Dietary Acid Load, Kidney Function and Disability in Elderly
Phase: NA
Conditions: Chronic Kidney Disease, Disability
Sponsor: Wake Forest University Health Sciences

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Official Title: Dietary Acid Load, Kidney Function and Disability in Elderly 
 
NCT02691663 
 
Date IRB-Approved:  6/27/2018 

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Study Title: Dietary acid load, kidney function and disability in elderly 
Principal Investigator Snezana Petrovic, Co-investigator(s): Stephen Kritchevsky, Michael Miller, Kristen 
Beavers, Jeff Williamson 
Sponsor or funding source: (NIH/NIA and the Translational Science Center at Wake Forest University) 
 
Background, Rationale and Context 
Physical decline and frailty result from age- and disease-related impairments in organs and tissues. Frailty 
research has focused on the musculoskeletal, neurological and circulatory systems; yet interventions targeting 
these systems had limited success in preventing and treating functional decline. Given the aging of the US 
population, additional avenues for intervention development are urgently needed.  
 
Fragility and disability in people ≥65 strongly correlate with declining kidney function and are evident even in 
early stages of chronic kidney disease (CKD)(1, 2). Moreover, CKD is highly prevalent in the elderly and 
associates with sarcopenia, osteopenia, and increased incidence of fractures/falls with hospitalization. Low 
serum bicarbonate and impaired acid-base homeostasis, also common in CKD, are increasingly appreciated 
as contributors to functional decline with advancing age(3-6). With aging, the adaptive response of the kidney 
to low serum bicarbonate and high metabolic acid load becomes maladaptive, facilitating CKD progression. 
Conversely, in adult patients with CKD, maintenance of serum bicarbonate at 24 meq/L with oral bicarbonate 
supplementation or increased consumption of base-forming foods slows CKD progression(7).   
 
We proposed the current study and protocol based on the evidence summarized above and our preliminary 
studies, which suggest that: (1) In the Health Aging and Body Composition cohort (age 70-79) lower dietary 
acid load associates with stable kidney function over a 7-year follow-up, independent of age, race, gender, 
BMI, diabetes, hypertension or smoking status(8); (2) metabolomics analysis in participants of the African 
American Diabetes Heart Study suggested that it is feasible to segregate a urine metabolomics profile in the 
early stages of CKD (stages 2 and 3), and that lower consumption of base-forming fruits and vegetables and 
higher rates of acid excretion may be associated with CKD and its progression(9).   
 
We therefore hypothesized that decreasing metabolic acid production by titrating dietary acid load may 
ameliorate the generally expected, age-related decline in kidney function, decrease loss of lean body mass, 
preserve physical function, and ameliorate disability. This is not a treatment study as we are exploring the 
effects of bicarbonate on these age-related issues.   
 
Objectives 
The objectives of this exploratory R21 project are to establish the feasibility of the proposed approach in 
the elderly and the project is designed to follow three Specific Aims:   
Aim 1. Recruit and randomize up to 83 elderly participants to an oral bicarbonate intervention aimed at titrating 
net dietary acid load or placebo. The purpose of this aim is to determine the feasibility of achieving ~ 50% 
reduction in net acid excretion (NAE/Cr meq/g) by the kidney at 6 months in elderly participants following oral 
bicarbonate supplementation, compared to the placebo group.  
Aim 2. Ascertain recruitment yields, adherence to the assessment schedule, compliance with and 
sustainability of the intervention over 6 months; and collect data on variability and longitudinal correlation 
structure of the parameters related to potential endpoints of a future full-scale clinical trial (kidney function, lean 
body mass, and functional outcomes).  
Exploratory Aim 3. Explore the feasibility of using metabolomics to detect effects of decreased net acid load 
on kidney function as a potentially more sensitive method of monitoring kidney function than current clinical 
markers. Importantly, metabolomics will provide clues about the metabolic pathways activated/deactivated 
during the intervention, and help determine the mechanism of the beneficial effect of decreased acid load on 
the kidney.  
Impact. This proof-of-principle proposal 
is a first step towards development of a 
new intervention to improve prevention 
and treatment of mobility disability (Fig. 
1).  
 

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Methods and Measures 
Design 
This is a randomized, double-blind; placebo-controlled trial designed as exploratory R21 project aimed to 
establish the feasibility of the oral bicarbonate supplementation in the elderly.  
 
Setting 
The study will be conducted at the academic medical center, specifically the Clinical Research Unit (CRU) of 
the Wake Forest School of Medicine (WFSM) and with the support of the Pepper Center and Translational 
Science Institute.  The participants will be recruited from the general community and evaluated and followed by 
the CRU. 
 
Subjects selection criteria 
Elderly at risk for disability with mild impairment of kidney function will be selected for this study. 
 
