HTN: Minerals (2007)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
The purpose of this study was to perform a detailed study of diet and other lifestyle patterns (physical activity, alcohol consumption and smoking habits) of drug-treated hypertensives and to compare the data with population-based control subjects.
Inclusion Criteria:
  • The present study sample was part of a population-based epidemiological study addressing the risk factors and disease end-points of atherosclerotic cardiovascular diseases (Oulu Project Evaluating the Risk of Atherosclerosis, OPERA)
  • The hypertensive group, aged 40-59 years at time of selection, was randomly selected by age stratfication (15 subjects per year) from the Social Insurance Institute register for reimbursement of hypertensive medications
  • The age- and sex-matched controls were randomly selected from the social insurance register maintained by the Social Insurance Institute, covering the whole population of the city of Oulu.
Exclusion Criteria:
No exclusion criteria was reported.
Description of Study Protocol:

Recruitment

This study is a secondary analysis of the larger OPERA study

Recruitment criteria in the primary study indicated that the participants were recruited by the Social Insurance Institute.

Design

Cross-sectional design.

Blinding Used

Blinding did not appear to occur when evaluating outcomes.

Intervention

Not applicable.

Statistical Analysis

  • Mean differences between the treatment (hypertensives) and control (population-based, matched for age, sex) groups were evaluated using the Student's T-test for independent samples
  • For comparisons concerning consumption of alcohol, the Mann-Whitney U-test was employed
  • Pearson's correlation coefficients investigated the relationships between nutrient intake and other variables
  • The study cohort was divided into four age groups of approximately equal size, the analysis of variance (ANOVA) with Bonferroni correction was used to compare mean differences in nutrient intake between the age groups.
Data Collection Summary:

Timing of Measurements

Not applicable, as data collected at one point in time.

Dependent Variables

  • Body mass index (BMI) (kg per m2)
  • Waist-to-hip ratio
  • Systolic blood pressure (SBP) (mmHg)
  • Diastolic blood pressure (DBP) (mmHg)
  • Total cholesterol (mmol L-1)
  • LDL cholesterol (mmol L-1)
  • HDL cholesterol (mmol L-1)
  • Triglycerides (mmol L-1)
  • Fasting blood glucose (mmol L-1)
  • Alcohol consumption (g per week -1, range)
  • Smoking habits (yes or no)
  • Diabetes (percentage)
  • Physical activity (range of one (no leisure time physical activity) to five (regular heavy exercise)].

Independent Variables

  • Sex
  • Age
  • Nutrient Intake was measured using seven-day food records, analyzed using NUTRICA computer program (Social Insurance Institution, Helsinki) using the Finnish nutrient database.
  • Energy (kcal)
  • Protein (g)
  • Total fat (g)
  • Saturated fatty acids (g) (SAFA)
  • Monounsaturated fatty acids (g) (MUFA)
  • Polyunsaturated fatty acids (g) (PUFA)
  • Carbohydrate (g)
  • Alcohol (g)
  • Dietary fiber (g)
  • Sodium (mg)
  • Potassium (mg)
  • Calcium (mg)
  • Magnesium (mg).
Description of Actual Data Sample:

Initial N

  • The eligible study population consisted of 600 hypertensive subjects (300 men and 300 women), with 600 control subjects (300 men and 300 women)
  • 1,045 subjects (87.8%) participated in the study
  • 520 were hypertensive (262 men and 258 women)
  • 525 were controls (259 men and 262 women).

Attrition (Final N)

  • Of the 1,045 participants, 79% (N=857) completed the seven-day food records
  • 16% (N=141) were not accepted because they were inaccurate or incomplete. Thus, 84% (N=716) of the food records were of adequate detail and quality and were accepted as material for the dietary intake study.

Age

  • The study groups were dichotomized by sex
  • The mean age for the male controls (N=180) 51.1±6.1 years and the mean age of the male treatment group (N=165) (50.9±6.2 years) were not significantly different
  • Similar findings among females; controls (N=194) (52.3±6.0 years) and treatment group (N=177) (51.9±5.9 years).

Ethnicity

  • Not reported
  • Finnish residents participated in the study.

Anthropometrics

  • There were significant differences (P<0.001) for BMI between the hypertensive and control groups for both sexes
  • The male hypertensives had a mean BMI of 28.9±2.0 and the sex-matched controls had a mean BMI of 26.3±2.4
  • The female hypertensives had a mean BMI of 28.3±5.1 and the control group had a mean BMI of 25.9±5.1
  • There were significant differences (P<0.001) for waist-to-hip ratio between the sexes as well
  • For males, the waist-to-hip ratio for hypertensives and controls were 0.91±0.01 and 0.94±0.04, respectively
  • For females, the waist-to-hip ratio for hypertensives and controls were 0.78±0.05 and 0.81±0.06, respectively.

Location

Finland.

