Temporal evolution of C-reactive protein levels and its association with the incident hospitalization risk among individuals with stage 3-4 chronic kidney disease.

BACKGROUND: Elevated C-reactive protein (CRP) levels as an inflammatory marker have been associated with poor outcomes in patients with chronic kidney disease (CKD). However, its single assessment may not reflect clinical significance before an adverse clinical endpoint. We studied the CRP level trajectories, which may be related with the intensity of the inflammatory process, and its association with time-to-first hospitalization in CKD.
METHODS: A cohort of 739 patients with stage 3-4 CKD were retrospectively observed for seven years. The time-to-event outcome was all-cause hospitalization. Clinical and laboratory features were measured at baseline. Longitudinal changes in naturally logged CRP levels were modeled using the Joint Longitudinal-Survival model adjusted with baseline covariates.
RESULTS: Logged CRP changes were evaluated with a median measurement (interquartile range) of 4 (2, 7), during a median (interquartile range) follow-up of 2.3 (1.2, 3.9) years. The estimated mean increase in logged CRP was 0.35 mg/L per year. 299 (40.5%) patients reached the endpoint, and increase in logged CRP with time was associated with increased risk of hospitalization (HR 1.96; 95% CI 1.05-3.66; p = 0.034), but baseline logged CRP did not have a significant effect on the time-to-first hospitalization (HR 0.98; 95% CI 0.85-1.13; p = 0.736).
CONCLUSION: All-cause hospitalization was associated significantly with CRP trajectories. Temporal evolutions of these repeatedly measured biomarkers might predict clinical outcomes in patients with CKD and may be useful for individual risk profiling. Furthermore, early management may provide an opportunity to better patient survival.