A case-control study of 17 patients with Middle East respiratory syndrome (MERS) and 82 patients with community-acquired pneumonia (CAP) found several differences between the groups. Patients with MERS were more likely to have interstitial infiltrates on chest x-rays, a normal white blood cell count, and underlying conditions like diabetes or kidney disease. Outcomes were generally worse for MERS patients, with a high death rate. The findings may help identify clinical predictors that could help determine if a patient with CAP has MERS, but more research is still needed.

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July 02, 2014
Patients with Middle East respiratory syndrome coronavirus (MERS-CoV) were more likely to have interstitial infiltrates on
admission radiography, a normal white blood cell count (WBC), and certain underlying comorbidities compared with patients who
had community-acquired pneumonia (CAP), according to a new case-control study.
The study, published online April 9 in Clinical Infectious Diseases, involved 17 cases of laboratory-confirmed MERS (mean age,
60.7 years) and 82 control patients (mean age, 57 years), all initially presenting to a single facility within 3 days of febrile
respiratory disease onset. MERS cases were identified via reverse transcriptase polymerase chain reaction analysis of
nasopharyngeal swabs or tracheal aspirates.
Analyzing medical records, Jaffar A. Al-Tawfiq, MD, from the Medical Department, Saudi Aramco Medical Services Organization,
Dhahran, Saudi Arabia, and the Indiana University School of Medicine, Indianapolis, and colleagues found that patients with MERS
were 8.13 times more likely than control patients to have interstitial infiltrates on initial chest X-ray (67% vs 20%; odds ratio [OR],
8.13; P = .001), often in the absence of tachypnea (27% vs 60%; OR, 0.24; P = .031) or respiratory distress (15% vs 51%; OR,
0.15; P = .012).
"The presence of interstitial infiltrates is compatible with the severe presentation of the cases and may be a marker for cardiac
disease, as cardiomegaly was identified as a potential risk factor [53% vs 21%; OR, 4.29; P = .025]," the authors write.
Laboratory findings revealed that MERS patients were 4.33 times more likely than control patients to exhibit a normal WBC (82%
vs 52%; OR, 4.33; P = .029). Leukocytosis was significantly less common (12% vs 42%; OR, 0.18; P = .025), and the incidence of
lymphocytosis did not differ statistically between groups.
"[A] normal WBC count on admission of patients with CAP may help in predicting MERS-CoV positivity. This suggests that many of
the controls may have had bacterial pneumonia. However, blood and sputum cultures did not reveal any specific etiology of CAP in
those patients," the authors note.
Other key distinguishing features among patients with MERS included an increased likelihood of being overweight (mean body
mass index, 32 vs 27.8; P = .035) and having diabetes (87% vs 47%; OR, 7.24; P = .015) or end-stage renal disease (33% vs 7%;
OR, 7; P = .012).
According to the authors, the high proportion of cases with underlying medical conditions may be related to their epidemiologic link
with the Al-Hasa outbreak, which involved 4 healthcare facilities in the eastern province of Saudi Arabia between April 1 and May
23, 2013.
Outcomes among MERS patients were poor, despite increased admission to intensive care units (53% vs 20%; OR, 4.65; P =
.025), and the death rate remained high (76% vs 15%; OR, 18.96; P < .001); at day 77, only 23% of cases were alive compared
with 86% of controls.
"[T]he results suggest that few clinical predictors could enhance the ability to predict which patients with CAP would have MERS-
CoV. However, further prospective analysis and matched case-control studies may shed light on the possible predictors of
infection," the authors conclude.
The authors have disclosed no relevant financial relationships.
Clin Infect Dis. Published online April 9, 2014. Abstract
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Cite this article: MERS: Case-Control Study Sheds Light on Clinical Predictors. Medscape. Jul 02, 2014.
MERS: Case-Control Study Sheds Light on Clinical Predictors
Yael Waknine

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