Five comorbidities reflected the health status in patients with chronic obstructive pulmonary disease: the newly developed COMCOLD index.
OBJECTIVE
This study aimed to identify those comorbidities with greatest impact on patient-reported health status in patients with chronic obstructive pulmonary disease (COPD) and to develop a comorbidity index that reflects their combined impact.


METHODS
We included 408 Swiss and Dutch primary care patients with COPD from the International Collaborative Effort on Chronic Obstructive Lung Disease: Exacerbation Risk Index Cohorts (ICE COLD ERIC) in this cross-sectional analysis. Primary outcome was the Feeling Thermometer, a patient-reported health status instrument. We assessed the impact of comorbidities at five cohort assessment times using multiple linear regression adjusted for FEV1, retaining comorbidities with associations P ≤ 0.1. We developed an index that reflects strength of association of comorbidities with health status.


RESULTS
Depression (prevalence: 13.0%; regression coefficient: -9.00; 95% CI: -13.52, -4.48), anxiety (prevalence: 11.8%; regression coefficient: -5.53; 95% CI -10.25, -0.81), peripheral artery disease (prevalence: 6.4%; regression coefficient: -5.02; 95% CI-10.64, 0.60), cerebrovascular disease (prevalence: 8.8%; regression coefficient: -4.57; 95% CI -9.43, 0.29), and symptomatic heart disease (prevalence: 20.3%; regression coefficient: -3.81; 95% CI -7.23, -0.39) were most strongly associated with the Feeling Thermometer. These five comorbidities, weighted, compose the COMorbidities in Chronic Obstructive Lung Disease (COMCOLD) index.


CONCLUSIONS
The COMCOLD index reflects the combined impact of five important comorbidities from patients' perspective and complements existing comorbidity indices that predict death. It may help clinicians focus on comorbidities affecting patients' health status the most.
Institute of Social and Preventive Medicine, Department of Epidemiology, University of Zurich, Hirschengraben 84, 8001 Zurich, Switzerland; Institute of General Practice and Health Services Research, University of Zurich, Pestalozzistrasse 24, 8091 Zurich, Switzerland. Electronic address: Anja.Frei@ifspm.uzh.ch.
Anja
A
Frei
Horten Centre for Patient-Oriented Research, University of Zurich, Pestalozzistrasse 24, 8091 Zurich, Switzerland.
Patrick
P
Muggensturm
Division of Pulmonary & Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, 5501 Hopkins Bayview Circle JHAAC 4B.74, Baltimore, MD, 21224 USA.
Nirupama
N
Putcha
Department of General Practice, Academic Medical Centre, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands.
Lara
L
Siebeling
Institute of General Practice and Health Services Research, University of Zurich, Pestalozzistrasse 24, 8091 Zurich, Switzerland.
Marco
M
Zoller
Division of Geriatric Medicine and Gerontology, Department of Medicine, Johns Hopkins University School of Medicine, Center on Aging and Health 5200 Eastern Avenue Center Tower, 7th Floor, Mason F. Lord Building, Baltimore, MD, 21224 USA.
Cynthia M
CM
Boyd
Department of General Practice, Academic Medical Centre, University of Amsterdam, Meibergdreef 15, 1105 AZ, Amsterdam, The Netherlands.
Gerben
G
ter Riet
Institute of Social and Preventive Medicine, Department of Epidemiology, University of Zurich, Hirschengraben 84, 8001 Zurich, Switzerland; Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe St, Room E6153, Baltimore, MD, 21205 USA.
Milo A
MA
Puhan
D000368:Aged; D001007:Anxiety / Q000453:epidemiology* / Q000209:etiology; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000209:etiology; D015331:Cohort Studies; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003863:Depression / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000453:epidemiology*; D012044:Regression Analysis; D013557:Switzerland / Q000453:epidemiology
Chronic obstructive; Comorbidity; Comorbidity index; Health status; Health-related quality of life; Patient-reported outcome; Pulmonary disease