Reliability and validity of a questionnaire for diagnosis of clinical gastric related vertigo: A Traditional Persian Medicine perspective and prevalence assessment

Background: Chronic vertigo is a frustrating and expensive disease affecting individuals and society. Scientists of Traditional Persian Medicine (TPM) have a long held belief that there is a common type of vertigo originated from the stomach known as gastric related vertigo (GRV) and there are present, simple and low-cost treatments for GRV based on its categorization. Objective: To develop a valid tool for assessing GRV and determining the prevalence of this type of vertigo. Methods: In this cross-sectional study, a questionnaire was designed based on GRV indices. To determine the intra-rater reliability, a testretest method was used and kappa coefficient was measured by Statistical Package for the Social Sciences software (SPSS, version 17). Content validity ratio (CVR) and content validity index (CVI) for each question were calculated by using Lawshe table. The reliable version of the questionnaire was assessed in a sample of 135 patients with a chronic true vertigo which lasts more than three months and aged between 18 and 65 years. This study was conducted in the outpatient clinics of several university hospitals in Tehran, Iran, between May 2016 and November 2017. Results: A valid 30-item questionnaire with CVR more than 0.62, CVI more than 0.78 and kappa coefficient more than 0.7 was the main achievement of this study, which can be useful for assessment of GRV in future clinical trials. The study showed that 98 participants (72.59%) had at least one criterion of GRV. Conclusion: According to the high prevalence of GRV among patients who suffer from chronic vertigo, more studies in this field including clinical trial are suggested.