POS0182 MINIMAL CLINICALLY IMPORTANT IMPROVEMENT (MCII) AND PATIENT ACCEPTABLE SYMPTOM STATE (PASS) FOR PAIN AND FUNCTION INSTRUMENTS IN HAND OSTEOARTHRITIS (OA)
Authors: F. Kroon, L. Van de Stadt, D. Van der Heijde, M. Kloppenburg
Journal: Annals of the Rheumatic Diseases (2021)

Background: Australian/Canadian Hand OA Index (AUSCAN), Michigan Hand Outcomes Questionnaire (MHQ), Functional Index of Hand OA (FIHOA) and visual analogue scale (VAS) are frequently used instruments to measure pain and function in hand OA research. MCII and PASS are useful to interpret results of patient reported outcomes. Objectives: To estimate MCII and PASS for these instruments using anchor-based methods. Methods: Hand OA patients participating in a six-week randomised placebo-controlled trial with prednisolone (RCT; NTR5263) and those attending the two-year follow-up visit of the observational Hand OSTeoArthritiS cohort completed AUSCAN subscales pain and function, MHQ subscales pain, activities of daily living (ADL) and overall function, FIHOA and 100mm VAS pain. RCT participants were asked to indicate whether they changed compared to baseline (improved/no change/worse) and to rate the importance of improvement (very much/moderately/slightly/not at all). MCII was defined as the minimal improvement in symptoms achieved by 75% of participants who stated a slight/moderate improvement during the RCT, calculated as the 75th percentile of the distribution of change scores from baseline in this group. Absolute and relative percentage change were evaluated. For MCII direction of effect was unified, so positive values indicate worse symptoms and vice versa. Participants from both studies rated satisfaction with their state of health (acceptable/unacceptable). PASS was defined as the minimal score considered acceptable for 75% of participants, calculated as the 75th percentile of the distribution of scores in participants who rated their health ‘acceptable’. Results: Demographics of the RCT (n=92, mean age 63.9, 79% women) and cohort (n=383, 60.9 years, 84% women) participants were typical for hand OA. RCT participants were more symptomatic (e.g. mean [SD] VAS pain 54.0 [20.5] versus 35.2 [19.1]). Of the function instruments, only AUSCAN had a credible MCII (relative percentage improvement 9.8%), while the (positive) MCII values for FIHOA and MHQ subscales would indicate that worsening was rated as functional improvement (table 1). MCII was negative (corresponding to improvement) for all pain instruments, with relative percentage change around 25% for VAS and MHQ, compared to only 2% for AUSCAN. PASS values of all instruments were comparable in the two populations. Most instruments had a PASS around 50% of the possible maximum score, except for MHQ ADL, in which higher is better and a relatively high PASS is thus indicative of a floor effect (table 1). Conclusion: The only function instrument with an acceptable threshold for MCII was AUSCAN function, while for pain MHQ and VAS performed better than AUSCAN. PASS values show a relatively high level of tolerance of 50% of the maximum of the scale. Table 1. MCII and PASS of pain and function instruments in hand OA patients in two settings. MCII (95% CI) in RCT† PASS (95% CI) Instrument Absolute units Percentage [n] RCT (n=68) Cohort (n=126) MHQ Overall function, 0-100* 3.4 (-2.7;9.5) 3.6 (-9.1;16.3) [23] 55.6 (52.6;58.5) 48.1 (45.7;50.4) ADL, 0-100* 1.6 (-4.4;7.6) 2.8 (-9.6;15.3) [23] 71.7 (68.2;75.1) 62.9 (59.8;66.0) Pain, 0-100 -12.2 (-17.2;-7.1) -23.1 (-35.4;-10.8) [16] 47.0 (40.5;53.5) 55.7 (52.0;59.5) AUSCAN Function, 0-36 -3.3 (-5.7;-0.9) -9.8 (-23.9;4.2) [23] 17.1 (15.3;19.0) 20.9 (19.4;22.3) Pain, 0-20 -1.1 (-2.6;0.4) -1.8 (-18.5;14.9) [27] 9.0 (8.2;9.9) 11.1 (10.3;11.8) FIHOA, 0-30 0.1 (-1.6;1.7) 22.7 (-0.7;46.0) [23] 12.4 (11.1;13.7) 13.9 (12.8;15.0) VAS pain, 0-100 -11.5 (-18.2;-4.7) -24.4 (-36.1;-12.8) [27] 47.7 (42.2;53.3) 48.8 (44.6;53.0) Direction of effect of all instruments is higher is worse, except those with *. †For all MCII direction of effect was unified, so positive values indicate worse symptoms and negative values values indicate improved symptoms. Disclosure of Interests: Féline Kroon: None declared, Lotte van de Stadt Grant/research support from: The HOSTAS and HOPE studies were sponsored by the Dutch Arthritis Society., Désirée van der Heijde: None declared, Margreet Kloppenburg Grant/research support from: The HOSTAS and HOPE studies were sponsored by the Dutch Arthritis Society.