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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.