Relationship Between Systemic Immune-Inflammation Index and Risk of Respiratory Failure and Death in COPD: A Retrospective Cohort Study Based on the MIMIC-IV Database

Abstract

Purpose

Chronic obstructive pulmonary disease (COPD) concurrent with respiratory failure (RF) is devastating, and may result in death and disability. Systemic immune-inflammation index (SII) is a new prognostic biomarker linked to unfavorable outcomes of acute coronary syndrome, ischemic stroke, and heart failure. Nonetheless, its role in COPD is rarely investigated. Consequently, this study intends to assess the accuracy of SII in predicting the prognosis of COPD.

Patients and Methods

The clinical information was retrospectively acquired from the Medical Information Mart for Intensive Care-IV database. The outcomes encompassed the incidence of RF and mortality. The relationship between different SII and outcomes was examined utilizing the Cox proportional-hazards model and restricted cubic splines. Kaplan-Meier analysis was employed for all-cause mortality.

Results

The present study incorporated 1653 patients. During hospitalization, 697 patients (42.2%) developed RF, and 169 patients (10.2%) died. And 637 patients (38.5%) died during long-term follow-up. Higher SII increased the risk of RF (RF: HR: 1.19, 95% CI 1.12–1.28, P<0.001), in-hospital mortality (HR: 1.22, 95% CI 1.07–1.39, P=0.003), and long-term follow-up mortality (HR: 1.12, 95% CI 1.05–1.19, P<0.001). Kaplan-Meier analysis suggested a significantly elevated risk of all-cause death (log-rank P<0.001) in patients with higher SII, especially during the short-term follow-up period of 21 days.

Conclusion

SII is closely linked to an elevated risk of RF and death in COPD patients. It appears to be a potential predictor of the prognosis of COPD patients, which is helpful for the risk stratification of this population. However, more prospective studies are warranted to consolidate our conclusion.

Keywords:

• systemic immune-inflammation index
• chronic obstructive pulmonary disease
• respiratory failure
• mortality
• MIMIC-IV database

Abbreviations

COPD, chronic obstructive pulmonary disease; SII, Systemic immune-inflammation index; MIMIC-IV, Medical Information Mart for Intensive Care IV; RF, Respiratory failure; HRF, hypercapnic Respiratory failure; SOFA, The sequential organ failure assessment; HF, Heart failure; SOFA, Sequential organ failure assessment; APSIII, Acute physiology score III; SAPSII, Simplified acute physiological score II; CHD, Coronary heart disease; AF, Atrial fibrillation; DM, Diabetes mellitus; CKD, Chronic kidney disease; AKI, Acute kidney injury; IQR, Interquartile range; PSM, Propensity score matching; RCS, Restricted cubic spline; BMI, Body mass index; RBC, Red blood cell; ICU, Intensive care unit; ICD-9, The ninth revision of the International Classification of Diseases; ICD-10, The tenth revision of the International Classification of Diseases; NT-proBNP, N-terminal pro brain natriuretic peptide; AMI, Acute myocardial infarction; HR, Hazard ratio; CI, Confidence interval; N, Number; Q, Quartile; RR, Respiratory rate; MBP, Mean blood pressure; SpO2, Saturation of peripheral oxygen; IHD, Ischemic heart disease; WBC, White blood cell; RDW, Red cell distribution width; Scr, Serum creatinine; BUN, Blood urea nitrogen; CRP, C-reactive protein; CRRT, Continuous renal replacement therapy; OASIS, Oxford acute severity of illness; LOS, length of stay; MIT, the Massachusetts Institute of Technology; BIDMC, the Beth Israel Deaconess Medical Center; PaO2, arterial oxygen partial pressure; FiO2, fractions of inspired oxygen; CO2, carbon dioxide.

Data Sharing Statement

Relevant data were retrospectively acquired from the Medical Information Mart for Intensive Care-IV (MIMIC-IV version 2.2) database (https://physionet.org/content/mimiciv/2.2/).

Ethics Approval and Informed Consent

This project was approved by the institutional review committee of MIT and BIDMC. All the protected private information of patients has been de-identified. Ethical approval for this study was obtained from the Medical Research Ethics Committee of The First Hospital of Jiaxing (No. 2023-LY-633).

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors declare that they have no conflicts of interest in this work.

Additional information

Funding

This study was supported by Scientific Technology Plan Program for Healthcare in Zhejiang Province (NO. 2021KY1100), Jiaxing Science and Technology Plan Project (NO. 2022AD30055), the Key Discipline of JiaxingGenral Practice Medicine Construction Project (No.2023-fc-002), Key Construction Disciplines of Provincial and Municipal Co construction of Zhejiang [NO.2023-SSGJ-002].