BackgroundAnticoagulation for mechanical heart valves during pregnancy is essential to prevent thromboembolic events. Each regimen has drawbacks with regard to maternal or fetal risk.ObjectivesThis meta-analysis sought to estimate and compare the risk of adverse maternal and fetal outcomes in pregnant women with mechanical heart valves who received different methods of anticoagulation.MethodsStudies were identified using a Medline search including all publications up to June 5, 2016. Study inclusion required reporting of maternal death, thromboembolism, and valve failure, and/or fetal spontaneous abortion, death, and congenital defects in pregnant women treated with any of the following: 1) a vitamin K antagonist (VKA) throughout pregnancy; 2) low-molecular-weight heparin (LMWH) throughout pregnancy; 3) LMWH for the first trimester, followed by a VKA (LMWH and VKA); or 4) unfractionated heparin for the first trimester, followed by a VKA (UFH and VKA).ResultsA total of 800 pregnancies from 18 publications were included. Composite maternal risk was lowest with VKA (5%), compared with LMWH (16%; ratio of averaged risk [RAR]: 3.2; 95% confidence interval [CI]: 1.5 to 7.5), LMWH and VKA (16%; RAR: 3.1; 95% CI: 1.2 to 7.5), or UFH and VKA (16%; RAR: 3.1; 95% CI: 1.5 to 7.1). Composite fetal risk was lowest with LMWH (13%; RAR: 0.3; 95% CI: 0.1 to 0.8), compared with VKA (39%), LMWH and VKA (23%), or UFH and VKA (34%). No significant difference in fetal risk was observed between women taking ≤5 mg daily warfarin and those with an LMWH regimen (RAR: 0.9; 95% CI: 0.3 to 2.4).ConclusionsVKA treatment was associated with the lowest risk of adverse maternal outcomes, whereas the use of LMWH throughout pregnancy was associated with the lowest risk of adverse fetal outcomes. Fetal risk was similar between women taking ≤5 mg warfarin daily and women treated with LMWH.
To address gaps in traditional postlicensure vaccine safety surveillance and to promote rapid signal identification, new prospective monitoring systems using large health-care database cohorts have been developed. We newly adapted clinical trial group sequential methods to this observational setting in an original safety study of a combination diphtheria and tetanus toxoids and acellular pertussis adsorbed (DTaP), inactivated poliovirus (IPV), and Haemophilus influenzae type b (Hib) conjugate vaccine (DTaP-IPV-Hib) among children within the Vaccine Safety Datalink population. For each prespecified outcome, we conducted 11 sequential Poisson-based likelihood ratio tests during September 2008-January 2011 to compare DTaP-IPV-Hib vaccinees with historical recipients of other DTaP-containing vaccines. No increased risk was detected among 149,337 DTaP-IPV-Hib vaccinees versus historical comparators for any outcome, including medically attended fever, seizure, meningitis/encephalitis/myelitis, nonanaphylactic serious allergic reaction, anaphylaxis, Guillain-Barré syndrome, or invasive Hib disease. In end-of-study prespecified subgroup analyses, risk of medically attended fever was elevated among 1- to 2-year-olds who received DTaP-IPV-Hib vaccine versus historical comparators (relative risk = 1.83, 95% confidence interval: 1.34, 2.50) but not among infants under 1 year old (relative risk = 0.83, 95% confidence interval: 0.73, 0.94). Findings were similar in analyses with concurrent comparators who received other DTaP-containing vaccines during the study period. Although lack of a controlled experiment presents numerous challenges, implementation of group sequential monitoring methods in observational safety surveillance studies is promising and warrants further investigation.
BackgroundFever is common following infant vaccinations. Two randomized controlled trials demonstrated the efficacy of acetaminophen prophylaxis in preventing fever after whole cell pertussis vaccination, but acetaminophen prophylaxis has not been evaluated for prevention of fever following contemporary vaccines recommended for infants in the United States.MethodsChildren six weeks through nine months of age were randomized 1∶1 to receive up to five doses of acetaminophen (10–15 mg per kg) or placebo following routine vaccinations. The primary outcome was a rectal temperature ≥38°C within 32 hours following the vaccinations. Secondary outcomes included medical utilization, infant fussiness, and parents' time lost from work. Parents could request unblinding of the treatment assignment if the child developed fever or symptoms that would warrant supplementary acetaminophen treatment for children who had been receiving placebo.ResultsA temperature ≥38°C was recorded for 14% (25/176) of children randomized to acetaminophen compared with 22% (37/176) of those randomized to placebo but that difference was not statistically significant (relative risk [RR], 0.63; 95% CI, 0.40–1.01). Children randomized to acetaminophen were less likely to be reported as being much more fussy than usual (10% vs 24%) (RR, 0.42; 95% CI, 0.25–0.70) or to have the treatment assignment unblinded (3% vs 9%) (RR, 0.31; 95% CI, 0.11–0.83) than those randomized to placebo. In age-stratified analyses, among children ≥24 weeks of age, there was a significantly lower risk of temperature ≥38°C in the acetaminophen group (13% vs. 25%; p = 0.03).ConclusionThe results of this relatively small trial suggest that acetaminophen may reduce the risk of post-vaccination fever and fussiness.Trial registrationClinicaltrials.gov NCT00325819
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