According to a study published in the American Journal of Respiratory and Critical Care Medicine, decreasing alpha diversity in the microbiome profile of sputum samples from patients hospitalized with chronic obstructive pulmonary disease acute exacerbations (AECOPD) was associated with increased 1-year mortality. These findings demonstrate that the microbiome may offer predictive potential for prognosis in AECOPD.
A total of 102 patients who were hospitalized for AECOPD and had sputum samples collected at time of AECOPD were enrolled. Investigators followed each patient for up to 1 year after hospital discharge. For the purposes of this study, the researchers compared survivors with patients who did not survive. Sequencing of 16S rRNA gene was used to assess the microbiome profile. In addition, Cox proportional-hazards regression models were used to assess the effect of taxa features and alpha diversity measures on time to death.
Lower alpha diversity values were observed in patients who did not survive vs survivors (18.6% vs 81.4%, respectively). In addition, there was an observable trend toward a higher frequency of long-term oxygen therapy in patients who did not survive compared with survivors (31.6% vs 14.5%, respectively; P =.08). Significant differences were observed between the 2 groups in terms of beta diversity (P =.010).
Survivors also had a higher amount of Veillonella in sputum samples, whereas patients who did not survive had higher Staphylococcus levels. Lower survival was noted in patients with sputum samples negative for Veillonella (hazard ratio, 13.5; 95% CI, 4.2-43.9; P <.001) and positive for Staphylococcus (hazard ratio, 7.3; 95% CI, 1.6-33.2; P =.01). Decreasing alpha diversity was associated with increased 1-year mortality risk.
Limitations of the analysis included the relatively small number of patients, as well as the collection of sputum samples at only 1 point in time.
The researchers suggested that additional prospective trials are required to “confirm these findings and to investigate whether suppressive treatment against specific bacterial taxa identified in sputum or other specimens may modify the outcomes of COPD patients.”
Leitao Filho FS, Alotaibi NM, Ngan D, et al. Sputum microbiome is associated with 1-year mortality following COPD hospitalizations [published online October 30, 2018]. Am J Respir Crit Care Med. doi:10.1164/rccm.201806-1135OC