Clusters of Comorbidities Based on Validated Objective Measurements and Systemic Inflammation in Patients with Chronic Obstructive Pulmonary Disease

To cluster 13 clinically important objectively identified comorbidities, and to characterize the comorbidity clusters in terms of clinical outcomes and systemic inflammation.

A total of 213 patients with COPD (FEV1, 51 ± 17% predicted; men, 59%; age, 64 ± 7 yr) were included prospectively. Comorbidities were based on well-known cut-offs identified in the peer-reviewed English literature. Systemic inflammatory biomarkers were determined in all patients. Self-organizing maps were used to generate comorbidity clusters. MEASUREMENTS AND MAIN RESULTS: A total of 97.7% of all patients had one or more comorbidities and 53.5% had four or more comorbidities. Five comorbidity clusters were identified: (1) less comorbidity, (2) cardiovascular, (3) cachectic, (4) metabolic, and (5) psychological. Comorbidity clusters differed in health status but were comparable with respect to disease severity. An increased inflammatory state was observed only for tumor necrosis factor (TNF) receptors in the metabolic cluster (geometric mean [lower and upper limit]; TNF-R1, 2,377 [1,850, 3,055] pg/ml, confidence, 98.5%; TNF-R2, 4,080 [3,115, 5,344] pg/ml, confidence, 98.8%) and only for IL-6 in the cardiovascular cluster (IL-6, 3.4 [1.8, 6.6] pg/ml; confidence, 99.8%).