Sodium bicarbonate to improve physical function in patients over 60 years with advanced chronic kidney disease: the BiCARB RCT

BACKGROUND

Advanced chronic kidney disease is common in older people and is frequently accompanied by metabolic acidosis. Oral sodium bicarbonate is used to treat this acidosis, but evidence is lacking on whether or not this provides a net gain in health or quality of life for older people.

OBJECTIVES

The objectives were to determine whether or not oral bicarbonate therapy improves physical function, quality of life, markers of renal function, bone turnover and vascular health compared with placebo in older people with chronic kidney disease and mild acidosis; to assess the safety of oral bicarbonate; and to establish whether or not oral bicarbonate therapy is cost-effective in this setting.

DESIGN

A parallel-group, double-blind, placebo-controlled randomised trial.

SETTING

The setting was nephrology and geriatric medicine outpatient departments in 27 UK hospitals.

PARTICIPANTS

Participants were adults aged ≥ 60 years with advanced chronic kidney disease (glomerular filtration rate category 4 or 5, not on dialysis) with a serum bicarbonate concentration of < 22 mmol/l.

INTERVENTIONS

Eligible participants were randomised 1 : 1 to oral sodium bicarbonate or matching placebo. Dosing started at 500 mg three times daily, increasing to 1 g three times daily if the serum bicarbonate concentration was < 22 mmol/l at 3 months.

MAIN OUTCOME MEASURES

The primary outcome was the between-group difference in the Short Physical Performance Battery score at 12 months, adjusted for baseline. Other outcome measures included generic and disease-specific health-related quality of life, anthropometry, 6-minute walk speed, grip strength, renal function, markers of bone turnover, blood pressure and brain natriuretic peptide. All adverse events were recorded, including commencement of renal replacement therapy. For the health economic analysis, the incremental cost per quality-adjusted life-year was the main outcome.

RESULTS

In total, 300 participants were randomised, 152 to bicarbonate and 148 to placebo. The mean age of participants was 74 years and 86 (29%) were female. Adherence to study medication was 73% in both groups. A total of 220 (73%) participants were assessed at the 12-month visit. No significant treatment effect was evident for the primary outcome of the between-group difference in the Short Physical Performance Battery score at 12 months (-0.4 points, 95% confidence interval -0.9 to 0.1 points; p = 0.15). No significant treatment benefit was seen for any of the secondary outcomes. Adverse events were more frequent in the bicarbonate arm (457 vs. 400). Time to commencement of renal replacement therapy was similar in both groups (hazard ratio 1.22, 95% confidence interval 0.74 to 2.02; p = 0.43). Health economic analysis showed higher costs and lower quality of life in the bicarbonate arm at 1 year, with additional costs of £564 (95% confidence interval £88 to £1154) and a quality-adjusted life-year difference of -0.05 (95% confidence interval -0.08 to -0.01); placebo dominated bicarbonate under all sensitivity analyses for incremental cost-effectiveness.

LIMITATIONS

The trial population was predominantly white and male, limiting generalisability. The increment in serum bicarbonate concentrations achieved was small and a benefit from larger doses of bicarbonate cannot be excluded.

CONCLUSIONS

Oral sodium bicarbonate did not improve a range of health measures in people aged ≥ 60 years with chronic kidney disease category 4 or 5 and mild acidosis, and is unlikely to be cost-effective for use in the NHS in this patient group. Once other current trials of bicarbonate therapy in chronic kidney disease are complete, an individual participant meta-analysis would be helpful to determine which subgroups, if any, are more likely to benefit and which treatment regimens are more beneficial.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN09486651 and EudraCT 2011-005271-16. The systematic review is registered as PROSPERO CRD42018112908.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 27. See the NIHR Journals Library website for further project information.

104 Oral Sodium Bicarbonate Therapy for Older Patients with Chronic Kidney Disease and Low-Grade Acidosis: The BiCARB Randomised Controlled Trial

Background

Oral sodium bicarbonate is often used to treat metabolic acidosis in older people with advanced chronic kidney disease, but evidence is lacking on whether this provides a net gain in health or quality of life.

Methods

We conducted a multicentre, parallel group, double-blind, placebo-controlled randomised trial. Adults aged 60 years and over with category 4 or 5 chronic kidney disease, not on dialysis, with serum bicarbonate concentrations &lt;22 mmol/L were recruited from 27 UK centres. Participants were randomised 1:1 to oral sodium bicarbonate or matching placebo. The primary outcome was the between-group difference in the Short Physical Performance Battery at 12 months, adjusted for baseline. Other key outcome measures included generic and disease-specific health-related quality of life, anthropometry, physical performance, renal function, adverse events including commencement of renal replacement therapy, and health economic analysis.

Results

We randomised 300 participants, mean age 74 years; 86 (29%) were female. Mean baseline estimated GFR was 19 ml/min/1.73m2. Study medication adherence was 73% in both groups. No significant treatment effect was evident for the primary outcome of the between-group difference in the Short Physical Performance Battery at 12 months (-0.4 points; 95% CI -0.9 to 0.1, p=0.15). No significant treatment benefit was seen for any of the secondary outcomes. Adverse events were more frequent in the bicarbonate arm (457 versus 400). Time to commencing renal replacement therapy was similar in both groups (HR 1.22, 95% CI 0.74 to 2.02, p=0.43). Health economic analysis showed lower quality of life and higher costs in the bicarbonate arm at one year (£1234 vs £807); placebo dominated bicarbonate under all sensitivity analyses for incremental cost-effectiveness.

Conclusions

Oral sodium bicarbonate did not improve a wide range of health measures in this trial, and is unlikely to be cost-effective for use in the UK NHS in this patient group.

Management of acquired von Willebrand's sryndrome in a patient requiring major surgery

We present the case of a patient with acquired von Willebrand's syndrome and a monoclonal gammopathy of undetermined significance who required cystectomy for relapsed transitional cell carcinoma (TCC) of the bladder. We demonstrated that infused von Willebrand factor (VWF) containing factor VIII concentrates had an unacceptably short half-life, but that this was significantly prolonged following combined therapy with plasma exchange and intravenous immunoglobulin (IVIgG). This approach was successfully utilized peri-operatively, with the total surgical blood loss less than would be expected even for a haemostatically normal patient. Trough VWF antigen and Ristocetin co-factor activity levels fell on the second postoperative day and we therefore administered further IVIgG. Levels again fell on the fifth postoperative day with the development of a Staphylococcus aureus septicaemia. At this point bleeding occurred from a surgical drain site requiring 'factor VIII inhibitor bypass activity' to secure haemostasis while further plasma exchange and IVIgG were administered. Now 5 years later, there is no evidence of recurrence of the TCC or progression of the monoclonal gammopathy.