The study reports a high incidence of critical illness (22 per cent, 257/1,150) and a high dependency on mechanical ventilation to support breathing in critical patients (79 per cent, 203/257). Photographer: Sergei Bobylev/TASS/Getty Images

CRITICALLY ILL Covid-19 patients frequently require mechanical ventilation and death rates among them are high, according to a first prospective study of critical patients from New York City that sheds light on how the virus affects adult patients in USA. Risk factors linked with in-hospital death, including old age, chronic heart and lung disease, are consistent with reports from Italy, China and the UK, according to The Lancet.

Of particular interest is the finding that more than three quarters of critical patients required a ventilator and almost one-third required renal dialysis support.

A report from 257 Covid-19 patients admitted to two hospitals in New York City from March 2 to April 1, and followed for at least 28 days, has been published on Tuesday in The Lancet, offering a snapshot of how the virus affects adults requiring hospital care.

The study reports a high incidence of critical illness (22 per cent, 257/1,150) and a high dependency on mechanical ventilation to support breathing in critical patients (79 per cent, 203/257).

Researchers say this has important implications for US hospital systems and, specifically, the need to prepare for large numbers of patients requiring intensive care. The findings mirror reports from China, Italy and the UK, with old age and pre-existing conditions being the strongest risk factors associated with poor outcomes.

The study focused on two hospitals in New York City affiliated with Columbia University Irving Medical Center in northern Manhattan. Between March 2 and April 1, a total of 1,150 adults (aged 18 or above) were admitted to both hospitals with laboratory-confirmed Covid-19. Of those admitted to hospital, 257 (22 per cent) were critically ill and required treatment in a high dependency or intensive care unit.

The most common symptoms reported were shortness of breath, fever, cough, muscle pain and diarrhoea. As of April 28, 40 per cent of critically ill patients had died (39 per cent, 101/257) and over one-third remained in hospital (37 per cent, 94/257). Less than one quarter had been discharged alive (23 per cent, 58/257).

Over three quarters of critically ill patients needed mechanical ventilation to help them breathe (79 per cent, 203/257). Patients spent an average of 18 days on a ventilator (range nine to 28 days). People with pre-existing lung or heart conditions had highest risk of poorer outcomes. High blood pressure was also associated with poorer survival, consistent with reports from China and Italy.