Evaluating the Diagnostic Accuracy of the Head-Impulse Test
A Scoping Review
Leif Erik Walther, MD, PhD1; Jan Löhler, MD, PhD2; Yuri Agrawal, MD, MPH3; et al Edith Motschall4; Fabian Schubach,  MD3; Jörg J. Meerpohl, MD5; Christine Schmucker,  MD5
Author Affiliations Article Information
1Department of Otorhinolaryngology–Head and Neck Surgery, University Medicine Mannheim, University of Heidelberg, Mannheim, Germany
2Department of Otorhinolaryngology–Head and Neck Surgery, University Hospital of Schleswig-Holstein, Lübeck, Germany
3Department of Otolaryngology–Head and Neck Surgery, School of Medicine, Johns Hopkins University, Baltimore, Maryland
4Institute of Medical Biometry and Statistics, Faculty of Medicine and Medical Center–University of Freiburg, Freiburg, Germany
5Institute for Evidence in Medicine (for Cochrane Germany Foundation), Medical Center–University of Freiburg, Freiburg, Germany
JAMA Otolaryngol Head Neck Surg. 2019;145(6):550-560. doi:10.1001/jamaoto.2019.0243
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Comment
Key Points
Question  Is the increasingly used head-impulse test (HIT) a reliable method to diagnose the underlying causes of vestibular symptoms?

Findings  This scoping review of 27 diagnostic studies reveals uncertainties in clinical practice regarding the diagnostic accuracy (sensitivity and specificity) of different HIT methods compared with other vestibular tests or a clinical diagnosis.

Meaning  Based on the currently available diagnostic studies, the risk of misdiagnosis and associated undertreatment or overtreatment cannot be reliably estimated by HIT methods in patients presenting with vestibular symptoms.

Abstract
Importance  Vestibular symptoms rank among the most common complaints in medicine worldwide. Underlying disorders manifested by these symptoms are generally associated with an impairment of the vestibular-ocular reflex and can be assessed with different diagnostic procedures. In recent years, an increasing number of diagnostic test accuracy studies comparing various head-impulse test (HIT) methods with other diagnostic procedures have been published but not systematically reviewed.

Objective  To conduct a scoping review and describe key characteristics of the growing number of diagnostic studies in patients presenting with vestibular symptoms.

Evidence Review  In April 2017, published studies were identified through searches of 4 bibliographic databases: Medline, Science Citation Index Expanded, the Cochrane Library, and ScienceDirect. Studies were included if they provided diagnostic accuracy data (sensitivity and specificity) for any HIT method with reference to any other vestibular test or clinical diagnosis in patients with vestibular symptoms. Study key characteristics were extracted, and the current literature was described narratively. All analysis took place between June 2017 and July 2018.

Findings  We identified a total of 27 diagnostic studies (including 3821 participants). There were disagreements between diagnostic test accuracy data both within and between studies when different HIT methods were compared with other diagnostic procedures. The proportion of correctly identified people having the disease (sensitivity) ranged between 0% and 100% (median, 41%), whereas the proportion of correctly identified people without the disease (specificity) was higher and ranged between 56% and 100% (median, 94%).

Conclusions and Relevance  Based on the studies included in this review, sensitivity, specificity, and, more importantly, the risk of misdiagnosis and associated undertreatment or overtreatment cannot be reliably estimated by HIT methods for patients with vestibular symptoms. We recommend that further diagnostic studies consider (1) multiple possible underlying causes of vestibular symptoms and multiple test thresholds, (2) a representative sample of patients with and without the disease, and (3) reporting guidelines for diagnostic test accuracy studies.