Pulse oximetry to monitor patients with Covid-19 at home – A pragmatic, randomized trial
For the editor:
Reports of silent hypoxia in patients with coronavirus disease 2019 (Covid-19) have raised questions about whether patients should use home pulse oximeters to measure oxygen saturation rather than relying on subjective dyspnea as an indicator of clinical deterioration.1.2 Many Covid-19 telemonitoring programs include home pulse oximetry,3.4 but the effectiveness of these programs remains unknown. We report the results of a randomized trial that evaluated a remote monitoring program via SMS (COVID Watch) supplemented with monitoring of oxygen saturation using a pulse oximeter at home (ClinicalTrials.gov number, NCT04581863 ).
As part of routine care in our six-hospital health system (which includes more than 500 outpatient practices), adults in our electronic health record infected with Covid-19 – as determined by their clinician or a confirmed positive test for Covid-19 – are enrolled in COVID Watch, a 2-week program involving automated text messages twice a day requesting information about dyspnea and offering prompt reminders from nurses when needed. This program was associated with improved survival compared to no remote monitoring.5
From November 29, 2020 to February 5, 2021, we randomly assigned in a 1:1 ratio patients who were enrolled in COVID Watch to participate in the standard monitoring program in addition to home pulse oximetry or the standard program alone . Patients in the pulse oximetry group received a pulse oximeter and were monitored for subjective symptoms or low or declining oxygen saturation. Ethical considerations precluded assigning patients to no surveillance as control. The prespecified primary endpoint was the number of days the patient was alive and out of hospital at 30 days, assessed in patients with test-confirmed Covid-19. Exploratory outcomes included patient-reported levels of anxiety, use of health care services, and death at 30 days. Details regarding patients and trial methods are provided in the Supplementary Appendix, available with the full text of this letter on NEJM.org; the trial protocol is also available at NEJM.org.
A total of 1,041 patients (606 of whom had test-confirmed Covid-19) were assigned to the standard program group, and 1,056 patients (611 of whom had test-confirmed Covid-19) were assigned to the oximetry group. of pulse. Of the patients in the pulse oximetry group, 77.7% submitted at least one pulse oximetry reading; these patients submitted a mean (±SD) of 9.8±8.5 readings, corresponding to a response rate of 69.4±32.8% to pulse oximetry checks.
Among patients with test-confirmed Covid-19, there was no significant difference between groups in the number of days they were alive and out of hospital at 30 days (mean, 29.4 days in the pulse oximetry group and 29.5 days in the standard group program group; P = 0.58; difference, -0.1 day; 95% confidence interval [CI]-0.4 to 0.2) (Table 1). Pre-specified subgroup analyzes that were specifically powered to detect a difference in the number of days patients were alive and out of hospital among black patients compared to non-Hispanic white patients showed no significant differences. in this result. The mean number of telephone encounters within the healthcare system (exploratory outcome) was 3.3 ± 4.2 in the pulse oximetry group and 2.4 ± 3.3 in the standard program group (difference, 0.9; 95% CI, 0.4 to 1.3).
In patients with Covid-19, adding home pulse oximetry to remote monitoring did not result in more days alive and out of hospital than subjective assessments of dyspnea alone.
Kathleen C. Lee, MD
Anna U. Morgan, MD, MSHP
Krisda H. Chaiyachati, MD, MPH
David A. Asch, MD
Ruiying A. Xiong, MS
David Do, MD
Austin S. Kilaru, MD, MSHP
Doreen Lam, BA
Andrew Parambath, BA
Ari B. Friedman, MD, Ph.D.
Zachary F. Meisel, MD, MSHP
Christopher K. Snider, MPH
Deena L. Chisholm, MPH
Sheila Kelly, MPH
Jessica E. Hemmons, MS
Dina Abdel-Rahman, BS
Jeffrey Ebert, Ph.D.
