Published on in Vol 22, No 6 (2020): June

Preprints (earlier versions) of this paper are available at https://preprints.jmir.org/preprint/19855, first published .
Epidemiological Observations on the Association Between Anosmia and COVID-19 Infection: Analysis of Data From a Self-Assessment Web Application

Epidemiological Observations on the Association Between Anosmia and COVID-19 Infection: Analysis of Data From a Self-Assessment Web Application

Epidemiological Observations on the Association Between Anosmia and COVID-19 Infection: Analysis of Data From a Self-Assessment Web Application

Original Paper

1Inter-regional Cancer Institut Jean Bernard, Le Mans, France

2Emerging Diseases Epidemiology Unit, Institut Pasteur, Paris, France

3Service de maladies infectieuses et tropicales, Hôpital Raymond Poincaré, Assistance Publique - Hôpitaux de Paris, Garches, France

4Service de pneumologie, Centre Hospitalier Régional Universitaire de Lille, Lille, France

5Service de maladies infectieuses et réanimation médicale, Centre Hospitalier Universitaire de Rennes Pointchaillou, Rennes, France

6Infectious and Tropical Diseases Department, Bichat-Claude Bernard University Hospital and University of Paris, Assistance Publique - Hôpitaux de Paris, Paris, France

7Team DesCID, Infection, Antimicrobials, Modelling, Evolution - U1137, French Institute for Health and Medical Research, Institut national de la santé et de la recherche médicale, Paris, France

Corresponding Author:

Fabrice Denis, MD, PhD

Inter-regional Cancer Institut Jean Bernard

9, rue Beauverger

Le Mans, 72100

France

Phone: 33 243475810

Email: f.denis@cjb72.org


Background: We developed a self-assessment and participatory surveillance web application for coronavirus disease (COVID-19), which was launched in France in March 2020.

Objective: Our objective was to determine if self-reported symptoms could help monitor the dynamics of the COVID-19 outbreak in France.

Methods: Users were asked questions about underlying conditions, sociodemographic status, zip code, and COVID-19 symptoms. Depending on the symptoms reported and the presence of coexisting disorders, users were told to either stay at home, contact a general practitioner (GP), or call an emergency phone number. Data regarding COVID-19–related hospitalizations were retrieved from the Ministry of Health.

Results: As of March 29, 2020, the application was opened 4,126,789 times; 3,799,535 electronic questionnaires were filled out; and 2,477,174 users had at least one symptom. In total, 34.8% (n=1,322,361) reported no symptoms. The remaining users were directed to self-monitoring (n=858,878, 22.6%), GP visit or teleconsultation (n=1,033,922, 27.2%), or an emergency phone call (n=584,374, 15.4%). Emergency warning signs were reported by 39.1% of participants with anosmia, a loss of the sense of smell (n=127,586) versus 22.7% of participants without anosmia (n=1,597,289). Anosmia and fever and/or cough were correlated with hospitalizations for COVID-19 (Spearman correlation coefficients=0.87 and 0.82, respectively; P<.001 for both).

Conclusions: This study suggests that anosmia may be strongly associated with COVID-19 and its severity. Despite a lack of medical assessment and virological confirmation, self-checking application data could be a relevant tool to monitor outbreak trends.

Trial Registration: ClinicalTrials.gov NCT04331171; https://clinicaltrials.gov/ct2/show/NCT04331171

J Med Internet Res 2020;22(6):e19855

doi:10.2196/19855

Keywords



Web-based self-reporting of symptoms is a growing field and has been used to improve survival in oncology [1,2]; it can be used as a participatory surveillance tool for coronavirus disease (COVID-19) or other influenza-like illnesses as well [3,4]. We thought of applying the same technology to optimize patient triage for COVID-19 patients in France and alleviate the burden on emergency call centers. A self-assessment and participatory surveillance website [5] was developed and launched during the growing phase of the COVID-19 epidemic in France in March 2020. Our objective was to determine if self-reported symptoms could help monitor outbreak dynamics in France. We report here the analysis of the first 13 days of web application usage.


