Childhood cancer and nuclear power plants in Switzerland: a census-based cohort study.

BACKGROUND: Previous studies on childhood cancer and nuclear power plants (NPPs) produced conflicting results. We used a cohort approach to examine whether residence near NPPs was associated with leukaemia or any childhood cancer in Switzerland. METHODS: We computed person-years at risk for children aged 0-15 years born in Switzerland from 1985 to 2009, based on the Swiss censuses 1990 and 2000 and identified cancer cases from the Swiss Childhood Cancer Registry. We geo-coded place of residence at birth and calculated incidence rate ratios (IRRs) with 95% confidence intervals (CIs) comparing the risk of cancer in children born <5 km, 5-10 km and 10-15 km from the nearest NPP with children born >15 km away, using Poisson regression models. RESULTS: We included 2925 children diagnosed with cancer during 21 117 524 person-years of follow-up; 953 (32.6%) had leukaemia. Eight and 12 children diagnosed with leukaemia at ages 0-4 and 0-15 years, and 18 and 31 children diagnosed with any cancer were born <5 km from a NPP. Compared with children born >15 km away, the IRRs (95% CI) for leukaemia in 0-4 and 0-15 year olds were 1.20 (0.60-2.41) and 1.05 (0.60-1.86), respectively. For any cancer, corresponding IRRs were 0.97 (0.61-1.54) and 0.89 (0.63-1.27). There was no evidence of a dose-response relationship with distance (P > 0.30). Results were similar for residence at diagnosis and at birth, and when adjusted for potential confounders. Results from sensitivity analyses were consistent with main results. CONCLUSIONS: This nationwide cohort study found little evidence of an association between residence near NPPs and the risk of leukaemia or any childhood cancer.

Vaccines safety; effect of supervision or SMS on reporting rates of adverse events following immunization (AEFI) with meningitis vaccine (MenAfriVac?): a randomized controlled trial.

BACKGROUND: To ensure vaccines safety, given the weaknesses of the national pharmacovigilance system in Cameroon, there is a need to identify effective interventions that can contribute to improving AEFI reporting. OBJECTIVE: To assess the effect of: (i) sending weekly SMS, or (ii) weekly supervisory visits on AEFI reporting rate during a meningitis immunization campaign conducted in Cameroon in 2012 using the meningitis A conjugate vaccine (MenAfriVac?). METHODS: Health facilities that met the inclusion criteria were randomly assigned to receive: (i) a weekly standardized SMS, (ii) a weekly standardized supervisory visits or (iii) no intervention. The primary outcome was the reported AEFI incidence rate from week 5 to 8 after the immunization campaign. Poisson regression model was used to estimate the effect of interventions after adjusting for health region, type of health facility, type and position of health workers as well as the cumulative number of AEFI reported from weeks 1 to 4. RESULTS: A total of 348 (77.2%) of 451 health facility were included, and 116 assigned to each of three groups. The incidence rate of reported AEFI per 100 health facility per week was 20.0 (15.9-24.1) in the SMS group, 40.2 (34.4-46.0) in supervision group and 13.6 (10.1-16.9) in the control group. Supervision led to a significant increase of AEFI reporting rate compared to SMS [adjusted RR=2.1 (1.6-2.7); p<0.001] and control [RR=2.8(2.1-3.7); p<0.001)] groups. The effect of SMS led to some increase in AEFI reporting rate compared to the control group, but the difference was not statistically significant [RR=1.4(0.8-1.6); p=0.07)]. CONCLUSION: Supervision was more effective than SMS or routine surveillance in improving AEFI reporting rate. It should be part of any AEFI surveillance system. SMS could be useful in improving AEFI reporting rates but strategies need to be found to improve its effectiveness, and thus maximize its benefits.

