Background: While acute kidney injury (AKI) alone is associated with increased mortality, the incidence of hospital admission with acute kidney injury (AKI) among stable and exacerbating chronic obstructive pulmonary disease (COPD) patients and the effect of concurrent AKI at COPD exacerbation on mortality is not known.
Methods: 189,561 individuals with COPD were identified from the Clinical Practice Research Datalink (CPRD). Using Poisson and logistic regression we explored which factors predicted admission for acute kidney injury (AKI) (identified in Hospital Episode Statistics (HES)) in this COPD cohort, and concomitant AKI at a hospitalisation for COPD exacerbation. Using survival analysis we investigated the effect of concurrent AKI at exacerbation on mortality (n=36,107), and identified confounding factors.
Results: The incidence of AKI in the total COPD cohort was 128 per 100,000 person-years. The prevalence of concomitant AKI at exacerbation was 1.9% and the mortality rate in patients with AKI and an exacerbation was 521 per 1,000 person-years. Male gender, older age, and lower glomerular filtration rate predicted higher risk of AKI or death. There was a 1.80 fold (95%CI:1.61,2.03) increase in adjusted mortality within the first 6 months post COPD exacerbation in patients suffering AKI and COPD exacerbation compared to those who were AKI-free.
Conclusion: In comparison to previous studies on general populations and hospitalisations, the incidence and prevalence of AKI is relatively high in COPD patients. Coexisting AKI at exacerbation is prognostic of poor outcome.