Inclusion Criteria 
Exclusion Criteria 
Age 65+ years of age 
Uncontrolled (>160 mg/dl    fasting blood glucose), insulin-dependent 
diabetes and/or uncontrolled hypertension (SBP>160, DBP>100) 
SPPB (short physical performance 
battery) score >3 
a current diagnosis of psychotic disorder or taking anti-psychotic 
medication 
eGFR stage 2 (60-89) or 3 (30-59)  
take more than 14 alcoholic drinks per week 
 
plan to relocate out of the study area within the 8 months 
Net endogenous acid production 
(NEAP) >40 mEq/d 
self-reported inability to walk across a room 
Willing to provide informed consent 
and agrees to randomization 
those who reside in nursing homes 
Not involved in another intervention 
study 
have difficulty communicating with study personnel due to speech or 
language or hearing problems 
 
had cancer requiring treatment in the past 1 year 
 
lung disease requiring regular use of corticosteroids at a dose of 
>7.5 mg/d for the last 3 months or use of supplemental oxygen  
 
cardiovascular disease (Class III or IV congestive heart failure) 
 
significant valvular disease, uncontrolled angina 
 
myocardial infarction, major heart surgery (i.e., valve replacement or 
bypass surgery) in past 6 months 
 
stroke, deep vein thrombosis, or pulmonary embolus in the past 6 
months, 
 
Parkinson’s disease or other progressive neurological disorder 
 
other medical or behavioral factors that in the judgment of the 
principal investigator may interfere with study participation or the 
ability to follow the intervention 
 
clinical judgment concerning safety or noncompliance 
 
Individuals with BMI <18.5; or unintentional weight loss >4% in last 6 
months 
 
MoCA score under 24 
 
End Stage Renal Disease (ESRD) on dialysis or primary kidney 
disease 
 
Other illness of such severity that life expectancy is less than 12 
months 
 
Any tobacco or nicotine product use in the past year 
 
Serum HCO3>30meq/L; serum K+ out of normal range <3.5 or > 5.2 
 

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Sample Size 
Based on published studies(11-14), we have assumed a 6-month change in NAE/Cr within groups of 16.5 
mEq/g.  Assuming a conservative 12.5% loss-to-follow-up at 6 months (35 participants/group), we will have 
80% power to detect a difference between groups in NAE/Cr as small as 11.4 mEq/g with a two-sided, Type I 
error rate of 0.05. Considering that expected change in NEA/Cr will be about 20-30 meq/d(11, 12, 14), we 
should be able to detect clinically important changes in NEA/Cr from the proposed intervention. For Aim#2, we 
are interested in estimating recruitment yields, compliance and other parameters that will inform the feasibility 
of a full-scale trial.  With up to 83 participants recruited, we will be able to estimate the two-sided, 95% 
Clopper-Pearson Exact confidence interval with a width of 0.043 if the recruitment yield is 10%, and a width of 
0.14 if the recruitment yield is 40%. For correlational analyses, 83 participants will allow us to detect correlation 
coefficients of 0.31 or larger with at least 80% power assuming a 2-sided 0.05 . 
 
Interventions and Interactions 
Patients will be screened over the phone and in the clinic to see if they meet qualifications for the study.  Once 
screened, they will be randomized into one of two groups- taking an oral bicarbonate supplement or a placebo.   
 
Oral bicarbonate supplementation group. Participants will be advised to continue their usual dietary and 
exercise pattern, but to take supplementation capsules. They will receive 0.3 meq/kg/day NaHCO3, a dose 
based on the literature (14) and our Health ABC cohort preliminary study (8). The dose of 0.3 mg/kg/d 
NaHCO3 was reported to reduce net acid excretion ~50% in individuals with similar daily acid load(14), and 
was effective in decreasing the rate of yearly eGFR decline in patients with hypertensive nephropathy; the 
dose has also been reported as safe (14, 15). NaHCO3 will be provided in gelatin capsules containing 10 meq 
NaHCO3, so that NaHCO3 can be dosed to the nearest amount by total body weight; e.g, a 70kg person will 
receive 2 capsules daily, and an 85kg person would receive 3 capsules daily (14). Adherence will be assessed 
by pill count. Compliance will be measured at months 3 and 6 by determining the change from the baseline in 
net acid excreted (NEA) in 4hr-urine; an advantage of our approach is that compliance can be measured 
objectively rather than estimated. Oral bicarbonate has been used for decades in patients with CKD or distal 
renal tubular acidosis to treat metabolic acidosis(7), and is generally considered free from significant side 
effects. Participants will be withdrawn if any of the following occur: total carbon dioxide >30mmol/L, serum K+ 
<3.5mEq/L, hospitalization for congestive heart failure, weight gain >2kg due to edema, or increase in blood 
pressure (>15 mmHg systolic or diastolic) (7, 15).   
 
Placebo group. Participants will be advised to continue their usual dietary and exercise pattern, but to take 
supplementation capsules (methylcellulose). To ensure participants’ blinding, identical capsules will be taken 
and the total number of capsules kept constant. The placebo group will be followed in the same manner as the 
bicarbonate group; all assessors will be blinded with respect to group assignment. 
 
