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A simple double thin-film coating-based device is proposed to quantify the ethanol content in humid air featuring a 10 ppm resolution and spanning a dynamic range from 0 to 1000 ppm. The transduction involves the measurement of the direct optical reflection intensity, changing upon refractive index variations induced by water and ethanol adsorption within the coatings. The first thin-film coating is a microporous methyl-functionalized, silica xerogel material more sensitive to alcohol, and the second one is a microporous pure silica xerogel material more sensitive to water. The precision of the sensor is achieved through a mathematical treatment applied on the time resolved adsorption period. Reflection signals of both the ethanol- and water-sensitive coatings are taken into account in the treatment to correct for differences in ambient conditions (temperature, relative humidity, presence of volatile organic compounds) within the same chamber previous to data analysis, which corresponds to realistic operating conditions. As the adsorption mechanism is governed by molecular dynamic equilibrium, these sensors are fast and instantaneously regenerated in ambient air. The sensor is easy to assemble and was reusable for a period exceeding 1 year (maximal tested time).

Background: To analyze cost-effectiveness of two different strategies to treat H. pylori infection in peptic ulcer in the primary care setting., Patients and Methods: Consecutive patients with endoscopic diagnosis of peptic ulcer were randomized to one of two strategies: a) treatment during 7 days with omeprazole, tetracycline, metronidazole and bismuth subcitrate ("quadruple" therapy) and if failure second-line treatment with omeprazole, amoxycillin and clarithromycin during 7 days (OCA7), and b) initial treatment with OCA7 and if failure treatment with "quadruple therapy". End point was eradication 8 weeks after last treatment dose. Direct and indirect costs were estimated (euros, 1997) and a cost-effectiveness analysis using a decision-tree model was undertaken after real clinical data. 95% confidence intervals are given., Results: After screening 255 patients, 97 were finally included. 48 patients were given strategy a and 49 strategy b. Eradication was obtained (intention-to-treat) in 72.9% (CI 95%: 58.2-84.7) in group a versus 91.8% (CI 95%: 80.4-97.7) (p < 0.05) in group b. Mean cost per case treated was lower in group a (237 versus 268 euros) but cost per case eradicated was lower in group b (320 versus 296 euros). The cost was primarily determined by efficacy., Conclusions: Treatment with OCA7 followed by rescue with "quadruple" therapy if failure is more efficient in our area that the inverse strategy. Efficiency is mostly determined by efficacy.

Background: An economic, cost-effectiveness evaluation was carried out that compared a hypothetical program of routine mass vaccination against the chicken-pox-zoster virus in children aged 15 months in the Foral Community of Navarra against the present strategy of vaccination that is restricted to the high risk population., Material and Methods: Decision trees based on Markov models were used to calculate the costs of the health care of cases of infection and the costs of the effects of the vaccination program. The efficacy of the vaccination is 90-95%, and the scenario produces an immunogenicity of at least ten years, with a coverage of 90%. Account was taken of both the direct costs of health care and the indirect costs, with 1995 Pesetas taken as a constant, due to the loss in productivity of a family member, and a social view point was adopted for evaluating the study, Results: The index of cost-effectiveness reflects the additional cost or saving for each case of avoided infection brought about by vaccinating the children in comparison with vaccinating only those persons belonging to the high risk population sectors. The cost per avoided case is situated between 3,500 Ptas and 4,000 Ptas. For each Peseta invested in the vaccination program there would be a reimbursement of 0.45 Pesetas., Conclusions: The routine vaccination program produces an incremental cost. Only in the case of a reduction in the price of the vaccine by more than 50% would the cost-effectiveness index offer a net social profit.

A cost-effectiveness analysis was made to determine the effectiveness of the following strategies of mass immunization with the new recombinant vaccine against the hepatitis B virus in Spain: vaccination of adolescents, newborns, both populations, and vaccination plus passive immunization of newborns of HBsAg positive mothers. Decision trees supported on Markov models with Monte Carlo simulation have been used for the calculation of costs of the disease, and a mathematical model of differential equations was used for the simulation of the potential effectiveness of vaccination. The costs considered were those associated with the vaccination and travel of subjects, diagnosis, and treatment of the disease. The results are presented as additional cost or saving per case of infection prevented. In all assumptions, results showed that the most effective strategy for mass vaccination was the combination of vaccinating all adolescents together with active and passive immunization of children born to HBsAg positive mothers.

The aim of this study was to evaluate, in economic terms, the recently launched hepatitis A vaccine in comparison with the use of nonspecific immune globulin, for the prevention of hepatitis A. A cost-effectiveness analysis was performed, comparing mass and selective strategies for both active and passive immunisation in children, adolescents and the high-risk adult population. Direct costs of diagnosis, treatment and immunisation, and travelling expenses of the individuals, were considered. The alternative of mass vaccination for children and adolescents cost 2679 to 6394 European Currency Units (ECU) [$US 3040 to $US 8312; 1994 values] per case prevented. Selective vaccination of high-risk individuals cost ECU205 per case prevented for young adults (those aged about 20 years) when the annual risk of contracting the disease was 0.7%, while there were net savings for all age groups when there was a 2 to 3% risk. The most sensitive variables affecting the cost of mass-vaccination strategies were incidence of hepatitis A, vaccine coverage and vaccine cost; for the various high-risk groups, these were vaccine cost, incidence of hepatitis A and costs of treating infection. Selective vaccination, depending on the age of high-risk patients [mainly travellers to endemic areas for periods of over 6 months, or those under 'precarious' conditions (e.g. backpackers, even for short periods)], is the most efficient alternative; in fact, the cost-effectiveness ratio has not been calculated, since there were net savings. For occasional travellers (as above, and those travelling for periods of under 6 months in 10 years), passive immunisation is more efficient. Selective vaccination for package-tour, short-stay travellers (infection risk around 0.3%) and strategies for mass vaccination of children and adolescents are not justified from an efficiency point of view.

