High mortality rates reported in ill patients with MERS-CoV

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1. Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection in critically ill patients is characterized by severe hypoxemic respiratory failure and high rate of non-respiratory manifestations including acute kidney injury and shock.

2. There is a high mortality rate (58% at 90 days) associated with MERS-CoV infection in the critically ill. 

Evidence Rating Level: 4 (Poor)

Study Rundown: Middle East Respiratory Syndrome Coronavirus (MERS-CoV), a new coronavirus, was first isolated in September 2012 in a patient who presented with acute pneumonia. Since then, over 170 cases have been confirmed. Given that MERS-CoV infection appears to share many clinical characteristics with disease caused by severe acute respiratory syndrome (SARS-CoV), there has been great concern that the MERS-CoV may represent another impending pandemic and global health threat.

This case series described 12 critically ill patients with confirmed MERS-CoV infection in 3 intensive care units (ICUs) in Saudi Arabia. All patients presented with symptoms of lower respiratory tract infection that progressed to severe hypoxemic respiratory failure requiring invasive positive pressure ventilation (IPPV). There was a high rate of non-respiratory organ dysfunction, including shock requiring vasopressor support, acute kidney injury, lymphopenia and thrombocytopenia. MERS-CoV infection in this patient population was associated with a high mortality rate: the 90-day survival rate was 42%. It should be also noted that all patients had underlying comorbid conditions including diabetes, heart disease, asthma and kidney failure. Furthermore, the authors noted that person-to-person transmission does occur with unprotected exposure, although the rate appears to be low.

Overall, this case series is limited by the small study size and descriptive nature. However, the article outlines valuable information on clinical characteristics of disease caused by MERS-CoV infection. In particular, the article offers insight on the high virulence and high mortality rates associated with infection, as well as the apparent predilection of severe disease for patients with underlying comorbidities.

Click to read the study, published today in the Annals of Internal Medicine

Relevant Reading:  Isolation of a Novel Coronavirus from a Man with Pneumonia in Saudi Arabia

In-Depth [case series]:  This case series described 12 patients with confirmed or probable MERS-CoV infection between December 2012 and August 2013 in 3 ICUs in 2 tertiary care hospitals in Saudi Arabia. One patient was a health care worker (HCW) with asthma who became critically ill after contracting the virus from an unprotected exposure. Cases were identified after suspected cases were tested for MERS-CoV with real-time polymerase chain reaction (RT-PCR) testing from samples obtained from nasopharygeal swab, tracheal aspirates or bronchoalveolar lavage in intubated patients. Confirmed cases were defined as suspected case with positive result for the virus by RT-PCR.

A total of 8 cases were community-acquired and 3 occurred as part of a healthcare-associated cluster that included HCWs in one of the ICUs. Screening of 520 at-risk HCWs for MERS-CoV identified only 4 positive results (1%), all of which were nurses who experienced unprotected exposure. Presenting symptoms were mainly that of lower respiratory tract infection: dyspnea, cough, and fever. All patients developed acute hypoxemic respiratory failure requiring IPPV. Chest radiography at time of intubation showed changes from lobar involvement as well as changes consistent with acute respiratory distress syndrome (ARDS). Mean duration of IPPV was 16 days.  All patients received broad spectrum antibiotics, while 7 of them also received oseltamivir.  Eleven (92%) had at least one non-respiratory manifestation including shock (92%), acute kidney injury (58%), lymphopenia (92%), thrombocytopenia (58%), and 1 patient developed ischemic bowel with underlying vascular disease. Survival rates were 58% and 42% at day-28 and day-90, respectively.

By Aimee Li, MD and Andrew Cheung, MD

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