GDM: Postpartum Care (2008)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

This study used a cohort of women previously studied to evaluate the recurrence rate of GDM.

Inclusion Criteria:
None specifically mentioned.
Exclusion Criteria:
None specifically mentioned.
Description of Study Protocol:

Recruitment

The study took place in the 480 women were seen by one endocrinologist for medical management of GDM over a 5-yr period, Jan 1990 – Dec 1994.  100 women from the first study had a recurrence of GDM and were contacted to be in this study to evaluate the relationship between diet intake and the recurrence of GDM.

Design:  Case-Control Study

Blinding (if applicable):  not applicable

Intervention (if applicable):  not applicable

Statistical Analysis:

Statistical tests included the chi-square test for discrete variables and the two-tailed t test for continuous variables.  Results expressed as mean +/- standard deviation.

Data Collection Summary:

Timing of Measurments

Contact with 100 women from the first study was attempted by phone, letter and personal visit, June to August 1996.

Dependent Variables

  • Recurrence rate of GDM
  • Family history of diabetes

Independent Variables

  • Dietary assessment through diet history; food preparation questionnaire and food pattern questionnaire from the DCCT methodology and modified for use in Australia.  Questionnaires were tested for reliability and validity by dietetic students and patients.
  • Dietary assessment through food records; women were instructed on recording foods eaten on a standard form for 3-d and analyzed for energy, fiber, percentages of energy provided by macronutrients and types of fat using nutrient analysis software.

Control Variables

  • Weight
  • BMI
Description of Actual Data Sample:

Initial N:  Of the 100 eligible women, contact was made with 82 and 49 of the 82 (60%) agreed to be in the study.

Attrition (final N):  Of the 49 women, 1 was excluded because of a current pregnancy, 5 were excluded because they were on weight reducing diets, 3 did not complete questionnaires and 5 were under reporting.  The final sample contained 35 women.  21 of those without recurrence of GDM (32.3%) and 14 (40%) with recurrence of GDM were in the final sample.

Age:  mean 32.7 +/- 3.4 years

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:

Location:  Illawarra area of New South Wales, Australia.

Summary of Results:

No significant differences in demographic factors or family history for diabetes by group.

Means+SD
  Non RGDM GDM
  n=21 n=14

Age, yr

32.7+3.4 34.9+4.2

Parity  

2.4+0.8 3.0+1.0
BMI 28.0+8.0  27.0+5.3

Women with recurrence of GDM consumed 38.4 (diet history) and 41.4% (food record) of energy as fat compared with 34.1 (P<0.01) and 33.1% (P<0.001) respectively in women without recurrence.

Dietary intake by Food Record
  Non RGDM GDM P
  n=21 n=14  

Kcal

1,979+406 1,975+409 NS

Fat (%)

33.1+4.7 41.4+6.2 <0.001

Carbohydrate (%)

47.5+3.8 40.4+5.3 <0.001

Author Conclusion:

This is the first study to look at the diet of women who have had a recurrence of GDM compared with women who did not have a recurrence in a subsequent pregnancy. It is also the first to identify a macronutrient which may be associated with why some women who have a recurrence of GDM is consistent with data that suggests increased insulin resistance with high saturated fat intakes. 

Prospective studies looking at dietary intake of pregnant women with relationship to the development and recurrence of GDM are required.

Funding Source:
Government: Illawarna Area Health Service (Australia),
University/Hospital: University of Wollongong
Reviewer Comments:

Even in non-obese women, there appears to be a relationship between the recurrence of GDM and dietary fat intake.

Dietary intake is a modifiable risk factor for GDM.

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