Diagnostic accuracy of subjective dyspnoea in detecting hypoxaemia among outpatients with COVID-19: a retrospective cohort study

Abstract

ObjectivesThe majority of patients with mild-to-moderate COVID-19 can be managed using virtual care. Dyspnoea is challenging to assess remotely, and the accuracy of subjective dyspnoea measures in capturing hypoxaemia have not been formally evaluated for COVID-19. We explored the accuracy of subjective dyspnoea in diagnosing hypoxaemia in COVID-19 patients.MethodsThis is a retrospective cohort study of consecutive outpatients with COVID-19 who met criteria for home oxygen saturation monitoring at a university-affiliated acute care hospital in Toronto, Canada from 3 April 2020 to 13 September 2020. Dyspnoea measures were treated as diagnostic tests, and we determined their sensitivity (SN), specificity (SP), negative/positive predictive value (NPV/PPV) and positive/negative likelihood ratios (+LR/−LR) for detecting hypoxaemia. In the primary analysis, hypoxaemia was defined by oxygen saturation <95%; the diagnostic accuracy of subjective dyspnoea was also assessed across a range of oxygen saturation cutoffs from 92% to 97%.ResultsDuring the study period, 89/501 (17.8%) of patients met criteria for home oxygen saturation monitoring, and of these 17/89 (19.1%) were diagnosed with hypoxaemia. The presence/absence of dyspnoea had limited accuracy for diagnosing hypoxaemia, with SN 47% (95% CI 24% to 72%), SP 80% (95% CI 68% to 88%), NPV 86% (95% CI 75% to 93%), PPV 36% (95% CI 18% to 59%), +LR 2.4 (95% CI 1.2 to 4.7) and −LR 0.7 (95% CI 0.4 to 1.1). The SN of dyspnoea was 50% (95% CI 19% to 81%) when a cut-off of <92% was used to define hypoxaemia. A modified Medical Research Council dyspnoea score >1 (SP 98%, 95% CI 88% to 100%), Roth maximal count <12 (SP 100%, 95% CI 75% to 100%) and Roth counting time <8 s (SP 93%, 95% CI 66% to 100%) had high SP that could be used to rule in hypoxaemia, but displayed low SN (≤50%).ConclusionsSubjective dyspnoea measures have inadequate accuracy for ruling out hypoxaemia in high-risk patients with COVID-19. Safe home management of patients with COVID-19 should incorporate home oxygenation saturation monitoring.

Dispneia Ansiosa e Dispneia por COVID-19: um Diagnóstico Diferencial

“…Enquanto na COVID-19, a falta de ar pode vir associada à hipoxemia, por ser causada por uma lesão pulmonar [12]. Todavia, a ausência de hipoxemia não exclui a possibilidade de ser infecção por SARS-Cov-2, já que a dispneia pode vir na ausência de hipoxemia nesse grupo, como foi visto nos casos em que esses indivíduos com COVID-19 apresentavam altos níveis de ansiedade [1].…”

“…Na COVID-19, a dispneia está associada a quadros mais graves da doença, sendo considerada um preditor independente de morbimortalidade [1], [2], [9], [13], [15]. No exame físico dos pacientes graves, estavam presentes o aumento da frequência respiratória, a dispneia, o tremor de fala, murmúrios vesiculares diminuídos, presença de crepitação na ausculta pulmonar e embotamento à percussão pulmonar [3], [6].…”

Evaluating the impact of a virtual outpatient care programme in preventing hospitalizations, emergency department visits and mortality for patients with COVID-19: a matched cohort study

“…( 9 ) Oxygen-saturation monitoring devices were couriered to high-risk patients. ( 10 ) Patients were counselled to notify COVIDEO if they had significant decrease in oxygen saturation levels or subjective dyspnea. All patients were provided with an email for non-urgent concerns, and a direct-to-physician pager for urgent/emergent concerns which was staffed 24 hours/day, 7 days/week.…”

Outpatient Management of COVID-19 Disease: A Holistic Patient-Centered Proposal Based on the Greek Experience

“… The use of home pulse oximetry monitoring is recommended in patients seen in the ambulatory or ED setting and discharged home, but it is not always a flawless solution [ 26 ]. However, and as dyspnea may not correlate with the presence or degree of hypoxia in all patients, along with risk factors for developing severe disease ( Table 1 ), pulse oximetry can be used to guide clinicians in determining whether a patient requires in-person evaluation [ 29 ]. …”