Validation of the hip disability osteoarthritis outcome Score-12 shortform in a German cohort.

Introduction: To consider the inherent respondent burden of PROMs, the HOOS-12 as a shortform of the well-established HOOS questionnaire has been published. While the HOOS-12 has been validated in an initial study, further evaluation in other, non-English speaking cohorts is necessary. We therefore aimed to evaluate responsiveness, convergent construct validity, internal consistency, and floor and ceiling effects of the HOOS-12 in a cross-sectoral german cohort.

Materials and methods: European Quality of Life 5 Dimensions scores and HOOS data of patients undergoing total hip arthroplasty (THA) were used for the analyses. HOOS-12 scores were calculated from the full length HOOS. Statistical analysis was conducted, investigating internal consistency, floor and ceiling effects, convergent and discriminant validity, responsiveness, and known-group comparisons.

Results: A ceiling effect was present for postoperative HOOS-12 score and its pain, function and QoL subscales. Internal consistency was high between baseline and all follow ups, inter-item correlation was high (Cronbach's alpha > 0.30) for HOOS-12 score and all subscales. Correlation of HOOS-12 pain with HOOS pain was high (r = 0.9). Correlation of HOOS-12 function with HOOS ADL and HOOS S/R was high (r = 0.89, r = 0.74). Correlation was moderate between HOOS-12 pain and HOOS-12 function with its respective EQ-5D score (r=-0.58, r=-0.59).

Conclusion: The HOOS-12 showed good convergent construct validity and is responsive to changes in pain, function, QoL and hip impact between preoperatively and 1 year postoperatively. A substantial ceiling effect for all subscales at 1 year postoperatively limits the ability to capture variance across particularly well performing patients.

Trial registration: The Trial is registered with the German Clinical Trials Register ( https://www.drks.de ; DRKS00013972; 23 March 23, 2018).