Table 1.
Characteristics of included studies.
| Author, Year | Setting | Age, sample size | Study design | Prevalence of radiographic pneumonia | Inclusion criteria | Exclusion criteria | CXR | Index test | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Readers | Blinding | Interpretation | ||||||||
| Ebrahimzadeh, et al., 2015 |
Iran; Outpatient clinics and emergency clinics |
≥18 years; 840 |
Case control study | 50% | Acute respiratory symptoms with positive CXR | Acute respiratory symptoms with insignificant findings on CXR | A board certified radiologist | Yes | New consolidation without an air bronchogram, pleural effusion, abscess or empyema |
Socio-demographic: Age, gender Symptoms: Cough, sputum, dyspnea, chest pain Signs: Temperature ≥38 °C, pulse rate ≥100 min−1 respiratory rate ≥20 min−1 Laboratory tests: WBC, CRP |
| Flanders et al., 2004 |
USA; Outpatient clinics and emergency clinics |
≥18 years; 150 |
Prospective cohort | 13.3% | Acute cough (within past 3 weeks) | Pregnancy, systematic inflammatory disorders, coexistence infections, traumas, burns, myocardial infarct or unstable angina, cancer, HIV or immunosuppressive disorders | Radiologist | Yes | Infiltrate or consolidation on chest radiograph |
Socio-demographic: Age, gender, smoking Symptoms: Fever, muscle pain, fatigue, runny nose, sore throat, cough, yellow phlegm, blood in sputum, wheezing, dyspnea, chest pain Signs: Temperature ≥37.8 °C, pulse rate ≥100 min−1, respiratory rate ≥24 min−1, O2 saturationv ≤93%, decreased breath sounds, rales, wheezes Laboratory tests: CRP |
| Holm, Nexoe, et al., 2007 | Denmark; Outpatient clinics |
≥18 years; 364 |
Prospective cohort | 13% | Clinical diagnosis of LRTI | Pregnancy, hospitalization within preceding 7 days, severe illness requiring hospitalization, former participation in the study | Experienced specialist in infectious lung disease | Yes | Transient, non-malignant infiltrate on chest film |
Signs: Temperature ≥38 °C, pulse rate ≥100 min−1, respiratory rate ≥22 min−1, O2 saturation < 95% Laboratory tests: WBC and CRP |
| Holm, Pedersen, et al., 2007 | Denmark; Outpatient clinics |
≥18 years; 364 |
Prospective cohort | 13% | Clinical diagnosis of LRTI | Pregnancy, hospitalization within preceding 7 days, severe illness requiring hospitalization, former participation in the study | Experienced specialist in infectious lung disease | Yes | Transient, non-malignant infiltrate on chest film | Laboratory tests: PCT |
| Hopstaken et al., 2003 |
Netherlands; Outpatient clinics |
≥18 years; 243 |
Cross- sectional | 13% | New or increasing cough, combined with other clinical characteristics | Pregnancy and lactation, allergy to penicillin, concomitant treatment with ergot alkaloids and/or terfenadine, severe clinical disease, antibiotics treatment within 14 days, hospital stay for previous 4 weeks | 2 radiologists independently and 1 senior radiologist in case of disagreement | Yes | Infiltrates on chest radiograph |
Socio-demographic: Age Symptoms: Dry cough, purulent sputum, dyspnea, chest pain, fever, chills, diarrhea Signs: Temperature ≥38 °C, respiratory rate > 20 min−1, dullness on percussion, bronchial breathing, crackles Laboratory tests: ESR, CRP |
| Hopstaken et al., 2009 |
Netherlands; Outpatient clinics |
≥18 years; 95 |
Cross- sectional | 11.7% | New or increasing cough, combined with other clinical characteristics | Pregnancy and lactation, allergy to penicillin, concomitant treatment with ergot alkaloids and/or terfenadine, severe clinical disease, antibiotics treatment within 14 days, hospital stay for previous 4 weeks | 2 radiologists independently and 1 senior radiologist in case of disagreement | Yes | Infiltrates on chest radiograph |
Signs: Temperature ≥38 °C Laboratory tests: CRP, LBP, fibrinogen |
| Melbye et al., 1992 | Norway; Municipal emergency clinic |
