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. 2024 Dec 19;25(1):437.
doi: 10.1186/s12931-024-03071-y.

Longitudinal anemia status and risk for adverse outcomes in former smokers with COPD

Yukiko Kunitomo  1 , Han Woo  1 , Aparna Balasubramanian  1 , Ashraf Fawzy  1 , Cheng Ting Lin  2 , Sarath Raju  1 , Daniel C Belz  1 , Meredith C McCormack  1 , Kirsten Koehler  3 , Nadia N Hansel  1 , Nirupama Putcha  4
Affiliations

Longitudinal anemia status and risk for adverse outcomes in former smokers with COPD

Yukiko Kunitomo et al. Respir Res. .

Abstract

Background: Anemia is a prevalent comorbidity in COPD associated with increased morbidity. However, the significance of longitudinal anemia status and variation in anemia status trends over time in COPD are not known. Furthermore, individuals with COPD and smoking history often have multiple comorbidities, in particular cardiovascular disease. The objective of this study was to evaluate the association between longitudinal anemia status and COPD outcomes, accounting for comorbid cardiovascular disease.

Methods: Serial hemoglobin measures and clinical outcomes were obtained in former smokers with moderate to severe COPD from two clinical studies over a 6-to-9-month period. In the first analysis, the association between repeated measures of time-varying anemia status and outcomes was assessed by generalized estimating equations adjusted for covariates including cardiovascular disease. In the second analysis, each participant's anemia risk profile during the study period was characterized as high versus low anemia risk-growth rate. Mean differences in the progression of COPD outcomes over time between the two groups were assessed using a generalized linear mixed model. Effect modification by baseline coronary artery calcium (CAC) burden was explored.

Results: There were 159 individuals with mean age of 66.5 years (± 8.3) and mean FEV1% predicted of 51.4% (± 17.0), of which 41% were ever-anemic during the study period. Repeated measures of anemia status were associated with higher St. George's Respiratory Questionnaire (SGRQ) scores (β 2.5, 95% CI: 0.1,4.8, p = 0.04), lower 6-minute walk distance (6MWD) (β -38.6, 95% CI: -67.7,-7.4, p = 0.02), and higher rate of moderate-to-severe exacerbations over the prospective follow-up period (IRR 1.8, 95% CI: 1.1,2.8, p = 0.02). There was effect modification by CAC burden such that with higher burden the mean difference in COPD outcome by anemia status was greater for a subset of symptom scores. Participants with profiles of increasing anemia risk had higher estimated rates of decline in the FEV1% predicted and 6MWD and increase in SGRQ scores compared to those with stable or decreasing anemia risk.

Conclusions: Longitudinal anemia status trends may be predictive of COPD disease trajectory. Anemia status by repeated measures analysis is associated with COPD morbidity with potentially stronger associations in the setting of high CAC burden.

Keywords: Anemia; COPD; Comorbidity; Longitudinal analysis.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Informed consent was obtained from all participants in Clinical Trial of Air Cleaners to Improve Indoor Air Quality and COPD Health (CLEAN AIR, clinicaltrials.gov #NCT02236858, registration date 9/11/2014) and Obesity and Adverse Dietary Patterns as Susceptibility Factors to Pollutant Exposure in Urban COPD (CURE COPD). Both studies were approved by the Johns Hopkins Institutional Review Board (ID#: NA_00085617, IRB0069904) and conducted in accordance with the Declaration of Helsinki. Consent for publication: Not applicable. Competing interests: The authors declare they have no competing interests. Clinical trial number: Not applicable. However, part of the data utilized in this study was obtained from a previously completed clinical trial: CLEAN AIR, clinicaltrials.gov #NCT02236858, registration date 9/11/2014.

Figures

Fig. 1
Fig. 1
Predicted mean difference in symptom score with 95% confidence interval for repeated measures anemia vs. non-anemia, by CAC burden as measured by continuous baseline Agatston score. (Abbreviations: Pintx=p-value for interaction term)
Fig. 2
Fig. 2
Comparison of estimated change in COPD outcomes over time between participants with high anemia risk-growth rate (n = 37) versus low anemia risk-growth rate (n = 114)
See this image and copyright information in PMC

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