***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Metabolic acidosis is more common with advancing chronic kidney disease , and has been associated with impaired physical function , impaired bone health , accelerated decline in kidney function and increased vascular risk . Although oral sodium bicarbonate is widely used to correct metabolic acidosis , there exist potential risks of therapy including worsening hypertension and fluid overload . Little trial evidence exists to decide whether oral bicarbonate therapy is of net benefit in advanced chronic kidney disease , particularly in older people who are most commonly affected , and in whom physical function , quality of life and vascular health are at least as important outcomes as decline in renal function . Methods / Design BiCARB is a multi-centre , double-blind , placebo controlled , r and omised trial evaluating the clinical and cost-effectiveness of oral sodium bicarbonate in the management of older people with chronic kidney disease and severely reduced glomerular filtration rate ( GFR ) who have a mild degree of metabolic acidosis . The trial will recruit 380 patients from renal , Medicine for the Elderly , and primary care services across centres in the United Kingdom . Male and female patients aged 60 years and older with an estimated glomerular filtration rate of < 30 mL/min/1.73 m2 , not on dialysis , and with serum bicarbonate concentrations < 22 mmol/L will be eligible for participation . The primary clinical outcome for the trial is the between-group difference in the Short Physical Performance Battery score at 12 months . Secondary outcomes include muscle strength , quality of life measured using the EQ-5D score and KDQoL tools , cost effectiveness , renal function , presence of albuminuria and blood pressure . Markers of bone turnover ( 25-hydroxyvitamin D , 1,25-hydroxyvitamin D , tartrate-resistant acid phosphatase-5b and bone-specific alkaline phosphatase ) and vascular health ( B-type natriuretic peptide ) will be measured . Participants will receive a total of 24 months of either bicarbonate or placebo . The results will provide the first robust test of the overall clinical and cost-effectiveness of this commonly used therapy in older patients with severely reduced kidney function . Trial registration www.is rct n.com ; IS RCT N09486651 , registered 17 February Bicarbonate supplementation preserves renal function in experimental chronic kidney disease ( CKD ) , but whether the same benefit occurs in humans is unknown . Here , we r and omly assigned 134 adult patients with CKD ( creatinine clearance [ CrCl ] 15 to 30 ml/min per 1.73 m(2 ) ) and serum bicarbonate 16 to 20 mmol/L to either supplementation with oral sodium bicarbonate or st and ard care for 2 yr . The primary end points were rate of CrCl decline , the proportion of patients with rapid decline of CrCl ( > 3 ml/min per 1.73 m(2)/yr ) , and ESRD ( CrCl < 10 ml/min ) . Secondary end points were dietary protein intake , normalized protein nitrogen appearance , serum albumin , and mid-arm muscle circumference . Compared with the control group , decline in CrCl was slower with bicarbonate supplementation ( 5.93 versus 1.88 ml/min 1.73 m(2 ) ; P < 0.0001 ) . Patients supplemented with bicarbonate were significantly less likely to experience rapid progression ( 9 versus 45 % ; relative risk 0.15 ; 95 % confidence interval 0.06 to 0.40 ; P < 0.0001 ) . Similarly , fewer patients supplemented with bicarbonate developed ESRD ( 6.5 versus 33 % ; relative risk 0.13 ; 95 % confidence interval 0.04 to 0.40 ; P < 0.001 ) . Nutritional parameters improved significantly with bicarbonate supplementation , which was well tolerated . This study demonstrates that bicarbonate supplementation slows the rate of progression of renal failure to ESRD and improves nutritional status among patients with CKD In most patients with hypertensive nephropathy and low glomerular filtration rate ( GFR ) , the kidney function progressively declines despite the adequate control of the hypertension with angiotensin-converting enzyme inhibition . Previously we found that 2 years of oral sodium citrate slowed GFR decline in patients whose estimated GFR ( eGFR ) was very low ( mean 33 ml/min ) . This treatment also slowed GFR decline in an animal model of surgically reduced nephron mass . Here , we tested if daily oral sodium bicarbonate slowed GFR decline in patients with hypertensive nephropathy with reduced but relatively preserved eGFR ( mean 75 ml/min ) in a 5-year , prospect i ve , r and omized , placebo-controlled  , and blinded interventional study . Patients matched for age , ethnicity , albuminuria , and eGFR received daily placebo or equimolar sodium chloride or bicarbonate while maintaining antihypertensive regimens ( including angiotensin-converting enzyme inhibition ) aim ing for their recommended blood pressure targets . After 5 years , the rate of eGFR decline , estimated using plasma cystatin C , was slower and eGFR was higher in patients given sodium bicarbonate than in those given placebo or sodium chloride . Thus , our study shows that in hypertensive nephropathy , daily sodium bicarbonate is an effective kidney protective adjunct to blood pressure control along with angiotensin-converting enzyme inhibition 
    Output:
    
When limited to studies reporting outcomes at one year , the positive effect of oral  bicarbonate therapy on eGFR was attenuated .
There were no significant treatment effects in other parameters such as systolic blood pressure ( BP ) and weight .