Users were recruited via national media campaigns in France, including social media, radio, and magazine campaigns, between March 17-29, 2020. Participants were recruited through the maladiecoronavirus.fr website [5]. Respondents provided information on sociodemographic data, zip code, and coexisting disorders anonymously. They were asked about nine symptoms associated with possible COVID-19 infection—fever (body temperature >37.7°C), unusual cough, shortness of breath, sore throat, muscle aches, diarrhea, anorexia, and asthenia. Anosmia, a loss of the sense of smell, was added on March 21, 2020. Following symptom reporting, a notification was sent, recommending the user either to stay at home and use the website again in case of evolving symptomatology (self-monitoring), or to contact a general practitioner (GP), or to call an emergency number if they reported dyspnea or anorexia. A questionnaire was built according to Chinese reports and French experience [6]. The website was not considered a medical device by regulatory authorities since no tracking was performed and data were anonymous. We compared the distribution of web-based, self-reported symptoms to that of hospitalized COVID-19 patients according to Ministry of Health reports. Spearman correlation coefficients were used for statistical analysis.


Between March 17-29, 2020, the website was accessed 4,126,789 times; 3,799,535 electronic questionnaires were filled out; and 2,477,174 users had at least one out of the nine symptoms included in the questionnaire (Figure 1). In total, 1,322,361 (34.8%) participants reported no symptoms. The remaining patients (median age 37 years; range 15-99 years) were directed to self-monitoring (858,878, 22.6%), GP visit or teleconsultation (1,033,922, 27.2%), or an emergency phone call (584,374, 15.4%).

Of all symptomatic patients, anosmia was reported by 17.1% (325,910/1,903,741), fever was reported by 33.5% (828,952/2,477,174), and cough by 61.2% (1,515,557/2,477,174). Emergency warning signs (dyspnea or complete anorexia) were reported by 39.1% of participants with anosmia (n=127,586) versus 22.7% of participants without anosmia (n=1,597,289; P<.001; Table 1). Anosmia and fever and/or cough were correlated with COVID-19–related hospitalizations (Spearman correlation coefficients=0.87 and 0.82, respectively; P<.001 for both; Figure 2).

Figure 1. Flowchart of the study population.
View this figure
Table 1. Users characteristics.
CharacteristicValue (n=2,477,174a)
Age (years), average (range), median39.12 (15-99), 37
Sexb
Body mass index (kg/m2)

≥30436,609 (17.6)

<302,040,555 (82.4)
Comorbidities

Cardiovascular disease / uncontrolled hypertension401,888 (16.2)

Diabetes78,354 (3.2)

Malignancy72,577 (2.9)

Pulmonary disease243,247 (9.8)

Chronic kidney disease11,333 (0.5)

Chronic liver disease36,677 (1.5)

Pregnancy40,766 (1.6)

Immunodepression135,624 (5.5)

Immunosuppressive ongoing therapy70,927 (2.9)
Reported symptoms

Fever (body temperature greater >37.7°C)828,952 (33.5)

Cough1,515,557 (61.2)

Dyspnea658,442 (26.6)

Asthenia1,155,297 (46.6)

Complete anorexia103,122 (4.2)

Sore throat or muscle aches1,837,286 (74.1)

Diarrhea497,665 (20.1)

Anosmia or dysgeusiac325,910 (17.1)
Patient triage after questionnaire completiond

No symptoms1,322,361 (34.8)

Self-monitoring858,878 (22.6)

General practitioner / phone call1,033,922 (27.2)

aSymptomatic patient (reported at least one symptom).

bSex was not asked to protect the identity of the user.

cAnosmia was reported from March 21, 2020; the number of symptomatic patients during this period was 1,903,741.

dDenominator is N=3,799,535 (all respondents; symptomatic or not).