Clinical assessments, laboratory analysis and analytical tests.  
An 4-hour urine collections were chosen because they can be done during the day in the Clinical Research 
Unit (CRU). Participants will empty their bladders before beginning the timed collection; then all urine collected 
over 4hrs will be pooled into a collection container.  The specimen will be refrigerated during the collection 
period and subsequently frozen until analysis.  While total urinary nitrogen and Ca+2 will be done by LabCorp, a 
trained technician in our Geriatrics laboratory will determine NEA/Cr (urine ammonium + titratable acidity) 
using standard methods (16).  
 
For blood gas measurements, a blood sample will be obtained from a cannulated hand vein warmed for 10-15 
min at 55˚C before sampling. Samples will be analyzed immediately after phlebotomy(17), using an ABL5 
blood gas analyzer to measure blood pH and pCO2; based on these measurements, the analyzer calculates 
serum bicarbonate using Henderson-Hasselbalch equation.   
 
Kidney function will be determined using uACR and eGFRcys. (estimated with CKD Epidemiology 
Collaboration equation (CKD-EPI) (18), based on serum cystatin c levels, which will be measured by a particle-
enhanced immunonephelometric assay86). The Nutrition Data System for Research (NDSR) will be used to 
conduct 24-hour food recalls. NDSR is a computer-based software application  which will be used to assess 
daily protein and K+ intake needed for calculation of NEAP = [54.5x(prot (g/d) / pot (meq/d)] – 10.2, where 

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prot=g of protein consumed per day and pot=meqs of potassium consumed per day(19). The Short Physical 
Performance Battery (SPPB) is a well-characterized global measure of lower-extremity function and mobility. It 
will be assessed during screening (20, 21), at 3 and 6 months. The test consists of gait speed, chair stands, 
and balance; it is a strong predictor of disability and mortality in initially non-disabled older persons. SPPB 
scores of 4-9 have already been successfully used as a range associated with risk for developing mobility 
disability(21). The 400-meter walk is a measure of aerobic endurance where participants are instructed to 
complete the 400m distance (on a flat indoor surface) at their normal pace and the time to complete the walk is 
recorded in minutes and seconds. A comprehensive metabolic profile (CMP), including tCO2, electrolytes, 
blood glucose and creatinine will be assessed at baseline and at 6-month follow-up.  In conjunction with data 
from urine collections and analysis, CMP will allow calculation of fractional excretion of Na+, K+, Cl-, and the 
anion gap(22).  
 
Bone Health. Because the kidney’s capacity to excrete acid declines with age, acid-producing diets lead to a 
positive balance of protons and mild (often) subclinical acidosis. This acidic milieu facilitates release of Ca+2 
from bone and increases bone turnover; it impairs osteoblast function and activates osteoclasts through 
stimulation of the proton-sensing receptor OGR1 and release of prostaglandin E2. Phosphate and bicarbonate 
released from bone mineral neutralize acid by a physicochemical reaction, leading to further Ca+2 release 
from the bone. In addition, renal Ca+2 excretion increases, through suppression of Ca+2 transporters and the 
calcium-sensing receptor (CaSR), which is exquisitely pH sensitive.  CaSR regulates both renal Ca+2 
absorption and parathyroid hormone release.  Since a dietary acid load does not alter intestinal Ca+2 
absorption, negative Ca+2 balance persists as long as the proton balance remains positive (33-73).  This 
pathophysiologic mechanism explains why it is of great interest that we evaluate bone density in our study, 
which is testing the feasibility of neutralizing diet-dependent acid load in the elderly. 
 
Metabolomics. Metabolomics analysis of the urine samples collected at baseline and the last follow up visit will 
extend our preliminary findings: 1) to elderly individuals; 2) will test the predictive value of identified metabolites 
with targeted metabolomics and 3) will repeat the broad spectrum analysis in samples taken before and after 
the intervention, circumventing the uncertainty of the preliminary data, which relied on statistical associations. 
All analyses will be overseen by the Wake Forest School of Medicine Proteomics and Metabolomics Core (see 
the letter from the Director, Cristina Furdui); the metabolomics samples are processed in collaboration with NIH 
Eastern Metabolomics Core at RTI70-74. We will use targeted metabolomics and broad spectrum 1H NMR 
spectroscopy. 
 
The copy of the questionnaire that will be used during the initial phone call to determine initial eligibility (e.g. 
to exclude individuals with already high consumption of fruits and vegetables (base-forming foods) or those 
meeting exclusion criteria based on medical history (self-reported insulin-dependent diabetes, advanced heart 
disease, end stage renal disease) are included in the protocol application.  The questionnaires that will be 
used during follow up telephone call and follow up visits to evaluate safety and adherence and to collect 
24hr-food recall data are also included. 
 
