On March 1, New York City confirmed its first case of SARS CoV-2 infection. By the end of the month, thousands were infected and the hospitals were having trouble managing the influx of patients. On Wednesday, JAMA published an analysis of the results of thousands of patients who ended up in a large hospital system in the city and surrounding areas. While the data is annoyingly incomplete, it provides a comprehensive overview of how the pandemic is interacting with health demographics in the United States.
Some of this is expected because the kind of pre-existing conditions that make COVID-19 worse – obesity, high blood pressure, and diabetes – cause problems here. The study also suggests some dramatically poor results in elderly people who were on ventilation, with 97 percent mortality in those over 65 years of age. However, the study period ended before most patients' results could be tracked, so this number must be treated with a significant number. Caution.
At the recording
The work is based on electronic patient records from Northwell Health's hospital system, which has a dozen hospitals in New York City and the surrounding suburbs. The researchers (Safiya Richardson, Jamie S. Hirsch, and Mangala Narasimhan) pulled the records of individuals with confirmed SARS-CoV-2 infection from March 1 through April 4 of this year. This resulted in a study population of 5,700 patients, which is quite large. However, the study interrupted the patient's persecution on April 4. If a case had not resulted in discharge or death by then, the results could not be analyzed. Follow-up examinations for the discharged were also limited, with the mean duration being only four days.
As the number of cases increased dramatically over the month, there were only results for less than half of the patients who started the study (2,643 to be exact). While the study provides insight into the factors that may affect whether a person's COVID-19 symptoms are so bad that they are hospitalized, most of the participants were still in the hospital at the end of the study period. This could potentially skew the numbers, especially those related to survival, as there was an endpoint for everyone who died during that time.
So what can we say about the demographics of the US cases of COVID-19 that are serious enough to warrant hospitalization? As can be seen in other countries, the population is considerably older with an average age of 63 years. (Although the age range is from a low of less than a year to a 107-year-old patient.) More men than women had severe problems because the total population was less than 40 percent female.
In general, people had some significant health problems before the virus sent them to the hospital. Over half of them had high blood pressure; over 40 percent were clinically obese; and a third had diabetes. A measure of their overall health, called the Charlson Comorbidity Index, shows that people with this level of problem usually have roughly equal chances of living another decade. In contrast, only about 1 percent had an infection with another respiratory virus, indicating that SARS-CoV-2 generally did not take advantage of the damage caused by a previous infection.
After the hospital stay
What happens to these patients when they are brought to the hospital? Of the 2,634 patients who died or were discharged, just over 14 percent ended up in intensive care. Just below (12.2 percent) mechanical ventilation was required, and just over 3 percent required dialysis. Kidney problems appear to be a regular problem in a subset of patients with COVID-19 symptoms. The presence of diabetes (which also causes kidney problems) as an existing illness increased the frequency of dialysis.
The eye-opening numbers come when the mortality of these patients was taken into account (which in turn was limited to the population who had died or been released). Those connected to the ventilator in this population died in 88 percent of the cases. Mortality was a staggering 97 percent among those over 65. For those who did not need a ventilator, the mortality rate was 27 percent for those over 65 and 20 percent for those below. No one died under the age of 20.
At this point, it is important to repeat the problem mentioned above: Most of the patients in the study were not included in this part of the analysis because they were still in hospital at the end of the study period. Persecution of all these patients until they either die or are released will almost certainly reduce the mortality rate. This was also the first month in which COVID-19 patients were treated, and it is possible that hospital staff will improve with increasing experience of the disease. However, results like this seem to have caused some institutions to rethink the use of ventilators.
Overall, this study largely confirms the results from other countries: men have more problems than women, older people are extremely affected, and existing conditions significantly increase the risks of SARS-CoV-2. They are also driving the great fear of COVID-19 home: a significant percentage of patients who need to stay in hospital require extensive stays and aggressive interventions, which increases the risk that the pandemic can overwhelm our health care system. Only by limiting the number of people infected at the same time can our hospital system cope with the number of patients who need this kind of attention.
However, it is also important to note that this study does not answer some critical questions. We are still getting confused and somewhat contradictory results about how many of the infected eventually have to be hospitalized. And we don't really know the mortality rate among those who do. At this point, in late April, the same researchers could no doubt know the full history of all those admitted during the study period and thus provide a better measure of it – and this work has almost certainly been done. However, we will likely have to wait a few more weeks for the results to go through the peer review.
JAMA, 202nd DOI: 10.1001 / jama.2020.6775 (Via DOIs).