EAL

GDM: Postpartum Care (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To test the hypothesis that the development of abnormal glucose metabolism after gestational diabetes can be predicted readily by means of available clinical variables.

Inclusion Criteria:

Diagnosis of GDM during the index pregnancy using the following criteria on OGTT: (mg/dl)

Fasting plasma = >95
1-hr = >180
2-hr = >155
3-hr = >140

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Study period from October 1988 to December 1990. Data was collected from medical charts from women who delivered at Women and Infant’s Hospital between 1979 and 1989. Universal screening for GDM was recommended at the hospital in 1982. Subjects were recruited by letter and follow-up phone calls.

Design: Population-based descriptive study

Blinding Used (if applicable): not applicable

Intervention (if applicable):

Data collected from hospital medical records, physicians’ medical records, and by interviewing the subjects. Subjects were recruited by letter and follow-up phone calls.
75-g glucose tolerance test after 10-hr but no more than 16 hour fast. Diabetes: Fasting >140 mg/dl or if the 2-hr + any one of the 3 other values >200 mg/dl; IGT: 2-hr 140 mg/dl to 200 mg/dl; any other value >200 mg/dl
Heights and weights taken

Statistical Analysis

Subjects with diabetes and impaired glucose tolerance at follow-up were combined and considered, as a group, to have disordered glucose metabolism. Univariate comparisons were made by means of the two-tailed t test for independent means and the chi-square test. Logistic regression analysis was used to assess the relative predictive value of the variables that appeared significant on univariate analysis.

Data Collection Summary:

Timing of Measurements

Data collected from hospital medical records, physicians’ medical records, and by interviewing the subjects.

Dependent Variables:

Diagnosis of diabetes or IGT

Independent Variables:

75-g glucose tolerance test after 10-hr but no more than 16 hour fast. Diabetes: Fasting >140 mg/dl or if the 2-hr + any one of the 3 other values >200 mg/dl; IGT: 2-hr 140 mg/dl to 200 mg/dl; any other value >200 mg/dl
Heights and weights taken

Control Variables:

Description of Actual Data Sample:

Initial N: 652 women who delivered at Women and Infant’s Hospital between 1979 and 1989 who had GDM during the index pregnancy were identified by medical chart review.

Attrition (final N): 350 women volunteered for the study. 185 women could not be contacted and 117 refused to be in the study.

Age: mean age disordered glucose metabolism: 34.4 +/- 6 years, mean age normal GTT: 33.4 +/- 5 years

Ethnicity: 91% white, 5% Hispanic, 2% each black and Asian

Other relevant demographics: 24 diagnosed with diabetes, 15 diagnosed with OGT

Anthropometrics:

Location: Rhode Island

Summary of Results:

Univariate analysis: predictors for subsequent diabetes
	Disordered
Normal
	Glucose Metabolism	OGTT
Time since index Pregnancy, mo	46.7+28	30+22
(P<0.001)
Diabetes in first Degree relative, %	46	30
(P<0.04)
Prepregnancy BMI	28.5+7	25.0+5
(P<0.001)
BMI at diagnosis	33.5+8	29.0+5
(P<0.001)
Insulin during Pregnancy, %	41	19
(P<0.003)

Variables that distinguished subjects who later developed diabetes or impaired glucose tolerance included prepregnancy BMI and fasting glucose on the pregnant OGTT.

Logistic results with these two variables plus time since the index pregnancy predict subsequent abnormal OGTT.

Author Conclusion:

The three significant variables found to be most predictive of subsequent diabetes are similar to variables found to be important in shorter-term studies. Given that a patient has gestational diabetes, this logistic regression model allows the use of maternal BMI, fasting plasma glucose on the pregnancy OGTT, and time since the index pregnancy to assess the risk for future diabetes.

Reported rates of subsequent diabetes after GDM among different populations range from 3% in Hong Kong, 38% in Chicago within 1 yr of delivery to 14% at 7-12 years in Australia to as high as 65% at 12 to 18 years in a group of Hispanic women in Los Angeles.

Funding Source:

Reviewer Comments:

This information supports the need for nutrition counseling postpartum to promote weight loss and to have repeat OGTT’s .

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?		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?		N/A
	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?	N/A
	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?	Yes
	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?	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?	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