Trial Outcomes & Findings for Salt Loading and Thiazide Intervention Study (NCT NCT00896389)

Results Overview

Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured every 15 minutes for 4 hours. Blood pressure change is calculated by the trapezoid method. Essentially we use the average of blood pressure at each pair of time points (for example, DBP 30min + DBP 15min)/2 + (DBP 45min + DBP 30min)/2 + … up to 4 hours.) normalized by baseline SBP/DBP.

Recruitment status

COMPLETED

Study phase

PHASE4

Target enrollment

124 participants

Primary outcome timeframe

Every 15 minutes for 4 hours

Results posted on

2022-03-25

Participant Flow

Participant milestones

Participant milestones
Measure	Salt-loading and Thiazide Diuretics (HCTZ) Salt loading: 2 liters (L) of 0.9% sodium chloride (NaCl). HCTZ:12.5 or 25 mg of HCTZ for 1 week
Salt Loading STARTED	124
Salt Loading COMPLETED	124
Salt Loading NOT COMPLETED	0
HCTZ Low Dose STARTED	28
HCTZ Low Dose COMPLETED	28
HCTZ Low Dose NOT COMPLETED	0
HCTZ High Dose STARTED	25
HCTZ High Dose COMPLETED	25
HCTZ High Dose NOT COMPLETED	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Only subjects whose baseline blood pressure is high enough (SBP\>120 or DBP\>80 mmHg) and willing to undergo the multi-week intervention were enrolled into the HCTZ part of the study.

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Salt-loading and Thiazide Diuretic (HCTZ) n=124 Participants Salt loading: Subjects will arrive at the Amish Research Clinics after overnight fasting. After taking height, weight, BP, and body temperature, subjects will receive 2 L of 0.9% NaCl (sodium chloride) saline over 4 hours while their blood pressure is monitored every 15 minutes. Blood pressure will be taken every 15 minutes during this procedure. Blood and urine samples will be collected from all subjects pre- and post-infusion. Hydrochlorothiazide (HCTZ): After overnight fasting and having their height, weight, and BP measured, subjects are given 12.5 mg HCTZ tablets and instructed to take 1 tablet daily for one week. Ambulatory blood pressure, blood and urine will be collected on both day 1 and day 8. After a wash-out period, the subjects will repeat the HCTZ intervention, taking 25 mg HCTZ instead.
Age, Continuous Saline infusion only	50 years STANDARD_DEVIATION 7 • n=124 Participants • Only subjects whose baseline blood pressure is high enough (SBP\>120 or DBP\>80 mmHg) and willing to undergo the multi-week intervention were enrolled into the HCTZ part of the study.
Age, Continuous saline infusion and HCTZ	53 years STANDARD_DEVIATION 9 • n=28 Participants • Only subjects whose baseline blood pressure is high enough (SBP\>120 or DBP\>80 mmHg) and willing to undergo the multi-week intervention were enrolled into the HCTZ part of the study.
Sex: Female, Male Female	71 Participants n=124 Participants
Sex: Female, Male Male	53 Participants n=124 Participants
Systolic blood pressure Salt loading	114 mmHg STANDARD_DEVIATION 11 • n=124 Participants • Only subjects whose baseline blood pressure is high enough (SBP\>120 or DBP\>80 mmHg) and willing to undergo the multi-week intervention were enrolled into the HCTZ part of the study.
Systolic blood pressure HCTZ	126 mmHg STANDARD_DEVIATION 10 • n=28 Participants • Only subjects whose baseline blood pressure is high enough (SBP\>120 or DBP\>80 mmHg) and willing to undergo the multi-week intervention were enrolled into the HCTZ part of the study.
Diastolic blood pressure Salt Loading	71 mmHg STANDARD_DEVIATION 7 • n=124 Participants • Only subjects whose baseline blood pressure is high enough (SBP\>120 or DBP\>80 mmHg) and willing to undergo the multi-week intervention were enrolled into the HCTZ part of the study.
Diastolic blood pressure HCTZ	80 mmHg STANDARD_DEVIATION 7 • n=28 Participants • Only subjects whose baseline blood pressure is high enough (SBP\>120 or DBP\>80 mmHg) and willing to undergo the multi-week intervention were enrolled into the HCTZ part of the study.
BMI	26.1 kg/m2 STANDARD_DEVIATION 2.8 • n=124 Participants
creatinine	0.74 mg/dL STANDARD_DEVIATION 0.12 • n=124 Participants

PRIMARY outcome

Timeframe: Every 15 minutes for 4 hours

Population: 124 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype GG is homozygous for the minor allele G, genotype AG is heterozygous, and genotype AA is homozygous for the major allele A.

Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured every 15 minutes for 4 hours. Blood pressure change is calculated by the trapezoid method. Essentially we use the average of blood pressure at each pair of time points (for example, DBP 30min + DBP 15min)/2 + (DBP 45min + DBP 30min)/2 + … up to 4 hours.) normalized by baseline SBP/DBP.

