# Indeterminate QuantiFERON Results in Pediatric Kawasaki Disease: Inflammatory Predictors and Diagnostic Implications

## TL;DR

This study explores why TB tests often give unclear results in children with Kawasaki disease, linking it to inflammation and suggesting alternative diagnostic approaches.

## Contribution

The study identifies specific inflammatory markers associated with indeterminate TB test results in pediatric Kawasaki disease patients.

## Key findings

- Indeterminate QFT results were found in 20.4% of pediatric cases, with 80% linked to Kawasaki disease.
- Higher C-reactive protein and lower serum albumin levels were observed in KD patients with indeterminate QFT results.
- The study suggests considering alternative TB diagnostic tools for children with acute Kawasaki disease.

## Abstract

Introduction

Interferon-gamma release assays (IGRAs), such as the QuantiFERON®-TB Gold Plus (QFT), are widely used for tuberculosis (TB) screening in children. However, indeterminate QFT results remain a diagnostic challenge, particularly in patients with Kawasaki disease (KD), in whom systemic inflammation may transiently impair T-cell function. This study aimed to identify clinical and laboratory factors associated with indeterminate QFT results in pediatric patients, with a focus on KD.

Methods

We retrospectively analyzed 147 pediatric QFT tests performed at a tertiary medical center in Japan between September 2019 and May 2025. Clinical characteristics and laboratory parameters were compared between patients with indeterminate and negative QFT results. Subgroup analyses were conducted for children with KD.

Results

Among the 147 pediatric cases, 30 (20.4%) yielded indeterminate QFT results, 24 (80%) of which involved KD. In the KD subgroup, the indeterminate group had significantly higher C-reactive protein levels (median 5.65 vs. 3.21 mg/dL; p=0.016) and lower serum albumin levels (2.75 vs. 2.90 g/dL; p=0.013) compared to the negative group. No significant differences were observed in other laboratory parameters.

Conclusion

This study suggests that QFT may yield indeterminate results in pediatric KD during the acute inflammatory phase, potentially reflecting transient inflammation-induced T-cell suppression. Clinicians should consider the timing of IGRA testing, alternative assays such as T-SPOT.TB, and adjunctive diagnostic tools when screening for TB in this population.