Medha Ghosh, MPH
Julianne Reilly, BS
Christina J.O’Malley, MHA
Lauren Hahn, MBA
Nancy M. Mannion, DNP, RN
Ann M. Huffenberger, DBA, RN
Susan McGinley, CRNP
Mohan Balachandran, MA, MS
Neda Khan, MHCI
Judy A. Shea, Ph.D.
Nandita Mitra, Ph.D.
Mr. Kit Delgado, MD
Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
Supported by grants from the
The disclosure forms provided by the authors are available with the full text of this letter on NEJM.org.
This letter was published on April 6, 2022 on NEJM.org.
Drs. Lee and Morgan also contributed to this letter.
1. Tobin M.J., Laghi F, Jubran A. Why COVID-19’s silent hypoxemia baffles doctors. Am J Respir Crit Care Med 2020;202:356–360.
2. Greenhalgh T, M-Knight, Inda-Kim M, Fulop NJ, Leaching J, Vindrola-Padros C. Remote covid-19 management using home pulse oximetry and virtual service support. BMJ 2021;372:n677–n677.
3. UK National Health Service. COVID oximetry @home (https://www.england.nhs.uk/nhs-at-home/covid-oximetry-at-home/).
4. Huynh DN, Millan A, Quijada E, Jean D, Khan S, Funahashi T.. Description and initial results of the Kaiser Permanente Southern California COVID-19 home monitoring program. Permanent J 2021;25:1–7.
5. Delgado MK, Morgan AU, Asch DA, et al. Comparative effectiveness of an automated text messaging service for monitoring COVID-19 at home. Ann Medical Intern 2022;175:179–190.
|Results||Standard program + pulse oximetry
|Days alive and out of hospital||29.4±2.8||29.5±2.3||−0.1 (−0.4 to 0.2)||0.58|
|Registration day||2.8±1.3||2.9±1.3||−0.1 (−0.3 to 0.1)|
|Day 7||2.3±1.3||2.3±1.3||0.0 (−0.2 to 0.3)|
|Day 14||2.0±1.3||2.0±1.2||0.0 (−0.3 to 0.4)|
|Meeting in the emergency department – no. of patients (%)||57 (9.3)||68 (11.2)||−1.9 (−5.3 to 1.5)§|
|Within the health system — no. of patients/total number (%)||56/57 (98.2)||67/68 (98.5)||−0.3 (−23.9 to 23.3)§|
|Meeting registration days||9.2±6.9||8.8±7.3||0.4 (−2.1 to 3.0)|
|Lowest Recorded Systolic Blood Pressure — mm Hg¶||121.5±15.7||121.3±14.8||0.2 (−5.3 to 5.7)|
|Lowest recorded oxygen saturation — %¶||93.7±5.1||94.2±11.8||−0.5 (−3.7 to 2.7)|
|Supplemental oxygen provided – no. of patients/total number (%)¶||14/56 (25.0)||11/67 (16.4)||8.6 (−6.6 to 23.8)§|
|Maximum temperature — °F¶||99.1±1.1||98.7±1.2||0.4 (−0.1 to 0.8)|
|Hospitalization – no. of patients/total number (%)||43/611 (7.0)||41/606 (6.8)||0.2 (−2.6 to 3.2)§|
|Within the health system||39/43 (90.7)||41/41 (100.0)||−9.3 (−39.9 to 21.3)§|
|Intubation and ventilation support provided¶||4/39 (10.3)||1/41 (2.4)||7.8 (−3.1 to 18.8)§|
|Death – no. (%)||5 (0.8)||3 (0.5)||0.3 (−0.7 to 1.5)§|
|Meeting with the health system — no. per patient¶‖|
|Office visit||0.2±0.6||0.2±0.5||0.0 (−0.1 to 0.1)|
|Telemedecine||0.5±0.9||0.5±0.9||0.0 (−0.1 to 0.1)|
|Telephone||3.3±4.2||2.4±3.3||0.9 (0.4 to 1.3)|