Changing diagnostic criteria for gestational diabetes (CDC4G) in Sweden: A stepped wedge cluster randomised trial.

BACKGROUND: The World Health Organisation (WHO) 2013 diagnostic criteria for gestational diabetes mellitus (GDM) has been criticised due to the limited evidence of benefits on pregnancy outcomes in different populations when switching from previously higher glycemic thresholds to the lower WHO-2013 diagnostic criteria. The aim of this study was to determine whether the switch from previous Swedish (SWE-GDM) to the WHO-2013 GDM criteria in Sweden following risk factor-based screening improves pregnancy outcomes. METHODS AND FINDINGS: A stepped wedge cluster randomised trial was performed between January 1 and December 31, 2018 in 11 clusters (17 delivery units) across Sweden, including all pregnancies under care and excluding preexisting diabetes, gastric bypass surgery, or multifetal pregnancies from the analysis. After implementation of uniform clinical and laboratory guidelines, a number of clusters were randomised to intervention (switch to WHO-2013 GDM criteria) each month from February to November 2018. The primary outcome was large for gestational age (LGA, defined as birth weight >90th percentile). Other secondary and prespecified outcomes included maternal and neonatal birth complications. Primary analysis was by modified intention to treat (mITT), excluding 3 clusters that were randomised before study start but were unable to implement the intervention. Prespecified subgroup analysis was undertaken among those discordant for the definition of GDM. Multilevel mixed regression models were used to compare outcome LGA between WHO-2013 and SWE-GDM groups adjusted for clusters, time periods, and potential confounders. Multiple imputation was used for missing potential confounding variables. In the mITT analysis, 47 080 pregnancies were included with 6 882 (14.6%) oral glucose tolerance tests (OGTTs) performed. The GDM prevalence increased from 595/22 797 (2.6%) to 1 591/24 283 (6.6%) after the intervention. In the mITT population, the switch was associated with no change in primary outcome LGA (2 790/24 209 (11.5%) versus 2 584/22 707 (11.4%)) producing an adjusted risk ratio (aRR) of 0.97 (95% confidence interval 0.91 to 1.02, p = 0.26). In the subgroup, the prevalence of LGA was 273/956 (28.8%) before and 278/1 239 (22.5%) after the switch, aRR 0.87 (95% CI 0.75 to 1.01, p = 0.076). No serious events were reported. Potential limitations of this trial are mainly due to the trial design, including failure to adhere to guidelines within and between the clusters and influences of unidentified temporal variations. CONCLUSIONS: In this study, implementing the WHO-2013 criteria in Sweden with risk factor-based screening did not significantly reduce LGA prevalence defined as birth weight >90th percentile, in the total population, or in the subgroup discordant for the definition of GDM. Future studies are needed to evaluate the effects of treating different glucose thresholds during pregnancy in different populations, with different screening strategies and clinical management guidelines, to optimise women's and children's health in the short and long term. TRIAL REGISTRATION: The trial is registered with ISRCTN (41918550).

Previous pre-eclampsia, gestational diabetes mellitus and the risk of cardiovascular disease: A nested case-control study in Sweden.

OBJECTIVE: Pre-eclampsia and gestational diabetes mellitus (GDM) are two common pregnancy complications that affect birth outcomes and are associated with a long-term risk of cardiovascular disease (CVD). The aims of this study were to investigate if the pre-eclampsia association with CVD is independent of GDM and modified by body mass index (BMI) or GDM. DESIGN: Case-control study. SETTING: Sweden. POPULATION: Cases were women with a first CVD event between 1991 and 2008 and a previous pregnancy who were matched with controls without CVD (1:5) by year of birth, age and region of birth. METHODS: Conditional logistic regression was used to evaluate the associations of GDM, pre-eclampsia and maternal BMI with CVD adjusted for potential confounders and effect modifications with interaction tests. MAIN OUTCOME MEASURES: CVD. RESULTS: There were 2639 cases and 13 310 controls with complete data. Pre-eclampsia and GDM were independent risk factors for CVD (adjusted odds ratio [aOR] 2.59, 95% CI 2.12-3.17 and aOR 1.47, 95% CI 1.04-2.09, respectively). After stratifying by maternal BMI, the adjusted association of pre-eclampsia with CVD did not differ notably between BMI groups: normal weight (aOR 2.65, 95% CI 1.90-3.69), overweight (aOR 2.67, 95% CI 1.52-4.68) and obesity (aOR 3.03, 95% CI 0.74-12.4). Similar findings were seen when stratifying on GDM/non-GDM. CONCLUSIONS: Pre-eclampsia and GDM are independent risk factors for later CVD and having both during pregnancy is a major risk factor for later CVD. The association between pre-eclampsia and CVD is not modified by BMI. Effective CVD preventive programs for high-risk women are urgently needed in order to improve women's long-term health.

