New health care data suggests that about a quarter of all coronavirus patients placed on ventilators in New York's largest health care system died, first reported by CNN.

The data was gathered at Northwell Health, New York state's largest hospital system. The study, published in the Journal of the American Medical Association (JAMA) examines 5,700 patients hospitalized with coronavirus infections in the New York City region, with final outcomes recorded for 2,634 patients. The average patient age was 63 years old.

New data confirms that out of 1151 patients placed on mechanical ventilation, 282, or 24.5 percent, died. A corresponding 72.2 percent remained in hospital care, while 3.3 percent were discharged alive.

Speaking with CNN, Karina Davidson, the senior vice president of Northwell Health, said on Saturday that researchers decided to update the report's wording.

"We are updating our figures," Davidson told CNN reporters. "These are updated for how many we know have had an outcome and how many remain in the hospital."

The original report published said that about 12 percent of COVID-19 patients needed emergency ventilation, and 88.1 percent of those placed on ventilators died. These numbers only represent a fraction of the entire patient pool who remained in hospital care, whose outcomes are now known.

The final data now reveals that the mortality rate for COVID-19 patients on ventilators is about 25 percent.

Analyzed by age group, mortality rates for patients aged 18 to 65 were 76.4 percent. For the next oldest age group, ages 66 years and older, patients receiving mechanical ventilation recorded a 97.2 percent mortality rate.

There were no deaths for patients placed on ventilators who were younger than age 18.

Comparable mortality rates of coronavirus patients in the same age ranges who were not placed on ventilators were lower; in the 18 to 65 and the 66 years and older age groups, mortality rates were 19.8 percent and 26.6 percent, respectively. There were no deaths recorded for patients under the age of 18.

The case series also documented comorbidities among patients, with the most common being hypertension, obesity and diabetes. The study illustrates how most people who become severely ill with the coronavirus have some sort of underlying condition, CNN reports.

Almost 42 percent of all patients hospitalized with coronavirus were reportedly obese, with a body mass index (BMI) of more than or at 30.

More than half of COVID-19 patients, or 56.6 percent, simultaneously had hypertension, a cardiovascular disease. Diabetes was also found to be a prevalent pre-existing condition, with 33.8 percent of coronavirus patients reported as being diabetic.

The study notes that of patients who died, those with diabetes were more likely to have been placed on ventilators or received care in the hospital's intensive care unit (ICU) compared to patients who did not have diabetes.

The study notes that it was only conducted in the New York City metropolitan region, and is therefore not a representative sample for the U.S.

Report authors also said that since this study reported mortality rates "only for patients with definite outcomes (discharge or death), and longer-term study may find different mortality rates as different segments of the population are infected."