Multiple Comorbid Conditions Identified as Risk Factors for Death in Severe COPD, Study Finds

The prevalence of comorbidities in patients with severe chronic obstructive pulmonary disease (COPD), including impaired kidney function, are predictors of long-term mortality, study finds.

Researchers found impaired kidney function may be an important risk factor for mortality in addition to other well-known comorbid predictors: high age, low body mass index (BMI), and poor lung function, in patients with chronic obstructive pulmonary disease (COPD). These factors should be taken into consideration when identifying and treating patients with severe chronic COPD, according to one study.

“The aim of the present study was to explore the frequency of several comorbid conditions in severe COPD, and to investigate and compare their associations with long-term mortality,” wrote the researchers of this study.

The results of this retrospective follow-up study were published in the European Clinical Respiratory Journal.

This study is a continuation of a prior study, which included 373 patients with COPD stage 3 or 4 in Sweden from May 2011 to March 2012. At the time of the present study, 241 patients could be identified as having mortality data from the Natural Cause of Death Register, in the years leading up to December 31, 2019.

The researchers collected physician data at baseline from of these patients, including medical records, sex, age, smoking history, bodyweight, height, current pharmacological treatment, and number of exacerbations in the recent year. Additionally, researchers collected data on the phenotype of patients’ chronic comorbid conditions for cardiovascular disease, diabetes, impaired kidney function, malnutrition, musculoskeletal symptoms, osteoporosis, or depression.

Of the total patients included in the follow-up, 155 (64%) were deceased at the end of the study period, in which 103 (66%) died of respiratory disease and 25 (16%) died of cardiovascular disease.

As a result, impaired kidney function was the only compound comorbid factor independently associated with an increased all-cause mortality (hazard ratio [HR], 3.41; 95% CI, 1.47-7.93; P = .004) and respiratory mortality (HR, 4.63; 95% CI, 1.61-13.4; P = .004).

Lastly, high age (≥70), low BMI (<22), and lower FEV1 expressed as % predicted, were significantly associated with increased all-cause mortality and respiratory mortality.

The researchers acknowledged some limitations to their study, including the fact that the definition for comorbid conditions was defined in an assessment by the responsible physician of existing pharmacologically and non-pharmacology treatments. Additionally, the diagnosis of patients with COPD was not confirmed by the lab or in examinations done by researchers of the study, which may have resulted in overdiagnosis.

Despite limitations or the fact that the number of patients who died from impaired kidney function was low, the researchers believe this study believe the study shows a clear and significant association with mortality. Furthermore, the researchers suggest future research should consider a possible association with mild and advanced renal failure and mortality.

“In addition to the well-known predictors high age, low BMI, and poor lung function; we demonstrate that impaired kidney function is an important predictor of long-term mortality in patients with severe COPD, which should be taken into account in the medical care of these patients,” concluded the researchers.

Reference

Eliasson G, Janson C, Johansson G, et al. Comorbid conditions as predictors of mortality in severe COPD – an eight-year follow-up cohort study. European Clinical Respiratory Journal. 2023;10(1). doi:10.1080/20018525.2023.2181291

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