{Reference Type}: Journal Article
{Title}: Validation of symptom measures in patients under investigation for postural orthostatic tachycardia syndrome (POTS): The Orthostatic Grading Scale (OGS) and the Symptom Screen for Small-fiber Polyneuropathy (SSS).
{Author}: Knoop I;Jones ASK;Gall N;Chilcot J;Pascoe W;Moss-Morris R;
{Journal}: Auton Neurosci
{Volume}: 250
{Issue}: 0
{Year}: 2023 12
{Factor}: 2.355
{DOI}: 10.1016/j.autneu.2023.103130
{Abstract}: Postural Orthostatic Tachycardia Syndrome (POTS) presents with a range of poorly delineated symptoms across several domains. There is an urgent need for standardized symptom reporting in POTS, but a lack of validated symptom burden instruments. Our aim was to evaluate the psychometric properties of two symptom burden measures: the Orthostatic Grading Scale (OGS) and the Symptom Screen for Small-Fiber Polyneuropathy (SSS), in patients under investigation for suspected POTS.<BR>Psychometric validation study.<BR>Confirmatory factor analysis (CFA) tested the factor structure of the SSS and OGS completed by 149 patients under investigation for POTS. Scale reliability and validity were assessed. The uni-dimensionality of the SSS was assessed through principal component analysis (PCA).<BR>CFA of the OGS revealed that a 1-factor structure had adequate fit. CFA of the SSS revealed that a 5-factor structure had generally appropriate fit supporting the originally proposed 5 factors (1: Gastrointestinal, 2: Somatosensory, 3: Miscellaneous, 4: Microvascular, and 5: Urological). In addition, the SSS demonstrated sufficient uni-dimensionality in the PCA, warranting use of a single total score. Omega coefficients of both measures indicated satisfactory internal reliability (0.668-0.931). Correlations with related constructs (distress (K10 score), r = 0.317-0.404, p < 0.001) and heart rate indices (with the OGS, r = 0.211-0.294, p < 0.05) suggested sound convergent and divergent validity.<BR>Initial evidence suggests that the OGS and SSS have good psychometric properties for use in populations with suspected and confirmed POTS.