Prevalence of orthostatic intolerance in Long Covid clinic patients: A multicentre observational study

Purpose Orthostatic intolerance (OI), including postural orthostatic tachycardia syndrome (PoTS) and orthostatic hypotension (OH), are often reported in long covid, but published studies are small with inconsistent results. We sought to estimate the prevalence of objective OI in patients attending long covid clinics and healthy volunteers and associations with symptoms and comorbidities. Methods Participants were recruited from 8 UK long covid clinics, and healthy volunteers from general population. All undertook standardised National Aeronautics and Space Administration Lean Test (NLT). Participants’ history of typical OI symptoms (e.g. dizziness, palpitations) prior to and during the NLT were recorded. Results 277 long covid patients and 50 frequency-matched healthy volunteers were tested. Healthy volunteers had no history of OI symptoms or PoTS, 10% had asymptomatic OH. 130 (47%) long covid patients had previous history of OI symptoms and 144 (52%) developed symptoms during the NLT. 41 (15%) had an abnormal NLT, 20 (7%) met criteria for PoTS and 21 (8%) had OH. Of patients with an abnormal NLT, 45% had no prior symptoms of OI. Relaxing the diagnostic thresholds for PoTS from two consecutive to one reading, resulted in 11% of long covid participants meeting criteria for PoTS, but not in healthy volunteers. Conclusion More than half of long covid patients experienced OI symptoms during NLT and more than one in ten patients met the criteria for either PoTS or OH, half of whom did not report previous typical OI symptoms. We recommend all patients attending long covid clinics are offered an NLT and appropriate management commenced. Trial registration numbers [NCT05057260][1], ISRCTN15022307 ### Competing Interest Statement All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: all authors had financial support from National Institute for Health and Care Research for the submitted work; MS has received grants through his University from UKRI, is Editor-in-Chief of Advances in Rehabilitation Science and Practice, is Editorial Board Member of Frontiers in Pain Research, is President of British Society of Physical and Rehabilitation Medicine; DCG has received grants through his University from British Heart Foundation, NHS England, and NHS National Services Scotland; TG is Independent SAGE member; there are no other relationships or activities that could appear to have influenced the submitted work; JS has received research grants from the Wellcome Trust, Public Health Scotland and, Office of the Chief Scientific Adviser Scotland. ### Funding Statement This work is independent research funded by the National Institute for Health and Care Research (NIHR) (Long Covid grant, Ref: COV-LT2-0016). The views expressed in this publication are those of the authors and not necessarily those of NIHR or The Department of Health and Social Care. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics approval was granted by Yorkshire and The Humber, Bradford Leeds Research Ethics Committee (REC; ref: 21/YH/0276) and subsequent amendments. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT05057260&atom=%2Fmedrxiv%2Fearly%2F2023%2F12%2F18%2F2023.12.18.23299958.atom