The UBI study was a multicenter RCT that investigated whether treating metabolic acidosis in patients with CKD stages 3-5 using oral sodium bicarbonate could preserve kidney function compared to standard care. The study found that sodium bicarbonate treatment was associated with a lower rate of CKD progression, lower risk of doubling of serum creatinine, lower risk of starting renal replacement therapy, and lower risk of all-cause mortality compared to standard care. Treatment with sodium bicarbonate was also found to be safe with no adverse effects on blood pressure or fluid volume status. The results provide support for actively managing metabolic acidosis in CKD to help prevent disease progression.

1. Can treating metabolic acidosis of
CKD slow decline in eGFR? Analysis
of Available Data and the UBI study
Di Iorio, B.R., Bellasi, A., Raphael, K.L. et al. J Nephrol (2019) 32: 989.
https://doi.org/10.1007/s40620-019-00656-5
Presented by
Adeel Rafi Ahmed
MB BCh BAO MRCPI MRCP(UK) PGDip(ClinEd)
Holder of European Certificate in Nephrology
Nephrology Registrar, Beaumont Hospital, Dublin.

2. Background
• Correcting MA-CKD and maintaining serum bicarbonate levels above
22mmol/L has shown in small randomised control trials (RCT) to
reduce the progression of CKD(Ahmed and Lappin
2018)(Navaneethan et al. 2019).
• Bone is used as a buffer by excess hydrogen ions in acidotic state
which increases bone fragility
• Preservation of bone health was noted in some studies when
metabolic acidosis is corrected(Sebastian and Morris 1994).
• Increase in muscle mass, improved vascular endothelial
function(Kendrick et al. 2018) and better global cognitive and
executive performance has been demonstrated with improved serum
bicarbonate levels(Dobre et al. 2018).

3. Ahmed AR, Lappin D. Oral alkali therapy and the management of metabolic acidosis of chronic kidney disease: A narrative
literature review. World J Nephrol 2018; 7(6): 117-12
RCT Participants (n) Intervention and aim
eGFR (mL/min per 1.73
m2
) baseline
Serum HCO3 (mmol/L) at
baseline
Duration (months)
Rate of Decline of eGFR
(mL/min per 1.73 m2
)
De brito-ashurst et al[7]
Total: 134
Oral sodium bicarbonate
tablets to maintain serum
HCO3 > 23 mmol/L
15-29 16-20 24
HCO3 group: 1.88
Intervention: 62 Non treated group: 5.93
Mahajan et al[20]
Total: 120
Oral sodium bicarbonate
tablets
60-89 26 60
HCO3 group: 1.47 per year
Intervention: 30
Non treated group: 2.05
per year
Goraya et al[26]
Total: 71
Oral sodium bicarbonate
and F and V
15-29 < 22 12
HCO3 and F and V groups:
Preservation of eGFRIntervention: 30
Goraya et al[27]
Total : 108
Oral sodium bicarbonate
and F and V
30-59 22-24 36
Non treated group: 13.8
over 3 yr
Intervention: 72
HCO3: 5.4 over 3 yr
F and V: 5.4 over 3 yr
Disthabanchong et al[24]
Total: 41 Oral sodium bicarbonate
to maintain serum
bicarbonate > 24 mmol/L
< 35 < 22 2-3
HCO3 group: Preservation
of eGFR
Intervention: 21 Non treated group: 1.3
RCT: Randomised control trials; eGFR: Estimated glomerular filtration rate; F and V: Fruits and Vegetables

4. Forest plot shows slower decline in eGFR at the end of study period with oral akali
supplementation or reduction of dietary acid intake.
Sankar D. Navaneethan et al. CJASN 2019;14:1011-1020
©2019 by American Society of Nephrology

5. Aim of UBI study
• Determine whether treatment of metabolic acidosis with alkali
supplementation using oral sodium bicarbonate in patients with CKD
stage 3-5 preserves kidney function.
• Secondary outcomes included all-cause mortality and initiation of
renal replacement therapy

6. Methods
• Multicentre RCT : 10 centres from Italy
• Unblinded
• Pragmatic Controlled trial
• 740 patients.
• Eligibility: 18 <HCO3 <24, CKD 3-5, 18+
• Exclusion: NYHA 3-4 symptoms, BP >150/90, Ureterosigmoidostomy,
neurogenic bladder, CVA, active vasculitis or cancer , using calcium
carbonate.
• Duration aim: 36months ( 30months)

7. Intervention
• OSB was given to the intervention group (IG) with the aim to maintain
HCO3 between 24-28mmol/L ,compared to
• standard therapy (ST) who received only dietary input of low protein
diet (0.3-0.8g/kg/day), low phosphorus diet (<800mg/day) and
controlled sodium diet(<7g/day) which is conventional management
in most centres around the world.

