Association Between Serum Albumin and Mortality in Dialysis Patients Is Partly Explained by Inflammation, and Not by Malnutrition
Objective
We investigated the effects of inflammatory and nutritional status on the association between serum albumin and mortality in hemodialysis (HD) and peritoneal dialysis (PD) patients.
Design and Patients
This was a prospective cohort study of incident dialysis patients starting HD or PD. Inflammation (C-reactive protein ≥5 or ≥10 mg/L), malnutrition (1 to 5 on the 7-point subjective global assessment [SGA]), and low protein intake (normalized protein equivalent of nitrogen appearance [nPNA] <0.99 g/kg/day) were measured at 3 months after the start of dialysis.
Setting
The study involved 38 dialysis centers in The Netherlands.
Main Outcome Measure
We ascertained all-cause mortality during the first 2 years after the start of dialysis.
Results
In total, 700 patients were included (mean SD age, 59 [±15] years; serum albumin, 3.3 (0.7) g/dL; 60% men; 454 starting HD, and 246 starting PD). The 2-year mortality was 21%. In HD patients, the mortality (hazard ratio [HR], with 95% confidence interval [95% CI]) per unit decrease in serum albumin (g/dL) was 1.47 (95% CI, 1.07 to 2.00). Adjustment for SGA did not decrease this risk, whereas adjustment for nPNA decreased the HR to 1.45 (95% CI, 1.06 to 1.97). The mortality risk decreased to 1.30 (95% CI, 0.95 to 1.78) after adjustment for inflammation, and did not further decrease after additional adjustment for SGA and nPNA. Additional adjustments for age, sex, and comorbidity decreased the HR to 1.09 (95% CI, 0.79 to 1.51). In PD patients, the effects of adjustments on the mortality risk of serum albumin (1.38; 95% CI, 0.87 to 2.20) were similar.
Conclusion
In dialysis patients, a 1-g/dL decrease in serum albumin was associated with an increased mortality risk of 47% in HD patients and 38% in PD patients. These mortality risks were in part explained by the inflammatory pathway. The mortality risks associated with serum albumin were not a consequence of malnutrition, as measured with SGA and nPNA. These findings imply that nutritional status cannot be assessed with precision by the measurement of serum albumin in dialysis patients.
∗Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
‡Department of Nephrology, Academic Medical Center, Amsterdam, The Netherlands
Address reprint requests to Renée de Mutsert, MSc, Department of Clinical Epidemiology, Room C9-19, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
The Netherlands Cooperative Study on the Adequacy of Dialysis-II was supported by unrestricted grants from the Dutch Kidney Foundation and from Amgen BV, Breda, The Netherlands.
The Netherlands Cooperative Study on the Adequacy of Dialysis-II Study Group includes A.J. Apperloo, J.A. Bijlsma, M. Boekhout, W.H. Boer, P.J.M. van der Boog, H.R. Büller, M. van Buren, F.T. de Charro, C.J. Doorenbos, M.A. van den Dorpel, A. van Es, W.J. Fagel, G.W. Feith, C.W.H. de Fijter, L.A.M. Frenken, J.A.C.A. van Geelen, P.G.G. Gerlag, J.P.M.C. Gorgels, W. Grave, R.M. Huisman, K.J. Jager, K. Jie, W.A.H. Koning-Mulder, M.I. Koolen, T.K. Kremer Hovinga, A.T.J. Lavrijssen, A.J. Luik, J. van der Meulen, K.J. Parlevliet, M.H.M. Raasveld, F.M. van der Sande, M.J.M. Schonck, M.M.J. Schuurmans, C.E.H. Siegert, C.A. Stegeman, P. Stevens, J.G.P. Thijssen, R.M. Valentijn, G.H. Vastenburg, C.A. Verburgh, H.H. Vincent, and P.F. Vos.
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