Cost analysis of Down syndrome screening in advanced maternal age.

OBJECTIVE: To analyze the potential cost and efficacy of Down syndrome screening in the population with advanced maternal age. METHODS: Three screening methods defining Down syndrome risk for women with advanced maternal age were analyzed: advanced maternal age; advanced maternal age and maternal serum triple screen; and advanced maternal age, maternal serum triple screen and genetic sonogram. Costs for all tests and procedures were estimated. Procedure-related loss for amniocentesis was assumed to be 1:200. Efficacy was defined as: number of amniocenteses performed, number of Down syndrome cases detected, procedure-related losses, Down syndrome cases detected per fetal loss, cost per Down syndrome case detected and total cost of screening. RESULTS: In 1999 in the USA, there were 530,610 women with advanced maternal age at 16 weeks' gestation carrying an estimated 4,043 fetuses with Down syndrome. Screening by maternal age alone would result in the 100% detection of Down syndrome cases, but would require over 530,000 amniocenteses and result in 2,653 procedure-related losses. Combining age with serum screen and genetic sonogram would detect 97.6% of Down syndrome cases, but would require only 119,791 amniocenteses and result in 599 procedure-related losses. The projected cost per Down syndrome case detected using age screening is 219,109 dollars versus 155,992 dollars using serum screen and genetic sonogram. CONCLUSIONS: The combination of advanced maternal age, maternal serum screen and genetic sonogram would result in the fewest procedure-related losses and lowest cost per Down syndrome case detected.

Efficacy of screening for fetal Down syndrome in the United States from 1974 to 1997.

OBJECTIVE: To estimate the 16-week prevalence of Down syndrome in the United States from 1974 to 1997 and to determine the efficacy of maternal age cutoffs and triple screens for detecting it antenatally. METHODS: Using natality statistics for the United States from 1974 to 1997 of maternal-age-specific live births to women 13-49 years old, we evaluated advanced maternal age (35-49 years at delivery) and the triple serum test (maternal serum alpha-fetoprotein, hCG, and unconjugated estriol) as screening tests for Down syndrome. Efficacy was evaluated using sensitivity, false-positive rate, positive predictive value, and likelihood ratio (likelihood ratio = sensitivity/false-positive rate). RESULTS: In 1974, the estimated second-trimester prevalence of Down syndrome was one in 740, but by 1997 that had increased to one in 504. The proportion of Down syndrome fetuses at 16 weeks' gestation in women 35-49 years old increased from 28.5% in 1974 to 47.3% in 1997. However, live births to women 35-49 years old increased more rapidly from 4.7% in 1974 to 12.6% in 1997. The likelihood ratio for maternal age to identify an affected pregnancy decreased during the study period and was substantially lower than that using the serum test. CONCLUSION: A maternal age cutoff of 35 years in the 1990s resulted in high false-positive rates and was less efficacious based on likelihood ratio and positive predictive value. Serum testing of all pregnant women would reduce the number of amniocenteses and decrease procedure-related losses.

Transvaginal endometrial sonography in postmenopausal women taking tamoxifen.

OBJECTIVE: To evaluate sonographic measurements of endometrial thickness in postmenopausal women taking adjuvant tamoxifen therapy for breast cancer, and to correlate sonographic and pathologic findings to symptoms and duration of tamoxifen therapy. METHODS: Medical records and sonograms of 80 postmenopausal women treated for breast cancer with adjuvant tamoxifen therapy were reviewed retrospectively. Endometrial thickness was recorded as a single-layer thickness and considered abnormal when greater than 2.5 mm for postmenopausal women. Sonographic endometrial thickness was correlated to histologic findings, symptoms, and duration of tamoxifen therapy. RESULTS: Fifty-seven of 80 postmenopausal women (69%) had single-layer endometrial thicknesses of 2.5 mm or greater, measured by transvaginal sonography, and 55 of 57 had endometrial biopsies or dilatations and curettage. Biopsies detected 24 cases of abnormal endometria, including endometrial carcinoma (two), breast carcinoma metastatic to the endometrium (one), endometrial polyps (13), tubal metaplasia (three), and benign endometrial hyperplasia (five). Using a single-layer endometrial thickness greater than 2.5 mm by transvaginal ultrasound, 21 of 24 (87.5%) women with abnormal endometria were detected. Women with abnormal pathologic findings had a significantly thicker mean single-layer endometrial thickness than those with normal findings, 7 mm versus 4 mm (P < .01). Twelve women had postmenopausal bleeding, all of whom had a single-layer endometrial thickness greater than 2.5 mm on transvaginal sonography. CONCLUSION: With a sensitivity of detecting endometrial abnormalities of 84%, transvaginal sonography was useful for studying postmenopausal tamoxifen-treated women.