Impact of acute kidney injury on in-hospital outcomes in Chinese patients with community acquired pneumonia

Background Acute kidney injury (AKI) is a frequent complication of community acquired pneumonia (CAP). However, the impact of AKI on in-hospital outcomes of patients with CAP in the Chinese population remains unclear. Methods Patients diagnosed with CAP were evaluated in this retrospective observational study. Multiple Cox regression models were employed to identify the association between AKI and in-hospital mortality and 30-day mortality, respectively. Results A total of 4213 patients were recruited; 950 (22.5%) patients were diagnosed with AKI. Independent risk factors for AKI were age, male gender, hypertension, cardiac dysfunction, diabetes, chronic kidney disease, acute respiratory failure, use of diuretics, use of vasoactive drugs, and CURB-65. Cox proportional hazards regression revealed AKI, use of angiotensin receptor blocker, hypertension, CURB-65, acute respiratory failure, and use of vasoactive drugs to be independent risk factors for both in-hospital and 30-day mortality. Compared to patients without AKI, those suffering AKI were found to have 1.31-fold (HR 1.31, 95% CI, 1.04–1.66; P = 0.023) and 1.29-fold (HR 1.29, 95% CI, 1.02–1.62; P = 0.033) increased in-hospital and 30-day mortality risks, respectively. In addition, patients with AKI were likely to require admission to intensive care unit (ICU) (42.9% versus 11.4%; P < 0.001), mechanical ventilation (33.8% versus 9.3%; P < 0.001), invasive mechanical ventilation (25.9% versus 5.8%; P < 0.001), non-invasive mechanical ventilation (25.4% versus 7.1%; P < 0.001), and experienced a longer duration of hospital stay (14 days versus 10 days; P < 0.001) than those without AKI. However, no significant difference in ICU stay (11 days versus 10 days; P = 0.099) and duration of mechanical ventilation (8 days versus 8 days; P = 0.369) between AKI and non-AKI groups was found. Conclusion AKI was common in Chinese patients with CAP. Patients with CAP who developed AKI had worse in-hospital outcomes.