Participants will be required to attend a Screening Visit (SV) after they qualify based on the phone screener.  
During the screening visit they will be explained the Informed Consent and must sign to agree to participate.  
They will complete a Short Physical Performance Battery (SPPB) and a MoCA (Montreal Cognitive 
Assessment) and scores from these tests will determine initial eligibility.  Study Coordinators will then ask 
questions regarding medical history and medications, and a Comprehensive Metabolic Panel (CMP) and 
urinalysis will be completed.  If participants prove to be eligible based on their scores and blood work, they will 
be asked to come back for their Baseline Visit (BV). Usual dietary intake will also be assessed via a food 
frequency questionnaire at the BV1, and FV3 visits. We plan to use the VioFFQTM (Viocare, Inc., Princeton, 
NJ), which is a validated, web-format system for collecting food frequency data. VioFFQ collects data on a 
subject’s dietary behavior and food use patterns, provides estimates of macronutrients, micronutrients, and 
servings of particular foods of interest, and delivers detailed dietary analysis data and reports. 
Dietary intake will also be assessed by 24-hour diet recalls. Data will be collected and analyzed using the 
NDSR software developed and supported by the Nutrition Coordinating Center (NCC) of the University of 
Minnesota.  NDSR allows use of the multiple pass approach, providing interview prompts to guide and 
standardize data entry.  Subjects will be screened to assure that they are accessible by telephone for the 

6.25.18 
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collection of these data throughout the study. The first recall will be conducted at the SV to review all 
procedures and tools to be used.  A “Food Amounts” booklet containing 2-D visual portions will be provided to 
the participant for use in standardizing portion sizes.  Subsequent recalls will be conducted by telephone with 
trained interviewers from the CRU placing unscheduled telephone calls to participants at seven additional 
timepoints.  When contacted by the staff, subjects will be asked to recall and report their dietary intake from the 
previous day’s 24-hour period.  In addition to the first in-person SV recall, telephone recalls will be done within 
one week of the SV (1) to further assess eligibility (an average of both protein intake and K+ will be used to 
calculate the NEAP score), and within a 1-week period of each follow-up visit for a total of eight recalls during 
the study. Recalls will be randomly scheduled and will reflect both weekday and weekend intakes.   
 
At the baseline visit and remaining in-clinic follow up visits, participants will spend approximately 4hr in the 
Clinical Research Unit (CRU), have their physical ability tested (FV2 and FV3 only), have blood drawn for 
blood gas analysis as well as blood for cystatin c and blood for storage.  The blood gas draw will be performed 
in the CRU. Urine will be collected over the 4hr period (this is necessary because urine collections need to 
monitored and refrigerated). Participants will be encouraged to take 500 ml of water during their stay at the 
CRU, to stimulate urine production. During these visits (not at FV2) the participants will also provide 
information about their dietary habits using the VioFFQTM (Viocare, Inc., Princeton, NJ), which is a validated, 
web-format system for collecting food frequency data on a subject’s dietary behavior and food use patterns. 
The questionnaire will be self-administered. Participants will also receive a DXA scan of their hip at BV and 
FV3.  
  
 
Table showing Study Schedule of events 
SV 
BV 
FV1 
FV2 
FV3 
Location of Visit 
CRU 
CRU 
Phone 
Call 
CRU 
CRU 
Study Week Number Activity/Assessment 
-1 wk 
    0 
1 mo 
3 mo 
6 mo 
Informed Consent 
X 
 
 
 
 
Cognitive Screen (MoCA) 
X 
 
 
 
 
Fasting blood draw (CMP) 
X 
 
  
X 
X 
Urinalysis (Spot Urine)  
X 
 
 
 
X 
SPPB 
X 
 
 
X 
X 
400m walk test 
 
X 
 
X 
X 
VITALS 
X 
X 
 
X 
X 
DXA 
 
X 
 
 
X 
24-hour Diet Recall to calculate NEAP 
X 
 
X 
X 
X 
Medical History and Medications 
X 
 
X 
X 
X 
Food Frequency 
 
X 
 
 
X 
Blood Gas, Cystatin C, blood for storage 
 
X 
 
 
X 
4hr urine collection  to determine (Net acid 
excretion (NAE); urinary nitrogen and Ca+2 
excretion, uACR) Urea Nitrogen, Uric Acid, Urine 
Creatinine,) and obtain urine for storage 
 
X 
 
X 
X 
Randomization 
 
X 
 
 
 
Urine Metabolomics 
 
X 
 
 
X 
Dispense Medication 
 
X 
 
X 
 
Medication Adherence  
 
 
 
X 
X 
 
Outcome Measure(s) 
1. Determine the feasibility of achieving ~50% reduction in net acid excretion (NEA/Cr meq/g) following 
6 months of oral bicarbonate supplementation, compared to the placebo group 
2. Determine  
a. Recruitment yields 
b. Adherence to the assessment schedule 
c. Compliance with intervention over 6 months 

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d. Collect data on variability and longitudinal correlation structure of kidney function, lean body 
mass and functional outcomes 
3. Ascertain feasibility of using metabolomics to detect changes in kidney function following the 
intervention  
 
Analytical Plan 
All data will be entered as collected into web-based forms; analysis datasets will be stored in SAS. All data will 
be examined monthly by histograms and scatterplots to check for internal inconsistencies, unusual data 
needing further verification, and outliers. In few case of outliers and unusual data, participant’s charts were 
reviewed to ascertain whether any adverse measurement conditions or circumstances or potential artefacts 
existed. Only in cases where measurement artefacts were identified or other circumstances were found that 
adversely affected data collection were the measurements removed. Otherwise all data remained within the 
data set.  Sensitivity analyses will be performed with and without potential outliers included in individual 
analyses. 
 