Hepatitis B virus (HBV) infection is an important public health problem all over the world. Vaccination is one way to prevent it, and several strategies can be used depending on endemicity, the main pattern of HBV transmission and the demographic structure of the population. In this study, an economic comparison of 3 vaccination strategies (mass adolescent vaccination, mass infant vaccination and mass combined vaccination) was performed in Catalonia, Spain. Screening pregnant women for HBV infection in combination with these strategies was also evaluated. Epidemiological models to analyse patterns of HBV infection with and without vaccination and to calculate HBV-associated costs were designed. Comparison between strategies was done using cost-effectiveness analysis from the perspective of the healthcare system. Epidemiological model results indicate that implementation of HBV vaccination could prevent as many as 104,778 new acute infections, and avoid up to 5239 chronic infections, 2096 cases of cirrhosis and 419 cases of hepatocarcinoma over a 20-year period in Catalonia. Cost-effectiveness analysis shows that mass adolescent vaccination is the most efficient strategy, with lower costs per avoided case than the other 2 strategies. When any of these strategies is complemented by screening for HBV in pregnant women, the number of avoided cases is always higher and the cost per avoided case decreases or remains unchanged.

Background: The epidemiological patron of hepatitis A has changed in the last few years and a decrease of the anti-hepatitis A antibodies IgG (Anti-HVA) have been observed at early ages, which will accompany in the future an increase of symptomatic hepatitis. The prevention of hepatitis A requires a strict application of the norms of personal and environmental hygiene and the administration of vaccines or immunoglobulins. In order to determine the convenience of immunization actively or passively with or without the previous detection of Anti-HVA, requires the knowledge of with strategy is more efficient., Methods: An analysis is carried out to determine the threshold of prevalence, where the reason of efficiency is established by comparing the unit cost of immunization either actively or passively of the population, with a cost of immunizing only the negative Anti-HVA by previous screening, with the formula: the unit cost of the active or passive immunization (unit cost of screening + cost of active or passive (in specific immunoglobuline) immunization in the negative Anti-HVA). The results correlate with the prevalence of Anti-HVA in age group founded in sero-epidemiological studies published by Salleras (1992 and Pérez-Trallero (1994)., Results: The threshold of prevalence, the reason of efficiency equals 1, it's situated in 18% and 65% respectively for the active and passive immunization, which corresponds to the age group of 10-19 years and 20-29 years based on sero-epidemiological studies used., Conclusions: With prevalence of Anti-HVA equal to or above 18% of the population the most efficient strategy is to determine the Anti-HVA before the active immunization; This threshold of prevalence move to up to 65% with passive immunization. Beneath these prevalence it's more efficient to immunize actively or passively without prior screening.

Background: The aim of the study was to economically evaluate the prophylactic use of the recombinant factor of the stimulation of granulocyte colonies (rG-CSF) for the prevention of episodes of febrile neutropenia (EFN) following antineoplasic chemotherapy., Methods: The methods of economic evaluation used were those of cost analysis and cost-effectivity analysis. The probability of occurence of EFN was estimated by the application of the Delphi method and the costs were calculated., Results: The costs of EFN for the patients with solid tumors is situated between 236,000-377,000 pesetas according to hospitalary centers. For patients with acute leukemia the value was estimated as between 391,000-667,000 pesetas. The results of the cost analysis indicate that the net cost per patient prophylactically treated is between 4,000-64,000 pesetas. The results of the cost-effectivity analysis indicate that the cost per case of no incidence of EFN is between 20,000-320,000 pesetas., Conclusions: Episodes of febrile neutropenia carry expansive hospital and antibiotic clinical treatment. The prophylactic use of new medication for patients between the first and second cycle of chemotherapy, in agreement with the estimates calculated, does not save health care costs but may improve the quality of life in these patients and permit the continuation of a therapeutic schedule without interruption which may improve the life expectancy of the patient.

Background: The incidence of hepatitis B is on the increase despite immunization of people susceptible to risk populations. After the introduction of a recombinant vaccine in 1986, it has become possible to evaluate different alternatives of immunization, from the point of view of efficacy, with the aim of controlling the disease., Methods: A cost-effectiveness analysis was performed with the use of decision trees and calculation of the cost per avoided case of infection in the different strategies evaluated, vaccination to risk groups, pubescent youth, newborns, and communicated accidental exposure. An evaluation of the different alternatives was carried out in a simple model associated to a passive and active immunization program of newborns of mothers who are carriers of HbsAg and finally, the possibility of revaccination is added., Results: Costs and future profits are presented in pesetas for 1990 and rates of social discounts of 4% and 7% are applied actualizing the same. For the prevalence estimated in the bibliography consulted, the cost per avoided case oscillated between 115,000 and 310,000 ptas in the most numerous risk groups (those living with carriers and ADVP) with lower covering; in massive immunization of pubescent youth the costs are from 30,000 to 130,000 ptas; the costs for newborns is of about 400,000 ptas; and accidental exposure rises to 500,000 ptas per avoided case., Conclusions: In vaccination versus the hepatitis B virus systematic vaccination of adolescents is proposed as most efficient and with the aim of disease control a program of passive and active immunization of newborns of carrier mothers should be included.