DLM: Hypertension (2010)
Citation:
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To clarify the main dietary and non-dietary risk factors between hypertension and normal blood pressure in a Chinese urban population.
Inclusion Criteria:
Subjects aged 15 to 64 living in Tianjin, China.
Exclusion Criteria:
None specified.
Description of Study Protocol:
- Recruitment: Subjects selected by random stratified cluster sampling
- Design: Cross-sectional study
- Blinding used: Not applicable
- Intervention: Cross-sectional population surveys.
Statistical Analysis
- Differences of dietary factors between hypertension and normal blood pressure people were tested by using general factorial ANOVA
- To assess the relationship between hypertension and dietary and non-dietary risk factors, adjusted odds ratios were calculated by logistic regression.
Data Collection Summary:
Timing of Measurements
Health status, health behaviors, dietary intake and anthropometry assessed in two independent cross-sectional population surveys in 1989 and 1992.
Dependent Variables
Blood pressure measured using standard mercury sphygmomanometer.Independent Variables
- Dietary intake assessed by food weighing plus consecutive individual three-day food records
- Food intake analyzed using Chinese Food Composition Tables
- Physical activity assessed through questionnaire
- Smoking
- Alcohol consumption
- Family history of hypertension
Control Variables
- Age
- Height
- Weight
- Time of survey.
Description of Actual Data Sample:
- Initial N: 2,068 subjects total; 1,550 in 1989 and 2,317 in 1992
- Attrition (final N): 2,068; 990 men and 1,078 women. Response rates of 97% in 1989 and 96% in 1992.
- Age: Data reported on those aged 35 to 64 years
- Ethnicity: Not mentioned
- Location: Tianjin, China.
Summary of Results:
Odds Ratio - Men | P-Value | Odds Ratio - Women | P-Value | |
Sodium Intake | 1.07 | 0.040 | 1.07 | 0.047 |
Potassium Intake | 0.98 | 0.840 | 0.80 | 0.118 |
Na:K Ratio |
1.12 |
0.061 |
1.18 |
0.005 |
Age |
1.09 |
0.000 |
1.08 |
0.000 |
BMI | 1.18 | 0.000 | 1.16 | 0.000 |
Overweight | 3.14 | 0.000 | 3.23 | 0.000 |
Family history | 1.59 | 0.048 | 2.26 | 0.000 |
Commuting Activity | 0.80 | 0.044 | 1.10 | 0.693 |
Other Findings
- 367 men and 395 women were hypertensive and 623 men and 683 women had normal blood pressure
- The whole population had a high sodium and low potassium consumption level
- Hypertensive men and women had significantly higher dietary sodium-to-potassium ratio (P<0.01) than men and women with normal blood pressure
- Age, body mass index, overweight and family history of hypertension were positively related to high blood pressure
- Dietary sodium intake and dietary sodium-to-potassium ratio were positively associated with high blood pressure
- Education level in women and commuting physical activity in men were inversely associated with high blood pressure
- Income, smoking, alcohol consumption, occupational and leisure time physical activity were not significantly associated with hypertension.
Author Conclusion:
- The present study has shown that there were high sodium and low potassium consumption levels in the whole of the Tianjin urban population and the hypertensive group had a high dietary sodium intake and high dietary sodium-to-potassium ratio
- Age, BMI, overweight, family history of hypertension, dietary sodium intake and dietary sodium-to-potassium ratio were positively associated with high blood pressure
- Education level in women and commuting physical activity in men were inversely associated with high blood pressure.
Funding Source:
University/Hospital: | University of Kuopio, Institute Tianjin (The People's Republic of China) |
Reviewer Comments:
- Questionnaires not tested for reliability and validity
- High response rates
- Surveys were done four years apart and all results pooled together.
Quality Criteria Checklist: Primary Research
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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? | 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? | Yes | |
3. | Were study groups comparable? | N/A | |
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? | N/A | |
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? | 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? | 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? | ??? | |
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? | 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.) | N/A | |
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? | Yes | |
6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | N/A | |
6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | N/A | |
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? | 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? | ??? | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | Yes | |
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)? | Yes | |
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 | |