International Hip Outcome Tool (iHOT)
The International Hip Outcome Tool (iHOT) was developed by Mohtadi et al as a means of assessing a patient’s ability to return to an active lifestyle through obtaining subjective measures of symptoms, as well as determining emotional and social health status. Mohtadi et al noted that most of the existing hip pathology questionnaires were for patients with either a hip fracture or for those undergoing a total hip arthroplasty. As such, these outcome measures often suffer from a ceiling effect, and therefore their usefulness is limited when applying it to a younger active population.
The iHOT was developed for younger active patients age 18-60 years presenting with a variety of hip pathologies. “Active” is defined as an activity level ≥4 on a modified Tegner Activity Scale, with “hip pathology” being defined as abnormal hip functioning leading to pain, stiffness, instability, or physical impairment due to improper joint biomechanics. This iHOT was intended for those presenting with hip pain as the result of bony pathology (e.g. avascular necrosis or osteochondral fracture), cartilaginous damage in the form of chondral lesions and arthritis, ligamentous injury, labral or joint capsule tearing, inflammation in the hip joint and surrounding structures, loose bodies, or abnormal anatomy leading to dysplasia, impingement, or instability. This outcome measure was not intended for patients with muscular strains or referred pain from the back or knee.
Method of Use
The iHOT is comprised of 33 questions relating to:
- Symptoms and Functional Limitations
- Sports and Recreational Activities
- Job-Related Concerns
- Social, Emotional, and Lifestyle Concerns
Patients are asked to place a mark on a Visual Analog Scale (VAS) line for each question, with “significantly impaired” on the far left and “no problems at all” on the far right (see Figure 1 below).
Figure 1. Example of VAS scoring for an iHOT-33 question.
The answers provided should reflect the typical situation felt within the past month. The total score is then calculated as the mean of all VAS scores as measured in millimetres.
The intra-class correlation statistic for the iHOT-33 is 0.78 with Cronbach’s alpha being 0.99. Face and content validity were ensured during development and construct validity was demonstrated with a correlation of 0.81 to the Non-Arthritic Hip Score. Responsiveness was demonstrated with a paired t-test (p ≤ 0.01), effect size of 2.0, standardized response mean of 1.7, responsiveness ratio of 6.7. The minimal clinically important difference (MCID) was determined to be 6 points.
Additional Optional Modules
Griffin et al later developed the shorter iHOT-12 outcome measure after the iHOT-33, finding it to be in excellent agreement with the longer version. These authors found that it captured 95.9% (95% CI: 95.0-96.8%) of the variation of the iHOT-33, and showed equivalent sensitivity to change with a standardized effect size of 0.98 (0.67 to 1.28). Due to its brevity, Griffin et al state the iHOT-12 as being more appropriate for use in the clinical setting for initial assessments and post-operative follow-up. Unfortunately, these authors did not state an MCID value for this version of the iHOT.
- The full research article and questionnaire by Mohtadi et al for the iHOT-33 can be found here: http://tinyurl.com/l54vabe
- The full research article and questionnaire by Griffin et al for the iHOT-12 can be found here: http://tinyurl.com/lprlgrn
- Mohtadi NG, Griffin DR, Pedersen ME, Chan D, Safran MR, Parsons N, Sekiya JK, Kelly BT, Werle JR, Leunig M, McCarthy JC, Martin HD, Byrd JW, Philippon MJ, Martin RL, Guanche CA, Clohisy JC, Sampson TG, Kocher MS, Larson CM. The development and validation of a self-administered quality-of-life outcome measure for young, active patients with symptomatic hip disease: The International Hip Outcome Tool (iHOT-33). Arthroscopy. 2012. 28(5): 595-610.
- Griffin DR, Parsons N, Mohtadi NG, Safran MR. A short version of the International Hip Outcome Tool (iHOT-12) for use in routine clinical practice. Arthroscopy. 2012, 28(5):611-6.
- Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop Relat Res 1985; 198: 43-9.