# High-Sensitivity C-reactive Protein (hs-CRP) as a Biomarker for Predicting Urinary Tract Infection (UTI) Severity and Associated Complications

## TL;DR

This study shows that high-sensitivity C-reactive protein (hs-CRP) can predict the severity of urinary tract infections and related complications, helping improve patient care.

## Contribution

The study demonstrates hs-CRP's potential as a prognostic tool for UTI severity and complications, particularly in relation to comorbidities.

## Key findings

- Elevated hs-CRP levels correlate with more severe UTIs, with severe cases averaging 26.5 mg/L.
- hs-CRP levels are significantly higher in patients with comorbidities like hypertension, diabetes, and chronic kidney disease.
- Decision tree analysis identified hs-CRP thresholds that effectively predict infection severity and complications.

## Abstract

Background

Urinary tract infections (UTIs) are a common health issue, particularly among women and the elderly, leading to significant morbidity and healthcare burdens. The severity of UTIs can range from uncomplicated cystitis to more severe conditions like pyelonephritis and sepsis, which may cause long-term complications such as renal scarring. High-sensitivity C-reactive protein (hs-CRP), a biomarker of systemic inflammation, has gained attention for its potential role in predicting UTI severity and complications. Understanding the relationship between hs-CRP levels and UTI severity could enhance patient management and treatment strategies.

Objective

This study aims to investigate the relationship between hs-CRP levels and UTI severity, as well as their association with clinical factors such as comorbidities, infection type, and hospital outcomes, with a focus on determining the potential of hs-CRP as a prognostic tool for UTI complications.

Methodology

A cross-sectional observational study was conducted at Mardan Medical Complex from December 2024 to June 2025. A total of 173 UTI patients were included. Participants were categorized into mild, moderate, and severe infection groups based on clinical signs, symptoms, and laboratory results. hs-CRP levels were measured using the Roche Cobas e411 analyzer. Demographic data, comorbidities, infection type, and hospitalization details were collected. Statistical analysis, including ANOVA, Kruskal-Wallis H tests, Mann-Whitney U tests, and decision tree modeling, was used to assess associations between hs-CRP levels and infection severity.

Results

The findings of this study indicate a significant association between elevated hs-CRP levels and the severity of UTIs. The highest hs-CRP concentrations were observed in patients with severe infections, with a mean level of 26.5 mg/L. Moreover, hs-CRP levels were notably correlated with several comorbidities, including hypertension, diabetes, and chronic kidney disease. Specifically, patients with hypertension exhibited a mean hs-CRP level of 24.8 mg/L, while those with diabetes had an average level of 22.6 mg/L. Among individuals with chronic kidney disease, hs-CRP levels were even higher, with a mean of 27.34 mg/L. A decision tree analysis identified distinct hs-CRP thresholds that effectively predicted the severity of infections and the likelihood of complications, such as renal scarring and nephrolithiasis. In terms of pathogen distribution, Escherichia coli was the most frequently identified pathogen, found in 54 patients (31.21%). Notably, antibiotic resistance did not have a significant impact on hs-CRP levels (p=0.972). Nevertheless, hs-CRP was confirmed as a reliable biomarker for assessing infection severity and predicting potential complications. Further analysis revealed a clear gradation in hs-CRP levels corresponding to the severity of infection. Patients with mild infections had a mean hs-CRP level of 15.2 mg/L, those with moderate infections had an average of 21.5 mg/L, and individuals with severe infections presented the highest mean hs-CRP levels of 26.5 mg/L (p<0.001).

Conclusion

Hs-CRP is a reliable biomarker for evaluating UTI severity and predicting complications. Its association with infection severity, comorbidities, and clinical outcomes suggests its potential in clinical decision-making.