Psychometric evaluation of a Korean Health Assessment Questionnaire for clinical research

The Health Assessment Questionnaire (HAQ) is a widely used, easily administered functional scale that has high reliability and validity. Although translated versions of HAQ are available, no Korean version exists. Our aim was to translate and confirm the reliability and validity of a Korean language version of the HAQ.

HAQ was translated into Korean by 3 translators and translated back into English by 3 different translators. Four questions were modified for the Korean culture. Fifty-six consecutive patients with RA were asked to rate the comprehensibility of the questions on a 4 point scale. The comprehensibility (responding with "3 or above") ranged from 76 to 98%. Another 60 consecutive patients with RA were studied for the psychometric properties of the Korean version.

The test-retest reliability of the Korean HAQ (KHAQ) yielded an intraclass correlation coefficient of 0.99. The Cronbach standardized alpha was 0.95 among 20 items. For construct validity, the correlation of KHAQ scores with disease severity [tender joint count, swollen joint count, patient's self-assessment of pain, erythrocyte sedimentation rate (ESR), Ritchie Index] was high and statistically significant, except for ESR. The 4 revised items were appropriate expressions of physical function since the correlations between each of the revised items and the first principal component are similar in magnitude to those between the 16 unchanged items and the principal component.

The reliability and validity of the KHAQ is confirmed. The evaluation of responsiveness of the KHAQ is in progress.