Théorie bayesienne de la décision statistique et mesure de la radioactivité

L'objet de ce travail est l'évaluation de l'activité de radionucléides présents à l'état de traces, par exemple dans l'environnement. Lorsque les mesures sont de courte durée, ou si les sources sont peu actives, l'analyse statistique standard ne donne plus une estimation fiable de l'activité et de son incertitude. L'introduction du concept bayesien d'a priori permet de modéliser l'information à disposition de l'observateur avant qu'il effectue la mesure. Cette information conduit à une estimation plus cohérente des grandeurs physiques recherchées. Le cadre de la théorie est tout d'abord présenté, définissant les concepts d'état, d'observation et de décision. La mesure physique est traduite par un modèle statistique qui est une probabilité de transition des états vers les observations. L'information de Fisher et celle de Shannon-Kullback sont introduites dans le but d'obtenir les a priori nécessaires au théorème de Bayes. Les modèles propres à la mesure de la radioactivité sont ensuite traités. Si l'on peut considérer l'activité comme constante, le modèle est celui de Poisson et conduit à des a priori de type gamma. Pour les grandes activités, ces deux lois se rapprochent des gaussiennes et l'on retrouve l'analyse statistique classique. Lorsque la décroissance du nombre de noyaux n'est plus négligeable, ou lors de l'évaluation de certains temps d'attente, d'autres modèles sont développés. Quelques applications sont présentées ensuite, notamment une définition cohérente des intervalles de confiance et l'estimation de l'activité de radionucléides à schéma complexe par spectrométrie gamma, où l'obtention de tout un spectre permet une analyse multidimensionnelle. Le paradigme bayesien conduit à une répartition complète et globale pour l'état du système physique mesuré. L'observateur obtient ainsi la meilleure estimation possible de l'état basée sur son modèle d'expérience et l'information préalable en sa possession.

Breast cancer incidence and overdiagnosis in Catalonia (Spain)

Introduction: Early detection of breast cancer (BC) with mammography may cause overdiagnosis and overtreatment, detecting tumors which would remain undiagnosed during a lifetime. The aims of this study were: first, to model invasive BC incidence trends in Catalonia (Spain) taking into account reproductive and screening data; and second, to quantify the extent of BC overdiagnosis. Methods: We modeled the incidence of invasive BC using a Poisson regression model. Explanatory variables were: age at diagnosis and cohort characteristics (completed fertility rate, percentage of women that use mammography at age 50, and year of birth). This model also was used to estimate the background incidence in the absence of screening. We used a probabilistic model to estimate the expected BC incidence if women in the population used mammography as reported in health surveys. The difference between the observed and expected cumulative incidences provided an estimate of overdiagnosis. Results: Incidence of invasive BC increased, especially in cohorts born from 1940 to 1955. The biggest increase was observed in these cohorts between the ages of 50 to 65 years, where the final BC incidence rates more than doubled the initial ones. Dissemination of mammography was significantly associated with BC incidence and overdiagnosis. Our estimates of overdiagnosis ranged from 0.4% to 46.6%, for women born around 1935 and 1950, respectively. Conclusions: Our results support the existence of overdiagnosis in Catalonia attributed to mammography usage, and the limited malignant potential of some tumors may play an important role. Women should be better informed about this risk. Research should be oriented towards personalized screening and risk assessment tools.

Estimation of age- and stage-specific Catalan breast cancer survival functions using US and Catalan survival data

