key: cord-0853406-ousp81rp
authors: Tandon, Pranai; Leibner, Evan; Ahmed, Sanam; Acquah, Samuel O.; Kohli-Seth, Roopa
title: Comparing Seasonal Trends in Coronavirus Disease 2019 Patient Data at a Quaternary Hospital in New York City
date: 2021-03-26
journal: Crit Care Explor
DOI: 10.1097/cce.0000000000000381
sha: 782f5be0342a5a33be61fb9328021695e71f1a6d
doc_id: 853406
cord_uid: ousp81rp

Coronavirus disease 2019 has been a worldwide pandemic since early 2020 with New York City being the epicenter in the United States during early 2020. Although cases of decreased coronavirus disease 2019 during the summer, cases began to rise once more in the fall-winter period. Little is known about trends in patient characteristics, medical care, and outcome between these time periods. We report initial patient characteristics and outcomes from a large quaternary referral center in New York City between Spring (March to June), Summer (July to September), and Winter (October to December), including prevalence of renal failure, respiratory failure, and mortality; stratified across several key populations of interest including all patients, ICU patients, those requiring of noninvasive positive pressure ventilation and high-flow nasal cannula, and those intubated in each time period.

T he severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus continues to infect thousands of Americans daily, with exponentially rising case counts during the end of fall (1) . New York City became the center of the pandemic in the United States in March and April of 2020, accounting for more than 30% of all U.S. cases at that time (2) . The initial surge of patients resulted in significant morbidity and mortality, especially among those requiring invasive mechanical ventilation (2) . After the initial surge in the spring, a second, albeit smaller, rise in cases was observed in the city during the fall (3). We report initial patient characteristics and outcomes in a large quaternary referral center in New York City between three distinct time periods of coronavirus disease 2019 (COVID-19) pandemic.

The study population consists of all adult inpatients admitted to or transferred to the Mount Sinai Hospital, with COVID-19 identified by positive SARS-CoV-2 polymerase chain reaction on that admission or clinical documentation of infection. Patients are separated into three periods based on visual analysis of the epidemic curve: Spring (March 1, 2020, to June 30, 2020), Summer (July 1, 2020, until September 30, 2020), and Winter (October 1 to December 25); all patients included in this study were followed for 

The temporal distribution of admissions is shown in Figure 1A . A total of 3,088 inpatient admissions were included in this analysis; 2,305 in the spring cohort, 217 in the summer cohort, and 566 in the winter cohort ( 150% increase in creatinine through admission (19%, 13%, 10%; p < 0.001).

Six-hundred eighty-seven patients were admitted to an ICU; 573 in the spring, 48 in the summer, and 66 in the winter. ICU patients showed similar trends over time in age, intubation rate, SOFA scores, and d-dimers; however, rates of AKI did not fall as much as in the total patient cohort (48%, 31%, 36%; p = 0.005) ( Table 1) .

Changes in use of respiratory support over time are shown in Figure 2 . Use of HFNC significantly increased through the pandemic (15% of all patients in spring, 18% in summer, and 25% in winter p < 0.001), along with a decreasing intubation rate (17%, 9.7%, 8.8%; p < 0.001). Summary data for patients who required HFNC or NIPPV but never invasive mechanical ventilation versus those who did are shown in Table 2 . Patients who required HFNC or NIPPV did not demonstrate declining SOFA scores (mean SOFA 1.85, 1.57, 1.45; p = 0.6) but had similar trends in rate of AKI to the general population. Patients who were intubated did not demonstrate a decline in SOFA (mean SOFA 6.4, 6.6, 7.1; p = 0.3, or rate of AKI (65%, 52%, 62%; p = 0.5).

Overall death rate declined dramatically through the pandemic (Fig. 1B) . Among all patients, 20% of spring admissions, 4.6% of summer admissions, and 9.0% of winter admissions died during follow-up (p < 0.001); at the time of analysis, disposition was known for greater than 97% of patients in every time period. ICU patients had a similar trend with higher mortality than all patients (43% spring, 31% summer, 35% fall; p < 0.001). Patients requiring HFNC or NIPPV but not mechanical ventilation also had significant reduction in mortality rate over time and by winter was similar to the general population (45% spring, 10% summer, 10% winter; p < 0.001). Intubated patients had a high mortality which rose in the winter cohort (56% spring, 19% summer, 72% winter; p < 0.001).

In the current report, we find a greater than 50% reduction in death rate over time for patients admitted for COVID-19 in a large hospital system in New York City. We note a large first peak in the spring followed by a large drop during the summer and steady but slower rise of cases during the winter. Despite increasing case count, mortality in the winter months remains lower than at the beginning of the pandemic. In general, patients admitted with COVID-19 in the winter, compared with the spring, are similar in age but have lower SOFA scores, lower d-dimer levels, and lower prevalence of AKI. These differences persisted among ICU patients, suggesting that their degree of illness is lower than the patients admitted to ICU in the early days of COVID-19.

Change in practice pattern regarding use of noninvasive respiratory support is seen with an increasing utilization of HFNC and NIPPV with falling intubation rate. Anecdotally, this may reflect lower concern among providers regarding the aerosolizing potential of noninvasive modalities and a switch to a later intubation strategy.

Patients who require noninvasive respiratory support have similar outcomes to the general population; however, those who were intubated had high rates of mortality. Studies of publicly available datasets from the World Health Organization (WHO) and private companies have suggested there is a decreasing case fatality rate of COVID-19 worldwide (4). Fan showed a median reduction of 38.3% in case fatality rate between first and second waves using WHO data aggregated across 53 countries, including a 67% reduction (7) demonstrated a decline in crude and risk-adjusted mortality among patients admitted to another large New York health system through August 2020 but did not assess other outcomes such as rate of intubation or AKI. To our knowledge, no other study has analyzed outcomes of patients with COVID-19 admitted once cases began to rise once more in the winter and fall. To our knowledge, this is the first attempt at indepth comparison of patients admitted for COVID-19 between three time periods in the United States and with the longest period of follow-up extending into winter. Although mortality is significantly lower in the winter compared with the spring of the pandemic, due to the retrospective nature of this review, it is difficult to determine the cause of this improvement. Several hypotheses have been put forward, including a "harvesting" bias where the most susceptible patients died early on in the course of the pandemic (4); a reduction in hospital overcrowding resulting in more optimal patient outcomes (8); a decrease in level of illness among admitted patients or less ill patients presenting to hospital; or evolution in therapeutics including the routine use of anticoagulation, steroids, and antivirals (6) .

In conclusion, it is found that outcomes in patients admitted to a large referral center for COVID-19 are improving after over the time period of the pandemic, with clinically and statistically significantly lower rates of respiratory failure and death for all admitted patients. This benefit persists among those who require HFNC or NIPPV but do not require intubation; however, the smaller subset of patients who progress to severe disease requiring intubation and mechanical ventilation remain with similarly elevated mortality. Although the cause of these changes is not yet fully understood, a careful follow-up analysis is planned to explore several proposed hypotheses.

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Declines in mortality over time for critically ill adults with coronavirus disease 2019

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The authors have disclosed that they do not have any potential conflicts of interest.For information regarding this article, E-mail: evan.leibner@ mountsinai.org