Objective: To compare statistical properties of data from the Health Assessment Questionnaire (HAQ) with those from an alternative version (AHAQ) that used a different scoring system for the item categories and disability index. Comparisons included descriptive statistics, correlations, and inferential statistics to determine whether the AHAQ would be a more sensitive measure of change in functional status.
Methods: The subjects were 107 adults diagnosed with rheumatoid arthritis and hospitalized for exacerbations in their arthritis or arthritis related joint surgery. Disability was assessed upon admission to hospital and at one year followup with the HAQ. AHAQ scores were generated for the item categories making up the disability index by taking the mean of the item scores in a category instead of the worst item score; the disability index was the mean of the alternative category scores.
Results: The standard method of scoring the HAQ was found to generate greater variance on category scores, lower correlations between category scores and the total disability index, and lower correlations between first and 2nd administrations of the instrument, compared to the AHAQ. HAQ disability index scores also correlated slightly lower than those of AHAQ to scores from the HAQ pain scales, and to scores from 2 other measures of functional disability. In addition, the AHAQ was found to be more powerful in detecting functional changes at one year followup.
Conclusion: Because of its statistical properties the AHAQ scoring method may be preferable to the HAQ method when the instrument is used for documenting change in functional outcomes.