Measurement Characteristics and Clinical Utility of the ABILHAND Among People With Rheumatoid Arthritis

Evaluating functional disability in people with rheumatoid arthritis is important in evaluating disease progression and therapy effectiveness.¹ The ABILHAND questionnaire measures the patient’s perceived difficulty in performing everyday unimanual and bimanual activities. Durez et al¹ used ABILHAND to examine self-perceived functional limitation in 112 people with rheumatoid arthritis; the study evaluated content validity with Rasch Measurement Theory. The statistical analysis with the Rasch Measurement Theory led to a selection of 27 items rated on a 3-point scale (0=impossible; 1=any difficulty; 2=easy), that fitted the Rasch measurement model. The items ranged from -2.18 to 2.65 “logits,” with higher logits indicating more difficult activities. The item-difficulty hierarchy was stable across demographic and clinical subgroups and over time. Only items about tasks that might require moderate physical strength (eg, screwing on a nut, hammering a nail, and handling a stapler) were more difficult for women than for men.¹ ABILHAND has excellent internal consistency (person item separation=0.96)² and adequate to excellent test-retest reliability (ICC 0.74-0.86).^{1.,  3.} The minimal clinically important difference was 0.47 logits for a small change, 1.18 logits for moderate change, and 1.89 logits for large change.³ Questionnaire completion takes 5-10 minutes. The website at http://www.rehab-scales.org/abilhand-rasch-analysis-rheumatoid-arthritis.html provides a free online scoring sheet, a conversion of the total score into a logit score, and a Rasch-converted percentage for each patient. ABILHAND has fair to moderate correlations with grip strength, pinch strength, and digital dexterity, ranging from r=0.42-0.56; and excellent convergent validity with the health assessment portion of the ABILHAND questionnaire (P=0.78).¹