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Objective: To investigate factors associated with fetal fraction and to develop a new predictive method for low fetal fraction before noninvasive prenatal testing. Methods: The study was a retrospective cohort analysis based on the results of noninvasive prenatal testing, complete blood count, thyroxin test, and Down's syndrome screening during the first or second trimester in 14,043 pregnant women. Random forests algorithm was applied to predict the low fetal fraction status (fetal fraction < 4%) through individual information and laboratory records. The performance of the model was evaluated and compared to predictions using maternal weight. Results: Of 14,043 cases, maternal weight, red blood cell, hemoglobin, and free T3 were significantly negatively correlated with fetal fraction while gestation age, free T4, pregnancy-associated plasma protein-A, alpha-fetoprotein, unconjugated estriol, and β-human chorionic gonadotropin were significantly positively correlated with fetal fraction. Compared to predictions using maternal weight as an isolated parameter, the model had a higher area under the curve of receiver operating characteristic and overall accuracy. Conclusions: The comprehensive predictive method based on combined multiple factors was more effective than a single-factor model in low fetal fraction status prediction. This method can provide more pretest quality control for noninvasive prenatal testing. [ABSTRACT FROM AUTHOR]

We searched PubMed, EMBASE, Cochrane Library, and Web of Science for studies using fractional flow reserve (FFR) to determine whether revascularization should be performed or deferred for patients with coronary stenosis and grey zone FFR. Meta-analysis was performed using the generic inverse variance method, and hazard ratios (HR) were synthesized with a random-effects model. Of 2766 records, 7 nonrandomized studies including 2683 patients were selected. The pooled results demonstrated, during a median follow-up of 32 months, that revascularization significantly reduced the risk of major adverse cardiac events (MACE; 7 studies: HR [95% confidence interval, CI]: 0.65 [0.45-0.93], P =.02) and target vessel revascularization (TVR; 4 studies: HR [95% CI]: 0.52 [0.36-0.76], P <.01). Whereas revascularization was not significantly superior in terms of all-cause death (3 studies: HR [95% CI]: 0.56 [0.26-1.22], P =.14), cardiac death (2 studies: HR [95% CI]: 0.57 [0.16-2.01], P =.38), myocardial infarction (MI; 4 studies: HR [95% CI]: 1.03 [0.26-4.03]), and all-cause death or MI (3 studies: HR [95% CI]: 0.66 [0.20-2.19], P =.50). Therefore, revascularization appeared to be superior to deferral for patients with grey zone FFR in MACE and TVR, while hard end points did not show such significance. This work was registered in PROSPERO (CRD42019118432). [ABSTRACT FROM AUTHOR]