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Study of Dietary Additive Phosphorus on Proteinuria and Fibroblast Growth Factor-23 (SODA-POP)

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ClinicalTrials.gov Identifier: NCT02020785
Recruitment Status : Completed
First Posted : December 25, 2013
Results First Posted : June 5, 2019
Last Update Posted : June 5, 2019
Sponsor:
Collaborator:
Johns Hopkins University
Information provided by (Responsible Party):
Alexander Chang, Geisinger Clinic

Study Type Interventional
Study Design Allocation: Randomized;   Intervention Model: Crossover Assignment;   Masking: Triple (Participant, Investigator, Outcomes Assessor);   Primary Purpose: Treatment
Condition Albuminuria
Interventions Other: Higher phosphorus period
Other: Lower phosphorus period
Enrollment 31
Recruitment Details Primary recruitment strategies included mass mailing of study brochures to individuals with self-reported type 2 diabetes in neighboring zip codes and to past and current participants of other research studies.
Pre-assignment Details  
Arm/Group Title Higher Phosphorus Period First, Then Lower Phosphorus Period Lower Phosphorus Period First, Then Higher Phosphorus Period
Hide Arm/Group Description

Randomized to higher phosphorus period first, then lower phosphorus period second.

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Randomized to higher phosphorus period first, then lower phosphorus period second.

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Period Title: First Intervention (3 Weeks)
Started 15 16
Completed 15 16
Not Completed 0 0
Period Title: Second Intervention (3 Weeks)
Started 15 16
Completed 15 16
Not Completed 0 0
Arm/Group Title Higher Phosphorus Period Then Lower Phosphorus Period Lower Phosphorus Period Then Higher Phosphorus Period Total
Hide Arm/Group Description

Randomized to higher phosphorus period first, then lower phosphorus period second.

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Randomized to higher phosphorus period first, then lower phosphorus period second.

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Total of all reporting groups
Overall Number of Baseline Participants 15 16 31
Hide Baseline Analysis Population Description
[Not Specified]
Age, Categorical  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 15 participants 16 participants 31 participants
<=18 years
0
   0.0%
0
   0.0%
0
   0.0%
Between 18 and 65 years
7
  46.7%
9
  56.3%
16
  51.6%
>=65 years
8
  53.3%
7
  43.8%
15
  48.4%
Age, Continuous  
Mean (Standard Deviation)
Unit of measure:  Years
Number Analyzed 15 participants 16 participants 31 participants
68.0  (7.3) 64.2  (9.9) 66.0  (8.8)
Sex: Female, Male  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 15 participants 16 participants 31 participants
Female
6
  40.0%
12
  75.0%
18
  58.1%
Male
9
  60.0%
4
  25.0%
13
  41.9%
Ethnicity (NIH/OMB)  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 15 participants 16 participants 31 participants
Hispanic or Latino
0
   0.0%
0
   0.0%
0
   0.0%
Not Hispanic or Latino
15
 100.0%
16
 100.0%
31
 100.0%
Unknown or Not Reported
0
   0.0%
0
   0.0%
0
   0.0%
Race (NIH/OMB)  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 15 participants 16 participants 31 participants
American Indian or Alaska Native
0
   0.0%
0
   0.0%
0
   0.0%
Asian
0
   0.0%
0
   0.0%
0
   0.0%
Native Hawaiian or Other Pacific Islander
0
   0.0%
0
   0.0%
0
   0.0%
Black or African American
14
  93.3%
14
  87.5%
28
  90.3%
White
1
   6.7%
2
  12.5%
3
   9.7%
More than one race
0
   0.0%
0
   0.0%
0
   0.0%
Unknown or Not Reported
0
   0.0%
0
   0.0%
0
   0.0%
Region of Enrollment  
Measure Type: Number
Unit of measure:  Participants
United States Number Analyzed 15 participants 16 participants 31 participants
15 16 31
1.Primary Outcome
Title 24-hour Urine Albumin Excretion
Hide Description Two 24-hour urine collections will be collected during the 3rd week of each period
Time Frame 3 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Higher Phosphorus Period Lower Phosphorus Period
Hide Arm/Group Description:

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.

Patients then randomized to higher phosphorus period or lower phosphorus period first.

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.

Patients then randomized to higher phosphorus period or lower phosphorus period first.