≥18 years; 402 |
Prospective cohort |
41% (21 out of 51 CXR patients) |
Symptoms of respiratory tract or throat infection | Pregnancy, severe dyspnea patients | 2 radiologists and 1 senior chest physician independently | NR | A density on chest film |
Typical symptoms: Dry cough, purulent sputum, dyspnea, chest pain, fever, chills Atypical symptoms: Fatigue, myalgia/arthralgia, coryza, sore throat Signs: Wheezes, crackles, decreased breath sounds, dullness to percussion |
| Melbye et al., 1992 | Norway; Municipal emergency clinic |
≥18 years; 402 |
Prospective cohort |
41% (21 out of 51 CXR patients) |
Symptoms of respiratory tract or throat infection | Pregnancy, severe dyspnea patients | 2 radiologists and 1 senior chest physician independently | NR | A density on chest film | Laboratory tests: ESR, WBC and CRP |
| Moberg et al., 2016 | Sweden; Primary care centres |
≥18 years; 103 |
Prospective cohort | 45% | Respiratory tract infection symptoms for 24 hour | Pregnancy, COPD, received antibiotics less than 2 weeks, patients living in nursing home | Radiologists on duty and a board certified radiologist | No | Infiltrates on chest radiograph |
Socio-demographic: Gender, smoking Symptoms: Chest pain Signs: Temperature > 38 °C, pulse rate > 100 min−1, respiratory rate > 20 min−1, O2 saturation < 95% crackles, rales, decreased breath sounds, dullness on percussion Laboratory tests: WBC, CRP |
| Nolt et al., 2007 | USA; Emergency clinics |
≥18 years; 4464 |
Retrospective charts review | 12% | Acute cough illness | Any visits without a chief complaint of cough | Radiography notes were abstracted by research coordinators | NR | Haziness, density, consolidation, inflammation, infiltration or acute pulmonary abnormality in radiology report |
Socio-demographic: Age, smoking Signs: Temperature ≥100.4 °F, pulse rate >100 min−1, respiratory rate ≥20 min−1, O2 saturation <95% |
| Signal et al., 1989 |
USA; Emergency clinics |
≥18 years; 255 |
Prospective cohort | 15.6% | Patients who perform chest radiography | Critically ill patients | A board certified radiologist and final typed report was reviewed by the investigators | NR | Infiltrates on chest radiograph |
Socio-demographic: Age, gender Symptom: Cough, chest pain and dyspnea Signs: Crackles, wheezes, tachycardia, tachypnea |
| Steurer et al., 2011 | Switzerland; GP clinics |
≥18 years; 642 |
Prospective cohort | 20.5% | New or worsening cough for 24 hour, with increased body temperature | Pregnancy, chronic lung diseases, HIV patients taking oral steroid, on chemotherapy, organ transplantation, mental disorder | Radiologists | Yes | Shadow on radiograph |
Socio-demographic: Age, gender, smoking Symptoms: Cough, fever, dyspnea, wheezing, chest pain, muco-purulent sputum, bloody sputum Signs: Decreased breath sound, bronchial breath sound, dullness on percussion Laboratory tests: CRP |
| van Vugt et al., 2013 | Europe; Primary care centres |
≥18 years; 2820 |
Cross sectional | 5% | Acute cough | No chest radiograph performed or insufficient quality of radiograph | Radiologists | Yes | Diagnosis by selecting one of the following fixed option responses such as normal chest radiograph, acute bronchitis, pneumonia, or other diagnosis |
Socio-demographic: Age, gender, smoking Symptoms: Cough, phlegm, dyspnea, runny nose, fever, chest pain, diarrhea Signs: Diminished vesicular breath sound, crackles, temperature > 37.8 °C, pulse rate > 100 min−1, respiratory rate > 24 min−1 Laboratory tests: PCT and CRP |
COPD = chronic obstructive pulmonary disease. CRP = C-reactive protein. CXR = chest X-ray. ESR = erythrocyte sedimentation rate. HIV = human immunodeficiency virus. LBP = lipopolysaccharide binding protein.
LRTI = lower respiratory tract infection. NR = not reported. PCT = procalcitonin. WBC = white blood cell count.