Characteristics of indeterminate QuantiFERON-TB Gold PLUS results in pediatric lupus nephritis at Beijing Children's Hospital, 2023-2024.

OBJECTIVES: Tuberculosis screening in pediatric lupus nephritis (LN) patients presents unique diagnostic challenges. This study aimed to analyze the frequency of indeterminate QuantiFERON-TB Gold Plus (QFT-Plus) results among children with LN and the potential influence factors.

METHODS: A retrospective cohort study was conducted among patients under 18 years old with a confirmed diagnosis of LN screened for tuberculosis infection from January 2023 and August 2024. Demographic and clinical data were extracted from their electronic medical record, with categorical variables presented as frequencies and continuous variables as medians. Using SPSS 18.0 (Chicago, IL), we first performed univariate logistic regression to identify factors associated with indeterminate IFN-&#x3b3; results (P&#x2009;<&#x2009;0.05), then entered significant variables into multivariate models to determine independent predictors, reporting results as ORs, with statistical significance set at P&#x2009;<&#x2009;0.05.

RESULTS: Of 111 patients with LN, 49 (44.14%) had indeterminate QFT-Plus results, with 43 (87.76%) due to positive control failure. In the 30-day period prior to the QFT-Plus test, 46 (41.44%) patients were treated with immunotherapy. Univariable logistic regression analysis indicated that the indeterminate group had significantly lower levels of hemoglobin, albumin, and alkaline phosphatase, fewer hospitalizations, and more frequent use of immunotherapy, and higher triglyceride and D-dimers levels. Multivariable logistic regression analysis revealed that triglycerides level (OR 1.847; 95% CI 1.195-2.856; P&#x2009;=&#x2009;0.006) and immunotherapy use (OR 12.306; 95% CI 3.937-38.463; P<0.0001) were independently associated with increased risk of indeterminate QFT-Plus results. The area under the ROC curve for a triglycerides level of 2.155 mmol/L, and it was 0.751 for discriminating between indeterminate and determinate QFT-Plus results.

CONCLUSIONS: Hospitalized patients with LN had a high rate of an indeterminate QFT-Plus result, predominantly in positive control failure. Besides, our data showed that the use of immunotherapy agents and high triglycerides level represent factors associated with indeterminate QFT-Plus results in our cohort of pediatric lupus nephritis patients.