The Diagnostic Accuracy of Subjective Dyspnea in Detecting Hypoxemia Among Outpatients with COVID-19

Berezin, L.; Zhabokritsky, A.; Andany, N.; Chan, A. K.; Gershon, A.; Lam, P. W.; Leis, J. A.; MacPhee, S.; Mubareka, S.; Simor, A. E.; Daneman, N.

Objectives: The majority of patients with mild-to-moderate COVID-19 can be managed using virtual care. Dyspnea is challenging to assess remotely, and the accuracy of subjective dyspnea measures in capturing hypoxemia have not been formally evaluated for COVID-19. We explored the accuracy of subjective dyspnea in diagnosing hypoxemia in COVID-19 patients. Methods: This 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 April 3, 2020 to June 8, 2020. Hypoxemia was defined by oxygen saturation <95%. Dyspnea 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 hypoxemia. Results: During the study period 64/298 (21.5%) of patients met criteria for home oxygen saturation monitoring, and of these 14/64 (21.9%) were diagnosed with hypoxemia. The presence/absence of dyspnea had limited accuracy for diagnosing hypoxemia, with SN 57% (95% CI 30-81%), SP 78% (63%-88%), NPV 86% (72%-94%), PPV 42% (21%-66%), +LR 2.55 (1.3-5.1), -LR 0.55 (0.3-1.0). An mMRC dyspnea score >1 (SP 97%, 95%CI 82%-100%), Roth Maximal Count <12 (SP 100%, 95%CI 75-100%), and Roth Counting time < 8 seconds (SP 93%, 95%CI 66%-100%) had high SP that could be used to rule in hypoxemia, but displayed low SN ([≤]50%). Conclusions: Subjective dyspnea measures have inadequate accuracy for ruling out hypoxemia in high-risk patients with COVID-19. Safe home management of patients with COVID-19 should incorporate home oxygenation saturation monitoring.