EAL

HTN: Minerals (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To investigate the relationship between arterial compliance and blood pressure, glucose and lipid metabolism and also to observe the effects of oral magnesium potassium supplementation on arterial compliance in essential HTN.

Inclusion Criteria:

Essential HTN
SBP above 140mm Hg or DBP above 90mm Hg at end of one-week placebo run-in period.

Exclusion Criteria:

Patients with any relevant, concomitant, cardiovascular or non-cardiovascular diseases, such as secondary HTN, serious infection and liver or kidney disease.

Description of Study Protocol:

Recruitment: Patients with essential HTN in the Shaanxi district; methods not described
Design: Randomized controlled trial
Intervention: Potassium magnesium supplementation or lacidipine for four weeks.

Statistical Analysis

Descriptive data expressed as mean±SD
The clinical variables, biochemical measurements and arterial compliance between the two groups were compared by an unpaired Student's T-test
After the treatment, blood pressure and arterial compliance were compared with the baseline by the paired T-test
Statistical significance was inferred at a two-tailed P-value of <0.05.

Data Collection Summary:

Timing of Measurements

Before and after the four weeks, blood pressure, blood samples, large arterial compliance and small arterial compliance were measured.

Dependent Variables

Large arterial compliance and small arterial compliance measured by CVProfilor DO-2020 CardioVascular Profiling System, showed good reproducibility in Chinese subjects
Blood pressure
Blood samples evaluated for serum total and HDL cholesterol, triglycerides
Whole blood glucose measured with one-touch test strips
LDL calculated through Friedewald formula.

Independent Variables

Magnesium potassium supplementation (70.8mg magnesium per day, 217.2mg potassium per day) for four weeks
Lacidipine (four mg per day) for four weeks
Patients instructed to follow usual diet.

Description of Actual Data Sample:

Initial N

133 patients with essential HTN
147 healthy subjects enrolled
67 of the 133 agreed to receive further treatment.

Attrition (Final N)

35 subjects received potassium magnesium supplementation (10 males, 25 females)
32 received lacidipine (nine males, 23 females)
147 healthy subjects (68 males, 79 females).

Age

Potassium magnesium: Mean, 58±7 years (range 41-70 years)

Lacidipine: Mean, 56±8 years, range 39-70 years

Controls: Mean, 54±9 years (range 39-75 years).

Ethnicity

Not mentioned.

Other Relevant Demographics

Healthy subjects matched for age, sex and body surface area.

Anthropometrics

There were no differences in the prescribed anti-hypertensive medications between the two groups before the one-week placebo run-in period

No significant differences in clinical characteristics, metabolic plasma parameters, pre-treatment BP or arterial compliance values were noted between the two treatment groups.

Location

Shaanxi, China.

Summary of Results:

	Lacidipine - Before	Lacidipine - After	K/Mg - Before	K/Mg - After
SBP (mm Hg)	148.73±19.21	135.47±17.55, P<0.01	142.36±17.14	134.53±12.69, P<0.01
DBP (mm Hg)	86.06±13.09	79.73±10.53, P<0.01	82.46±9.04	78.79±7.96, P<0.05
MAP (mm Hg)	110.38±14.03	101.73±12.64, P<0.01	106.03±11.73	99.61±9.51, P<0.01
PP (mm Hg)	61.55±12.46	55.73±10.01, P<0.01	59.90±14.40	55.73±9.21, P<0.05
SVR	2038±359	1795±304, p <0.01	2058±405	1717±262, P<0.01
HR (beats/min)	74.11±9.23	71.05±10.76	67.99±9.03	68.34±9.98
Large Arterial Compliance (ml/mm Hg x 10)	10.413±3.680	12.503±4.871, P<0.01	12.961±4.032	13.571±4.157
Small Arterial Compliance (ml/mm Hg x 100)	3.412±1.526	4.033±1.807, P<0.01	3.241±1.569	3.897±2.040, P<0.05

Other Findings

It was found that arterial compliance was significantly lower in patients with essential HTN, compared with healthy subjects

Large arterial compliance: 12.53±0.33 vs. 15.63±0.30ml per mm Hg x 10, P<0.01
Small arterial compliance: 3.79±0.17 vs. 5.69±0.25ml per mm Hg x 100, P<0.01.

On lacidipine, SBP and DBP decreased 13.27±1.76mm Hg and 6.33±1.55mm Hg. Large arterial compliance increased 25.05%±4.49% and small arterial compliance increased 34.50±7.40%.
On potassium magnesium supplementation, SBP and DBP decreased 7.83±1.87mm Hg and 3.67±1.03mm Hg. Large arterial compliance increased 12.44%±4.43% and small arterial compliance increased 45.25%±6.67%.
Decreases in systemic vascular resistance by 11.9% for lacidipine and 16.6% for potassium magnesium supplementation (P<0.01) were seen between the drug-induced changes
The changes in SBP and DBP did not differ significantly between the different drug therapies, but the post-treatment pressures differed significantly from pre-treatment (P<0.01).

Author Conclusion:

Both large and small arterial compliance were decreased in essential HTN patients
Magnesium and potassium supplementation show an improvement in small arterial compliance mostly, while lacidipine improved large arterial compliance significantly.

Funding Source:

Reviewer Comments:

Recruitment methods not well-defined and subjects self-selected, based on agreement to further treatment
Validity of CVProfilor measurements is questionable
Compliance and dietary intake not assessed.

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?		???
	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)	???
	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?		???
	4.1.	Were follow-up methods described and the same for all groups?	???
	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%.)	???
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	???
	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?	No
	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?	No
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	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?		???
	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?	???
	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?	No
	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)?	N/A
	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