Table 1

Studies assessing correlation between CRP levels and bacterial infection and diagnostic performance of CRP in LMICs

StudyCountryAge groupInpatients/OutpatientsDisease characteristicsNumber of patientsGold standard for bacterial infectionCRP testDiagnostic performanceCorrelation with bacterial infection
AUROC (95% CI)Cut-off*Sensitivity†Specificity†
Studies in Africa
Carrol et al5Malawi2 months to 16 yearsInpatientsPneumonia or meningitis377Culture, microscopy, antigen or PCR from blood, cerebrospinal fluid and/or lung aspirateBeckman Coulter image immunochemistry system0.81 (0.73 to 0.89) for serious bacterialN/AN/AN/AMedian CRP values were significantly higher in HIV-negative and HIV-positive patients with serious bacterial infections compared with those without (253 vs 127 mg/L, p=0.0005 and 291 vs 135 mg/L, p=0.0005, respectively).
Díez-Padrisa et al6Mozambique<5 yearsInpatientsClinical severe pneumonia (no malaria)586Blood cultureImmunoturbidimetric assay, ADVIA Chemisty CRP 2 (Siemens)0.7920.99545CRP levels were higher in those with positive bacterial culture vs those with negative bacterial culture (177.65 mg⁄L vs 26.5 mg⁄L, p<0.001). Median CRP levels (>18.5 to ≤97.9) were predictive of bacterial culture positivity (OR 15.31, 95% CI 1.91 to 122.45, p=0.01).
Hildenwall et al14Tanzania3 months to 5 yearsOutpatientsFever (malaria negative)428Positive urine or blood culture or symptoms suggestive pneumonia as defined in the IMCIAfinion AS100 Analyzer (Axis-Shield)0.621944.6
(33.2 to 56.6)
(73.0 to 83.1)
Of those with CRP <20 mg/L (n=256, 59.8%), 84% had no signs of bacterial infection. Of those with CRP >80 mg/L (n=33, 7.7%), 36.7% were positive for bacterial infection.
Huang et al8Gambia and Kenya2 months to 5 yearsInpatientsPneumoniaPneumonia: n=204 Matched controls: n=186Blood culture or radiographELISA (R&D Systems)0.72
(0.59 to 0.86)
150, ≥20070.556.1Median CRP plasma concentration was significantly higher in those with probable bacterial infection (positive blood culture or radiograph) vs those with probable viral infection (negative radiograph and low WBC) (283 vs 175 µg/mL, p<0.001).
Mahende et al10Tanzania2 months to 5 yearsOutpatientsFever691Blood cultureCobas c111 (Roche Diagnostics)0.8337.374.277.8
Page et al12Niger6 months to 5 yearsInpatientsSevere acute malnutrition256Blood, urine, stool culture and radiographNycoCard Reader (Abott)0.66 (0.59 to 0.79) all patients, 0.72 (0.63 to 0.80) malaria-negative patients47.546.580.4Median CRP levels were significantly higher in those with pneumonia (radiograph positive) vs those with no proved bacterial infection (40.8 vs 12 mg/L, p=0.0014).
Studies in South-East Asia
Mueller et al11Cambodia7–49 yearsOutpatientsAcute feverFebrile patients: 1193, Matched controls: 282Microbiological results including culture, PCR, ELISA, RDTsLatex bead immune-turbidimetric method adapted on Integra 400 (Roche Diagnostics)NA21.352.584.3
Wangrangsimakul et al13Thailand≥15 yearsInpatients and outpatientsAcute fever231Microbiological results including culture, PCR, ELISA, RDTsNycoCard Reader (Abott, USA)0.91
(0.85 to 0.96)
(79.3 to 95.1)
(65.1 to 97.1)
Lubell et al9Cambodia, Laos, Thailand5–49 yearsInpatients and outpatientsAcute fever1372Microbiological results including culture, antigen detection, PCR and ELISA for JEV IgM ELISANycoCard Reader (Abott, USA)0.89 (0.8 to 0.97)1095
(92 to 97)
(46 to 53)
CRP levels were significantly lower in patients with a viral infection than other infections (p<0.0001 in all comparisons across countries).
(82 to 88)
(63 to 71)
Studies in multiple settings
Higdon et al7Bangladesh, Gambia, Kenya, Mali, South Africa, Thailand and Zambia<5 yearsInpatientsPneumoniaPneumonia: n=3597, controls: n=822Blood culture or positive lung aspirate or pleural fluid culture or PCR‡CRP Gen3 or CRP VARIO (Roche Diagnostics)0.8737.177
(69 to 84)
(78 to 85)
77% of HIV-negative cases with confirmed bacterial pneumonia vs 17% (n=556) cases with RSV pneumonia had CRP ≥40 mg/L (p<0.001).
  • *mg/L.

  • †%; 95% CI.

  • ‡Compared with ‘RSV pneumonia’—nasopharyngeal/oropharyngeal or induced sputum PCR-positive without confirmed/suspected bacterial pneumonia.

  • AUROC, area under the receiver operator characteristic curve; CRP, C reactive protein; IMCI, integrated management of childhood illness; LMICs, low-income and middle-income countries; N/A, not available; RDT, rapid diagnostic test; RSV, respiratory syncytial virus; WBC, white blood cell count.