Possible clinical predictors of MERS identified

Researchers have identified possible clinical predictors of infection with Middle East respiratory syndrome, or MERS, coronavirus, including being overweight and the presence of interstitial infiltrates on chest X-rays, according to recent findings.

In a case-control study, researchers from Saudi Arabia compared the clinical characteristics of 17 hospitalized patients who tested positive for MERS (mean age, 60.7 years) and 82 controls (mean age, 57 years) admitted to the same medical facility who were suspected of having the disease during the same period. Some of the patients included in the analyses were affected by the Al-Hasa outbreak, which involved four health care facilities in the eastern province of Saudi Arabia between April 1 and May 23, 2013, resulting in 23 cases of MERS infection.

To confirm whether a patient was infected with MERS, researchers submitted specimens from nasopharyngeal swabs or tracheal aspirates to the Saudi Ministry of Health for PCR analysis. The researchers also reviewed paper and electronic medical records to collect epidemiological, demographic, clinical, radiographic and laboratory data on patients.

The researchers found no significant differences between the two patient groups in relation to sex, the presence of a fever or cough on admission and whether patients had single or multilobar infiltrates noted on chest X-rays. However, patients with MERS were more likely to be overweight compared with controls (mean BMI, 32 vs. 27.8; P=.03).

Patients with MERS also were more likely to have diabetes (87% vs. 47%; OR=7.24), as well as end-stage renal disease (33% vs. 7%; OR=7) — a noted risk factor for MERS infection.

Patients who tested positive for MERS were more likely than controls to have normal white blood cell counts (82% vs. 52%; OR=4.33), according to the researchers. Tachypnea (27% vs. 60%; OR=0.24) and respiratory distress (15% vs. 51%; OR=0.15) were less frequent among patients with MERS, although the exact reason for this is unknown, they said.

Chest X-rays noting interstitial infiltrates on admission were more common in MERS cases (67% vs. 20%; OR=8.13). The researchers said this is compatible with the presentation of severe disease and may be a marker for cardiac disease.

Mortality was significantly higher in patients with MERS vs. controls (76% vs. 15%; OR=18.96), which is consistent with previous findings.

Since the outbreak began in Saudi Arabia in September 2012, there have been 253 laboratory-confirmed cases of infection with MERS, including 93 deaths, according to WHO. The researchers wrote that further study of the clinical characteristics of MERS cases would be helpful in identifying at-risk patients and to determine their likelihood of acquiring the respiratory infection.

“The results suggest that few clinical predictors could enhance the ability to predict which patients with [community-acquired pneumonia] would have [MERS],” they concluded. “However, further prospective analysis and matched case controls may shed light on possible predictors of infection.”

-Updated 4/23/14

For more information:

Al-Tawfiq JA. Clin Infect Dis. 2014;doi:10.1093/cid/ciu226.

Assiri A. N Engl J Med. 2013;369:407-416.

Disclosure: The researchers report no relevant financial disclosures.