Psychological, cachectic comorbidities up death risk, exacerbations in COPD

Individuals with potential chronic obstructive pulmonary disease (COPD) in the psychological and cachectic clusters appear to be at increased risk of mortality over 25 years of follow-up, according to a population-based Norwegian study. In addition, these clusters appear to increase the risk of severe COPD exacerbations.

The authors recruited participants with potential COPD from the second (1995‒1997) and third (2006‒2008) survey of the HUNT Study and followed them until April 2020. They clustered 10 comorbidities using self-organizing maps and assessed severe COPD exacerbations requiring hospitalization using hospital data. All-cause mortality data were obtained from national registries.

Hazard ratios (HRs) with 95 percent confidence intervals (CIs) for the association between comorbidity clusters and all-cause mortality were calculated using multivariable Cox regression, while incidence rate ratios (IRRs) for the cumulative number of severe exacerbations for each cluster were estimated using Poisson regression.

The authors identified five distinct clusters, namely ‘less comorbidity’, ‘psychological’, ‘cardiovascular’, ‘metabolic’, and ‘cachectic’ clusters.

Using the less comorbidity cluster as the reference, the psychological (adjusted HR, 1.23, 95 percent CI, 1.04‒1.45) and cachectic clusters (adjusted HR, 1.83, 95 percent CI, 1.52‒2.20) correlated with all-cause mortality. These two clusters also contributed to an increased risk of COPD exacerbations (psychological cluster: unadjusted IRR, 1.24, 95 percent CI, 1.04‒1.48; cachectic cluster: unadjusted IRR, 1.50, 95 percent CI, 1.23‒1.83).

“COPD is a heterogeneous disease often viewed as part of a multimorbidity complex,” the authors said. “There is a need for better phenotyping of the disease, characterization of its interplay with other comorbidities and its association with long-term outcomes.”