Temporal discrepancies in the association between the apoB/apoA-I ratio and mortality in incident dialysis patients.

BACKGROUND: In the general population, a high apoB/apoA-I ratio is a strong risk factor for cardiovascular disease and mortality. However, whether this is the case in chronic kidney disease (CKD) patients is currently unknown. STUDY DESIGN: The apoB/apoA-I ratio was evaluated in 391 incident CKD stage 5 patients examined close to dialysis initiation, and again after 1 year of dialysis in a subgroup of 182 patients, subsequently followed for up to 3 years. RESULTS: Baseline values of the apoB/apoA-I ratio as well as changes in the ratio during the first year of dialysis correlated with body mass index (BMI) and fat mass. The baseline apoB/apoA-I ratio showed no association with 4-year mortality. However, after adjustment for confounders, a high apoB/apoA-I ratio (>0.9) predicted short-term (first year) survival [hazard ratio (HR): 0.35; 95% confidence interval (CI): 0.13-0.85)] and long-term (next 3 years) mortality (HR: 1.72; 95% CI: 1.01-2.96). An increase in the apoB/apoA-I ratio during the first year of dialysis was linked to a survival advantage thereafter (HR: 0.48; 95% CI: 0.22-0.98). However, this association lost its significance (HR: 0.62; 95% CI: 0.26-1.36) after adjustment for indices of protein-energy wasting. CONCLUSIONS: A high apoB/apoA-I ratio and an increase in this ratio during the first year on dialysis were associated with short-term survival advantage in CKD patients. This paradoxical relationship represents an example of the so-called reverse epidemiology phenomenon in CKD patients and suggests that the apoB/apoA-I ratio should always be interpreted with caution in this patient population.