Summary of Results:

Basic Characteristics and Cardiovascular Risk Factors of Hypertensive and Controls 

Variables

Male Controls
(N=180)
Mean (SD)

Male Hypertensives
(N=165)
Mean (SD)

P-Value

Female Controls
(N=194)
Mean (SD)

Female Hypertensives
(N=177)
Mean (SD)

P-Value

SBP, (mm HG)

145 (20)

159 (21)

<0.001

138 (22)

154 (21)

<0.001

DBP, (mm HG)

88 (10)

96 (10)

<0.001

82 (12)

90 (11)

<0.001

Total Cholesterol (mmol/L)

5.8 (1.1)

5.7 (1.1)

NS

5.6 (1.0)

5.8 (1.0)

NS

LDL Cholesterol
(mmol/L)

3.7 (0.9)

3.6 (1.0)

NS

3.4 (0.9)

3.5 (0.9)

NS

HDL Cholesterol (mmol/L)

1.2 (0.3)

1.2 (0.3)

NS

1.6 (0.4)

1.5 (0.4)

<0.05

Triglycerides (mmol/L)

1.5 (0.8)

1.8 (1.0)

<0.01

1.2 (0.6)

1.5 (0.9)

<0.001

Fasting Blood Glucose (mmol/L)

4.6 (1.1)

5.0 (1.7)

<0.01

4.3 (0.5)

4.7 (1.4)

<0.001

Alcohol, (g/week)

87 (101)

99 (123)

NS

21 (33)

26 (42)

NS

Smokers, (%)

36

27

NS

25

16

NS

Diabetes, (%)

2

12

NS

1

5

NS

Physical Activity (Range from 1-5)

3.2 (0.9)

2.8 (0.9)

<0.001

3.1 (0.9)

2.9 (1.0)

<0.05

NS=Not significant.

Average Daily Intakes of Energy and Nutrients by Hypertensives and Controls

Variables

Male Controls (N=180)
Mean (SD)

Male Hypertensive
(N=165)
Mean (SD)

P-Value

Female Controls
(N=194)
Mean (SD)

Female Hypertensive
(N=177)
Mean (SD)

P-Value

Energy, (kcal)

2,227 (498)

2,098 (507)

<0.05

1,600 (332)

1,595 (359)

NS

Protein, (g)

89 (21)

88 (22)

NS

67 (15)

68 (16)

NS

Total fat, (g)

92 (27)

85 (26)

<0.01

64 (18)

65 (19)

NS

SAFA, (g)

38 (13)

34 (11)

<0.01

27 (9)

27 (9)

NS

MUFA, (g)

32 (10)

29 (9)

<0.01

21 (6)

22 (7)

NS

PUFA, (g)

15 (6)

14 (6)

NS

10 (4)

10 (4)

NS

Carbo-hydrate, (g)

233 (64)

215 (63)

<0.01

176 (42)

170 (42)

NS

Alcohol, (g)

11 (16)

13 (20)

NS

4 (7)

5 (9)

NS

Dietary fiber, (g)

23 (7)

22 (8)

NS

18 (5)

18 (5)

NS

Sodium, (mg)

4,223 (1122)

4,121 (1105)

NS

2,810 (703)

2,962 (765)

<0.05

Potassium (mg)

4,033 (977)

3,932 (994)

NS

3,190 (720)

3,191 (653)

NS

Calcium (mg)

1,121 (400)

1,110 (442)

NS

950 (321)

929 (304)

NS

Magnesium (mg)

402 (91)

392 (101)

NS

310 (68)

308 (66)

NS

NS=Not significant

Other Findings

  • When sodium intake adjusted for energy, the sodium intake among the female hypertensives was significantly higher (P<0.01) than controls
  • There were no differences seen between intakes of potassium, calcium and magnesium for the hypertensives or controls for both sexes
  • Smoking was associated with intake of carbohydrate and consumption of alcohol.
Author Conclusion:
  • Non-pharmacological treatment, including dietary management, of hypertensive patients at high risk for cardiovascular complications seems still to be inadequate
  • Additional well-focused efforts are needed to intensify the dietary treatments as well as to reduce alcohol consumption and smoking amongst hypertensives. 
Funding Source:
University/Hospital: Academy of Finland
Not-for-profit
0
Foundation associated with industry:
Reviewer Comments:
  • The investigators conclusions are based solely on the completion of seven-day dietary food records completed by only 69% of the subjects
  • The accuracy of the food records are questioned, when comparing total energy intake from the hypertensives to the control groups.
  • Although the hypertensives had significantly higher BMIs and waist-to-hip ratios than the controls, the total energy intake was significantly different between the groups, suggesting that the hypertensive subjects potentially under-reported their food intake. Therefore, some of the investigators' conclusions are suspect.
  • In addition, there is no information on the impact of dietary counseling on changes in nutrient intake.
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) N/A
  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) N/A
 
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? ???
  2.2. Were criteria applied equally to all study groups? ???
  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) N/A
  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.) N/A
  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? Yes
  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.) Yes
  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? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  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%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  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? N/A
  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.) ???
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? N/A
  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? N/A
  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? ???
  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? N/A
  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? ???
  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? No
  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)? No
  8.6. Was clinical significance as well as statistical significance reported? No
  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? No
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
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