Figure 2. Maps displaying the correlation between fever and/or cough and anosmia with hospitalizations for COVID-19. (A) The cumulative number of hospitalized COVID-19–positive patients in France on March 29, 2020. (B) Fever and/or cough reported by users via the application; cumulative amount in French counties from March 17-29, 2020: 3,799,535 respondents (828,952 with fever and 1,515,557 with cough). (C) Anosmia reported by users; cumulative number from March 21-29, 2020: 325,910 positive respondents.
View this figure

This study suggests that self-reported symptoms of COVID-19 are correlated with COVID-19–related hospitalizations and that anosmia may be strongly associated with COVID-19. This could be explained by a greater specificity compared to other reported symptoms that could result from other respiratory viruses [7,8]. Limitations include lack of medical assessment and virological confirmation of COVID-19 and comparison of application-retrieved data with a distinct set of data from the Ministry of Health reports on hospitalizations. Self-checking application data could be a relevant tool to monitor the dynamics of an outbreak and thus can be a real-time health system response to the epidemic.

Conflicts of Interest

FD received personal fees from AstraZeneca, Ipsen, Sivan Innovation, Pfizer, Chugai, Takeda, and Roche. All other authors declared no conflicts of interest.

References

  1. Denis F, Basch E, Septans A, Bennouna J, Urban T, Dueck AC, et al. Two-Year Survival Comparing Web-Based Symptom Monitoring vs Routine Surveillance Following Treatment for Lung Cancer. JAMA 2019 Jan 22;321(3):306-307 [FREE Full text] [CrossRef] [Medline]
  2. Basch E, Deal AM, Dueck AC, Scher HI, Kris MG, Hudis C, et al. Overall Survival Results of a Trial Assessing Patient-Reported Outcomes for Symptom Monitoring During Routine Cancer Treatment. JAMA 2017 Jul 11;318(2):197-198 [FREE Full text] [CrossRef] [Medline]
  3. Luo H, Lie Y, Prinzen FW. Surveillance of COVID-19 in the General Population Using an Online Questionnaire: Report From 18,161 Respondents in China. JMIR Public Health Surveill 2020 Apr 27;6(2):e18576 [FREE Full text] [CrossRef] [Medline]
  4. Guerrisi C, Turbelin C, Blanchon T, Hanslik T, Bonmarin I, Levy-Bruhl D, et al. Participatory Syndromic Surveillance of Influenza in Europe. J Infect Dis 2016 Dec 01;214(suppl_4):S386-S392. [CrossRef] [Medline]
  5. maladiecoronavirus.fr. 2020.   URL: https://maladiecoronavirus.fr/ [accessed 2020-03-17]
  6. Guan W, Ni Z, Hu Y, Liang W, Ou C, He J, China Medical Treatment Expert Group for Covid-19. Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med 2020 Apr 30;382(18):1708-1720 [FREE Full text] [CrossRef] [Medline]
  7. Menni C, Valdes AM, Freidin MB, Sudre CH, Nguyen LH, Drew DA, et al. Real-time tracking of self-reported symptoms to predict potential COVID-19. Nat Med 2020 May 11. [CrossRef] [Medline]
  8. Bénézit F, Le Turnier P, Declerck C, Paillé C, Revest M, Dubée V, et al. Utility of hyposmia and hypogeusia for the diagnosis of COVID-19. The Lancet Infectious Diseases 2020 Apr 15 [FREE Full text] [CrossRef] [Medline]


COVID-19: coronavirus disease
GP: general practitioner


Edited by G Eysenbach; submitted 04.05.20; peer-reviewed by F Lanternier, E Stavaux, O Leal Neto; comments to author 27.05.20; revised version received 02.06.20; accepted 03.06.20; published 11.06.20

Copyright

©Fabrice Denis, Simon Galmiche, Aurélien Dinh, Arnaud Fontanet, Arnaud Scherpereel, Francois Benezit, François-Xavier Lescure. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 11.06.2020.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on http://www.jmir.org/, as well as this copyright and license information must be included.