Table 3.

Studies of acid-base status in patients on dialysis

Cohort	Time period, study design, country of origin	n	Study poppulation	Acid-base measurement	Summary of findings on acid-base status
Davita database46	7/2001–6/2006; database; USA	121,351	Maintenance dialysis patients; 8.6% on PD -mean age was 56 years -47% were women -24% were black -48% were diabetic -median dialysis vintage was 2.8 years 91.4% on HD -mean age was 61 years -45% were women -32% were black -58% were diabetic -median dialysis vintage was 2.3 years	Bicarbonate was obtained immediately before hemodialysis session and all samples were shipped to a single central laboratory in Florida. Time-average bicarbonate was defined as the average value of pre-HD in HD patients and steady state measurement in PD patients -low bicarbonate defined as <22 mEq/L	-PD patients had lower odds of having low bicarbonate compared to HD patients (OR 0.41, 95% CI 0.36 to 0.43). -Irrespective of dialysis modality, adjusted risk for all-cause mortality was higher in patients with bicarbonate <22mEq/L compared to those with those with bicarbonate between 24 and <25 mEq/L.
Japanese Society of Dialysis Therapy registry47	2008–2009, registry; Japan	15,132	Renal registry of dialysis patients ≥16 years -median age was 66 years -38.4% were women -33.4% were diabetic -41.5% had glomerulonephritis -median dialysis vintage was 6.5 years	Acid-base parameters were measured with a blood gas analyzer in local laboratories and bicarbonate level was calculated using Henderson-Hasselbalch equation	-Mean pre-dialysis pH was 7.35±0.05; mean bicarbonate was 20.5±2.9 mEq/L. -The mean postdialysis pH was 7.44±0.05; mean bicarbonate was 25.1±2.8 mEq/L. -Higher predialysis pH was associated with higher all-cause mortality with adjusted HR of 1.18 per 0.1 high pH (95% CI 1.02 to 1.37).

Abbreviation: HD, hemodialysis; PD, peritoneal dialysis