8. Endpoints
• 24hr creatinine clearance/ 3months
• eGFR using MDRD
• 376 patients in the final analysis with 80% power for primary end
point ( preservation of renal function)
• Primary: doubling of serum creatinine
• Secondary: all cause mortality + RRT
• Safety endpoint: effect on BP, volume and hospitalisations

9. Stats
• Univariable- and multivariable-adjusted survival analysis were performed
• Cumulative incidence of the study endpoints (creatinine doubling, dialysis,
death) by treatment assignment were constructed by the Kaplan–Meier method
and the log rank test was used to determine statistical significance
• Cox proportional hazard regression analyses were applied to estimate the hazard
ratios (HR) of SB relative to SC for the three endpoints (creatinine doubling,
dialysis, death). The Cox proportional hazard assumption was verified in the
unadjusted models by using the Schoenfeld residuals against the transformed
time method. Cox proportional hazard regression analysis are presented as: (1)
unadjusted; (2) adjusted for age and sex (model 1); (3) adjusted for model 1 and
body mass index (BMI), systolic and diastolic BP (model 2); (4) adjusted for model
2 and baseline creatinine clearance, cardiovascular disease (CVD), diabetes,
hypertension (model 3); (5) adjusted for model 3 and proteinuria and use of
medications that inhibit the renin–angiotensin–aldosterone system (RAAS)
(model 4). All covariates were selected a priori as potential confounders

10. Results

15. Variation in sHCO3 during the course of study

16. Primary Endpoint
• Doubling of Serum Creatinine occurred in 87 participants [62 (17.0%)
in Standard care vs 25 (6.6%) in Sodium bicarb, logrank test p
value < 0.0001]
• Treatment with SB was associated with a significantly lower CKD
progression (− 1.4 vs − 3.4 ml/min/year creatinine clearance decline in
SB vs SC, respectively) irrespective of the multiple adjustment for
confounders, further corroborating the results of the UBI study
primary endpoint (participants who did not attain primary endpoint)

17. Primary Endpoint: Doubling of serum
Creatinine

18. Secondary Endpoints
• At the end of the study, 71 participants [45 (12.3%) in SC and 26
(6.9%) in SB, Log-rank test p value = 0.004] initiated RRT
• Thirty-seven participants died during follow-up; 25 (6.8%) in SC and
12 (3.1%) in SB (log-rank test p value = 0.016) (Fig. 3c). The survival
analysis showed that participants treated with SB had a 57% lower HR
of all-cause mortality during follow-up [HR 0.43; 95% CI 0.22–0.87;
Cox-model p value = 0.01] and progressive adjustment for factors
associated with the outcome of interest did not affect this association
• Similarly, rates of hospitalizations and length of stay progressively
decreased among participants treated with SB while no difference
was noted among patients allocated to SC

19. Secondary Endpoints: All cause mortality and RRT initiation

20. Safety Endpoint Hospitalisations

21. Safety Endpoint: Blood pressure

22. In case you are wondering about
antihypertensives……
• During follow-up, 81 vs 68 participants increased anti-hypertensive
drugs in SC and SB, while 91 and 122 decreased the number of
medications to control hypertension in SC and SB groups,
respectively.
• Although sodium intake was similar in the 2 study arms during follow-
up (9.0 vs 8.8 g/day in SB and SC group. respectively)

23. Safety Endpoint: volume as per body weight

24. Authors Conclusion
• Correction of metabolic acidosis with oral sodium bicarbonate is safe
and reduces the risk of CKD progression and all-cause mortality in
patients with CKD 3–5 without advanced stages of chronic heart
failure.

25. Presenters Comments
• A variety of aetiologies were seen in the randomised CKD participants
including autosomal dominant polycystic kidney disease (10.7%), diabetes
(30.7%) and hypertension (17.7%). Previous RCTs primarily involved
hypertensive nephropathy
• CKD is multifactorial and the authors had to use multiple adjustment
models to justify the results, particularly the study was not powered to
identify mortality differences
• More patients were on renin-angiotensin aldosterone system (RAAS)
inhibition in the IG, however, proteinuria was also higher at baseline and by
the end of the follow-up period more participants had reduced the number
antihypertensives when compared to ST (122 VS 91)
• The study was unblinded and risk of selection bias exists regardless of
centralisation of randomisation.

26. Presenters Comments
• Despite some shortcomings, it is a well-conducted trial, replicating a
nephrology outpatient setting and is the largest trial on the subject.
Combined with previous studies, the UBI study adds mounting
evidence for nephrologists to actively manage MA-CKD and maintain
HCO3 above 22mmol/L to prevent progression of CKD.

27. Current Practice in Republic of Ireland? (Ahmed
et al. 2019)

28. Ongoing Study
• National data collection using eMED.
• Preliminary results
- 267 patients identified with HCO3 less than 22 between time period 1st
November 2018 till 1st November 2019. Renal Tx, HD,PD AKI excluded.
- Only 57 of the identified patients were on Sodium bicarbonate therapy.
- 22.1% of the potentially eligible patients were on sodium bicarbonate.

29. Proposed pathophysiology of Metabolic Acidosis
of CKD leading to decrease in eGFR (Wesson et al.
2011)
1- Nephron hypertrophy: As CKD progresses, nephrons are lost,
remaining nephrons hypertrophy and increase NH3 production
2- Complement activation: per nephron rise in NH3 leads to activation
of alternate complement pathway (C3 cleavage) Tuboluinterstitial
Fibrosis
3- Rise in Endothelin-1: To maintain normal pH ET-1 levels rise 
increase in adrenal aldosterone levels to secrete H+, Distal Na+/H+
exchange & decrease in distal bicarbonate secretion. However ET-1
causes Vasoconstriction + Inflammation TI fibrosis.
4- Rise in Angiotensin 2: Intrarenal RAAS activation  TI Fibrosis.

30. Łoniewski, Igor, and Donald E. Wesson. 2014. 'Bicarbonate therapy for prevention of chronic kidney
disease progression', Kidney International, 85: 529-35.

31. References
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