Mortality in COPD Post Hospitalization for Pneumonia vs Exacerbation

In patients with chronic obstructive pulmonary disease (COPD), the 30-day risk of death was higher after hospitalization for pneumonia than after hospitalization for a severe COPD exacerbation. This finding was reported by a group of researchers from the UK, US, and Canada in a recent research letter published in the European Respiratory Journal.

The researchers compared mortality in COPD following hospitalization for exacerbation vs pneumonia using data from the Salford Lung Study (SLS), a large, phase 3 randomized United Kingdom study assessing safety and effectiveness of once-daily combined fluticasone furoate and vilanterol for COPD. The analysis found that a persistently elevated risk of mortality after 30 days was seen only in patients in whom independent radiological assessment confirmed the diagnosis of pneumonia.

The original SLS recruited 2799 patients age 40 years or older with a documented diagnosis of COPD made by a general practitioner and 1 or more COPD exacerbations in the previous 3 years. All patients took standard maintenance inhaler therapy. The mean age was 67 years, the mean FEV₁ was 1.62 liters, and 49% of participants were women. For the current study, the researchers combined all inhaled corticosteroid (ICS) patients so that a sufficient number of events could be analyzed.

In the SLS, criteria for a severe exacerbation included hospital admission and a diagnosis of exacerbation. Admission for pneumonia was established by the initial diagnosis made by the treating physician. For the authors’ added classification analysis, diagnosis was based on a radiologist’s evaluation of the chest radiograph.

Of the original 2799 SLS patients, 111 were admitted to the hospital with an initial diagnosis of a COPD exacerbation and 86 were admitted with an original diagnosis of pneumonia. Patients admitted with pneumonia were chiefly male but less often current smokers, compared with patients admitted for COPD exacerbation or not admitted. Of patients admitted with COPD, 60% experienced severe or very severe COPD, as did 47% of those admitted with pneumonia. A history of 2 or more exacerbations as well as cardiac comorbidity in the year before the study period were more prevalent in patients admitted with COPD (77% and 47%, respectively) than in those with pneumonia (53% and 42%).

Among the 111 patients hospitalized for an exacerbation, 8 (7%) expired during the 6-month follow-up, whereas 14 (16%) of the 86 with a pneumonia admission died. Using a Cox regression model with the covariates age, sex, exacerbation history, use of ICS at study entry, score from the COPD Assessment Test, and smoking status, the investigators found that hazard ratios for mortality within 30 days of hospitalization were 29.6 (95% CI, 12.5-69.9) for an exacerbation admission and 176.8 (95% CI,102.6-304.7) for a pneumonia admission. In a comparable model examining mortality 31 to 180 days after hospital admission, hazard ratios were 0.85 (0.1-6.2) for an exacerbation admission and 11.6 (5.1-26.3) for a pneumonia admission. Deaths continued to occur in the months after the index hospitalization, but the risk of death continued to rise for roughly 3 months.

Shortcomings of the SLS data include the use of varying diagnostic procedures, differences in clinicians’ diagnostic evaluations, and the effect of later readmissions. A shortcoming of the current analysis is that 90% of individuals studied were treated with ICS because of the study design, so the added risk from ICS could not be measured.

“The impact of a radiologist’s diagnosis of an infiltrate consistent with pneumonia was significant and important for prognosis,” the authors of the research letter noted. “This has implications for clinical care as the importance of a distinction between an exacerbation and a pneumonia is rarely highlighted and is a salient lesson for interpreting past and future studies of pneumonia in the setting of COPD,” they advised.

Disclosure: Multiple authors declared affiliations with the pharmaceutical industries. Please refer to the original article for a full list of disclosures. The study was fully funded by GlaxoSmithKline plc.

Reference

Vestbo J, Waterer G, Leather D, et al. Mortality after admission with pneumonia is higher than after admission with an exacerbation of COPD. Eur Respir J. Published online March 10, 2022. doi:10.1183/13993003.02899-2021