Background: During the last part of the 1990s the chance of surviving breast cancer increased. Changes in survival functions reflect a mixture of effects. Both, the introduction of adjuvant treatments and early screening with mammography played a role in the decline in mortality. Evaluating the contribution of these interventions using mathematical models requires survival functions before and after their introduction. Furthermore, required survival functions may be different by age groups and are related to disease stage at diagnosis. Sometimes detailed information is not available, as was the case for the region of Catalonia (Spain). Then one may derive the functions using information from other geographical areas. This work presents the methodology used to estimate age- and stage-specific Catalan breast cancer survival functions from scarce Catalan survival data by adapting the age- and stage-specific US functions. Methods: Cubic splines were used to smooth data and obtain continuous hazard rate functions. After, we fitted a Poisson model to derive hazard ratios. The model included time as a covariate. Then the hazard ratios were applied to US survival functions detailed by age and stage to obtain Catalan estimations. Results: We started estimating the hazard ratios for Catalonia versus the USA before and after the introduction of screening. The hazard ratios were then multiplied by the age- and stage-specific breast cancer hazard rates from the USA to obtain the Catalan hazard rates. We also compared breast cancer survival in Catalonia and the USA in two time periods, before cancer control interventions (USA 1975–79, Catalonia 1980–89) and after (USA and Catalonia 1990–2001). Survival in Catalonia in the 1980–89 period was worse than in the USA during 1975–79, but the differences disappeared in 1990–2001. Conclusion: Our results suggest that access to better treatments and quality of care contributed to large improvements in survival in Catalonia. On the other hand, we obtained detailed breast cancer survival functions that will be used for modeling the effect of screening and adjuvant treatments in Catalonia.

Emergency hospital services utilization in Lleida (Spain): a cross-sectional study of immigrant and Spanish-born populations

Background: The use of emergency hospital services (EHS) has increased steadily in Spain in the last decade while the number of immigrants has increased dramatically. Studies show that immigrants use EHS differently than native-born individuals, and this work investigates demographics, diagnoses and utilization rates of EHS in Lleida (Spain). Methods: Cross-sectional study of all the 96,916 EHS visits by patients 15 to 64 years old, attended during the years 2004 and 2005 in a public teaching hospital. Demographic data, diagnoses of the EHS visits, frequency of hospital admissions, mortality and diagnoses at hospital discharge were obtained. Utilization rates were estimated by group of origin. Poisson regression was used to estimate the rate ratios of being visited in the EHS with respect to the Spanish-born population. Results: Immigrants from low-income countries use EHS services more than the Spanish-born population. Differences in utilization patterns are particularly marked for Maghrebi men and women and sub-Saharan women. Immigrant males are at lower risk of being admitted to the hospital, as compared with Spanish-born males. On the other hand, immigrant women are at higher risk of being admitted. After excluding the visits with gynecologic and obstetric diagnoses, women from sub-Saharan Africa and the Maghreb are still at a higher risk of being admitted than their Spanish-born counterparts. Conclusion: In Lleida (Spain), immigrants use more EHS than the Spanish born population. Future research should indicate whether the same pattern is found in other areas of Spain and whether EHS use is attributable to health needs, barriers to access to the primary care services or similarities in the way immigrants access health care in their countries of origin.

Evolución de la mortalidad por cáncer de mama y diseminación de la mamografía de cribado en Cataluña: un análisis por regiones sanitarias

Fundamento: El descenso de las tasas de mortalidad por cáncer de mama (CM) se ha atribuido a la implantación de programas de cribado y a avances terapéuticos. El objetivo de este trabajo es comparar la evolución de su mortalidad en las regiones sanitarias de Cataluña en el periodo 1993-2007. Paralelamente, se ha analizado la diseminación de la mamografía periódica en las regiones sanitarias. Métodos: Se analizaron los datos del registro de mortalidad y encuestas de salud. Se utilizaron regresiones de Poisson y «joinpoint» para comparar las tasas de mortalidad por CM y analizar su evolución temporal. Se utilizaron modelos de efectos mixtos para comparar el nivel y la evolución de la mortalidad por regiones. Resultados. La tasa de mortalidad por CM descendió un 3% anual en Cataluña. Entre 1993 y 2007, la tasa estandarizada varió de 34,8 a 23,3 por 100.000 mujeres. Barcelona ciutat presentó unas tasas de mortalidad más elevadas que las regiones Centre (ratio de tasas (RT)=0,87), Costa de Ponent (RT=0,89), Tarragona (RT=0,9) y Lleida (RT=0,915), pero estas diferencias tendieron a desaparecer. No se observaron cambios de tendencia en la evolución de la mortalidad de las regiones, excepto en la región Centre. Durante los años 1990 Barcelona ciutat presentó unos porcentajes de utilización de mamografía periódica del 36,1% de las mujeres de 40-74 años, en la encuesta de 1994, la región Centre (23,7%) y Costa de Ponent (25,2%). Conclusiones: La progresiva utilización de mamografía periódica y la disminución de la mortalidad por CM fueron similares en las regiones sanitarias de Cataluña.