For each analysis, regression diagnostics and exploratory analyses will be performed to find appropriate 
transformations of the variables, if needed. Priority in choosing a transformation will be to satisfy: 1) linearity, 2) 
homogeneity, and 3) normality assumptions. Initial analyses will follow the “intent-to-treat” principle. Due to 
having low power to detect potentially important relationships within this pilot, emphasis will be on using 
confidence intervals to described estimated parameters and relationships. When hypothesis testing is 
performed, we will set the significance level at α=0.05.  We have chosen this level for all hypothesis tests 
within the pilot because risk of missing an association by making a Type II error outweighs the concern for 
falsely identifying relationships via a Type I error.  
 
Aim 1 Determine the feasibility of achieving ~50% reduction in net acid excretion (NAE/Cr meq/g) by the 
kidney after 6-months of oral bicarbonate supplementation vs. placebo. (NAE/Cr was measured at each visit.)  
 
We will use mixed effects analysis of covariance (ANCOVA) to estimate change in NAE/Cr within randomized 
groups, including the baseline value of NEA/Cr and the intervention effect in the model.  A contrast will be sued 
to obtain estimates and 95% confidence intervals after 6-months.  This approach utilizes all measurements 
obtained during follow-up and can provide unbiased estimates, if missing outcomes are related to outcomes 
obtained at other time points. 
 
Aim 2 Ascertain recruitment yields, adherence to the intervention, adherence to the assessments, and 
sustainability of the intervention over 6 months; and collect data on variability and longitudinal correlations in 
kidney function, lean body mass, and functional outcomes to design a future full-scale clinical trial.  
 
For recruitment yields, we will calculate the proportion of screened participants randomized, overall, and within 
gender and ethnic subgroups.  
 
Adherence to the intervention will be measured as the proportion of the prescribed dose (bicarbonate or 
placebo) taken, based on pill counts.  
 
Compliance with assessments will be determined by calculating proportion lost to follow-up at each visit and 
the percent of missing measurements.  
 
Sustainability of the intervention will be assessed via by: a) generalized estimating equations for repeated 
measures on the proportion of expected pills a participant took.  
 
Means (proportions), variances, and 95% confidence intervals (exact CI where needed) will be calculated 
within intervention groups and for the difference between groups for all endpoints.  
 
Correlations coefficients (both Pearson and Spearman) will be used to investigate the association between net 
endogenous acid production (NEAP) and other measures of interest, as well as changes in net acid excretion 

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(NAE) and measures of interest. (Measures of interest: tCO2, blood bicarbonate (blood gas), eGFR, urineACR, 
SPPB, 400m walk, bone density). 
 
Power analysis: Based on published studies, we have assumed a 6-month change in NAE/Cr of 16.5 mEq/g 
within groups. Assuming a conservative 12.5% loss-to-follow-up at 6 months (35 participants/group remaining), 
we will have 80% power to detect a difference between groups in NAE/Cr as small as 11.4 mEq/g with a two-
sided Type I error rate of 0.05. Considering that expected change in NEA/Cr will be about 20-30 meq/d 
we should be able to detect clinically important changes in NEA/Cr from the proposed intervention. For 
correlational analyses, 80 participants will allow us to detect correlation coefficients of 0.31 or larger with at 
least 80% power assuming a 2-sided 0.05 . 
 
Other Exploratory/Sensitivity Analyses: 
Do NEAP and NAE correlate at baseline, when controlled for kidney function and caloric intake? 
Do NAE and calcium excretion correlate at baseline and other time points, when controlled for kidney function 
and calcium intake? 
Do NAE and sodium intake correlate? Do NAE and sodium excretion in the urine correlate? (An important one, 
if so, we will need to treat sodium intake as a confounder. There is physiological feasibility that these two may 
correlate.) 
Does NEAP calculated from food recalls correlate with NEAP calculated from FFQs? 
 
 
Human Subjects Protection 
 
Human Subjects Involvement and Characteristics 
We plan to recruit and randomize up to 83 older men and women who meet the inclusion/exclusion criteria 
described above.  Participants will be randomized to bicarbonate capsules or placebo for 6 months.  All 
assessments will be conducted during following visits and phone calls: screening phone call, 1 screening visit 
(SV1); 1 baseline visit (BV1); 1-month phone call, 3-months mid-intervention follow-up visit (FV1); and 1 post-
intervention follow-up visit at 6-month (FV2). 
 
