A new study by a medical journal revealed that most of the people in New York City who were hospitalized due to coronavirus had one or more underlying health issues.

Health records from 5,700 patients hospitalized within the Northwell Health system — which housed the most patients in the country throughout the pandemic — showed that 94 percent of patients had more than one disease other than COVID-19, according to the Journal of the American Medical Association (JAMA).

Data taken from March to early April showed that the median age of patients was 63 years old and 53 percent of all coronavirus patients suffered from hypertension, the most prevalent of the ailments among patients.

In addition, 42 percent of coronavirus patients who had body mass index (BMI) data on file suffered from obesity while 32 percent of all patients suffered from diabetes.

The study also revealed that the overwhelming majority of patients who were on ventilators eventually died, and those who did more often had diabetes.

Data gathered from 2,634 patients who either died or were discharged from the hospital showed that 12 percent of them were placed on ventilators and of those who were, 88 percent of them died.

“Having serious comorbidities increases your risk,” said Karina Davidson, one of the study’s authors and senior vice president for the Feinstein Institutes for Medical Research, which is part of the Northwell Health system, according to reports by Time.

“This is a very serious disease with a very poor outcome for those who have severe infections from it. We want patients with serious chronic disease to take a special precaution and to seek medical attention early, should they start showing signs and symptoms of being infected. That includes knowing that they’ve been exposed to someone who has this virus.”

Doctors are beginning to notice that blood clots could be another troubling complication for patients who are hospitalized with coronavirus.

The clots present the latest challenge for doctors working to understand the new virus that is known to cause respiratory disease. These clots are being found in younger patients and can result in sudden strokes, according to reports Wednesday.

“It’s very striking how much this disease causes clots to form,” Dr. J Mocco, a neurosurgeon at Mount Sinai Hospital, in New York stated.

Mocco said he saw 32 stroke patients with large blockages in the brain, and at least half tested positive for the virus. Five of the patients had no risk factors for strokes and were under the age of 49, which he said was “Very, very atypical.”

Dr. Hooman Poor, a lung specialist at the hospital, noticed blood was not flowing well through the lungs of 14 patients on ventilators, which he determined was due to clotting.

“I feel like all these patients have blood clots in their lungs,’” Poor said, according to the news organization.

On April 13, a study published by researchers in the Netherlands found that 31 percent of intensive-care unit coronavirus patients they observed had a complication associated with clotting. The study described the findings as “remarkably high.”

Michael Reagan, a 49-year-old COVID-19 patient in New York, was informed by a pulmonologist that he had dozens of blood clots throughout his lungs.

“It feels like a toxin is in my body,” Reagan told Business Insider. “I had no idea a blood clot could hurt so bad.”

Certain treatments could involve having patients take high doses of a blood-thinning drug to prevent the clotting from appearing, although they haven’t been proven, according to Reuters.

Tony Award-nominated actor Nick Cordero has had his right leg amputated after suffering complications from the coronavirus, including clotting, his wife said earlier this month.

“We took him off blood thinners but that again was going to cause some clotting in the right leg, so the right leg will be amputated today,” she added.

Blood thinners on high-risk patients may also lead to bleeding in the brain or certain vital organs, health officials told the news organization.

While clotting can happen in anyone who stays idle on a ventilator for long periods of time, doctors said it appears to show up sooner in COVID-19 patients.