Valuing equity-linked death benefits in jump diffusion models

The paper is motivated by the valuation problem of guaranteed minimum death benefits in various equity-linked products. At the time of death, a benefit payment is due. It may depend not only on the price of a stock or stock fund at that time, but also on prior prices. The problem is to calculate the expected discounted value of the benefit payment. Because the distribution of the time of death can be approximated by a combination of exponential distributions, it suffices to solve the problem for an exponentially distributed time of death. The stock price process is assumed to be the exponential of a Brownian motion plus an independent compound Poisson process whose upward and downward jumps are modeled by combinations (or mixtures) of exponential distributions. Results for exponential stopping of a Lévy process are used to derive a series of closed-form formulas for call, put, lookback, and barrier options, dynamic fund protection, and dynamic withdrawal benefit with guarantee. We also discuss how barrier options can be used to model lapses and surrenders.

Prevalence and management of cardiovascular risk factors in Portuguese living in Portugal and Portuguese who migrated to Switzerland.

BACKGROUND: Information regarding the health status of migrants compared to subjects who remain in the country of origin is scarce. We compared the levels and management of the main cardiovascular risk factors between Portuguese living in Porto (Portugal) and Portuguese migrants living in Lausanne (Switzerland). METHODS: Cross-sectional studies conducted in Porto (EPIPorto, 1999 to 2003, n = 1150) and Lausanne (CoLaus, 2003 to 2006, n = 388) among subjects aged 35-65 years. Educational level, medical history and time since migration were collected using structured questionnaires. Body mass index, blood pressure, cholesterol and glucose levels were measured using standardized procedures. RESULTS: Portuguese living in Lausanne were younger, more frequently male and had lower education than Portuguese living in Porto. After multivariate adjustment using Poisson regression, no differences were found between Portuguese living in Porto or in Lausanne: prevalence rate ratio (PRR) and (95% confidence interval) for Portuguese living in Lausanne relative to Portuguese living in Porto: 0.92 (0.71 - 1.18) for current smoking; 0.78 (0.59 - 1.04) for obesity; 0.81 (0.62 - 1.05) for abdominal obesity; 0.82 (0.64 - 1.06) for hypertension; 0.88 (0.75 - 1.04) for hypercholesterolemia and 0.92 (0.49 - 1.73) for diabetes. Treatment and control rates for hypercholesterolemia were higher among Portuguese living in Lausanne: PRR = 1.91 (1.15 - 3.19) and 3.98 (1.59 - 9.99) for treatment and control, respectively. Conversely, no differences were found regarding hypertension treatment and control rates: PRR = 0.98 (0.66 - 1.46) and 0.97 (0.49 - 1.91), respectively, and for treatment rates of diabetes: PRR = 1.51 (0.70 - 3.25). CONCLUSIONS: Portuguese living in Lausanne, Switzerland, present a similar cardiovascular risk profile but tend to be better managed regarding hypercholesterolemia than Portuguese living in Porto, Portugal.

Intracranial Aneurysm Rupture Is Predicted by Measures of Solar Activity.

