Defining the Minimal Clinically Important Difference (MCID), Patient Acceptable Symptom State (PASS), and Maximal Outcome Improvement (MOI) values for individuals with acetabular dysplasia (AD) undergoing non-operative management
Ashley E. Disantis, Tom Ellis, Robert Kollmorgen, Connor Luck, Michael McClincy, Zain Shkoukani, David Young, RobRoy MartinBackground
The International Hip Outcome Tool 12 (iHOT-12) is commonly utilized to track outcomes in individuals with acetabular dysplasia (AD). Clinically important outcome values (CIOVs) of the iHOT-12 in individuals with AD are not yet defined.
Purpose
To define the minimal clinically important difference (MCID), patient acceptable symptom state (PASS) change score, absolute PASS threshold, and maximal outcome improvement (MOI) value for the iHOT-12 in individuals undergoing physiotherapy (PT) for AD.
Study Design
Prospective cohort; psychometric property analysis
Methods
This prospective study included individuals aged 10-35 years with a clinical and radiographic diagnosis of AD who were referred for conservative management at two centers between December 2023 and February 2025. At baseline assessment and after 8-10 weeks of PT, individuals completed the iHOT-12. At 8–10-week follow-up, individuals also completed three anchor questions on satisfaction and function. The MCID was calculated utilizing 0.5 times the standard deviation of baseline iHOT-12 scores. Receiver operator curve analysis was utilized to determine the PASS change score, absolute PASS threshold, and MOI value.
Results
Forty-five patients (42 females, mean age 16.5 + 7.8) met the inclusion criteria. After 8-10 weeks of PT (mean follow-up time = 69 days), 25 (55.6%) participants were in the “improved” group and 20 (44.4%) were in the “not improved” group. The MCID was 8.5 points. A PASS change score of 15.2 was calculated for individuals who were satisfied with high sensitivity (.77) and specificity (.78) with an AUC = .76 (95% CI: .59-.93). An absolute PASS iHOT-12 threshold score of 62 (sensitivity = .62, specificity = .87) identified those who were satisfied with their hip function after a trial of PT with an AUC = .82 (95% CI: .67-.97). An MOI threshold of 22.9% was also calculated with high sensitivity (.69) and specificity (.88) with an AUC = .78 (95% CI: .61-.95).
Conclusion
This study defines MCID, PASS change score, absolute PASS threshold, and MOI threshold for the iHOT-12 in patients with AD after 8-10 weeks of PT. While most individuals reported improvement in symptoms, only half of individuals were satisfied with their current level of function.
Level of Evidence
Level 2