IRCT2017010331737N1 IRCT 2017-02-24 Arak University of Medical Sciences Use of Procalcitonin in therapy of Pneumonia Clinical trial for evaluation of effect of procalcitonin-based algorithm in duration of antibiotic therapy and hospitalization of community acquired pneumonia and chronic obstructive pulmonary disease exacerbation 2015-05-12 anticipated 140 Complete https://irct.ir/trial/24903 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment. N/A Condition 1: Chronic obstructive pulmonary disease. Condition 2: Pneumonia. Intervention 1: In the case group, the antibiotic therapy is guided by serum procalcitonin. In this group, the patients are classified into four groups, according to the procalcitonin algorithm that is validated in previous studies. A procalcitonin level of less than 0.1g/L suggested the absence of bacterial infection and the initiation or continuation of antibiotics is strongly discouraged. A procalcitonin level between 0.1 and 0.25 g/L indicated that bacterial infection is unlikely, and the initiation or continuation of antibiotics is discouraged. A procalcitonin level from 0.25 to 0.5 g/L is considered to indicate a possible bacterial infection and the initiation or continuation of antibiotic therapy is encouraged. A procalcitonin level greater than 0.5 g/L strongly suggested the presence of bacterial infection and antibiotic treatment and continuation is strongly encouraged. Reassessment of procalcitonin is done in procalcitonin group at 3, 5, and 7 days if antibiotic therapy initiated and antibiotics are discontinued on the cutoffs defined above. Intervention 2: In the control group, the antibiotic therapy is chosen on the basis of usual practice guidelines.