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=124 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Blood Pressure Change During Salt Loading SBP, Genotype GG	-41.4 mmHg Standard Error 8.4
Blood Pressure Change During Salt Loading DBP, Genotype GG	-25.5 mmHg Standard Error 4.3
Blood Pressure Change During Salt Loading DBP, Genotype AG	34.6 mmHg Standard Error 11.6
Blood Pressure Change During Salt Loading DBP, Genotype AA	23.2 mmHg Standard Error 7.7
Blood Pressure Change During Salt Loading SBP, Genotype AG	62.9 mmHg Standard Error 15.7
Blood Pressure Change During Salt Loading SBP, Genotype AA	44.8 mmHg Standard Error 10.6

PRIMARY outcome

Timeframe: 24-hr Ambulatory blood pressure were measured every hour on day 0 and day 8

Population: 28 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype GG is homozygous for the minor allele G, genotype AG is heterozygous, genotype AA is homozygous for the major allele A.

Blood pressure change is defined as SBP or DBP average over the 24 hour period, Day 8 subtracts Day 0.

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=28 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Blood Pressure Change After 7 Days of Low Dose (12.5 mg) of HCTZ DBP, Genotype GG	0 mmHg Standard Error 0
Blood Pressure Change After 7 Days of Low Dose (12.5 mg) of HCTZ DBP, Genotype AG	2.0 mmHg Standard Error 2.4
Blood Pressure Change After 7 Days of Low Dose (12.5 mg) of HCTZ DBP, Genotype AA	-1.1 mmHg Standard Error 1.1
Blood Pressure Change After 7 Days of Low Dose (12.5 mg) of HCTZ SBP, Genotype GG	1.0 mmHg Standard Error 0
Blood Pressure Change After 7 Days of Low Dose (12.5 mg) of HCTZ SBP, Genotype AG	-0.7 mmHg Standard Error 4.3
Blood Pressure Change After 7 Days of Low Dose (12.5 mg) of HCTZ SBP, Genotype AA	-4.2 mmHg Standard Error 1.3

PRIMARY outcome

Timeframe: 24-hr Ambulatory blood pressure were measured every hour on day 0 and day 8

Population: 25 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype GG is homozygous for the minor allele G, genotype AG is heterozygous, genotype AA is homozygous for the major allele A.

Blood pressure change is defined as SBP or DBP average over the 24 hour period, Day 8 subtracts Day 0.

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=25 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Blood Pressure Change After 7 Days of High Dose (25 mg) of HCTZ DBP, Genotype GG	-2 mmHg Standard Error 0
Blood Pressure Change After 7 Days of High Dose (25 mg) of HCTZ DBP, Genotype AG	0.7 mmHg Standard Error 2.4
Blood Pressure Change After 7 Days of High Dose (25 mg) of HCTZ DBP, Genotype AA	-1.7 mmHg Standard Error 1.1
Blood Pressure Change After 7 Days of High Dose (25 mg) of HCTZ SBP, Genotype GG	1 mmHg Standard Error 0
Blood Pressure Change After 7 Days of High Dose (25 mg) of HCTZ SBP, Genotype AG	-1.3 mmHg Standard Error 4.2
Blood Pressure Change After 7 Days of High Dose (25 mg) of HCTZ SBP, Genotype AA	-4.5 mmHg Standard Error 1.3

PRIMARY outcome

Timeframe: Fasting glucose was measured on day 0 and day 8

Population: 28 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype GG is homozygous for the minor allele G, genotype AG is heterozygous, genotype AA is homozygous for the major allele A.

Values on Day 8 subtracts Day 0.

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=28 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Fasting Glucose Change After 7 Days of Low Dose (12.5 mg) of HCTZ Fasting glucose, GG Genotype	9 mmHg Standard Error 0
Fasting Glucose Change After 7 Days of Low Dose (12.5 mg) of HCTZ Fasting glucose, AG Genotype	2 mmHg Standard Error 2.5
Fasting Glucose Change After 7 Days of Low Dose (12.5 mg) of HCTZ Fasting glucose, AA Genotype	-0.1 mmHg Standard Error 1.2

PRIMARY outcome

Timeframe: Fasting glucose was measured on day 0 and day 8

Population: 25 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype 11 is homozygous for the minor allele G, genotype 12 is heterozygous, genotype 22 is homozygous for the major allele A.

Values on Day 8 subtracts Day 0.

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=25 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Fasting Glucose Change After 7 Days of High Dose (25mg) of HCTZ Fasting glucose, GG Genotype	1.0 mmHg Standard Error 0
Fasting Glucose Change After 7 Days of High Dose (25mg) of HCTZ Fasting glucose, AG Genotype	1.0 mmHg Standard Error 2.3
Fasting Glucose Change After 7 Days of High Dose (25mg) of HCTZ Fasting glucose, AA Genotype	2.3 mmHg Standard Error 2.1

SECONDARY outcome

Timeframe: Aldosterone was measured from blood collected pre and post salt loading

Population: 124 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype GG is homozygous for the minor allele G, genotype AG is heterozygous, genotype AA is homozygous for the major allele A.

