COMPARATIVE STUDY OF PROCALCITONIN VERSUS C-REACTIVE PROTEIN LEVELS IN DIAGNOSIS OF ACUTE PYELONEPHRITIS

Abstract

Objective: To compare the diagnostic accuracy of serum procalcitonin and C-reactive protein levels in distinguishing acute pyelonephritis from lower urinary tract infection in adult patients.

Study Design: Cross-sectional analytical study.

Place and Duration of Study: Armed Forces Institute of Urology (AFIU), Rawalpindi, Pakistan, from 1st March 2024 to 31st August 2024.

Methodology: This study included 164 patients selected by consecutive non-probability sampling. The selection criteria was based on the signs of UTI on clinical assessment. The age range of these patients was kept between 18-65 years old. A detailed diagnostic protocol was used to evaluate quantitative urine culture, estimation of serum procalcitonin and C-protein concentrations, and sonographic evaluation of the kidneys. A composite reference standard served as the basis for confirming acute pyelonephritis. The effectiveness of the biomarkers to contrast between the two experimental groups under study was determined with the help of the receiver operating characteristic. The ROC was used determine the threshold values of AUC, sensitivity and specificity. Statistical computations were carried out on SPSS version 24.

Results: The results of this study clearly showed a high occurrence of lower urinary tract infection in patients i.e. 56.1% in comparison to acute pyelonephritis in patients i.e. 43.9%. Procalcitonin concentrations in serum were substantially elevated in the pyelonephritis cohort relative to the lower tract group (3.74 ± 3.28 ng/mL versus 0.41 ± 0.36 ng/mL; p<0.001), and C-reactive protein followed a parallel trend (74.6 ± 42.3 mg/L versus 18.8 ± 13.7 mg/L; p<0.001). A remarkable accuracy was shown by procalcitonin with an AUC of 0.943. With a threshold of 0.4 ng/mL the sensitivity and specificity were 91.7% and 89.1% respectively. For C-reactive protein at 30 mg/L, the corresponding figures were 87.5%, 54.3%, and 0.812 respectively, with a statistically significant difference between the two curves on DeLong testing (p<0.001).

Conclusion: In the task of separating acute pyelonephritis from infections confined to the lower urinary tract, procalcitonin in serum outperformed C-reactive protein across key diagnostic indices, most notably in specificity and positive predictive value.