Published: 10 February 2022

Authors: Sigrid Anna Aalberg Vikjord, Ben Michael Brumpton, Xiao-Mei Mai, Solfrid Romundstad, Arnulf Langhammer, Lowie Vanfleteren

Source: This abstract has been sourced from NZ Respiratory Research Review Issue 198


    Background and objective

    Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease often viewed as part of a multimorbidity complex. There is a need for better phenotyping of the disease, characterization of its interplay with other comorbidities and its association with long-term outcomes. This study aims to examine how clusters of comorbidities are associated with severe exacerbations and mortality in COPD.


    Participants with potential COPD were recruited from the second (1995–1997) and third (2006–2008) survey of the HUNT Study and followed up until April 2020. Ten objectively identified comorbidities were clustered using self-organizing maps. Severe COPD exacerbations requiring hospitalization were assessed using hospital data. All-cause mortality was collected from national registries. Multivariable Cox regression was used to calculate hazard ratios (HRs) with 95% CIs for the association between comorbidity clusters and all-cause mortality. Poisson regression was used to calculate incidence rate ratios (IRRs) with 95% CI for the cumulative number of severe exacerbations for each cluster.


    Five distinct clusters were identified, including ‘less comorbidity’, ‘psychological’, ‘cardiovascular’, ‘metabolic’ and ‘cachectic’ clusters. Using the less comorbidity cluster as reference, the psychological and cachectic clusters were associated with all-cause mortality (HR 1.23 [1.04–1.45] and HR 1.83 [1.52–2.20], adjusted for age and sex). The same clusters also had increased risk of exacerbations (unadjusted IRR of 1.24 [95% CI 1.04–1.48] and 1.50 [95% CI 1.23–1.83], respectively).


    During 25 years of follow-up, individuals in the psychological and cachectic clusters had increased mortality. Furthermore, these clusters were associated with increased risk of severe COPD exacerbations.

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