GDM: Postpartum Care (2008)

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

To determine the recurrence rate of GDM during a subsequent pregnancy among women who had GDM during an index pregnancy and to identify factors associated with the probability of recurrence.

Inclusion Criteria:
  • History of a pregnancy with a diagnosis of GDM (index pregnancy) and at least one subsequent pregnancy
  • Diagnosis of GDM is standardized in Nova Scotia: screening at 24 to 28 wk gestation with a 50-g glucose challenge and 1-hr venous plasma glucose >7.8 mmol/L or 3-hr, 100-g glucose tolerance test with >2 of the following: fasting >5.3 mmol/L; 1-hr >10.6 mmol/L; 2-hr >9.2 mmol/L; 3-hr: >8.1 mmol/L
  • Women who developed diabetes between the index pregnancy and a subsequent pregnancy.
Exclusion Criteria:
None specifically mentioned.
Description of Study Protocol:

Recruitment

The cohort was identified from the Nova Scotia Atlee Perinatal Database and includes Nova Scotia residents who delivered an infant weighing >500 g between 1980 and 1996.

Design:  Cohort Study

Blinding Used (if applicable):  not applicable

Intervention (if applicable):

  • Data was abstracted from hospital medical records after discharge using standardized data collection forms as part of an ongoing data quality assurance program.
  • Database includes information on maternal medical conditions, labor and delivery and neonatal outcomes.

Statistical Analysis

Possible predictors were initially analyzed in a univariate fashion by estimating relative risks and 95% confidence intervals.  Potential predictors were modeled using stepwise logistic regression.  Since the recurrence rate of GDM is estimated to be >30%, odds ratios calculated from a logistic model will overestimate the relative risk.  Therefore, odds ratios were converted to relative risks using log-linear models with a binary error term.

Data Collection Summary:

Timing of Measurements

Data was abstracted from hospital medical records after discharge using standardized data collection forms as part of an ongoing data quality assurance program.

Dependent Variables:

  • Recurrence of GDM

Independent Variables

  • GDM during an index pregnancy
  • Database includes information on maternal medical conditions, labor and delivery and neonatal outcomes

Control Variables

Description of Actual Data Sample:

Initial N:  651 women who had a diagnosis of GDM during an index pregnancy and then had a subsequent pregnancy.

Attrition (final N):  651

Age:  not mentioned

Ethnicity:  not mentioned

Other relevant demographics:

Anthropometrics:

Location:  Canada

Summary of Results:

Other Findings

The index pregnancy was the first pregnancy for 68% of the 651 subjects; the index pregnancy was the second pregnancy for 20% of the 651 subjects.

232 (35.6%) of the women who had GDM during the index pregnancy had diabetes in the subsequent pregnancy (95% CI, 31.9% - 39.3%).

16 of the 232 women developed diabetes in the interval between the index pregnancy and the subsequent pregnancy.

Multivariate regression models showed that infant birth weight in the index pregnancy and maternal prepregnancy weight before the subsequent pregnancy were predictive of recurrent GDM.

Women who had a macrosomic infant (>4,000 g from their index pregnancy were 40% more likely to have a recurrence compared with women whose infant was 2,500-3,999 g.

Women whose prepregnancy weight at the start of the subsequent pregnancy was >190 lb were 70% more likely to have a recurrence of GDM, adjusting for infant birth weight in the index pregnancy.

The rate of recurrence in the second subsequent pregnancy was 72.4% among those who had GDM during both the index pregnancy and the first subsequent pregnancy and 21.5% among those who had GDM during the index pregnancy but did not have GDM recurrence during the first subsequent pregnancy.

Author Conclusion:

In this large cohort of mostly white women, ~one-third of the subjects had diabetes in a subsequent pregnancy. These results are comparable to other white populations.

Strategies to reduce the occurrence of neonatal macrosomia and maternal prepregnancy obesity may help lower the rate of recurrence of GDM.

This information will assist health care providers in counseling women with GDM about the recurrence risk and the importance of appropriate prenatal screening in subsequent pregnancies.

Funding Source:
Not-for-profit
0
Foundation associated with industry:
Reviewer Comments:
Preventing excessive weight during pregnancy and postpartum through diet and physical activity should be promoted in women at risk for GDM to prevent recurrence of GDM and possibly the onset of type 2 diabetes mellitus.
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? Yes
  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? Yes
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) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  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? 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? Yes
  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.) Yes
  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? N/A
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