Model Development and Validation

The UTIWizard Calculator is a clinical decision-support and research tool designed to estimate the likelihood of a urinary tract infection (UTI) using point-of-care (POC) urinalysis results and basic patient demographics (age and sex). The model was developed using 22,066 POC urinalysis encounters over three years and evaluated in a prospective, blinded external validation study. The calculator uses urinalysis and demographics only and does not incorporate symptoms or clinical history.

How to Use the Calculator

1.Select POC Urinalysis Results: Choose the appropriate point-of-care urinalysis values using the drop-down menus.

2.Review or Adjust the Classification Threshold: The classification threshold specifies the probability level used to classify results as Positive or Negative. Adjusting the threshold allows exploration of model behavior at different decision cutoffs.

3.Review Results: The calculator displays the estimated probability of UTI along with classification results and performance metrics.

Using the Classification Threshold

The classification threshold represents the probability cutoff used to interpret the model’s UTI risk estimate.

• Lower thresholds prioritize sensitivity (fewer missed UTIs)

• Higher thresholds prioritize specificity (fewer false positives)

For convenience, the calculator always displays results at the three most commonly used clinical thresholds, which reflect how clinicians typically stratify patients by risk.

Understanding the Three Reported Outcomes

1. Sensitivity 95%

Represents a higher-risk scenario where avoiding missed UTIs is prioritized.

2. Equal Sensitivity and Specificity

Represents an intermediate-risk scenario balancing false positives and false negatives.

3. Specificity 95%

Represents a lower-risk scenario where clinicians may prefer observation or waiting.

This tool is provided for research purposes only and should not be used for clinical diagnosis or treatment decisions.