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Citation: 

Crowther CA, Hiller JE, Moss JR, McPhee AJ, Jeffries WS, Robinson JS, for the Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS) Trial Group.  Effect of treatment of gestational diabetes mellitus on pregnancy outcomes.  N Engl J Med 2005;352:2477-86.


PubMed ID: 15951574
Study Design: 
Randomized Controlled Trial
Class: 
A - Click here for explanation of classification scheme.
Quality Rating: 
NEUTRAL: See Quality Criteria Checklist below.
Research Purpose: 
To assess whether the treatment of gestational diabetes would reduce perinatal complications and to assess the effects of treatment on maternal outcome, mood and quality of life.
Inclusion Criteria: 
  • Singleton or twin pregnancy between 16 and 30 weeks' gestation
  • Attended antenatal clinics at the collaborating hospitals
  • Had 1 or more risk factors for gestational diabetes on selective screening or a positive 50-g oral glucose challenge test (glucose level 1 hour after glucose challenge at least 7.8 mmol per liter)
  • 75-g oral glucose tolerance test at 24 to 34 weeks' gestation in which the venous plasma glucose level was less than 7.8 mmol per liter after an overnight fast and was 7.8 to 11.0 mmol per liter at 2 hours
Exclusion Criteria: 
  • Women with severe glucose impairment
  • Women with previously treated gestational diabetes or active chronic systemic disease (except essential hypertension)
Description of Study Protocol: 

Recruitment

Women recruited from 18 collaborating hospitals in Australia and the United Kingdom. Recruitment started in September 1993 and stopped in June 2003.

Design

Randomized Clinical Trial. Stratification was according to center and singleton or twin gestation. Randomization performed centrally with the use of numbers generated by computer with variable block sizes of 6, 8 and 10.

Blinding used (if applicable)

Proportion of women with normal glucose tolerance test results were assigned to routine care group to help maintain blinding (not fewer than 1 in 5).

Intervention (if applicable)

Intervention group: received individualized dietary advice by RD, blood glucose monitoring, and insulin therapy as needed

Routine care: women unaware of diagnosis of glucose intolerance of pregnancy, and treated with clinical care in which screening not available

Statistical Analysis

Binary outcomes are presented as relative risks with 95% confidence intervals. Relative risks calculated with use of log binomial regression. Continuous variables analyzed by means of ANOVA if normally distributed and nonparametric tests if distribution not normal. Step-down Sidak adjustment made for analyses involving multiple primary clinical end points. Power analysis resulted in estimation of 1000 subjects needed.

Data Collection Summary: 

Timing of Measurements

Measurements made at birth and after birth. Subjects evaluated over 10 year span.

Dependent Variables

  • Serious perinatal complications, defined as death, shoulder dystocia, bone fracture, and nerve palsy
  • Admission to the neonatal nursery
  • Jaundice requiring phototherapy
  • Induction of labor
  • Cesarean birth
  • Maternal anxiety, depression and health status, as assessed by Medical Outcomes Study 36-item Short Form General Survey, Spielberger State-Trait Anxiety Inventory, Edinburgh Postnatal Depression Scale

Independent Variables

  • Dietary advice, blood glucose monitoring, and insulin therapy as needed (intervention group) or routine care

Control Variables

  • Maternal age
  • Race or ethnic group
  • Parity
Description of Actual Data Sample: 

Initial N: 1000 women; 490 women in intervention group, 510 women in routine care

Attrition (final N): 1000 women, 0 lost to follow up

Age: Intervention group: mean age 30.9 +/- 5.4 years, routine care: mean age 30.1 +/- 5.5 years

Ethnicity: Intervention group: 73% White, 19% Asian, 9% Other, routine care: 78% White, 14% Asian, 8% Other

Other relevant demographics: 93% of women had been found to be at risk for gestational diabetes based on oral glucose challenge test.

Anthropometrics: Women in intervention group were older and less likely to be white or primiparous. Differences between groups were not statistically analyzed.

Location: Australia and United Kingdom

Summary of Results: 

Outcome

Intervention Group (no/%)

Routine Care Group (no/%)

Adjusted RR (95% CI)

Adjusted P value

Any serious perinatal complication

7 (1%) 23 (4%) 0.33 (0.14 - 0.75) 0.01

Death

0 (0%)

5 (1%)

0.07

Stillbirth

0 (0%)

3 (1%)

0.26
Neonatal death 0 (0%) 2 (<1%) 0.50
Shoulder dystocia 7 (1%) 16 (3%) 0.46 (0.19 - 1.10) 0.08
Bone fracture 0 (0%) 1 (<1%) 0.38
Nerve palsy 0 (0%) 3 (1%) 0.11
Admission to neonatal nursery 357 (71%) 321 (61%) 1.13 (1.03 - 1.23) 0.01
Jaundice requiring phototherapy 44 (9%) 48 (9%) 0.93 (0.63 - 1.37) 0.72
Induction of labor 189 (39%) 150 (29%) 1.36 (1.15 - 1.62) <0.001
Cesarean delivery 152 (31%) 164 (32%) 0.97 (0.81 - 1.16) 0.73
Elective Cesarean 72 (15%) 61 (12%) 1.17 (0.85 - 1.60) 0.33
Emergency Cesarean 80 (16%) 103 (20%) 0.87 (0.68 - 1.13) 0.31

Other Findings

The rate of serious perinatal complications was significantly lower among infants of the women in the intervention group than those in the routine care group (1% vs 4%, adjusted relative risk = 0.33, 95% CI: 0.14 to 0.75, P = 0.01).

More infants of women in intervention group were admitted to neonatal nursery (71% vs 61%, adjusted relative risk = 1.13, 95% CI: 1.03 to 1.23, P = 0.01).

Women in the intervention group had a higher rate of induction of labor than the women in the routine care group (39% vs 29%, adjusted relative risk = 1.36, 95% CI: 1.15 to 1.62, P < 0.001).

There were no significant differences between groups in percentage of infants who had jaundice requiring phototherapy.

Rates of cesarean delivery were similar (31% for intervention group, 32% for routine care, adjusted relative risk = 0.97, 95% CI: 0.81 to 1.16, P = 0.73).

At 3 months post-partum, data on the women's mood and quality of life, available for 573 women, revealed lower rates of depression and higher scores, consistent with improved health status, in the intervention group.

Author Conclusion: 
Treatment of gestational diabetes reduces serious perinatal morbidity and may also improve the woman's health related quality of life. Our results indicate that treatment of gestational diabetes in the form of dietary advice, blood glucose monitoring and insulin therapy as required for glycemic control reduces the rate of serious perinatal complications, without increasing the rate of cesarean delivery.
Funding Source: 
Reviewer Comments: 
Large sample sizes. Data collected over 10 year span. Differences between groups were not statistically analyzed, but authors adjusted for age, race or ethnic group and parity. Routine care not well described.

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?
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 used? (Concurrent preferred over historical controls.)
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?
N/A
  3.5. If case control or cross-sectional 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. Criterion may not be applicable in some cross-sectional studies.)
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?
Yes
  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?
Yes
  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?
N/A
  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?
N/A
  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
 
 
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