Risk of pneumonia among patients with chronic kidney disease in outpatient and inpatient settings

Patients with chronic kidney disease (CKD) are more at risk for pneumonia than the general population. Patients with pneumonia are usually treated as outpatients. However, previous studies were conducted on the basis of inpatient pneumonia. This method may underestimate the risk of pneumonia in patients with CKD. Therefore, we investigated the risk of pneumonia among CKD patients in both outpatient and inpatient settings. A total of 15, 562 patients with CKD and 62, 109 individuals without CKD (matched for age and gender) were taken as subjects in the Longitudinal Health Insurance Database of Taiwan National Insurance from 1996 to 2010. The incidence density rates of inpatient and outpatient pneumonia were calculated. The risk factors associated with pneumonia were analyzed using Cox proportional hazard models with adjustments for confounders. The incidence density rate of pneumonia was 65.6 per 1000 personyears in patients with CKD and 28.4 per 1000 person-years in individuals without CKD. The incidence density rate of inpatient pneumonia was 43.3 per 1000 person-years in patients with CKD and 16.6 per 1000 person-years in individuals without CKD. CKD was associated with increased risk of pneumonia (adjusted hazard ratio [aHR], 1.97; 95% confidence interval [CI], 1.89-2.05; P<0.001), outpatient pneumonia (aHR, 1.40; 95% CI, 1.31-1.49), and inpatient pneumonia (aHR, 2.17; 95% CI, 2.07-2.29, P<0.001). Patients' comorbidities, including diabetes, cardiovascular disease (CVD), asthma, and chronic obstructive pulmonary disease (COPD), were independently associated with increased risk of pneumonia. CKD is associated with the increased risk of both outpatient and inpatient pneumonia. This association is independent of comorbid diabetes, CVD, asthma, and COPD.