The nature, purpose, and risks of all procedures and protocols will be explained to each participant prior to 
obtaining the written consent.  All examiners are trained in the standardized conduct of all assessments before 
data collection.  Participants will be instructed to wear appropriate and comfortable clothing and standardized 
written instructions will be provided prior to each study visit.  The primary outcome of interest (change in net 
acid excretion (NAE) by the kidney) was selected as an indicator of feasibility of implementing this intervention 
in elderly individuals.  Oral bicarbonate will titrate dietary acid load, decrease net endogenous acid production 
(NEAP) and this will result in decreased acid excretion by the kidney.  This dose (0.3mg/kg) was selected 
according to published studies, which indicated that it is generally safe and can decrease NEA ~ 50%(14).  We 
have extensive experience measuring all of these outcomes in our research studies and the fact that there is 
such an easy-to-assess and inexpensive (simple chemical titration of titratable acid and ammonium) outcome 
to measure is an important advantage of our approach.  Importantly, decreased NEA will also serve as 
quantitative measure of compliance.   
 
Sources of Research Material 
Participants will self-report personal information on paper survey forms including personal demographic data, 
race, health information, and psychological and social data.  Results will also be recorded in a computer 
database.  Data from the paper forms will be entered into an electronic database on a computer workstation.  
All material and data will be obtained solely for research purposes. 
 
Potential Risks 
The potential risks to study participants receiving bicarbonate supplementation have recently been reviewed by 
Dr. Wesson who is a consultant on this study (7).  In summary, the potential risks of this study include: 
 

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1) Blood Draw. Participants may experience temporary pain, bruising, bleeding and a small  
risk of infection or fainting or dizziness during the blood sample collection process. Only trained staff 
will be responsible for the collection of blood samples.   
 
2) Metabolic alkalosis (increased serum bicarbonate). Theoretically, administration of bicarbonate can 
cause metabolic alkalosis, but that is unlikely because the kidney excretes excess of bicarbonate 
efficiently.  We will be enrolling participants with CKD 2 or 3; at this level of kidney function, the 
participants should not experience problems with elimination of any excess of bicarbonate.  Moreover, it 
has been demonstrated that oral bicarbonate supplementation for 1 year at 1 meq/kg/bw/day (70 
mEq/day for 70 kg =5.9g/d) even in patients with substantially decreased glomerular filtration rate 
(stage 4 CKD) did not increase serum bicarbonate above normal levels (24).  An exception would be a 
participant who developed e.g. vomiting and hypokalemia because of some unrelated e.g. viral illness.  
In that case, the participant would be advised to discontinue bicarbonate supplementation until 
recovery, since these individuals might be susceptible to develop metabolic alkalosis.     
 
3) Volume overload. Studies that used bicarbonate supplementation for up to 5 years did not report 
increases in blood pressure or required increased dose of anti-hypertensive agents (7, 24).  This is not 
surprising given that NaCl supplementation, but not sodium bicarbonate supplementation has been 
shown to affect blood pressure.  Regarding other electrolyte and volume abnormalities, we will initially 
select participants who do not have edema.  Nevertheless, the participants will be carefully monitored 
for edema development.  It is important to note that a recent pilot trial, which tested safety and dose of 
sodium bicarbonate in CKD patients did not find development of edema as a side effect (15).  Of 
interest for our application is that the dose we proposed to use is in the range which according to 
Abramowitz et al.(15) did not show any difference in adverse effects compared to placebo: 
 
 
4) Increased risk of cardiovascular disease.  Lower all-cause mortality has been reported for individuals 
with serum bicarbonate >23 mmol/L vs. <23 mmol/L.  A recent study however reported slightly higher 
risk of heart failure in kidney patients with serum bicarbonate >24 mmol/L.  Serum bicarbonate >24 
mmol/L did not however associate with any increase in mortality or ischemic events in the same group 
of patients (25).  As an additional precaution, we will calculate bicarbonate deficit (if any) for each 
individual (=serum bicarbonate x 50% body weight (kg)) to help adjust dosing regimen and will monitor 
serum bicarbonate after the initiation of the intervention to adjust the amount of bicarbonate 
administered, if needed.   
5) Predisposition to vascular calcifications as a result of reduced solubility of calcium.  There is a 
theoretical concern from in vitro cell culture studies that raising extracellular pH may reduce solubility of 
calcium and predispose participants to vascular calcifications(26).  There are currently no studies 
suggesting that this occurs in vivo with bicarbonate therapy, but this issue has not yet been addressed 
specifically in clinical trials.  This may be more relevant to patients with advanced kidney disease and 
patients with Ca x Pi ratio >50, receiving phosphate binders, who are in fact prone to vascular 
calcification, than to population that we plan to recruit (CKD2 and 3a)(27).   

