• Increase Font Size
  • Decrease Font Size
  • View as PDF

HTN: Potassium (2015)

Citation:

Franzoni F, Santoro G, Carpi A, DaPrato F, Bartolomucci F, Femia FR, Prattichizzo F, Galetta F. Antihypertensive effect of oral potassium aspartate supplementation in mild to moderate arterial hypertension. Biomedicine & Pharmacotherapy. 2005; 59: 25-29.

PubMed ID: 15740932
 
Study Design:
Non-Randomized Controlled Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To evaluate the effect of a lower dose of potassium aspartate salt on BP in individuals with essential arterial hypertension.
Inclusion Criteria:
  • Established or newly diagnosed mild to moderate hypertension (SBP higher than 140mm Hg or DBP higher than 90mm Hg)
  • Free from coronary artery disease, valvular or primary myocardial heart disease, diabetes, dyslipidemia and arrhythmias.
Exclusion Criteria:
  • SBP higher than 200mm Hg
  • Suspected or defined secondary hypertension.
Description of Study Protocol:

Recruitment    

Patients referred to a hospital outpatient clinic.

Design 

Non-randomized controlled trial.

Blinding Used

Implied with measurements.

Intervention

  • Subjects were allocated to receive or not receive potassium aspartate supplementation daily for four weeks:
    • 30mmol potassium aspartate
    • Placebo.
  • Constant dietary intake of sodium and potassium
  • Compliance assessed by vial count and measurement of urinary potassium excretion.

Statistical Analysis

  • One-way ANOVA
  • Repeated measures ANOVA for repeated observations
  • Linear regression analysis to assess correlations between parameters
  • Significance level: P<0.05.
Data Collection Summary:

Timing of Measurements

Measurements made at baseline and at four weeks.

Dependent Variables

  • Blood pressure:
    • Office BP: Two measurements with sphygmomanometer
    • 24-hour BP: Measurements every 30 minutes in the non-dominant arm using SpaceLabs monitor
    • Daytime BP: Mean value from 9 a.m. to 11 p.m.
    • Nighttime BP: Mean value from 11:30 p.m. to 6:30 a.m.
  • Fasting blood samples
  • 24-hour urine samples.

Independent Variables

  • 30mmol potassium aspartate supplementation vs placebo for four weeks
  • Compliance assessed by vial count and measurement of urinary potassium excretion.
Description of Actual Data Sample:
  • Initial N: N=104 (65 males, 39 females)
  • Attrition (final N): N=104, no withdrawals from the study
  • Age: Aged 35 years to 66 years. The treated group;s mean age was 51±11 years while the untreated group;s mean age was 53±12 years.
Anthropometrics

Treated (N=52) vs. untreated (N=52):

  • BMI: 24.3±1.2kg/m2 vs. 24.5±1.5kg/m2
  • Office SBP: 154.4±8.2mm Hg vs. 153.8±11.6mm Hg
  • Office DBP: 95.0±5.6mm Hg vs. 96.4±4.4mm Hg
  • 24-hour SBP: 142.7±8.2mm Hg vs. 141.8±8.5mm Hg
  • 24-hour DBP: 90.8±4.4mm Hg vs. 91.6±3.2mm Hg.

Location

Italy.

Summary of Results:

Key Findings

  • Treated group (N=52):
    • Significant changes in office and 24-hour SBP and DBP (P<0.001)
    • Changes in day and night time SBP and DBP were similar
    • Significant increase in serum potassium (4.14mmol to 4.38mmol per L) and 24-hour urinary potassium (57.8mmol to 81.6mmol per 24 hours) (P<0.01)
    • Significant decrease in urinary Na/K ratio ( 3.3 to 2.4) (P<0.01)
    • Significant correlation between urinary Na/K ratio and changes in office SBP (R=0.58, P<0.001) and 24-hour SBP (R=0.51, P<0.001), but not DBP.
  • Untreated group (N=52): No significant changes in any outcome
Changes in Office and 24-Hour BP in Treated and Untreated Patients After Four Weeks
Arterial BP
mmHg		 Treated Sub-Group Untreated Sub-Group
Baseline Four Weeks Baseline Four Weeks
Office SBP 154.4±8.2 142.2±7.6*,** 153.8±11.6 152.2±9.4
DBP 95.0±5.6 87.2±4.3*, ** 96.6±4.4 96.0±4.7
24-Hour SBP 142.7±8.2 134.8±6.3*, ** 141.8±8.5 140.5±7.6
DBP 90.8±4.4 84.6±3.8*, ** 91.6±3.2 91.2±4.3
Day SBP 143.8±6.0 136.5±5.2*, ** 142.5±9.1 142.2±7.4
Day DBP 93.5±4.1 85.9±3.0*, ** 92.8±3.7 92.6±3.8
Night SBP 128.7±6.2 121.6±4.9*, ** 127.0±7.5 128.3±8.1
Night DBP 77.5±3.7 74.4±3.2*, ** 78.6±4.0 78.3±3.5

* P<0.001 vs. treated and untreated sub-groups at baseline
** P<0.001 vs. untreated sub-group at follow-up visit after four weeks.

Author Conclusion:
Potassium aspartate in a dose lower than previously reported lowers office and 24-hour ambulatory BP in subjects with mild to moderate hypertension and should be considered in initial treatment.
Funding Source:
University/Hospital:
Reviewer Comments:
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) No
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? ???
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes