Maja Pohar

Alveolar echinococcosis: from a deadly disease to a well-controlled infection. Relative survival and economic analysis in Switzerland over the last 35 years.

BACKGROUND/AIMS Alveolar echinococcosis (AE) is a serious liver disease. The aim of this study was to explore the long-term prognosis of AE patients, the burden of this disease in Switzerland and the cost-effectiveness of treatment. METHODS Relative survival analysis was undertaken using a national database with 329 patient records. 155 representative cases had sufficient details regarding treatment costs and patient outcome to estimate the financial implications and treatment costs of AE. RESULTS For an average 54-year-old patient diagnosed with AE in 1970 the life expectancy was estimated to be reduced by 18.2 and 21.3 years for men and women, respectively. By 2005 this was reduced to approximately 3.5 and 2.6 years, respectively. Patients undergoing radical surgery had a better outcome, whereas the older patients had a poorer prognosis than the younger patients. Costs amount to approximately Euro108,762 per patient. Assuming the improved life expectancy of AE patients is due to modern treatment the cost per disability-adjusted life years (DALY) saved is approximately Euro6,032. CONCLUSIONS Current treatments have substantially improved the prognosis of AE patients compared to the 1970s. The cost per DALY saved is low compared to the average national annual income. Hence, AE treatment is highly cost-effective in Switzerland.

Augmented convex hull plots: Rationale, implementation in R and biomedical applications

The paper addresses the possibility to replace cluttered multi-group scatter-plots with augmented convex hull plots. By replacing scatter-plot points with convex hulls, space is gained for visualization of descriptive statistics with error bars or confidence ellipses within the convex hulls. An informative addition to the plot is calculation of the area of convex hull divided by corresponding group size as a bivariate dispersion measure. Marginal distributions can be depicted on the sides of the main plot in established ways. Bivariate density plots might be used instead of convex hulls in the presence of outliers. Like any scatter-plot type visualization, the technique is not limited to raw data -- points can be derived from any dimension reduction technique, or simple functions can be used as axes instead of original dimensions. The limited possibilities for producing such plots in existing software are surveyed, and our general and flexible implementation in R -- the publicly available chplot function -- is presented. Examples based on our daily biostatistical consulting practice illustrate the technique with various options.

Risk assessment of trisomy 21 by maternal age and fetal nuchal translucency thickness in 7096 unselected pregnancies in Slovenia

Abstract Aim: To evaluate the screening for trisomy 21 by maternal age and nuchal translucency in a low-risk population. Methods: Screening was performed in 7096 singleton pregnancies. The estimated risk for trisomy 21, the detection rate (DR), false positive rate (FPR) and the cut-off nuchal translucency thickness to obtain a 5% FPR were calculated. Results: The median maternal age was 28.6 years. The estimated risk for trisomy 21 was 1 in 300 or greater in 2.4% (171 of 7096) of all pregnancies and in 75% (9 of 12) of trisomy 21 pregnancies. The DR for all aneuploidies was 83.3%, and 75% for trisomy 21. The estimated FPR at risk 1 in 300 for the whole population in 2004 was 3.8%. It is predicted to remain below 4% at least until 2007; to achieve a 5% FPR in 2007 the risk limit 1 in 400 is proposed. Conclusions: Screening for trisomy 21 in a low-risk population in Slovenia gives comparable results to those in other countries. The only result that varies is the percentage of screen positive patients at the risk limit 1 in 300. We believe the risk limit should be specifically estimated for each country based on its population distribution of maternal age.

Corrigendum to “Alveolar echinococcosis: From a deadly disease to a well-controlled infection. Relative survival and economic analysis in Switzerland over the last 35 years” [J Hepatol 49 (2008) 72–77]

Institute of Parasitology, University of Zürich, CH-8057 Zürich, Switzerland; Department of Medical Informatics, University of Ljubljana, Vrazov trg 2, SI-1000 Ljubljana, Slovenia; Institute of Clinical Pharmacology, University of Bern, CH-3010 Bern, Switzerland; Gastroenterology and Hepatology, University Hospital of Zürich, Rämistrasse 100, Zürich CH-8091, Switzerland; Infectious Diseases, University Hospital of Lausanne, CH-1011 Lausanne, Switzerland; Surgery Services, University Hospital of Lausanne, CH-1011 Lausanne, Switzerland; Swiss HBP Center, University Hospital of Zürich, Rämistrasse 100, Zürich CH-8091, Switzerland

OP25.15: Assesment of risk of trisomy 21 by maternal age and fetal nuchal translucency thickness in 7096 unselected pregnancies in Slovenia

Serum Institut (SSI) in Copenhagen, where serum samples were referred from 17 centers in Denmark at gestational weeks 8–13. Methods: 23 653 serum samples received at SSI in the twoyear period 2004–2005 were studied. The gestational age, and maternal age and weight were obtained from referral sheets. The chromosomal abnormalities–58 trisomy 21, 19 trisomy 18 and five trisomy 13–were identifed from the Danish Cytogenetic Central Registry. Pregnancy outcome was ascertained via the PKU-registry of newborns. Pregnancy-associated plasma protein A (PAPP-A) and free beta human chorionic gonadotropin (β-hCG) was determined on either the AutoDelfia platform or the Kryptor platform. Risk calculation was performed by an algorithm embedded in the Laboratory Information System (LIMS) using continously monitored parameters. Results: Using a DS risk cut-off of 1 : 250 at birth, the detection rate (DR) for DS was 79% in weeks 8–13 with an overall screen positive rate of 7%. The DRs for Edwards and Pataus syndromes were 60% and 20%, respectively. 93–99% of the pregnancies resulted in a live fetus. The median MoMs of β-hCG and PAPP-A in weeks 8–13 were 1.50 and 0.38 in DS pregnancies, respectively. The median MoMs of β-hCG and PAPP-A increased and decreased, respectively, with advancing gestational age. Conclusions: First-trimester maternal serum screening for DS performs well in a multicenter setting using centralized monitoring by registers of cytogenetic abnormalities and a register of all newborns. The central registration makes it possible to monitor the performance of many centers simultaneously and to perform bench-marking.

P01.17: Assessment of risk of trisomy 21 by maternal age and fetal nuchal translucency thickness at 11–14 weeks of gestation in 3526 unselected pregnancies in Slovenia

percentile, in other chromosomally abnormal fetuses it was in normal ranges. Conclusion: US screening in the first trimester of pregnancy increases the detection of fetal chromosomal diseases. It is worthwhile to use NT as a marker of fetal chromosomal diseases in US screening. At first glance absence of fetal NB is not so sensitive marker in our population because in almost all fetuses with chromosomal aberrations NB are already ossified in 11–13 weeks of pregnancy. Large studies are needed to confirm whether the measurement of NB length provides any benefits as a marker of fetal chromosomal diseases.