Aldosterone is a hormone that plays a critical role in homeostatic regulation of blood pressure. Change is defined as the post-salt loading values minus the pre-salt loading values

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=124 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Change in Plasma Aldosterone Level Due to Salt-loading Genotype GG	-7.5 ng/dL Standard Error 4.5
Change in Plasma Aldosterone Level Due to Salt-loading Genotype AG	-1.2 ng/dL Standard Error 0.7
Change in Plasma Aldosterone Level Due to Salt-loading Genotype AA	-1.9 ng/dL Standard Error 0.6

SECONDARY outcome

Timeframe: Renin was measured from blood collected pre and post salt loading

Population: 124 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype GG is homozygous for the minor allele G, genotype AG is heterozygous, genotype AA is homozygous for the major allele A.

Renin is an enzyme that mediates extracellular fluid and regulates blood pressure. Plasma renin activity (PRA) is a measure of the activity of the plasma enzyme renin. PRA is measured in the laboratory by incubating plasma at physiologic temperature in a buffer that facilitates its enzymatic activity. The natural substrate for the enzyme renin is angiotensinogen. Exogenous angiotensinogen is not added to the reaction mixture. This means that, in effect, the PRA results reported are dependent on both renin concentration and the concentration of its substrate in the patient's plasma. Renin cleaves angiotensinogen to produce a decapeptide, angiotensin I, the concentration of which is assayed using liquid chromatography accompanied by tandem mass spectroscopic detection (LC/MS/MS). PRA levels are reported as the amount of angiotensin I generated per unit of time. Change is defined as the post-salt loading values minus the pre-salt loading values

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=124 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Change in Plasma Renin Activity Due to Salt-loading Genotype GG	-0.8 ng/ml/h Standard Error 0.3
Change in Plasma Renin Activity Due to Salt-loading Genotype AG	-0.3 ng/ml/h Standard Error 0.1
Change in Plasma Renin Activity Due to Salt-loading Genotype AA	-0.4 ng/ml/h Standard Error 0.1

SECONDARY outcome

Timeframe: Plasma sodium and potassium measured from blood collected pre and post salt loading

Population: 124 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype GG is homozygous for the minor allele G, genotype AG is heterozygous, genotype AA is homozygous for the major allele A.

Na/K ratio is a function of kidney function

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=124 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Change in Plasma Sodium/Potassium Level Due to Salt-loading Genotype GG	0.3 ratio Standard Error 0.8
Change in Plasma Sodium/Potassium Level Due to Salt-loading Genotype AG	-0.3 ratio Standard Error 0.4
Change in Plasma Sodium/Potassium Level Due to Salt-loading Genotype AA	0.1 ratio Standard Error 0.2

SECONDARY outcome

Timeframe: Plasma sodium and potassium measured from blood collected pre and post salt loading

Population: 28 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype 11 is homozygous for the minor allele G, genotype 12 is heterozygous, genotype 22 is homozygous for the major allele A.

Na/K ratio is a function of kidney function

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=28 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Change in Plasma Sodium/Potassium Level During Low Dose of HCTZ Genotype GG	0 ratio Standard Error 0
Change in Plasma Sodium/Potassium Level During Low Dose of HCTZ Genotype AG	1.0 ratio Standard Error 0.6
Change in Plasma Sodium/Potassium Level During Low Dose of HCTZ Genotype AA	0.6 ratio Standard Error 0.4

SECONDARY outcome

Timeframe: Plasma sodium and potassium measured from blood collected pre and post salt loading

Population: 25 subjects were divided into 3 genotype groups based on their rs35929607 genotypes. Genotype GG is homozygous for the minor allele G, genotype AG is heterozygous, genotype AA is homozygous for the major allele A.

Na/K ratio is a function of kidney function

Outcome measures

Outcome measures
Measure	rs35929607 SNP n=25 Participants Single nucleotide polymorphism (SNP) rs35929607, located in an intron of serine threonine kinase 39 (STK39) gene, is associated with blood pressure in the Amish population. This SNP, rs35929607, has 2 alleles, A and G. Allele G is found less frequently and has an allele frequency of approximately 0.2-0.4 in populations studied thus far. We genotyped all participants of this study and determine if they are homozygous for the G allele, i.e., have the GG genotype, or are heterozygous (AG genotype), or are homozygous for the A allele and have the AA genotype.
Change in Plasma Sodium/Potassium Level During High Dose of HCTZ Genotype GG	1 ratio Standard Error 0
Change in Plasma Sodium/Potassium Level During High Dose of HCTZ Genotype AG	0 ratio Standard Error 2.3
Change in Plasma Sodium/Potassium Level During High Dose of HCTZ Genotype AA	2.3 ratio Standard Error 2.1

Adverse Events

Salt Loading

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

HCTZ

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Dr. Yen Pei Christy Chang

University of Maryland, Baltimore

Phone: 410-706-6737

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place