EAL

FNOA: Antioxidants (2011-2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To identify dietary patterns by a mixed clustering method and to analyze their relationship with cognitive function, depressive symptoms and self-rated health in older people.

Inclusion Criteria:

Three-City Study participants
Individuals had to be living in Bordeaux, Dijon or Montpellier, France
Aged 65 years and older
Not institutionalized.

Exclusion Criteria:

Participants who presented two missing values or more among the dietary items were excluded.

Description of Study Protocol:

Recruitment

Study was conducted among participants in the Three-City study, a large ongoing prospective cohort study of vascular risk factors for dementia that included community-dwellers in Bordeaux, Dijon, and Montpellier, France, at baseline in 1999-2000. Recruitment methods not described.

Design

Cross-sectional population-based study

Blinding used

Not applicable

Intervention

Not applicable

Statistical Analysis

Cluster analysis, combining hybrid clustering and research for stable groups during the k-means step on mean number of weekly servings of 20 predetermined food groups, separately in men and women
Analysis of variance was used to compare continuous sociodemographic and health variables across clusters
Chi-square tests were performed on categorical variables.

Data Collection Summary:

Timing of Measurements

Baseline data collection included sociodemographic and lifestyle characteristics, symptoms and complaints, main chronic conditions, neuropsychological testing, a physical examination, and blood sampling
Present study is based on the first follow-up conducted in 2001-2002 which placed particular emphasis on nutritional data.

Dependent Variables

Neuropsychological examination performed by trained psychologists
Cognitive function assessed by Mini-Mental State Examination
Depressive symptoms assessed using Center for Epidemiologic Studies-Depression (CEDS)
Self-rated health (very good, good, fair, bad or very bad).

Independent Variables

Dietary patterns derived from food frequency questionnaire and hybrid clustering

Control Variables

Age
Sex
Marital status
Living arrangement
Educational level
Income
Body mass index
Medical history
Medication use.

Description of Actual Data Sample:

Initial N: 9,294 elderly community dwellers in the Three-City Study.
- 1,811 participants enrolled at baseline participated in the first follow-up in Bordeaux
- 1,796 completed the dietary assessment
Attrition (final N): 1,724 elderly community dwellers included in the final analysis
- 647 men and 1,077 women
- 66 participants presented two missing values or more among the dietary items
Age: Mean age 76.0±4.97 years
Ethnicity: Not reported
Other relevant demographics:
Anthropometrics: Mean BMI 26.9±3.59kg/m²
Location: France.

Summary of Results:

Key Findings

Five dietary clusters were identified in each sex
Among both men and women, the first cluster labeled "small eaters" (31% of participants) did not represent a particular food group
A "healthy" cluster characterized by higher consumption of fish in men (n=157, 24.3%) and fruits and vegetables in women (n=267, 24.8%) had significantly lower mean number of errors to Mini-Mental State score after adjustment for socio-demographic variables (β= -0.11, 95% confidence interval: -0.22 to -0.004 in men, β= -0.13, 95% confidence interval: -0.22 to -0.04 in women).
The same cluster was associated with borderline significance with lower depressive symptoms in women (β= -0.16, 95% confidence interval: -0.33 to 0.007)
Men in the "pasta eaters" cluster (n=136, 21%) had higher depressive symptoms (β=0.26, 95% confidence interval: 0.06 to 0.46) and higher risk to report poor health (polytomous regression, odds ratio=1.91, 95% confidence interval: 1.21 to 3.01) than the "healthy" cluster.
Women in the "biscuits and snacking" cluster (n=162, 15%) had greater risk of poor perceived health (odds ratio=1.69, 95% confidence interval: 1.15 to 2.48) compared to "healthy" eaters
Additional adjustment for body mass index and medication use strengthened these associations.

Author Conclusion:

Sex-specific dietary patterns derived by hybrid clustering method are associated with fewer cognitive and depressive symptoms and better perceived health in older people. Our findings reinforce the importance of a healthful dietary pattern including regular consumption of fish, fruits and vegetables, in accordance with the Department of Health and Human Services' 2005 Dietary Guidelines for Americans.

Funding Source:

Government:

Agence Nationale de la Recherche

Not-for-profit

Fondation pour la Recherche Medicale

Other non-profit:

Reviewer Comments:

Recruitment methods not described. Only Three-City Study subjects from Bordeaux were included. 31% of subjects were categorized as "small eaters" and did not pertain to any food group-may have underreported their intake. Health was based on self-rating. Authors note the following limitations:

Although the clusters are consistent with similar patterns that have shown reproducibility across populations, further research will be necessary to describe the nutrient profiles of each cluster and ascertain their internal validity
Analysis was based on intake frequency that may not accurately reflect portion size
No causal link can be inferred from this cross-sectional study
Depressed or slightly cognitively impaired subjects may have changed their diet in reaction to their disease
Adjustment for potential confounding factors does not eliminate the possibility of residual confounding.

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?	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)	Yes
	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?	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.)	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?		N/A
	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?	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?	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?	N/A
	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