Pregnancy As a Risk Factor for Small Bowel Obstruction After Laparoscopic Gastric Bypass Surgery.

OBJECTIVE: To evaluate whether pregnancy is associated with increased risk for small bowel obstruction after laparoscopic gastric bypass surgery. BACKGROUND: Small bowel obstruction is a common and feared long-term complication to laparoscopic gastric bypass surgery that may be more common during pregnancy. It is unclear if the risk truly increases during pregnancy. METHODS: Women, 18 to 55 years, operated with a primary laparoscopic gastric bypass procedure from 2010 until 2015 were identified through the Scandinavian Obesity Surgery Registry (n = 25,853). Through record-linkage to the Medical Birth Registry, the National Patient Registry, and review of hospital charts, information on pregnancy periods and outcome were obtained. The main outcome was operation due to small bowel obstruction after the laparoscopic gastric bypass procedure. RESULTS: Pregnancy was associated with increased risk for small bowel obstruction following laparoscopic gastric bypass surgery (incidence rates 46.5, 95% CI 38.0-56.9/1000 person-years, vs 20.9 95% CI 19.9-22.0; adjusted-HR 1.72, 95% CI 1.39-2.12, P < 0.001). While no excess risk was observed during the first trimester, the second (adjusted-HR 1.67, 95% CI 1.17-2.39, P = 0.005) and third (adjusted-HR 2.69, 95% CI 2.02-3.59, P < 0.001) conferred increased risk. The incidence rate of small bowel obstruction during pregnancy was 42.9 (95% CI 32.4-57.0/1000 person-years) among women for whom the mesenteric defects had been closed during the primary procedure, and 53.2 (95% CI 38.9-72.8/1000 person-years) for women in whom they had been left open. CONCLUSION: Pregnancy is associated with increased risk for small bowel obstruction after laparoscopic gastric bypass surgery during the second and third trimesters.

Changing diagnostic criteria for gestational diabetes in Sweden - a stepped wedge national cluster randomised controlled trial - the CDC4G study protocol.

BACKGROUND: The optimal criteria to diagnose gestational diabetes mellitus (GDM) remain contested. The Swedish National Board of Health introduced the 2013 WHO criteria in 2015 as a recommendation for initiation of treatment for hyperglycaemia during pregnancy. With variation in GDM screening and diagnostic practice across the country, it was agreed that the shift to new guidelines should be in a scientific and structured way. The aim of the Changing Diagnostic Criteria for Gestational Diabetes (CDC4G) in Sweden ( www.cdc4g.se/en ) is to evaluate the clinical and health economic impacts of changing diagnostic criteria for GDM in Sweden and to create a prospective cohort to compare the many long-term outcomes in mother and baby under the old and new diagnostic approaches. METHODS: This is a stepped wedge cluster randomised controlled trial, comparing pregnancy outcomes before and after the switch in GDM criteria across 11 centres in a randomised manner. The trial includes all pregnant women screened for GDM across the participating centres during January-December 2018, approximately two thirds of all pregnancies in Sweden in a year. Women with pre-existing diabetes will be excluded. Data will be collected through the national Swedish Pregnancy register and for follow up studies other health registers will be included. DISCUSSION: The stepped wedge RCT was chosen to be the best study design for evaluating the shift from old to new diagnostic criteria of GDM in Sweden. The national quality registers provide data on the whole pregnant population and gives a possibility for follow up studies of both mother and child. The health economic analysis from the study will give a solid evidence base for future changes in order to improve immediate pregnancy, as well as long term, outcomes for mother and child. TRIAL REGISTRATION: CDC4G is listed on the ISRCTN registry with study ID ISRCTN41918550 (15/12/2017).