The risk of infection-related hospitalization with decreased kidney function

Background: Moderate kidney disease may predispose to infection. We sought to determine whether decreased kidney function, estimated by serum cystatin C level, was associated with the risk of infection-related hospitalization in older individuals. Study Design: Cohort study. Setting & Participants: 5,142 Cardiovascular Health Study (CHS) participants with measured serum creatinine and cystatin C and without estimated glomerular filtration rate (eGFR) <15 mL/min/1.73 m ² at enrollment. Predictor: The primary exposure of interest was eGFR using serum cystatin C level (eGFR _SCysC). Outcome: Infection-related hospitalizations during a median follow-up of 11.5 years. Results: In adjusted analyses, eGFR _SCysC categories of 60-89, 45-59, and 15-44 mL/min/1.73 m ² were associated with 16%, 37%, and 64% greater risk of all-cause infection-related hospitalization, respectively, compared with eGFR _SCysC <90 mL/min/1.73 m ². When cause-specific infection was examined, eGFR _SCysC of 15-44 mL/min/1.73 m ² was associated with an 80% greater risk of pulmonary and 160% greater risk of genitourinary infection compared with eGFR _SCysC <90 mL/min/1.73 m ². Limitations: No measures of urinary protein, study limited to principal discharge diagnosis. Conclusions: Lower kidney function, estimated using cystatin C level, was associated with a linear and graded risk of infection-related hospitalization. These findings highlight that even moderate degrees of decreased kidney function are associated with clinically significant higher risks of serious infection in older individuals.