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10 
6) Simultaneous ingestion of bicarbonate and non-absorbable antacids (aluminum and magnesium 
carbonate in combination with cation-exchange resins). This causes formation of easily absorbable 
bicarbonate in the small intestine and in this case metabolic alkalosis can occur, if bicarbonate 
excretion by the kidney is limited, again unlikely in participants with CKD 2 and 3a. Nevertheless, 
participants will be advised to avoid concomitant use of non-absorbable antacids and bicarbonate.  
7) DXA scans.  Exposure to radiation from the hip DXA (20 mRem total) for baseline and follow-up scans. 
 
Adequacy of protection against risks 
Recruitment and Informed Consent 
We will use a number of recruitment strategies, including the use of mass mailing, newspaper ads, letters to 
potential participants, community advertising, and volunteers among participants from previous studies. We will 
also advertise in the VITAL newsletter (BG99-559) and participate in community outreach events.  Participants 
who are eligible via a telephone screening interview, and who agree to go through the screening process, are 
invited to a screening visit.  The informed consent process will follow the procedures of the WFSM Institutional 
Review Board.  The study interviewers explain the purpose, methods and extent of the study to prospective 
participants.  The potential participant is asked to read the informed consent form and ask questions.  The form 
is written in simple easy to understand language.  We require study staff to review all of the key aspects of the 
study verbally with the potential participants.  Staff are provided with a structured checklist for this purpose.  
Staff are then required to question potential participants to ascertain whether they understood the information.  
Potential participants who are illiterate or have impaired vision must have the consent read to them, followed 
by review of the checklist, opportunity for questions, and discussion.  A copy of the signed and dated consent 
form will be given to participants, and the original document will be placed in participants’ individual study files, 
which will be stored in a secure location.   
 
Safety measures during the bicarbonate intervention period   
There is plethora of published data on use of bicarbonate supplementation and that has simplified 
determination of a safe dose for this study.  An average dose per 85 kg patient will be ~ 25 meq/d as gel 
capsules containing 10 meq NaHCO3 with sucrose in 3 daily doses; placebo capsules will contain sucrose 
only.  Per published studies(14), each subject will be dosed to the nearest “one-half capsule” by lean body 
weight in kg (e.g., a 70 kg subject will receive two doses daily; capsules with half a dose can easily be 
prepared by our pharmacy as needed)).  Participants will be monitored for evaluation of medication tolerability.  
Adherence to study medication will be assessed by pill count and deducted from net acid excretion 
measurements.  Participants will be withdrawn from the study at their FV2 visit if their total carbon dioxide >30 
mmol/L, their eGFR falls below 15 ml/min, they experience weight gain of more than 2 kg due to edema, 
develop serum potassium<3.5mmol/L, or have an increase in blood pressure (systolic or diastolic) of more 
than 15 mmHg (7, 15). These parameters will be assessed at each visit. 
 
Safety measures during the assessments 
All study assessments will be conducted by trained and certified staff.  Safety precautions will be taken during 
all testing (e.g. gait speed) by applying standardized stopping criteria.  If the participant reports pain, tightness 
or pressure in the chest, feeling faint, lightheaded or dizzy, or significant other medical problems, the test will 
be stopped.  The PI and Co-I Dr. Williamson, will review lab data for medical concerns.  When there are 
medically relevant findings, the participant will be told the cause for concern, and may be advised to consult his 
or her physician.  If given permission by the participant, a letter will be sent to her/his primary care physician 
stating the concern.  
 
Adverse events include any event that occurs during the course of the study that results in a participant 
suffering physical or mental injury, pain or suffering. Adverse events can be major, such as a subject who 
suffers cardiac arrest during neuromuscular function testing, or minor such as a subject pulling a muscle during 
neuromuscular function testing. This includes any events occurring while a subject is enrolled in the study, 
even if the event did not occur while s/he was actively participating in the activities called for in the research 
protocol. Deviations from the study’s protocol are also considered an adverse, unexpected, or notable event 
and will be reported to the PI. 
 

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11 
Both major and minor events will be reported using the study’s Adverse, Unexpected, or Notable Event 
Reporting Form. Any major event, i.e., any serious injury or life-threatening event, will be reported immediately 
right after completing any and all actions that are necessary to protect the subject’s health and safety. Minor 
events will be reported within seven days. A description of the event, and the date and location of the event will 
be recorded on this form, which will be kept in the subject’s research file. 
 
Confidentiality 
Data will be used only in aggregate and no identifying characteristics of individuals will be published or 
presented.  Results of testing will be sent to participants’ private physicians if participants agree to this. 
Confidentiality of data is maintained by using research identification numbers, which uniquely identify each 
individual.  The information collected from participants in this study has a low potential for abuse because the 
data does not address sensitive issues.  Nevertheless, appropriate measures are taken to prevent 
unauthorized use of study information.  Data other than demographic information do not use names as an 
identifier.  The research ID number is used.  The research records are kept in locked cabinets in the Geriatric 
Research Clinic.  The files matching the participants' names and demographic information with the research ID 
numbers are kept in a separate room and locked file that uses a different key from that of all other files.  Files 
may not be obtained from the research unit by persons other than research personnel, who are asked to sign a 
document agreeing to maintain the confidentiality of the information.  After the study is completed, the local 
data will be stored with other completed research studies in a secured storage area. 
 
