Study design, setting, and population.
The study is a prospective cohort investigation of patients with lab-confirmed COVID-19 in the SN who required any of the Centers to respond from April 1, 2021, to June 30, 2021, a period spanning the peak of the second wave. The recruitment was consecutive.
We used a flow chart, following the STROBE guidelines12.
The evaluation of the patient begins with triage in the emergency room, where the patient is classified as a suspected case of COVID-19. Swabbing for PCR determination of SARS-CoV-2 was performed.
While waiting for the PCR result, the patient was considered to be infected with SARS-CoV-2, and all precautions for personal protection and patient isolation were taken.
Clinical, laboratory and radiological evaluations were carried out.
The severity of the clinical picture is classified to determine the place of hospitalization and indicate the treatment.
The inclusion criteria were hospitalized patients. In the first stage of the study, patients with suspected and confirmed COVID were admitted. However, in the data analysis, only patients with a confirmed diagnosis of COVID-19 by PCR determination of SARS-CoV-2 in nasopharyngeal exudate were included. The exclusion criteria were patients without a confirmed diagnosis of COVID-19 and not hospitalized.
The investigation was designed and reported with consideration of observational studies in epidemiology reporting guidelines of the Health Ministry of Province of Buenos Aires (https://www.ms.gba.gov.ar/ssps/investigacion/DocTecnicos/TipoInvestigaciones-Identificacionriesgos.pdf. Accessibility verified November 5, 2021) 13. Because the investigation was considered minimal risk, the requirement for consent was only verbal to patients or their relatives. (Ethics Committee, El Cruce Hospital N Kirchner).
All experimental protocols of the study were approved by the ethics committee of ’Hospital El Cruce’, Argentina. COVID-19 was diagnosed by real-time reverse transcription–polymerase chain reaction (RT–PCR) detection of SARS-CoV-2 from nasopharyngeal swabs. Molecular technique-based RT–PCR is considered the gold standard for COVID-19 diagnosis, and real-time RT–PCR detects the amplified SARS-CoV-2 genome14.
The RT–PCR determination was centralized in one laboratory (El Cruce Hospital). Test results were available a median of 1–2 days after the SN encounter.
SN is a large periurban region, covering an area of 661 square kilometers, with 1.8 million inhabitants residing in urban, suburban, and rural areas. Argentina is considered a developing country with a high human development index (0.830 in 2018); however, there are significant structural development gaps and heterogeneities between different areas. The municipalities of the southeast region are located in the lowest ranking of the municipalities of the Province of Buenos Aires
A total of 14 health centers with different levels of care complexity provide care to patients in the region. The centers are administered by the Ministry of Health of the Nation, by Province of Buenos Aires, of both, and by municipalities (Supplementary appendix).
The SN medical response is 2 tiered. The first tier is provided by medical doctors (MDs) in the emergency room of each health center. All patients go to the emergency room, and the majority consult spontaneously in the center of their neighborhoods.
If the patients had symptoms compatible with COVID-19 and more severe illness, it was decided whether they should be hospitalized as suspected. The second-tier response in confirmed cases also comprises MD in Intensive Therapy Unit (ITU) stay, General Ward with oxygen therapy (GWo), or General Ward (GW) stay.
Data sources
The information of each patient with COVID-19 evaluated by SN was incorporated in an Epidemiological Dashboard created by specialists (CI, BL) from the design of software, especially for this project. The current investigation used an electronic medical record from April 8 and incorporated the diagnosis of suspected or known COVID-19. In the first stage, a "window" was established that allowed the visualization of the occupation and availability of beds by establishment and by sector. In the Dashboard, each patient had an identification (ID) generated automatically, name, identity document and address, gender, age, and date of admission were incorporated, and the system automatically generated the days of hospitalization. Clinical risk was adapted from the National Health Ministry guidelines15 in three categories. Mild, when patients have unilateral radiological involvement and SatO2 is > 95%, the Internment in WGo, or WG is decided.
Moderately, when radiological involvement is bilateral, patients saturate below 95%, and they are admitted to WGo. Severe when they present ATS/IDSA (American Thoracic Society-ATS) (Infectious Diseases Society of America -IDSA-) criteria: one of two major (-Need for invasive MRA- Septic shock) or three minor (-Tachypnea ≥ 30/min.- PaO2/FiO2 < 250, Confusion/disorientation Multilobar infiltrates, Urea > 42 mg/100 ml, Leukopenia (<4000/mm3), Plaquetopenia (< 100,000/mm3), Temperature < 36 °C, Hypotension requiring aggressive hydration). They are admitted to ITU. Safe discharge for the patient and for third parties was used for those patients who, in case of being discharged from the hospital, could not return home because they did not have or because they lived in crowded conditions and could not be isolated. A socioeconomic and food security survey was started, but its analysis was not yet completed; for this reason, it was not included in this study.
From the beginning, a monitoring and follow-up of the data entry was organized twice a day, morning and night, by the HEC technical team (DAV, OL, YA). A "Procedures Manual" was prepared and distributed among the users of the project.
Regarding the registry of the vaccinated population, it was partially registered in the database because the start of the vaccination of the population in our country began to take place in April 2021 for those over 60 with pre-existing diseases. For this reason, it was not included in the original protocol of registration.
Statistical analysis.
We analyzed the distribution of the characteristics of the entire hospitalized population and stratified it by type of bed (ITU, WGo, WG). The characteristics in relation to clinical and safe discharge were compared. We used descriptive statistics, χ2 and Fisher’s exact test for categorical variables, and t and Wilcoxon’s test for continuous variables. Additionally, to analyze risk factors, we used multivariate analysis and logistic regression. All analyses were performed using SPSS version 24 statistical software (IBM Corp). A P ≤ 0.05 was considered statistically significant, and all the tests were 2-tailed.