Bronchial Hyperresponsiveness in Sarcoidosis

This was an observational, analytical, cross-sectional study with a retrospective component. The prospective component of the study assessed BHR using methacholine bronchial challenge testing in patients with established sarcoidosis.

Of the 81 patients with sarcoidosis assessed for eligibility, 70 were ultimately included in the study, having met all inclusion criteria and none of the exclusion criteria. The study protocol was developed in accordance with ATS/ERS recommendations. A 2-minute tidal breathing method with continuous inhalation of progressively increasing methacholine concentrations was used. Patients who exhibited less than a 20% decline in FEV1 at concentrations above 16 mg/ml were classified as having normal bronchial responsiveness. Based on the methacholine bronchial challenge test results, participants were classified into two groups according to the presence or absence of bronchial hyperresponsiveness. The groups were subsequently compared with respect to restrospectively obtained data (age, gender, smoking status, comorbidities, laboratory parameters, and skin prick test results to inhalant allergens). Assessed laboratory parameters included C-reactive protein serum levels, ionized and total serum calcium, and 24-hour urinary calcium excretion.

The groups were additionally compared with respect to the radiological findings (obtained retrospectively). Radiological phenotypes were classified according to the predominant pattern of pulmonary abnormalities observed on chest HRCT, using a seven-category (1-7) Delphi HRCT Phenotype Classification designed in 2024. Sarcoidosis stages were determined according to the Scadding classification (stages 0-IV), both at the time of initial diagnosis and at the time of methacholine challenge testing. HRCT findings were used to improve the accuracy of radiological assessment compared to conventional chest radiography. Changes in pulmonary parenchymal abnormalities over time were classified as radiological progression, regression, stability, or de novo presentation. This assessment was based on chest HRCT examinations performed at the time of methacholine challenge testing and compared with previous examinations obtained 6-12 months earlier during follow-up hospital admissions. Patients diagnosed with sarcoidosis less than one week before methacholine challenge testing were classified as de novo cases, whereas patients diagnosed at least six months earlier were classified as having pre-existing sarcoidosis. Radiological phenotypes, Scadding stages, and changes in radiological findings over time were jointly assessed by two pulmonologists and one radiologist. Consensus was reached on all classifications reported in the study.

In the group with a positive metacholine test result, the analysis included an assessment of bronchial hyperresponsiveness severity in relation to all the parameters.