Mortality and morbidity peaks modeling: An extreme value theory approach.

Hospitalizations and deaths belong to the most studied health variables in public health. Those variables are usually analyzed through mean events and trends, based on the whole dataset. However, this approach is not appropriate to comprehend health outcome peaks which are unusual events that strongly impact the health care network (e.g. overflow in hospital emergency rooms). Peaks can also be of interest in etiological research, for instance when analyzing relationships with extreme exposures (meteorological conditions, air pollution, social stress, etc.). Therefore, this paper aims at modeling health variables exclusively through the peaks, which is rarely done except over short periods. Establishing a rigorous and general methodology to identify peaks is another goal of this study. To this end, the extreme value theory appears adequate with statistical tools for selecting and modeling peaks. Selection and analysis for deaths and hospitalizations peaks using extreme value theory have not been applied in public health yet. Therefore, this study also has an exploratory goal. A declustering procedure is applied to the raw data in order to meet extreme value theory requirements. The application is done on hospitalization and death peaks for cardiovascular diseases, in the Montreal and Quebec metropolitan communities (Canada) for the period 1981-2011. The peak return levels are obtained from the modeling and can be useful in hospital management or planning future capacity needs for health care facilities, for example. This paper focuses on one class of diseases in two cities, but the methodology can be applied to any other health peaks series anywhere, as it is data driven.

Secular trends of hip fractures in Québec, Canada.

UNLABELLED: This study examined the secular trends of hip fracture incidence among individuals 50 years and older in Québec between 1993 and 2004. Age-standardized rates decreased at both the provincial and regional levels. The largest relative decrease was observed among younger females, and rates declined more slowly in the elderly. INTRODUCTION: The population of the province of Québec is among the oldest in North America. Before the trend rupture reported in the late 1990s in several countries, hip fracture (HF) incidence rates did not show a secular trend (between 1981 and 1992). This study examined the secular trends of HF incidence at the provincial level and in two of the most important urban areas of the province, Montréal and Québec City, between 1993 and 2004. METHODS: All hospitalisations of individuals 50 years and older living in the province of Québec between 1993 and 2004 with a main diagnosis of HF were included. Standardized rates of HF incidence were calculated for females and males, 50-74 years and 75 years and older. RESULTS: The Québec City area showed a strong decreasing trend in HF rates for younger females, but the other groups did not show an obvious trend. Although our models did not support the existence of significant differences in trends between both areas, the rates of HF of younger males and, to a lesser extent, of older women in the Montréal area were significantly higher than in the Québec City area. CONCLUSIONS: Differences observed in hip fracture rates as well as in secular trends between age groups and gender emphasise the need for decision makers to rely on results based on age-specific and sex-specific analyses.