Potential benefits of the proposed research to the participants and others  
Individuals may experience clinical benefit from knowing some of their physiological parameters, such as their 
muscle strength and physical performance.  Participants randomized to bicarbonate intervention may 
experience improved physical function.  Individuals will be informed of their results at the end of the study and 
provided a copy to give to their health care providers. Those who do not qualify will be told the reasons for 
disqualification and referred for appropriate care.  Therefore, the risk/benefit ratio is acceptable since potential 
risks of these research procedures are minimal and/or infrequent, and possible complication will be carefully 
guarded against.  Potential risks are reasonable in relation to anticipated benefits to health from the 
intervention, which may include improved kidney function, positive nitrogen balance, improved muscle 
strength, and increased bone density.   
 
Importance of the knowledge to be gained 
These studies focus on using base (bicarbonate) to titrate high dietary acid load, which is emerging as a new 
risk factor for disability mediated through the progression of the aging associated-decline of kidney function.  
We plan to determine the feasibility (this application) and ultimately effectiveness (the subsequent R01) of a 
comparably simple and generally safe intervention to decrease dietary acid load in elderly, which, in spite of 
strong evidence in support of its potential effectiveness, has not been tested in the age group who is also most 
likely to benefit from this intervention and at risk for disability.  This intervention may ultimately help protect 
kidney function and reduce the associated disability in elderly, with a hope that it may work synergistically with 
exercise, the only other intervention demonstrated in a randomized, controlled clinical trial to ameliorate 
disability, albeit modestly (the LIFE trial).  The importance of the high dietary acid load in face of declining 
kidney function is a public health issue pointed out ~ 20 years ago, at which time the term “presbynephria” was 
coined to alert the medical community to consequences of the diminishing capacity of the aging kidney to 
excrete acid, including osteopenia, sarcopenia, adverse functional outcomes and disability(30-32).  
 
Data quality and management 
The study investigators and staff have experience and expertise in quality control procedures and successful 
participant tracking in randomized controlled trials.  We will use a computerized tracking system to document 
participant attendance, generate quality control reports for identifying protocol deviations and to assess 
protocol adherence over time.  All data will be entered into web-based forms on a continuous basis as 
collected, and analysis datasets will be stored in SAS.  All data will be examined monthly by histograms and 
scatterplots to check for internal inconsistencies, unusual data needing further verification, and outliers.  
Telephone screening and in-person assessment interviews will be conducted by trained study staff who will 
use computer-assisted technology, entering the data directly into desktop computers.  

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12 
Data entry is facilitated by automated skip patterns and alerts for out of range values.  We will develop 
standardized reports that will be used for quality control.  Careful development of data collection forms is 
crucial (a) to allow for systematic and uniform recording of participants’ data, (b) help maintain complete data 
collection, and (c) to minimize the possibilities for data entry errors.  Data entry screens are created to mimic 
the forms.  Forms are designed so to make data entry easy and straightforward.  In addition the above 
precautions, procedures to monitor screening, data collection, follow-up, clinical measures, forms and data 
entry will also be used. 
 
Data and Safety Monitoring Plan 
We will use the WFU Pepper Center’s appointed Data Safety Monitoring Board. This board meets twice a year 
and reviews all studies that are supported by the WFU Pepper Center. A copy of the report will be reported to 
the IRB after each meeting. 
 
Informed Consent 
Informed consent will be obtained by a trained study coordinator in a clinic room with closed doors. The study 
interviewers explain the purpose, methods and extent of the study to prospective participants. The potential 
participant is asked to read the informed consent form and ask questions. We require study staff to review all 
of the key aspects of the study verbally with the potential participants. Staff is then required to question 
potential participants to ascertain whether he/she has understood the information. The consent form will only 
be signed once the participant has read the form and is satisfied with all information given. The person 
administering consent will also sign and a copy of the signed and dated consent form will be given to the CRU, 
and to participants, and the original document will be placed in subjects’ individual study files, which will be 
stored in a secure location. 
 
Storage and disposal of biological material 
Blood and urine samples will be stored at Wake Forest Baptist Medical Center for twenty years after the end of 
the trial at which time the samples will be destroyed. Biological specimens will be stored in locked –70oC 
alarmed Revco freezers located in a locked room. The Wake Forest Pepper Center Integrative Biology Core 
lab coordinator (Karin Murphy) and the Core Leader (Dr. Nicklas) have access to the keys of the freezers. All 
the specimens will have numerical study IDs with no personal identifiers of the participants. These are stored 
under the Pepper Center Tissue Repository (IRB#1219). 
 
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