[Importance of AFPplus-screening in daily practice. Evaluation of 2641 analyses]

Since 1991 the measurement of 3 biochemical parameters for the risk assessment of trisomy 21 pregnancy (AFPplus, Alpha-check) is also offered by private laboratories in Switzerland. This work aimed at the proof of reliability of this risk analysis in the hands of practitioners and private laboratories. The investigated cohort included 2,641 pregnant women. An anonymous questionnaire on the outcome of pregnancy furnished informations in 97% of cases (2,561 cases). At a trisomy 21 risk cutoff of one to 380, 9% of the pregnant women had conspicuous AFPplus results (trisomy 21-risk > 1 to 380; age distribution at term: 17 to 45 years; median 29.4 years). Among the conspicuous cases were 8 with trisomy 21, 1 with trisomy 18, 5 spontaneous abortions and 3 special cases. Seven of a total of 9 trisomies were detected by the screening. From these data the following diagnostic parameters for AFPplus have been calculated: specificity 91.0%, sensitivity 77.8%, positive predictive value 99.9%, false positive rate 9.0%, false negative rate 22.2%. The use of AFPplus by a practitioner cooperating with a private laboratory thus reveals a detection rate comparable to that known from larger centers. AFPplus by a practitioner cooperating with a private laboratory thus reveals a detection rate comparable to that known from larger centers. AFPplus allows to individualize the statistical age-related risk of a pregnant women before age 35. Above age 35 AFPplus may support the indication for cases suitable for cytogenetic investigation. Thorough personal information of the patient before the 16th pregnancy week by the practitioner or by genetic counseling has without any doubt first priority.