OBJECTIVE: The cause precipitating intracranial aneurysm rupture remains unknown in many cases. It has been observed that aneurysm ruptures are clustered in time, but the trigger mechanism remains obscure. Because solar activity has been associated with cardiovascular mortality and morbidity, we decided to study its association to aneurysm rupture in the Swiss population. METHODS: Patient data were extracted from the Swiss SOS database, at time of analysis covering 918 consecutive patients with angiography-proven aneurysmal subarachnoid hemorrhage treated at 7 Swiss neurovascular centers between January 1, 2009, and December 31, 2011. The daily rupture frequency (RF) was correlated to the absolute amount and the change in various parameters of interest representing continuous measurements of solar activity (radioflux [F10.7 index], solar proton flux, solar flare occurrence, planetary K-index/planetary A-index, Space Environment Services Center [SESC] sunspot number and sunspot area) using Poisson regression analysis. RESULTS: During the period of interest, there were 517 days without recorded aneurysm rupture. There were 398, 139, 27, 12, 1, and 1 days with 1, 2, 3, 4, 5, and 6 ruptures per day. Poisson regression analysis demonstrated a significant correlation of F10.7 index and RF (incidence rate ratio [IRR] = 1.006303; standard error (SE) 0.0013201; 95% confidence interval (CI) 1.003719-1.008894; P < 0.001), according to which every 1-unit increase of the F10.7 index increased the count for an aneurysm to rupture by 0.63%. A likewise statistically significant relationship of both the SESC sunspot number (IRR 1.003413; SE 0.0007913; 95% CI 1.001864-1.004965; P < 0.001) and the sunspot area (IRR 1.000419; SE 0.0000866; 95% CI 1.000249-1.000589; P < 0.001) emerged. All other variables analyzed showed no significant correlation with RF. CONCLUSIONS: We found greater radioflux, SESC sunspot number, and sunspot area to be associated with an increased count of aneurysm rupture. The clinical meaningfulness of this statistical association must be interpreted carefully and future studies are warranted to rule out a type-1 error.

Adjusting fracture probability by trabecular bone score.

The aim of the present study was to determine the impact of trabecular bone score on the probability of fracture above that provided by the clinical risk factors utilized in FRAX. We performed a retrospective cohort study of 33,352 women aged 40-99 years from the province of Manitoba, Canada, with baseline measurements of lumbar spine trabecular bone score (TBS) and FRAX risk variables. The analysis was cohort-specific rather than based on the Canadian version of FRAX. The associations between trabecular bone score, the FRAX risk factors and the risk of fracture or death were examined using an extension of the Poisson regression model and used to calculate 10-year probabilities of fracture with and without TBS and to derive an algorithm to adjust fracture probability to take account of the independent contribution of TBS to fracture and mortality risk. During a mean follow-up of 4.7 years, 1754 women died and 1639 sustained one or more major osteoporotic fractures excluding hip fracture and 306 women sustained one or more hip fracture. When fully adjusted for FRAX risk variables, TBS remained a statistically significant predictor of major osteoporotic fractures excluding hip fracture (HR/SD 1.18, 95 % CI 1.12-1.24), death (HR/SD 1.20, 95 % CI 1.14-1.26) and hip fracture (HR/SD 1.23, 95 % CI 1.09-1.38). Models adjusting major osteoporotic fracture and hip fracture probability were derived, accounting for age and trabecular bone score with death considered as a competing event. Lumbar spine texture analysis using TBS is a risk factor for osteoporotic fracture and a risk factor for death. The predictive ability of TBS is independent of FRAX clinical risk factors and femoral neck BMD. Adjustment of fracture probability to take account of the independent contribution of TBS to fracture and mortality risk requires validation in independent cohorts.

Health care usage among immigrants and native-born elderly populations in eleven European countries: results from SHARE

Differences in health care utilization of immigrants 50 years of age and older relative to the native-born populations in eleven European countries are investigated. Negative binomial and zero-inflated Poisson regression are used to examine differences between immigrants and native-borns in number of doctor visits, visits to general practitioners, and hospital stays using the 2004 Survey of Health, Ageing, and Retirement in Europe database. In the pooled European sample and in some individual countries, older immigrants use from 13 to 20% more health services than native-borns after demographic characteristics are controlled. After controlling for the need for health care, differences between immigrants and native-borns in the use of physicians, but not hospitals, are reduced by about half. These are not changed much with the incorporation of indicators of socioeconomic status and extra insurance coverage. Higher country-level relative expenditures on health, paying physicians a fee-for-service, and physician density are associated with higher usage of physician services among immigrants.