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Overall Number of Participants Analyzed 31 31
Mean (95% Confidence Interval)
Unit of Measure: mg/day
86.2
(51.8 to 143.4)
76.4
(47.2 to 123.8)
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Higher Phosphorus Period, Lower Phosphorus Period
Comments Sample size for this study was calculated using the xsampsi module in STATA, based on a previous study with repeat 24-hour urine collections (standard deviation, 1.04). At an α level of 0.05, we anticipated that a sample size of 30 participants with mean albuminuria of 100 mg/d would result in >80% power to detect a 13% difference in log- transformed albuminuria between the higher and lower phosphorus additive periods.
Type of Statistical Test Superiority
Comments Main analyses were intention-to-treat using mixed effects models allowing intercepts to vary for each individual. Carryover effects were examined by using treatment by assignment-order interaction terms. Pre-specified sensitivity analyses were conducted excluding patients who were non-compliant, prior to data analysis: 1st, noncompliance based on missing product pickups and follow-up visits; 2nd, suspected poor compliance (< 250 mg difference between the higher and lower period).]
Statistical Test of Hypothesis P-Value 0.05
Comments For each outcome, a p value < 0.05 was considered statistically significant without adjustment for multiple comparisons.
Method Mixed Models Analysis
Comments [Not Specified]
Method of Estimation Estimation Parameter Mean Difference (Final Values)
Estimated Value 0.143
Confidence Interval (2-Sided) 95%
-0.025 to 0.34
Estimation Comments Estimate (14.3%, 95% CI: -2.5%, 34.0%) is the estimated difference between end of higher phosphorus period and end of lower phosphorus period from mixed effects analyses for log-transformed 24-hour urine albumin excretion
2.Primary Outcome
Title Fibroblast Growth Factor-23 (FGF-23)
Hide Description

Plasma FGF-23 will be measured at the end of each 3 week period in the morning after an overnight fast.

As this is a small pilot study, we will not adjust for multiple comparisons. A p value<0.05 will be considered statistically significant for both outcomes

Time Frame 3 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Higher Phosphorus Period Lower Phosphorus Period
Hide Arm/Group Description:

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.

Patients then randomized to higher phosphorus period or lower phosphorus period first.

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.

Patients then randomized to higher phosphorus period or lower phosphorus period first.

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Overall Number of Participants Analyzed 31 31
Geometric Mean (95% Confidence Interval)
Unit of Measure: Relative units/ml
132.6
(115.4 to 152.3)
128.2
(113.1 to 145.3)
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Higher Phosphorus Period, Lower Phosphorus Period
Comments [Not Specified]
Type of Statistical Test Superiority
Comments [Not Specified]
Statistical Test of Hypothesis P-Value 0.05
Comments For each outcome, a p value < 0.05 was considered statistically significant without adjustment for multiple comparisons.
Method Mixed Models Analysis
Comments [Not Specified]
Method of Estimation Estimation Parameter Mean Difference (Final Values)
Estimated Value 0.034
Confidence Interval (2-Sided) 95%
-0.059 to 0.136
Estimation Comments Estimate (3.4%, 95% CI: -5.9%, 13.6%) is the estimated difference between end of higher phosphorus period and end of lower phosphorus period from mixed effects analyses for log-transformed fibroblast growth factor 23
3.Secondary Outcome
Title Systolic Blood Pressure
Hide Description Blood pressure was measured at the end of weeks 1, 2, and 3. At each visit, 3 readings were obtained in the seated position by trained and certified observers after 5 minutes of rest with an Omron HEM-907 device (Omron Healthcare Inc, Bannockburn, Ill) using a standardized protocol. We used the average of all blood pressure measurements at the end of weeks 1, 2, and 3 for each period.
Time Frame 2-3 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Higher Phosphorus Period Lower Phosphorus Period
Hide Arm/Group Description:

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.

Patients then randomized to higher phosphorus period or lower phosphorus period first.

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.

Patients then randomized to higher phosphorus period or lower phosphorus period first.

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Overall Number of Participants Analyzed 31 31
Mean (Standard Deviation)
Unit of Measure: mmHg
126.9  (13.5) 128  (15.6)
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Higher Phosphorus Period, Lower Phosphorus Period
Comments [Not Specified]
Type of Statistical Test Superiority
Comments [Not Specified]
Statistical Test of Hypothesis P-Value 0.05
Comments For each outcome, a p value < 0.05 was considered statistically significant without adjustment for multiple comparisons.
Method Mixed Models Analysis
Comments [Not Specified]
Method of Estimation Estimation Parameter mean difference (during each period)
Estimated Value -1.1
Confidence Interval (2-Sided) 95%
-4.1 to 1.9
Estimation Comments [Not Specified]
4.Secondary Outcome
Title Diastolic Blood Pressure
Hide Description Blood pressure measured at the end of weeks 1, 2, and 3. At each visit, 3 readings were obtained in the seated position by trained and certified observers after 5 minutes of rest with an Omron HEM-907 device (Omron Healthcare Inc, Bannockburn, Ill) using a standardized protocol. We used the average of all these readings taken during end of weeks 1, 2, and 3 for each period.
Time Frame 2-3 weeks
Hide Outcome Measure Data
Hide Analysis Population Description
[Not Specified]
Arm/Group Title Higher Phosphorus Period Lower Phosphorus Period
Hide Arm/Group Description:

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.

