Relationship Between the Serum Level of C-Reactive Protein and Severity and Outcomes of Community-acquired Pneumonia

Evaluation of severity, complications, and risk of death due to community-acquired pneumonia (CAP) plays a major role in making decisions about treatment. Biomarkers are one of the tools used to diagnose the disease. The current study aimed at evaluating the relationship between C-reactive protein (CRP) serum level and outcomes of CAP in affected patients. CRP serum level was measured on the 1st and 3rd days of admission in 73 patients. Chest X-ray was taken and CURB-65 (confusion, blood urea > 42.8 mg/dL, respiratory rate > 30/minute, blood pressure < 90/60 mmHg, age > 65 years) criteria was also applied. The patients were followed up for 30 days and evaluated for admission to intensive care unit (ICU), need for mechanical ventilation, inotropic support, incidence of pleural effusion, empyema, lung abscess, and death. CRP level on the 3rd day of admission had a significant and direct relationship with the incidence of complications and death in patients. There were no significant relationship between CURB-65 score and mean CRP level on admission. There was a significant relationship between mean CRP level on 3rd day and CURB-65 score. Clinical status had a significant relationship with mean CRP levels on the 1st and 3rd days of admission. Considering a cutoff point of 25 for CRP level on the 3rd day of admission, there was a significant difference between two groups in terms of mortality rate and CURB-65 scores. The results of the current study showed that elevated CRP level on the 3rd day of admission could be a sign of increased risk of complications and severity of the disease as well as death. It can be used as a factor for the prognosis of complications and outcomes.