Archives of Biological Sciences 2011 Volume 63, Issue 3, Pages: 609-615
https://doi.org/10.2298/ABS1103609L
Full text ( 501 KB)
Non-invasive screening: The probability of events
Lončar D. (Gynecology and Obstetrics Clinic, Clinical Center Kragujevac, Kragujevac)
Janković S. (Department of Pharmacology, Kragujevac)
Milovanović D. (Department of Pharmacology, Kragujevac)
Milošević-Đorđević Olivera (Faculty of Science, Institute of Biology, Department of Genetics, Kragujevac)
Stojadinović M. (Clinic for Urology, Clinical Center Kragujevac, Kragujevac)
Lončar S. (Faculty of Dental Medicine, Belgrade)
Congenital anomalies are the cause of 20.0-25.0% of cases of perinatal death,
while 3.0% of children are born with malformations of varying size. We
examined the predictive values and defined the credibility ratio of the
combined test results. Sensitivity of the test is 94.0%, and specificity is
99.0%. The positive likelihood ratio [likelihood ratio test (LR+)] is 94.00;
a negative likelihood ratio [likelihood ratio test (LR-)] is 0.06. The
pretest probability that pregnant women carry a fetus with chromosomal
abnormality is 1:250. Posttest odds after the combined test to discover this
abnormality are 0.3760, and probability of the same case is 0.2732 if it
happens that the test result is positive. The result of our study confirms
the justification of combined test usage in routine clinical practice, since
the posttest odds rate in the case of a positive screening increases several
times over (almost 90 times); the probability of detecting a chromosomal
abnormality was about 70 times.
Keywords: Predictive value, combined test, ultrasonography, biochemical markers