Table 2.
Factors related to infection, transmission, severity, and mortality of MERS
| Author (year) | Study period | No. of participants (Total/death) |
Country | Predictors | Significant factors |
|---|---|---|---|---|---|
| Risk factors of infection | |||||
| Alraddadi (2016) [42] | 2014 | 146 (30 cases, 116 controls) | Saudi Arabia | Travel history, animal-related exposure, food exposure, underlying health conditions and behaviors | Direct dromedary exposure in 2 weeks, concomitant with diabetes or heart disease, currently smoking tobacco |
| Hastings (2016) [43] | 2014 | 78 | Saudi Arabia | Nationality, sex, age group, hospital setting, outbreak week | Older age, outbreak week, nationality |
| Risk factors of transmission (spreader) | |||||
| Kang (2017) [44] | 2015 | 186 | South Korea | Age, sex, comorbidity, symptoms, laboratory test, clinical outcome, phase in transmission, incubation period, symptom onset to isolation, non-isolated in-hospital days, symptom onset to diagnosis | Fever, chest X-ray abnormality in > 3 lung zones, more non-isolated in-hospital days |
| Kim (2017) [34] | 2015 | 186 | South Korea | Underlying respiratory disease, cycle threshold value, symptom onset to diagnosis, no. of contacts, hospitalization or emergency room before isolation | Lower cycle threshold value, hospitalization or emergency room visit before isolation |
| Majumder (2017) [45] | 2015 | 186 | South Korea | Sex, age, comorbidity, case class (HCW, visitor, patient), case outcome (recovered/deceased) | Deceased case outcome |
| Risk factors of severity | |||||
| Zhao (2017) [46] | 2014–2015 | 21 | Saudi Arabia | CD4 T cell, CD8 T cell, PRNT50 | Higher PRNT50, higher CD4 T cell response |
| Ko (2016) [48] | 2015 | 45 | South Korea | Demographics (age, sex, BMI, underlying disease), symptoms (fever, myalgia, cough, sputum, diarrhea), laboratory test (white blood cell, hemoglobin, thrombocytopenia, lymphopenia, albumin, bilirubin, aspartate transaminase, alanine transaminase, blood urea nitrogen, creatinine, C-reactive protein, lactate dehydrogenase, threshold cycle value of PCR) | • Pneumonia development: older age, fever, thrombocytopenia, lymphopenia, C-reactive protein ≥2 mg/dL, lower threshold cycle value of PCR < 28 • Respiratory failure: male, hypertension, low albumin concentration, thrombocytopenia, lymphopenia, C-reactive protein |
| Feikin (2015) [47] | 2014 | 102 | Saudi Arabia | Age, sex, underlying illness, week of specimen collection, MERS-CoV virus load | • Severity: older age, underlying illness, high MERS-CoV virus load • Mortality: older age, underlying illness, high MERS-CoV virus load |
| Saad (2014) [49] | 2012–2014 | 70 | Saudi Arabia | Age, gender, occupation, acquisition of infection, comorbidity, radiological findings, concomitant infections, laboratory abnormalities | • ICU care: concomitant infection, decreased albumin • Mortality: older age |
| Risk factors of mortality | |||||
| Adegboye (2017) [50] | 2012–2015 | 959/317 (33%) | Saudi Arabia | Sex, age, comorbidity, animal contact, camel contact, HCW, secondary contact, clinical experience | Older age, comorbidity, non-HCW, fatal clinical experience |
| Ahmed (2017) [51] | 2014–2016 | 660/197 (29.8%) | Saudi Arabia | Age, sex, nationality, symptomatic, HCW, severity, source of infection, regions | • 3-day mortality: older age, non-HCW, hospital-acquired infection • 30-day mortality: older age, non-HCW, pre-existing illness, severity, hospital-acquired infection |
| Sha (2017) [29] | 2012–2016 | 216/56 (25.9%) in Middle East area, 174/24 (13.8%) in South Korea | Middle East Area/South Korea | Age, sex, exposure to camel or other animals, comorbidity, disease progress (days) | Older age (Middle East, South Korea), high comorbidity (Middle East, South Korea), longer days from onset to confirmation of infection (Middle East), longer hospitalized days (Middle East) |
| Sherbini (2017) [32] | 2014 | 29/10 (34.5%) | Saudi Arabia | Sex, symptoms, history of chronic disease, duration of disease before hospitalization, vital signs, temperature, blood pressure | Older age, gastrointestinal symptoms, longer duration of symptoms prior to hospitalization, diabetes mellitus, chronic kidney disease, smokers, lower blood pressure |
| Nam (2017) [56] | 2015 | 25/11 (44%) | South Korea | - Epidemiologic (age, sex, hospital, inpatient, staying in the same room as the index case, smoking, preexisting pneumonia, chronic lung disease, incubation period) - Clinical symptom - Laboratory examinations |
Male, pre-existing pneumonia, smoking history, incubation period of less than 5 days, leukocytosis, abnormal renal function at diagnosis, respiratory symptoms. |
| Yang (2017) [52] | 2012–2016 | 1743/559 (32.1%) | Multiple area | Age, sex, comorbidity, epidemic period, contact pattern, country | Older age, comorbidity, epidemic later period |
| Almekhlafi (2016) [57] | 2012–2014 | 31/23 (74.2%) | Saudi Arabia | Age, comorbidity, initial manifestations, procedures (non-invasive ventilation, invasive ventilation, continuous renal replacement therapy), need for vasopressor | Need for vasopressors |
| Alsahafi (2016) [53] | 2012–2015 | 924/ 425 (46%) | Saudi Arabia | Age, sex, comorbidities, location of acquisition (household, inpatient, HCW) | Older age, cardiac disease, cancer, household patients, HCW |
| Virlogeux (2016) [25] | 2015 | 170/36 (21%) | South Korea | Age, sex, incubation period | Older age, shorter incubation period |
| Cha (2015) | 2015 | 30/5 (16.7%) | South Korea | Age, sex, chronic kidney disease, diabetes, hypertension, comorbidity, estimated glomerular filtration rate, mechanical ventilator | None |
| Majumder (2015) [54] | 2015 | 159/35 (22%) | South Korea | Five potential covariates were analyzed: sex, age, concurrent health condition status, health care worker status, time from onset to diagnosis | Older age, pre-existing concurrent health conditions |
| KCDC (2015) [4] | 2015 | 186/36 (19.4%) | South Korea | Sex, age, case classification, respiratory disease, diabetes, cardiac disease, chronic kidney disease, malignancy | Older age, underlying respiratory disease |
| Das (2015) [58] | 2014 | 55/19 (35%) | Saudi Arabia | Age, chest radiographic score, absolute lymphocyte count, no. of comorbidities, congestive heart failure, hypertension, diabetes | Chest radiographic score |
| Al Ghamdi (2016) [59] | 2014 | 51/19 (37%) | Saudi Arabia | Beta interferon, alpha interferon, hydrocortisone, Ribavirin, APACHE score | APACHE score |
| Choi (2016) [55] | 2016 | 186/33 (17.7%) | South Korea | Age, sex, HCW, coexisting medical condition, symptoms at admission, vital signs at admission, laboratory abnormalities at admission, treatment | Age ≥ 55 years, occurrence of dyspnea during the disease course, presence of concomitant medical conditions including diabetes or chronic lung disease, systolic blood pressure < 90 mmHg at admission, leukocytosis at admission, use of mechanical ventilation |
APACHE acute physiologic and chronic health evaluation, ICD intensive care unit, HCW healthcare worker, PCR polymerase chain reaction, PRNT plaque reduction neutralization test