Abstract：
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 OI symptoms and comorbidities. Participants with a diagnosis of long covid were recruited from eight UK long covid clinics, and healthy volunteers from general population. All undertook standardized National Aeronautics and Space Administration Lean Test (NLT). Participants\' history of typical OI symptoms (e.g., dizziness, palpitations) before and during the NLT were recorded. Two hundred seventy-seven long covid patients and 50 frequency-matched healthy volunteers were tested. Healthy volunteers had no history of OI symptoms or symptoms during NLT or PoTS, 10% had asymptomatic OH. One hundred thirty (47%) long covid patients had previous history of OI symptoms and 144 (52%) developed symptoms during the NLT. Forty-one (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 abnormal readings to one abnormal reading during the NLT, resulted in 11% of long covid participants (an additional 4%) meeting criteria for PoTS, but not in healthy volunteers. More than half of long covid patients experienced OI symptoms during NLT and more than one in 10 patients met the criteria for either PoTS or OH, half of whom did not report previous typical OI symptoms. We therefore recommend all patients attending long covid clinics are offered an NLT and appropriate management commenced.
摘要：
直立不耐受（OI），包括体位性心动过速综合征（PoTS）和体位性低血压（OH），经常以长covid的形式报道，但是已发表的研究规模很小，结果不一致。我们试图估计在长期诊所就诊的患者和健康志愿者中客观OI的患病率，以及与OI症状和合并症的关联。被诊断为长covid的参与者是从英国的八个长covid诊所招募的，和来自普通人群的健康志愿者。所有人都进行了标准化的国家航空航天局精益测试（NLT）。参与者有典型OI症状的病史(例如，头晕,心悸）记录了NLT之前和期间。测试了77名长covid患者和50名频率匹配的健康志愿者。健康志愿者在NLT或PoTS期间没有OI症状或症状史，10%无症状OH。一百三十（47％）长的covid患者先前有OI症状史，而144（52％）在NLT期间出现症状。41人(15%)有异常NLT,20（7%）符合PoTS标准，和21（8％）有OH。NLT异常的患者，45%以前没有OI症状。在NLT期间,将PoTS的诊断阈值从两个连续的异常读数放宽到一个异常读数,导致11%的长期covid参与者(另有4%)达到PoTS标准，但不是健康的志愿者。超过一半的长covid患者在NLT期间出现OI症状，超过十分之一的患者符合PoTS或OH的标准，其中一半以前没有报告典型的OI症状。因此，我们建议向所有在长期covid诊所就诊的患者提供NLT，并开始适当的管理。
