Serum creatinine level, a surrogate of muscle mass, predicts mortality in peritoneal dialysis patients

In hemodialysis patients, higher serum creatinine (Cr) concentration represents larger muscle mass and predicts greater survival. However, this association remains uncertain in peritoneal dialysis (PD) patients.

In a cohort of 10 896 PD patients enrolled from 1 July 2001 to 30 June 2006, the association of baseline serum Cr level and change during the first 3 months after enrollment with all-cause mortality was examined.

The cohort mean ± SD age was 55 ± 15 years old and included 52% women, 24% African-Americans and 48% diabetics. Compared with patients with serum Cr levels of 8.0-9.9 mg/dL, patients with serum Cr levels of <4.0 mg/dL and 4.0-5.9 mg/dL had higher risks of death {HR 1.36 [95% confidence interval (95% CI) 1.19-1.55] and 1.19 (1.08-1.31), respectively} whereas patients with serum Cr levels of 10.0-11.9 mg/dL, 12.0-13.9 mg/dL and ≥14.0 mg/dL had lower risks of death (HR 0.88 [95% CI 0.79-0.97], 0.71 [0.62-0.81] and 0.64 [0.55-0.75], respectively) in the fully adjusted model. Decrease in serum Cr level over 1.0 mg/dL during the 3 months predicted an increased risk of death additionally. The serum Cr-mortality association was robust in patients with PD treatment duration of ≥12 months, but was not observed in those with PD duration of <3 months.

Muscle mass reflected in serum Cr level may be associated with survival even in PD patients. However, the serum Cr-mortality association is attenuated in the early period of PD treatment, suggesting competing effect of muscle mass versus residual renal function on mortality.