Objective Exploration of Factors Influencing False-Negative Results in Interferon-Gamma Release Assay (IGRA) for Patients with Pulmonary Tuberculosis (PTB), and Development of a Nomogram Model to Predict IGRA False Negatives, to Optimize Clinical Diagnosis and Treatment Decisions. Methods A total of 143 patients diagnosed with Pulmonary Tuberculosis (PTB) were selected for this study. Among them, 63 patients who were IGRA negative but positive for pathogen detection formed the observation group, while 80 patients who were both IGRA positive and pathogen positive constituted the control group. After balancing potential confounding factors between the two groups using Propensity Score Matching (PSM), clinical characteristics and laboratory indicators of the two groups were compared. Logistic regression analysis was then employed to identify independent risk factors affecting IGRA results. Based on significantly associated factors, a nomogram model was constructed, and its predictive performance was evaluated. Results After propensity score matching, each group consisted of 55 patients. Compared to the control group, the observation group showed significant differences in white blood cell count (WBC), neutrophil count (NEUT), lymphocyte count (LYM), red blood cell count (RBC), hemoglobin (HGB), and albumin (ALB) levels (P < 0.05). Logistic regression analysis revealed that RBC and ALB were influencing factors for false-negative IGRA results. The constructed nomogram model demonstrated a good fit (χ²=6.444, P=0.598), with an area under the receiver operating characteristic curve (AUC) of 0.703 (95% CI: 0.605-0.800), accuracy of 0.682 (95% CI: 0.586-0.767), sensitivity of 0.691 (95% CI: 0.569-0.813), specificity of 0.673 (95% CI: 0.549-0.797), positive predictive value (PPV) of 0.679 (95% CI: 0.556-0.801), and negative predictive value (NPV) of 0.685 (95% CI: 0.561-0.809). Decision curve analysis indicated that the net benefit of predicting false-negative IGRA results using this nomogram model was greater than 0 when the threshold probability ranged from 0.15 to 0.75. Conclusion Lower levels of RBC and ALB may be significant factors contributing to false-negative IGRA results in PTB patients. The constructed nomogram model, incorporating these factors, holds considerable clinical application value for predicting IGRA false negatives, aiding in the improvement of early diagnosis and management strategies for PTB.

The authors have declared no competing interest.

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The study was approved by the Ethics Committee of the Second People's Hospital of Fuyang City (Approval No.: 20231112033). The research adhered to the principles outlined in the Declaration of Helsinki. Considering the retrospective nature of this study, the need for informed consent was waived by the Ethics Committee. All data were managed in strict compliance with ethical guidelines to ensure confidentiality and anonymity.

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