Assessment Questionnaire in Thai patients with rheumatoid arthritis
1 Division of Rheumatology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Road, Pathumwan, Bangkok 10330, Thailand
2 Department of Medicine, Nopparat Rajathani Hospital, 109 Ramindra Km, 12 Kunnayao, Bangkok 10230, Thailand
3 Division of Rheumatology, Department of Medicine, Srinakharinwirot University, Princess Maha Chakri Sirindhorn Medical Center, 63 Moo 7, Rangsit-Ongkharak Road, Ongkharak, Nakorn-Nayok 26120, Thailand
4 Division of Rheumatology, Department of Medicine, Faculty of Medicine, Thammasat University, Paholyotin Road, Amphur Klongluang, Pathumthani 12120, Thailand
5 Division of Rheumatology, Department of Medicine, Faculty of Medicine, Chiang Mai University, 110 Intawaroros Road, Amphur Muang, Chiang Mai 50200, Thailand
6 Division of Rheumatology, Department of Medicine, Faculty of Medicine, Prince of Songkla University, 15 Karnjanavanit Road, Hat Yai, Songkhla 90110, Thailand
Arthritis Research & Therapy 2009, 11:R129 doi:10.1186/ar2796Published: 27 August 2009
The Health Assessment Questionnaire Disability Index (HAQ-DI) is a commonly used instrument to assess functional status of patients with rheumatoid arthritis (RA). Translations and adaptations of the HAQ-DI have been carried out for use with RA patients in several countries. The objective of this study was to evaluate the psychometric properties of the Thai version of the HAQ-DI (Thai HAQ) in Thai patients with RA.
Comprehensibility of the Thai HAQ was assessed by 126 patients with RA from 6 medical centers in Thailand. Another group of 115 patients with active RA was enrolled to test the reliability (internal reliability and 1-week test-retest reliability), construct validity (correlations with other measures of RA disease activity), floor and ceiling effects, and sensitivity to change of the Thai HAQ at 3 months of treatment with disease-modifying antirheumatic drugs.
More than 98% of the patients regarded the Thai HAQ as comprehensible. The internal consistency of the Thai HAQ was satisfactory with the overall Cronbach alpha of 0.91. The test-retest reliability of the Thai HAQ was acceptable with the intraclass correlation coefficient of 0.89. Moderate correlations between the Thai HAQ and other outcomes of RA disease activity were observed, except erythrocyte sedimentation rate, with the Spearman correlation coefficients ranging from 0.42 to 0.57. The responsiveness of the Thai HAQ was moderate, with a standardized response mean of 0.75 (95% confidence interval 0.56 to 0.94).
The Thai HAQ is comprehensible, reliable, valid and sensitive to change in the evaluation of functional status of Thai patients with RA. The Thai HAQ is an essential tool to measure treatment effects and progression of disability in RA patients and should be applied in both clinical trials and routine clinical care settings.