HTN: Protein (2007)
Citation:
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To quantitatively review the data from observational studies in humans that examined the association between dietary protein intake and blood pressure.
Inclusion Criteria:
Research papers on dietary protein and BP in humans, including epidemiological cross-sectional and longitudinal studies.
Exclusion Criteria:
- Case-control studies that compared normotensive and hypertensive individuals
- Reports published in letter or abstract form.
Description of Study Protocol:
- Recruitment: N/A
- Design: Computer assisted searches of English language publications on MEDLINE from January 1980 to January 2001 were conducted. References cited in related publications were also reviewed.
- Statistical Analysis: The pooled regression coefficient (ß) and its standard error (SE) were estimated by taking the weighted average for each study of the ß and SE. If the values for ß, SE, t and units of measure for dietary protein intake were not reported, they were estimated according to a standard formula. A test of the homogeneity assumption was also performed.
Data Collection Summary:
- Timing of Measurements: N/A
- Dependent Variables: Systolic and diastolic blood pressure
- Independent Variables: Protein intake.
Description of Actual Data Sample:
- Initial N: 11 cross-sectional studies; two longitudinal studies
- Attrition (final N): Nine cross-sectional studies; two longitudinal studies (N=19,954 SBP and 19,982 SBP measurements in men; 950 measurements in women)
- Age: Not reported
- Ethnicity: Not reported
- Other relevant demographics: Not reported
- Anthropometrics: Not reported
- Location: Not reported.
Summary of Results:
Pooled Regression Coefficients (ßw) of Blood Pressure on Dietary Protein Intake by Sex and Method of Dietary Assessment Used
Variables |
SBP |
DBP |
||||||||
|
No | H-Test | ßw (SE) |
Z-Score |
P-Value | No. | H-Test |
ßw (SE) |
Z-Score |
P-Value |
Reported by Sex | ||||||||||
Men only | 19,954 | p* 0.05 | 0.030 (0.01) | 5.27 | 0.01 | 19,982 | p* 0.05 | 0.025 (0.01) | 3.78 | 0.01 |
Women only |
950 | p* 0.05 | 0.014 (0.01) |
2.28 |
0.022 | 950 | p* 0.05 |
0.021 (0.00) |
5.37 |
0.01 |
Combined sexes | 12,761 | p* 0.05 | 0.029 (0.01) | 4.01 | 0.01 | 12,508 | p* 0.05 | 0.015 (0.00) | 5.46 | 0.01 |
By methods of assessment | ||||||||||
FFQ | 402 | N/A | 0.516 (0.29) | 1.79 | 0.072 | 402 | N/A | 0.110 (0.05) | 2.20 | 0.02 |
3-day food record | 61 | N/A | 0.133 (0.06) | 2.10 | 0.034 | 28 | N/A | 0.168 (0.07) | 2.29 | 0.022 |
24-hour diet recall | 19,366 | p* 0.05 | 0.053 (0.01) | 5.84 | 0.01 | 19,348 | p* 0.05 | 0.046 (0.01) | 5.33 |
0.01 |
24-hour urine** | 11,999 | p* 0.05 | 0.025 (0.01) | 3.33 | 0.01 | 11,825 | p* 0.05 | 0.014 (0.00) | 5.40 | 0.01 |
H-test": test of the homogeneity association for pooled results from more than one study
NA, not applicable (because of one study only)
Values of Z score text (see text) may be different due to rounding calculation
**Included one study on overnight urine collection (N=74)
FFQ=food frequency questionnaire.
Author Conclusion:
- A convincing cross-sectional inverse association between dietary protein intake and BP was demonstrated by the meta-analysis of nine population-based studies
- Evidence from the longitudinal epidemiological studies was limited and further studies will be needed to confirm this hypothesis.
Funding Source:
Industry: |
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Reviewer Comments:
- While the number of male subjects is quite large, the number of female subjects is relatively small
- The age and location of the subjects is unspecified, which limits the generalizability of the findings
- Results may be potentially confounded by the different methods used to assess protein intake.
Quality Criteria Checklist: Review Articles
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Relevance Questions | |||
1. | Will the answer if true, have a direct bearing on the health of patients? | Yes | |
2. | Is the outcome or topic something that patients/clients/population groups would care about? | Yes | |
3. | Is the problem addressed in the review one that is relevant to dietetics practice? | Yes | |
4. | Will the information, if true, require a change in practice? | Yes | |
Validity Questions | |||
1. | Was the question for the review clearly focused and appropriate? | Yes | |
2. | Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described? | Yes | |
3. | Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified andappropriate? Wereselectionmethods unbiased? | ??? | |
4. | Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methodsspecified,appropriate, andreproducible? | Yes | |
5. | Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined? | ??? | |
6. | Was the outcome of interest clearly indicated? Were other potential harms and benefits considered? | ??? | |
7. | Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently acrossstudies and groups? Was thereappropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described? | ??? | |
8. | Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels ofsignificance and/or confidence intervals included? | Yes | |
9. | Are conclusions supported by results with biases and limitations taken into consideration? Are limitations ofthe review identified anddiscussed? | Yes | |
10. | Was bias due to the review's funding or sponsorship unlikely? | Yes | |