Prognostic Nomogram Stratifies Patients in ICU With Acute Exacerbation of COPD

A prognostic nomogram to assist with stratifying patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in the intensive care unit (ICU) has been developed and internally validated by researchers, who published the nomogram and supporting research in BMC Pulmonary Medicine. 

Recognizing that AECOPD contributes significantly to mortality among patients with COPD in the ICU, researchers sought to identify risk factors associated with 30-day mortality in patients with AECOPD admitted to ICU, and to use these risk factors — along with information on patient status at ICU admission — to create a prognostic nomogram. 

The researchers conducted a retrospective cohort study using data on patients admitted to the ICU at Beth Israel Deaconess Medical Center in Boston, Massachusetts, between 2001 and 2012, from the Medical Information Mart for Intensive Care III (MMIC-III) public database. Data from 494 adult patients (mean age, 70.8 years; 50.2% male) diagnosed with AECOPD were included in the study. Analysis of patient data found a mortality rate of 15.6% among patients studied. 

With respect to mortality risk factors, the analysis found that patients who died in the ICU tended to be older compared with those who survived (75.3±8.6 years vs 69.9±10.5 years, respectively; P <.001). Additional independent risk factors associated with 30-day ICU mortality were partial pressure of oxygen, neutrophil-to-lymphocyte ratio, prognostic nutritional index, invasive mechanical ventilation, and use of vasopressors. The 6 identified risk factors were then used to develop the nomogram via multivariate logistic regression based on Akaike information criterion. 

A bootstrap resampling approach with 1000 replications was used to perform internal validation of the nomogram. Harrell’s concordance index (C-index) and Hosmer–Lemeshow (HL) goodness-of-fit test were used for assessment of the discrimination and calibration of the nomogram. Researchers found that the adjusted C-index was 0.745 (95% CI, 0.712-0.778) with good calibration (HL test, P =.147). Kaplan-Meier survival curves demonstrated a significantly lower probability of survival in the high-risk group (ie, the 15.6% of patients who did not survive) compared with the low-risk group (P <.001), thus indicating the substantial discriminatory probability of the nomogram for stratification of participants’ risk. Decision curve analysis demonstrated that the nomogram was clinically useful.

Some limitations of the analysis should be noted, including substantial missing data on patients’ BMI, selection bias due to use of data from a single institution, and lack of external validation, which limits the generalizability of the nomogram.  

The researchers concluded that multicenter prospective studies are warranted to further explore the clinical application and usefulness of this nomogram.

Reference

Peng J-C, Gong W-W, Wu Y, Yan T-Y, Jiang X-Y. Development and validation of a prognostic nomogram among patients with acute exacerbation of chronic obstructive pulmonary disease in intensive care unit. BMC Pulm Med. 2022;22(1):306. doi:10.1186/s12890-022-02100-0