Autonomic dysfunction in patients with orthostatic dizziness: validation of orthostatic grading scale and comparison of Valsalva maneuver and head-up tilt testing results.

Objectives: To investigate whether the Korean version of the Orthostatic Grading Scale (KOGS) is a reliable and valid measure for evaluating the severity of symptoms of orthostatic intolerance (OI) and to compare the diagnostic accuracy of Valsalva maneuver (VM) and head-up tilt test (HUTT) in identifying sympathetic adrenergic failure (SF).

Methods: A back-translation approach was used to develop the KOGS. One hundred seventy two patients with orthostatic dizziness (OD) as a presenting symptom of OI and 133 healthy controls were enrolled. All patients completed the 5-item, self-report KOGS and 58% (100/172) of patients were randomly selected for a retest with the questionnaire. The degree of the severity of autonomic dysfunction was measured by the composite autonomic severity score (CASS).

Results: The incidence of orthostatic hypotension (OH) in HUTT was 21%. The KOGS scores in patients showed good internal consistency (Cronbach's α=0.90) and test-retest reliability (correlation coefficient=0.77 to 0.89). The total and each item scores of KOGS correlated with the degree of the severity of autonomic dysfunction estimated as CASSs in patients. Approximately 70% (116/172) of patients showed at least one abnormality in either HUTT or VM. The incidence (43%) of an abnormal BP response in VM was two times higher than the incidence of OH in HUTT.

Discussion: The KOGS is a reliable and valid tool for screening patients with OD. VM is superior to HUTT in detecting SF. Thus, VM and HUTT should be combined to evaluate adrenergic sympathetic function in patients with OD.