Patients then randomized to higher phosphorus period or lower phosphorus period first.

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) will be given for 3 weeks

At the beginning of the study participants receive dietary education to reduce their baseline consumption of phosphorus to a goal of ~1gm/d by receiving education on avoiding phosphorus-based additives.

Patients then randomized to higher phosphorus period or lower phosphorus period first.

Higher phosphorus period: Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks

Lower phosphorus period: Commercially-available unaltered food/beverage products without any phosphorus additives given for 3 weeks

Overall Number of Participants Analyzed 31 31
Mean (Standard Deviation)
Unit of Measure: mmHg
69.3  (10.8) 70.2  (11.4)
Hide Statistical Analysis 1
Statistical Analysis Overview Comparison Group Selection Higher Phosphorus Period, Lower Phosphorus Period
Comments [Not Specified]
Type of Statistical Test Superiority
Comments [Not Specified]
Statistical Test of Hypothesis P-Value 0.05
Comments For each outcome, a p value < 0.05 was considered statistically significant without adjustment for multiple comparisons.
Method Mixed Models Analysis
Comments [Not Specified]
Method of Estimation Estimation Parameter mean difference (during each period)
Estimated Value -0.8
Confidence Interval (2-Sided) 95%
-2.7 to 1.0
Estimation Comments [Not Specified]
Time Frame At the end of each 3 week study period.
Adverse Event Reporting Description Participants were asked at the end of each study period if they experienced possible side effects.
 
Arm/Group Title Higher Phosphorus Period Lower Phosphorus Period
Hide Arm/Group Description Commercially-available unaltered food/beverage products containing phosphorus additives (~1gm/d of phosphorus) given for 3 weeks Commercially-available unaltered food/beverage products without phosphorus additives (<10mg/d of phosphorus) given for 3 weeks
All-Cause Mortality
Higher Phosphorus Period Lower Phosphorus Period
Affected / at Risk (%) Affected / at Risk (%)
Total   0/31 (0.00%)      0/31 (0.00%)    
Hide Serious Adverse Events
Higher Phosphorus Period Lower Phosphorus Period
Affected / at Risk (%) # Events Affected / at Risk (%) # Events
Total   0/31 (0.00%)      0/31 (0.00%)    
Hide Other (Not Including Serious) Adverse Events
Frequency Threshold for Reporting Other Adverse Events 5%
Higher Phosphorus Period Lower Phosphorus Period
Affected / at Risk (%) # Events Affected / at Risk (%) # Events
Total   22/31 (70.97%)      23/31 (74.19%)    
Gastrointestinal disorders     
Gastrointestinal symptoms  [1]  19/31 (61.29%)  19 21/31 (67.74%)  21
General disorders     
Fatigue   7/31 (22.58%)  7 7/31 (22.58%)  7
Infections and infestations     
Flu-like symptoms   1/31 (3.23%)  1 3/31 (9.68%)  3
Musculoskeletal and connective tissue disorders     
Back pain   8/31 (25.81%)  8 12/31 (38.71%)  12
Skin and subcutaneous tissue disorders     
Skin rash   2/31 (6.45%)  2 3/31 (9.68%)  3
Indicates events were collected by systematic assessment
[1]
Participants were asked at the end of each study period if they experienced possible side effects. The specific adverse event terms cannot be separated due to the manner in which this was assessed.
Small sample size, short duration of intervention, changes in background diet during the intervention.
Certain Agreements
Principal Investigators are NOT employed by the organization sponsoring the study.
There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.
Results Point of Contact
Layout table for Results Point of Contact information
Name/Title: Alex Chang, MD
Organization: Geisinger
Phone: 570-271-8026
EMail: achang@geisinger.edu
Layout table for additonal information
Responsible Party: Alexander Chang, Geisinger Clinic
ClinicalTrials.gov Identifier: NCT02020785    
Other Study ID Numbers: NA_00082089
13CRP16970085 ( Other Grant/Funding Number: American Heart Association )
Satellite Dialysis ( Other Grant/Funding Number: National Kidney Foundation )
First Submitted: December 19, 2013
First Posted: December 25, 2013
Results First Submitted: November 17, 2017
Results First Posted: June 5, 2019
Last Update Posted: June 5, 2019