NSA: Serum Proteins (2009)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • To estimate the total dietary energy intake and the proportion of macronutrients (protein, carbohydrates and lipids) and major micronutrients (calcium, iron, vitamin A, thiamin, riboflavin, niacin and ascorbic acid) intakes in a group of patients with anorexia nervosa and to compare these findings with similar data obtained from normal subjects
  • To determine the serum cortisol, glucose, albumen, hemoglobin, hematocrit, iron, potassium, chlorides, sodium, calcium and phosphorus content of patients with anorexia nervosa.
Inclusion Criteria:
  • Diagnosis of anorexia nervosa defined by the American Psychological Association DSM III criteria except for the disturbance in body image, which was still a controversial criteria
  • Seen by a nutritionist at the clinic between 1975 and 1985
  • Classified as a restricter using fasting or restricted food intake to induce weight loss but without presenting with periods of bingeing accompanied by vomiting and laxative, diuretic or drug abuse.
Exclusion Criteria:

None mentioned.

Description of Study Protocol:

Recruitment

This study used information from medical records (patients with anorexia) and previous surveys (normal patients).

Design

This cross-sectional study look at two different sources of data in order to compare food intake of two groups. For anorexic patients, diet history and 24-hour food intake were obtained by interview with a nutritionist at time of diagnosis. The information corresponded to patients' dietary intake for the several weeks before the diagnosis. Food composition tables were used to calculate variables. Nutrient composition of new foods were not listed in the tables were obtained from the manufacturer. Data for normal patients (controls) were obtained from the subjects of a Quebec City regional study of the National Nutrition Canada survey from 1980. Researchers say they matched patients for age, sex and educational and occupational status. Although not reported in this article, the Quebec City regional study of the National Nutrition Canada survey collected a 24-hour dietary recall, food frequency questionnaire and demographics questionnaire. Weight and height were measured. 

Blood values were collected on the anorexic group only. Early morning fasting blood samples were collected and assayed using SMAC methodology and compared to SMAC reference values.

Statistical Analysis

Means and standard deviations for each variable were calculated and significance was tested by unpaired T-test.

Data Collection Summary:

Dependent Variables

Variables measured using 24-hour dietary recall and Food Composition Tables:

  • Total energy
  • Protein
  • Carbohydrate (total and "concentrated")
  • Lipids
  • Calcium
  • Iron
  • Vitamin A
  • Thiamin
  • Riboflavin
  • Niacin
  • Vitamin C.

Variables measured using blood collection:

  • Serum cortisol
  • Serum glucose
  • Albumin
  • Hemoglobin
  • Hematocrit
  • Potassium
  • Chlorides
  • Sodium
  • Calcium
  • Phosphorus.

 

Description of Actual Data Sample:

Initial N

39 patients:

  • Anorexic patients (one male, 24 females)
  • Normal patients (14 total; sex not reported but supposedly matched).

Attrition (final N)

No attrition (39 patients).

Age

  • All patients in the anorexic group were 18±5 years old
  • Age was not reported for normal group; supposedly matched but the National Nutrition Canada survey did not include anyone younger than 18.

Anthropometrics

Reported for anorexic patients only. Mean weight of 35.1±6.9kg and height of 157±9cm; mean duration of weight loss was 18 months; average loss from pre-illness weight was 26%.

Location

Quebec, Canada.

Summary of Results:

 

Variables

Patients with Anorexia

Normal Patients

Statistical Significance of Group Difference

Energy (kcal)

773±349

1,904±305

P<0.001

Protein (g)

37±14

68±11

P<0.001

Lipid (g) 31±18 76±15 P<0.001
Total carbohydrate (g) 87±42 235±44 P<0.001
Concentrated carbohydrate (g) 14±16 82±26

P<0.001

Calcium (mg) 365±217 782±183

P<0.001

Iron (mg) 7.7±2.9 10.3±1.9 P<0.01
Vitamin A (RE) 768±464 845±248 NS
Thiamin (mg) 0.59±0.29 0.90±0 P<0.001
Riboflavin (mg) 0.90±0.50 1.6±0.45 P<0.001
Niacin (NE) 11.8±5.1 15.8±2.8 P<0.01

Vitamin C (mg)

49±50

87±32

P<0.05

 

Other Findings

  • The weight and height of anorexic patients were consistently lower than the weight and height values reported for subjects of similar ages and sex in the control group (significance not reported)
  • Proportion of energy from macronutrients was 20% protein, 36% lipids and 45% and 6% from total and concentrated carbohydrates, respectively, in anorexic patients in contrast to 15% protein, 36% lipids and 49% and 17% from total and concentrated carbohydrates, respectively, in control patients (no significance reported)
  • Circadian cortisol variation was preserved but at a "somewhat higher level" than normal subjects (anorectics, eight hours, 27±7mcg per dL; 16 hours, 20±5mcg per dL, 20 hours, 15±6mcg per dL; normal values, eight hours, 5+25mcg per dL; 16 hours, 10mcg per dL; 20 hours, less than 10mcg per dL)
  • Fasting glucose of anorectics (69.6±7.8mg per dL) was at the lowest limit of the normal range (67 to 106mg per dL) as well as potassium level (anorectics, 4.1±0.5mmol per L; normal, 4.0 to 6.0mmol per L), but carotenemia was at the highest limit of normal range (anorectics, 194±33mcg per dL; normal, 70 to 200mcg per dL) and serum albumin level exceeded from normal values (anorectics, 58±12g per L; normal, 37 to 48g per L).
Author Conclusion:

Nutritional status of anorexics can be characterized by total energy restriction resulting in drastically reduced intake of macronutrients and selected micronutrients, an increased and decreased proportion of energy derived from protein and concentrated carbohydrates, respectively, with similar proportion derived from total carbohydrates and lipids. Also, early fasting morning serum biochemical analysis showed low serum glucose and serum potassium levels, high carotenemia and albuminemia, and high serum cortisol levels maintained throughout the circadian cycle.

Funding Source:
Government: CORPAQ (Council of Researchers for Agriculture in Quebec) which are now administered by the Directorate for Science and Technological Innovation (DIST)
Reviewer Comments:

It was hard to find information on the methodology for the National Nutrition Canada survey around 1980. What little information I could find said the National Nutrition Canada survey took place in 1970 to 1972 and a survey called the Canada Health Survey was done from 1978 to 1979.

This is an older study (1987) which used research methodology considered less rigorous by today's standards.

Weakness of this study:

  • No information about the methods of collecting the control group data
  • Limited information about the methods of collecting the anorexic group data
  • Limited information about the matching of cases
  • Single 24-hour dietary recall may not reflect usual 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? N/A
  1.3. Were the target population and setting specified? No
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? No
  2.2. Were criteria applied equally to all study groups? No
  2.3. Were health, demographics, and other characteristics of subjects described? No
  2.4. Were the subjects/patients a representative sample of the relevant population? No
3. Were study groups comparable? No
  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? No
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  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? No
  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.) No
  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? 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? N/A
  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? 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? N/A
  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? No
  7.1. Were primary and secondary endpoints described and relevant to the question? No
  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? No
  7.7. Were the measurements conducted consistently across groups? ???
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? No
  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? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? No
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