[Cost-benefit analysis of vaccinal prevention of hepatitis B policy]. / Analyse coût-avantage d'une politique de prévention vaccinale de l'hépatite virale B.

Morbidity and mortality related to hepatitis B (VHB) induce heavy costs even in low endemia countries as France. Recent changes in patterns of virus transmission (increasing heterosexual contamination) lead to discuss the opportunity of re-evaluation of current VHB vaccine policies aiming primarily at most exposed populations (patients under dialysis, hospital workers, infants born to VHB+ mothers). Using cost-benefit methodology, in a context where epidemiological and economical pertinent data are quite rare, this article evaluates different strategies ("no vaccination", "universal vaccination" and "vaccination after screening") for four different populations with contrasted exposure (French general population, young men adults, homosexual men and intravenous drug users). The cost-benefit ratios indicate that thresholds are, for low-risk populations, very far from usually accepted values attributed to epidemiological and economical parameters. If vaccine is administrated to young men adults, the cost-per-hepatitis saved relative to "no vaccination" is 36,000 F. For high-risk exposure groups, vaccination may be considered cost-benefit for attack rates near (homosexual men) or greater (drug users) than that observed; optimal strategy could be obtained if drug users are screened and vaccined. This is the result of combination of relatively low incidence of VHB and variability of medical course and chronic sequalae. Consequently, if universal vaccination has to be chosen, it would mean that the implicit value attributed to the prevention of one hepatitis is very high.

[Comparative analysis of the costs of cytogenetic techniques and molecular biology techniques in the diagnosis of fragile X disease]. / Analyse comparée du coût des techniques cytogénétiques et de biologie moléculaire dans le diagnostic de la maladie de l'X fragile.

Mental retardation is sometimes due to chromosomal abnormalities. Most frequent illnesses are Down syndrome and Fragile X syndrome. Using a cost analysis, we try to see what diagnosis method is the most relevant to find chromosomic causes for mental retardation in an institutionalized male population. Two techniques are compared: cytogenetic technique and molecular biology technique. Four diagnostic strategies are identified. They all have the same effectiveness, but, costs vary. Results depend on prevalence rates in the epidemiologic literature on Fragile X syndrome and other chromosomic abnormalities. The least-cost diagnostic strategy is molecular biology then constitutional karyotype in case of a negative result. This strategy costs about 600 FF1991 less compared with Fragile X karyotype and about 120 FF1991 less than when molecular biology is done in second, for fixed prevalence rates (i.e. Fragile X prevalence rate between 4.5 and 10% and other abnormalities between 2.2 and 25%). Fragile X karyotype strategy has the highest cost whatever the prevalence rates. Those results are discussed when introducing female population and delay to test results for prenatal diagnosis.