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)

Iris Knoop; Annie S K Jones; Nicholas Gall; Joseph Chilcot; William Pascoe; Rona Moss-Morris

doi:10.1016/j.autneu.2023.103130

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)

Auton Neurosci. 2023 Dec:250:103130. doi: 10.1016/j.autneu.2023.103130. Epub 2023 Nov 11.

Authors

Iris Knoop¹, Annie S K Jones¹, Nicholas Gall², Joseph Chilcot¹, William Pascoe¹, Rona Moss-Morris³

Affiliations

¹ Health Psychology Section, Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom.
² Cardiology Department, King's College Hospital, London, United Kingdom.
³ Health Psychology Section, Institute of Psychiatry, Psychology and Neuroscience, King's College London, United Kingdom. Electronic address: rona.moss-morris@kcl.ac.uk.

PMID: 37976608
DOI: 10.1016/j.autneu.2023.103130

Abstract

Objectives: 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.

Design: Psychometric validation study.

Methods: 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).

Results: 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.

Conclusions: Initial evidence suggests that the OGS and SSS have good psychometric properties for use in populations with suspected and confirmed POTS.

Keywords: Orthostatic symptoms; Postural Orthostatic Tachycardia Syndrome (POTS); Psychometric validation; Small-fiber neuropathy; Symptom burden; Symptom questionnaires.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Humans
Postural Orthostatic Tachycardia Syndrome* / diagnosis
Reproducibility of Results