The diagnostic accuracy of history taking and physical examination for patients with vertigo in general practice: the VERDI study

BACKGROUND Vertigo is a common symptom that increases with age. The impact for patients is enormous: four out of five patients with vertigo report severely impairing symptoms, leading to sick leave, medical consultation, interruption of daily activities, and/or avoidance of leaving the house. In older patients, vertigo is associated with anxiety, depression, social isolation, and falling. The economic burden is substantial, due to repeated consultations, excessive use of diagnostic imaging, emergency care, and decreased productivity. More than 80% of the patients with vertigo are primarily treated by their general practitioner (GP) and never referred to a medical specialist. Despite this therapeutic responsibility, the GP’s diagnostic toolkit has serious limitations. All recommended tests lack empirical evidence, because a diagnostic accuracy study on vestibular disease has never been performed in primary care. This scientific gap was identified and highly prioritized by the National General Practice Research Agenda (4.5.6 NERVOUS SYSTEM, ICPC N; priority 3/10; ID 549/554). With the VERtigo DIagnosis study (VERDI, a famous Italian composer who experienced frequent episodes of dizziness and died of stroke) we will fill this gap. We will construct a diagnostic algorithm that enables GPs to identify more accurately and efficiently underlying causes in patients with vertigo. This may lead to faster and more targeted treatment, less diagnostic imaging and referral, less prescribing of antivertigo drugs, and improvement of the overall outcome for patients with vertigo in general practice. MAIN OBJECTIVE To investigate the diagnostic accuracy of history taking and physical examination for patients with vertigo in general practice, in order to construct an easy-to-use diagnostic algorithm for daily clinical practice. KEY OBJECTIVES I. To assess the existing evidence on the accuracy of tests for diagnosing causes of vertigo in general practice; II. To determine which tests should be investigated in a diagnostic accuracy study for patients with vertigo in general practice; III. To investigate the diagnostic accuracy of selected tests for patients with vertigo in general practice; IV. To construct an easy-to-use diagnostic algorithm for vertigo in general practice; V. To compare the diagnostic accuracy of GP judgement with the constructed diagnostic algorithm. METHODS First, we will perform a SYSTEMATIC REVIEW (I) to assess the empirical evidence on diagnostic tests for patients with vertigo in general practice. The most promising tests will be studied during an international DELPHI PROCEDURE (II) to determine which tests should be investigated in a DIAGNOSTIC ACCURACY STUDY (III). During this study, we will compare each index test with its respective reference standard. We will focus on five target conditions that account for more than 95% of the vertigo diagnoses in general practice: 1. benign paroxysmal positional vertigo (BPPV), 2. vestibular neuritis, 3. Meniere’s disease, 4. vestibular migraine, and 5. central causes of vertigo. As these five target conditions have a different pathophysiology and all lack a generally accepted reference standard, we will use consensus diagnosis as reference standard. Data for each patient, including history, physical examination, and additional tests as recommended by international guidelines, will be recorded on a standardized form and independently reviewed by a neurologist and otorhinolaryngologist. For each patient, the reviewers have to decide about the presence/absence of each target condition. We will calculate sensitivity, specificity, predictive values, and likelihood ratios, followed by decision rules for each target condition. Subsequently, we will conduct semi-structured interviews among patients and GPs to investigate barriers and facilitators for successful implementation of the decision rules. The results of the interviews will be used to construct a final overarching DIAGNOSTIC ALGORITHM (IV). As clinical decision rules may have limited effect on physicians, we will perform a COMPARISON STUDY (V) to compare the accuracy of GP judgement with the constructed diagnostic algorithm. COLLABORATION Our unique consortium brings together national and international key players in the field of vertigo in general practice (dr. Maarsingh and dr. van Vugt), effective diagnostics in general practice (prof. dr. Cals), vertigo in secondary/tertiary care (prof. dr. Bronstein, prof. dr. Bruintjes, dr. van Leeuwen), biostatistics (dr. Lissenberg-Witte), and the patient’s perspective (drs. Rutgers, patient organisation Stichting Hoormij-NVVS). DELIVERABLES A. Clinical tools: 1. Easy-to-use diagnostic algorithm for GPs; 2. Video tutorials for GPs (www.nhg.org.nl); 3. Audio-visual information for patients (www.thuisarts.nl). B. PhD thesis, including at least six international peer-reviewed publications. C. Addendum to the Dutch Guideline on Dizziness.