Prognostic value of peripheral immune cell ratios and outcomes in bronchiectasis

SUMMARY BACKGROUND Easy-to-interpret peripheral blood biomarkers, or their combination with a discriminatory capacity for severity or prognosis, are needed in bronchiectasis. We aimed to analyse the clinical and prognostic values of the peripheral immune cell ratios (PICRs). METHODS Historical cohort series (n = 2.057) from the Spanish Registry of Bronchiectasis. General, clinical, etiological, complementary test, peripheral biomarkers, functional, microbiological, and therapeutic were collected. PICRs are composed of four cell types or molecules (SII = systemic inflammatory index; SIRI = systemic inflammatory response index; HALP = haemoglobin–albumin–lymphocyte–platelets index; and PIV = pan-immune-inflammation ratio). Outcomes to be analysed were exacerbations, severity, chronic bronchial infection (CBI) by Pseudomonas aeruginosa ( PA ), and 7-year long-term mortality. RESULTS Four-hundred eight patients died during follow-up. Multivariable regression was used to determine the independent relationship between the different baseline PICRs and exacerbations, severity, CBI by PA , and long-term mortality of bronchiectasis. SIRI was the unique PICR independently associated with all outcomes with an area under the receiver operating characteristic curve of 0.82 (95% confidence interval: 0.80–0.85). CONCLUSION SIRI is an inexpensive and easy-to-measure marker of systemic inflammation for determining severity, CBI by PA , exacerbations, and mortality in patients with bronchiectasis.