Dizziness is the second most common complaints in the daily clinical practice, with an estimated lifetime prevalence between 20%–30%.1,2 The feeling, however, is quite subjective and possibly originated from numerous disorders including vestibular, cardiovascular, neurologic, metabolic, and psychiatric diseases.3,4 Therefore, physicians often face some difficulty in diagnosing the cause of dizziness.5 Approximately three out of four patients complaining of dizziness get the correct diagnosis based only on their historical data.4,6 History taking plays a crucial part in evaluating patients with dizziness.4,6–12 Nevertheless, it is a difficult task. The meaning of the word “dizziness” itself is ambiguous and covers various sensations such as vertigo, faint, woozy, weak, or unsteady. Many patients have tendency to be uncertain and unreliable13 when describing their symptoms, and their complaints usually involve anxiety.9 Therefore, to make a differential diagnosis based on their description of symptoms is quite troublesome in primary care settings.6 In consequence, patients with dizziness occasionally receive either insufficient or inappropriate diagnosis and treatment.14 According to our literature review, some investigators attempted to create the questionnaire based on patients’ symptoms as a differential diagnosis tool. The predictive power ranged from 60% to 84% in those studies.6,8,12,15,16 However, prior studies were formulate with the numbers of self-administration questions (between 4–163 items) and available only in English language.6,8,12,16,17 Differences in language may affect the understanding and responses of patients. Furthermore, there has never been a general available report or publication about using an algorithm of a structured questionnaire.

Therefore, we aimed to create an interview questionnaire, using an algorithm approach to suggest the possible diagnosis of common vestibular disorders in Thai outpatients, and then evaluate its reliability and validity.

This study was conducted in two tertiary care settings from June 2018 to October 2019. The study protocol was reviewed and approved by the Khon Kaen University Ethics Committee for Human Research (HE601466) and the Committee for Research, Faculty of Medicine Ramathibodi Hospital, Mahidol University (MURA2017/915). All participants were given an explanation of purpose and procedure of the study and gave their written informed consent. Two phases were involved in this study: first, the development of the structural algorithm questionnaire version 1 (SAQ-1); second, the test-retest reliability and diagnostic accuracy of the SAQ-1 were investigated in patients with dizziness (Fig. 1).

Figure 1.

Flowchart represent the process of the study. 1Assessed in outpatients who diagnosed with common causes of dizziness. 2Assessed in outpatients with new dizziness complaints.

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History taking is the first and important step to evaluate those patients with dizziness complaints. Traditionally, the quality of symptoms such as dizziness, vertigo, or lightheaded was mainly in focus.28 This approach, however, was not practical as these symptoms are not specific and may arise from either vestibular or non-vestibular conditions. Then, the timing-trigger approach was proposed and become widely popular. This approach has an advantage over the traditional approach because patients could explain the characteristics of their symptoms more clearly and accurately.29–31 The algorithmic sequence of the SAQ-1 was also based on the timing-trigger approach.32–34 As the history taking is an essential part for diagnostic process, the SAQ-1 aims to help the history taking process to be more systematic, less time consuming, and to attain to a hypothetical diagnosis in the first visit. Several questionnaires have been developed over the years.6,8,15–17,19 The number of questions ranged from 4 to 163. All previous questionnaires were completed by the patients themselves.6,8,15–17,19 They would read the questions individually, choosing the answer that would best fit their problem. The SAQ-1, however, consists of scripted interview questions. The interviewer reads each question to them, and they only have 2 choices of answer: yes or no. Therefore, if they do not clearly understand any questions, they can ask for further explanation. A supplementary explanation will be then, read to them. The time taken for an interview lasts no longer than 15 min. Depending upon the algorithm, some will reach the diagnosis after 3 questions while some would need 10.

The clinical accuracy of the SAQ-1 was satisfying. The percentage of agreement between the hypothetical diagnosis from the questionnaire and medical diagnosis from otoneurologists was relatively substantial. However, there were 10% of participants who did not reach their final diagnosis or had inconclusive diagnosis. According to results of the SAQ-1, the possible diagnosis of five subjects were peripheral vestibulopathy such as Meniere’s disease or recurrent vestibulopathy, six subjects were vestibular migraine, and two subjects were non-vestibular causes such as PPPD. The ability of the SAQ-1 to detect the vestibular group is quite great. The ability to differentiate within the vestibular group, however, still needs some improvement. The reason for this fact is that some vestibular disorders have very similar symptoms and somewhat fluctuating.35 Vestibular migraine and MD occurs both in episodic attacks, with some overlapping symptoms. As far as we concern, the SAQ-1 adequately serves the purpose of being a screening questionnaire. To obtain the final diagnosis, vestibular function tests is still necessary.

Although the study has reached its aim, some inevitable limitations should be noted. First, the sample size was smaller than what we expected. This is partially due to the approximately 20% drop out and time limit. It is common that patients with dizziness do not come back for follow up when the symptoms are solved. Second, the SAQ-1 renders only single diagnosis. In reality, many patients with dizziness likely experience multifactor conditions. The patients will report only their dominant symptoms.

In summary, the SAQ-1 has a well-developed design and acceptable quality on both validity and reliability. It helps physicians differentiate the cause of dizziness between vestibular and non-vestibular disorders, especially of outpatients with non-acute, chronic, or recurrent vestibular symptoms. Further study should be conducted to test the performance of this instrument in different clinical settings, especially in primary care settings.

This work was supported by the Research Center on the Back, Neck, Other Joint Pain and Human Performance (BNOJPH), Faculty of Associated Medical Sciences, Khon Kaen University.

The authors declare no conflicts of interest.