40-OR

Abstract

Objectives Although routine use of prophylactic MgSO 4 is recommended for all women with pre-eclampsia, MgSO 4 is underutilized. We explored the causal variables that explain MgSO 4 use in women with severe or non-severe pre-eclampsia following admission to Canadian tertiary perinatal centers at Methods Data were used from the Canadian Perinatal Network, which collects information on women admitted for threatened preterm birth between 22+0 and 28+6 weeks, 2005–11. Univariate analyses of relative risks (RR) and population attributable risk percent (PAR%) were conducted to identify significant variables. A final generalized estimating equations model combining variables was used to estimate RR that explained MgSO 4 use in severe and non-severe pre-eclampsia, defined by 2014 Hypertension Guidelines. PAR% and 95% CI were estimated by bootstrapping. Results Of 631 women with pre-eclampsia, 190 (30.1%) had severe pre-eclampsia, of whom 139 (73.2%) received MgSO 4 . Of 441 with non-severe pre-eclampsia, 283 (64.2%) received MgSO 4 . RRs and PAR% for the variables included in the models are shown in the Table. In severe and non-severe pre-eclampsia, 56.3% and 45.9% of MgSO 4 use was due to maternal signs/symptoms of pre-eclampsia, 10.3% and 9.6% due to antepartum transfer, and 9.0% and 22.0% due to active management (i.e., not expectantly), respectively. In addition, 24.2% and 11.7% of MgSO 4 use in non-severe pre-eclampsia was due to severe hypertension and heavy proteinuria, respectively. Conclusions Physician administration of MgSO 4 in pre-eclampsia (regardless of severity) is driven by maternal signs/symptoms, as well as antepartum transfer and active management. In non-severe pre-eclampsia, severe hypertension and heavy proteinuria also drive use. These data should be used to identify missed therapeutic opportunities, especially with expectant care of pre-eclampsia. Disclosures D.A. De Silva: None. L. Eghdami: None. M. McKeever: None. T. Lee: None. D. Tu: None. J. Hutcheon: None. P. von Dadelszen: None. R. Liston: None. L. Magee: None. O. Collaborative Group: None.