Blood Cell Count Derived Inflammatory Indexes in Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Dynamic Blood Cell Count Derived Inflammatory Indexes as a Biomarker in Acute Exacerbation of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterized by progressive scarring. Sometimes, patients experience a sudden and severe worsening of their symptoms, known as an acute exacerbation (AE-IPF), which carries a high risk of mortality. Currently, doctors lack reliable bedside tools at the time of hospital admission to predict which patients will improve with standard care and which will require early escalation of treatment.

This prospective observational study aims to determine if simple, widely available blood tests can be used as biomarkers to predict patient outcomes during an acute exacerbation. Researchers will focus on complete blood count (CBC)-derived inflammatory indexes, which are calculated ratios of different types of blood cells (such as the neutrophil-to-lymphocyte ratio).

Participants hospitalized with AE-IPF will have their blood cell counts and oxygen levels (PaO2/FiO2 ratio) monitored on days 0 (admission), 3, 7, and 14. The study will evaluate the correlation between the change in these inflammatory indexes and the change in oxygen levels over the first week of hospitalization. Additionally, it will assess how accurately the admission blood test values, compared to the changes seen by day 3, can predict in-hospital clinical deterioration (such as the need for a ventilator, transfer to the intensive care unit, or death).

The aim is to find out if tracking changes in these simple blood test indexes can provide clinicians with a cost-effective, early-warning tool to guide treatment decisions for patients suffering from AE-IPF.

Inclusion Criteria:

• Age 18 years or older.
• Established diagnosis of idiopathic pulmonary fibrosis per the 2023 ATS/ERS/JRS/ALAT clinical practice guideline, based on a multidisciplinary assessment incorporating clinical features, high-resolution computed tomography pattern, and, where available, surgical lung biopsy.
• Hospital admission for acute exacerbation of IPF meeting the 2016 International Working Group criteria: previous or concurrent IPF diagnosis; acute worsening or development of dyspnea of less than one month duration; computed tomography showing new bilateral ground-glass abnormality or consolidation superimposed on a background pattern of usual interstitial pneumonia; deterioration not fully explained by cardiac failure or fluid overload and triggered exacerbations would be included.
• Admission within 72 hours of symptomatic worsening.
• Written informed consent from the patient or legally authorized representative.

Exclusion Criteria:

• Alternative explanation for acute respiratory deterioration confirmed at or shortly after admission, including but not limited to microbiologically confirmed bacterial pneumonia with positive blood or respiratory culture, computed-tomography-confirmed pulmonary embolism, cardiogenic pulmonary edema with elevated brain natriuretic peptide and supportive echocardiographic findings, or pneumothorax.
• Interstitial lung disease attributable to a defined cause: connective-tissue-disease-associated ILD, chronic hypersensitivity pneumonitis, occupational pneumoconiosis, sarcoidosis, or drug-induced ILD.
• Active solid or hematologic malignancy, including any malignancy under active treatment within the preceding 12 months.
• Receipt of cytotoxic chemotherapy, radiotherapy, or non-IPF immunosuppressive therapy (excluding maintenance corticosteroid at prednisolone-equivalent $\le$ 10 mg daily) within the preceding 30 days.
• Primary hematologic disorder altering the complete blood count, including leukemia, lymphoma, myelodysplastic syndrome, aplastic anemia, or known immune-mediated cytopenia.
• Anticipated transfer to another facility within 72 hours of admission.