EAL

AWM: High Calcium (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare dietary intakes and energy expenditure between middle-aged, premenopausal African American and white women participating in a longitudinal study of the menopausal transition.

Inclusion Criteria:

Healthy, over 43 years of age, and have had 5 or more menstrual periods in 6 months before screening. All potential volunteers underwent a 3-step screening process including measures of blood chemistry and lipids, a physical exam, and a psychological interview to determine their ability to complete a 4-year longitudinal study.

Exclusion Criteria:

Excluded if taking medication regularly (including hormones), were not having regular menstrual cycles, or had clinically abnormal results from laboratory tests or the physical exam.

Description of Study Protocol:

Recruitment

Volunteers recruited by advertisement and word of mouth.

Design

Cross-sectional cohort study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Dietary and exercise records, accelerometer, whole room indirect calorimetry.

Statistical Analysis

Descriptive statistics were calculated for each variable and normality assessed. Variables that were not normally distributed were log transformed before analysis. The general linear models procedure was used to assess differences between African American and white women, adjusted as needed for covariates. Partial correlation analyses (adjusted for energy intake) were performed to determine the relation between dietary intakes and body composition variables in the whole population and in African American and white women separately. The general linear models procedure was also used to compare the slopes of the relations between body composition and dietary variables by race. Multiple regression analysis with use of the R2 selection procedure was performed to examine the relative importance of diet and activity factors on body composition. A P value of 0.05 was considered significant.

Data Collection Summary:

Timing of Measurements

Eligible women completed baseline assessments. Whole room indirect calorimetry performed in a subset of 56 women.

Dependent Variables

Body composition by DEXA
Height and weight assessed in subjects wearing hospital gowns after fasting overnight

Independent Variables

Dietary intake by 4-day food record following instruction from a dietitian (in most cases it was the same 4 days of wearing accelerometer). Intake data analyzed using Moore's Extended Nutrient Database (MENu), a validated database
Energy expenditure by triaxial accelerometer for 4 consecutive days including 1 weekend day
Physical activity by self-report on previously validated physical activity recall questionnaire and detailed 24-hour activity record on days when wearing accelerometer
24 hour and sleeping energy expenditure by whole room indirect calorimetry

Control Variables

Description of Actual Data Sample:

Initial N: 97 white and 52 African American women.

Attrition (final N): See above

Age: Mean age 47.4 +/- 0.2 years

Ethnicity: white, African American

Other relevant demographics:

Anthropometrics African American women had a significantly higher BMI, fat mass, lean mass and percentage body fat than white women.

Location: Baton Rouge, Louisiana

Summary of Results:

	African American (n=52)	White (n=97)	P-value
Age (y)	46.7 +/- 0.3 (44-51)	47.7 +/- 0.2 (43-56)	< 0.05
Height (cm)	164.5 +/- 0.8 (152-181)	163.9 +/- 0.6 (147-175)	NS
Weight (kg)	78.3 +/- 2.3 (51.2 - 130.8)	68.0 +/- 1.2 (51.2 - 100.9)	NS
BMI (kg/m2)	28.9 +/- 0.8 (18.5 - 47.5)	25.4 +/- 0.4 (18.9 - 36.3)	< 0.05
Fat Mass (kg)	33.4 +/- 1.7 (13.0 - 71.9)	27.0 +/- 1.0 (10.5 - 56.4)	< 0.05
Lean Mass (kg)	41.0 +/- 0.8 (29.7 - 56.7)	37.7 +/- 0.4 (27.2 - 51.5)	< 0.05
% Body Fat	42.2 +/- 0.8 (24.2 - 55.9)	39.2 +/- 0.8 (20.0 - 57.0)	< 0.05
Total EE (kJ/day)	8494 +/- 134	8619 +/- 92	NS
Activity EE (kJ/day)	1958 +/- 130	2113 +/- 88	NS
Leisure Activity (kJ/day)	556 +/- 155	1079 +/- 100	< 0.05
Total Activity in Past Year (kJ/day)	4920 +/- 360	4489 +/- 259	NS
Stairs Climbed	1.4 +/- 0.9	4.7 +/- 0.7	< 0.05
Hours Standing/Day	3.2 +/- 0.3	4.1 +/- 0.2	< 0.05
TV Watching (hrs/day)	1.6 +/- 0.2	1.3 +/- 0.1	NS
Exercise (hrs/day)	0.34 +/- 0.1	0.45 +/- 0.1	NS
Total 24-hr EE (kJ/day)	8468 +/- 222	8874 +/- 105	NS
Sleeping EE (kJ/day)	5749 +/- 155	6176 +/- 75	< 0.05
Total Energy (kJ/day)	6740 +/- 1732	7067 +/- 1431	NS
Total Energy (kcal/day)	1611 +/- 414	1689 +/- 342	NS
Fat (g/day)	62 +/- 2	60 +/- 1	NS
Carbohydrate (g/day)	215 +/- 5	210 +/- 4	NS
Protein (g/day)	65 +/- 2	69 +/- 1	< 0.05
Saturated Fat (g/day)	19 +/- 1	20 +/- 1	NS
Monounsaturated Fat (g/day)	23 +/- 1	23 +/- 1	NS
Polyunsaturated Fat (g/day)	14 +/- 0.5	12 +/- 0.4	< 0.05
Fiber (g/day)	14 +/- 1	16 +/- 1	< 0.05
Cholesterol (mg/day)	200 +/- 14	198 +/- 10	NS
Calcium (mg/day)	518 +/- 34	758 +/- 25	< 0.05
Magnesium (mg/day)	216 +/- 9	271 +/- 6	< 0.05

Other Findings

African American women had significantly higher BMI, fat mass, lean mass and percentage body fat than white women (p < 0.05)

Sleeping energy expenditure (adjusted for lean and fat mass) was lower in African American than in white women (5749 +/- 155 compared with 6176 +/- 75 kJ/day, P = 0.02), however, there was no significant difference in 24-hour energy expenditure between groups.

Reported leisure activity over the course of a week was less in African American than in white women (556 +/- 155 compared with 1079 +/- 100 kJ/day, P = 0.02), as were the daily hours spent standing and climbing stairs, although total reported activity (leisure and occupational) did not differ by race.

Dietary intakes of protein, fiber, calcium, and magnesium were significantly less in African Americans, and polyunsaturated fat was higher, whereas there were no observed ethnic differences in intakes of energy, fat, carbohydrate or cholesterol.

Body fat within the group was positively correlated with total, saturated, and monounsaturated fat intakes and inversely associated with fiber and calcium intakes (p < 0.05). Fiber was the strongest single predictor of fatness.

Author Conclusion:

In conclusion, the present study suggests several ethnic differences in factors contributing to the energy balance in women nearing menopause. Specifically, African American women had significantly lower energy expenditure, both in terms of basal metabolism and self-reported physical activity, although measured total energy expenditure was not lower in this group. Furthermore, although reported total energy and total fat intakes did not differ significantly between groups, there were significant ethnic differences in intakes of fiber, protein, calcium and specific fatty acids that may have implications for the development of obesity. Longitudinal follow-up of this cohort will clarify the role of such energy expenditure and dietary differences on the development of obesity during menopause.

Funding Source:

Government:

NIH

Reviewer Comments:

EE measured several ways. Dietary and activity records rely on self-reporting. Almost twice as many whites than African Americans in group comparisons.

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?		No
	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?	No
3.	Were study groups comparable?		???
	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.)	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?	???
	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?	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?	Yes
	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?		Yes
	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?	Yes
	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?	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