Robert Bourbeau

Neck injuries among belted and unbelted occupants of the front seat of cars

This article, part of a recently completed research project on safety belts, presents results on neck injuries. A total of 3927 injured front-seat occupants (drivers and passengers) involved in two-car crashes were studied. Among them, 725 sustained neck sprains (ICD-9 code 847.0); some of them may have sustained other injuries as well. The more serious injuries to the cervical spine were more prevalent among the unbelted occupants. Neck sprains were relatively more numerous among belted occupants compared with unbelted ones, with a relative risk estimate of 1.68. Similar results hold also for subsets of the data on different types of collisions; the relative risks ranged from 1.39 to 2.42. A log linear model was constructed for the odds ratio (neck sprain vs. no neck sprain) taking into account the following factors: (1) seatbelt use, (2) direction of impact, (3) authorized speed limit, and (4) vehicle weight. The resulting relative risk estimate (belted vs. unbelted) became 1.58. The results raise questions about seatbelts and their protection against neck sprains.

Age-specific mortality during the 1918 influenza pandemic: unravelling the mystery of high young adult mortality.

The worldwide spread of a novel influenza A (H1N1) virus in 2009 showed that influenza remains a significant health threat, even for individuals in the prime of life. This paper focuses on the unusually high young adult mortality observed during the Spanish flu pandemic of 1918. Using historical records from Canada and the U.S., we report a peak of mortality at the exact age of 28 during the pandemic and argue that this increased mortality resulted from an early life exposure to influenza during the previous Russian flu pandemic of 1889–90. We posit that in specific instances, development of immunological memory to an influenza virus strain in early life may lead to a dysregulated immune response to antigenically novel strains encountered in later life, thereby increasing the risk of death. Exposure during critical periods of development could also create holes in the T cell repertoire and impair fetal maturation in general, thereby increasing mortality from infectious diseases later in life. Knowledge of the age-pattern of susceptibility to mortality from influenza could improve crisis management during future influenza pandemics.

Dealing with Problems in Data Quality for the Measurement of Mortality at Advanced Ages in Canada

Abstract The level and age trajectory of mortality at advanced ages in Canada are not readily and exactly obtained, because of problems with the reliability of data on deaths and on population counts beyond a certain point in the official statistics. There are two ways to ensure nonetheless the termination of the life tables. One consists of finding ways to validate a sufficient number of unbiased high ages at death to produce an accurate measure with the extinct, or almost extinct, generation method. This paper presents the results of a systematic verification of ages at death and a preliminary estimation of centenarian mortality based on observations, which seems to lend credence to a leveling off of mortality rates at the highest ages for females. Another is to establish convincing evidence as to the pattern of survival at the very highest ages; mathematical techniques can then be used to generate the rates as an extension of mortality at ages 70 to 90 or 100. Historical data were used here to give an insight on what this pattern of survival could be. Contrary to what might have been expected, the progression of mortality remains pretty much exponential until the unavoidable erratic values corresponding to the few extreme observations are reached. This entails that whatever the nature of the selections that would produce a slowing down of the rate of increase of the rates at the highest ages, they did not express themselves conclusively a few centuries ago.

Regional disparities in Canadian adult and old-age mortality: A comparative study based on smoothed mortality ratio surfaces and age at death distributions

This paper examines adult and old-age mortality differentials in Canada between 1930 and 2007 at the provincial level, using theCanadian Human Mortality Database and the flexible smoothing P-spline method in two-dimensions well-suited to the study of smallpopulations. Our analysis reveals that provincial disparities in adult mortality in general, and among the elderly population in particular,are substantial in Canada. Moreover, based on the modal age at death and the standard deviation of ages at death above the mode,provincial disparities at older ages have barely reduced over time, despite the great mortality improvements in all provinces since the early 20th century. In the last few years studied, evidence of the shifting mortality regime was found among females in most Western and Central provinces, while all males were still undergoing an old-age mortality compression regime.

Survival advantage of siblings and spouses of centenarians in 20th-century Quebec

Longevity runs in families, either through genetic or environmental influences. Using Quebec civil registration and historical Canadiancensuses, we compared the longevity of siblings and spouses of 806 centenarians to a group of controls, all born in Quebec at the turnof the 20th century. Our results show that siblings of centenarians, who share half of their genes and a common childhood environment,lived 3–4 years longer than their birth cohort. However, husbands and wives of centenarians lived 4 and 2.5 years longer than theircounterparts of the same sex, respectively, suggesting that longevity is also modulated by shared environment in adulthood.

Canadian mortality in perspective: a comparison with the United States and other developed countries

The purposes of this paper is to compare mortality patterns in Canada to the United States and to other industrialised countries to give support to the existence of a “North American Mortality Pattern” (NAMP), and to try to explain this pattern in the context of the specific features of Canadian society. Using data from the WHO mortality database for total and cause-specific mortality, we applied a decomposition method to explain the changes in mortality rate ratios during the 1950-1995 period. Our findings show that Canada has experienced a general increase of its mortality rate ratios compared to other developed countries. There is no evidence that the NAMP fits for Canada. In fact, Canadian mortality below age 65 is quite comparable to mortality in other developed countries. However there is a contrasting low mortality level for the oldest-old (80+).

Pandemic Paradox: Early Life H2N2 Pandemic Influenza Infection Enhanced Susceptibility to Death during the 2009 H1N1 Pandemic

ABSTRACT Recent outbreaks of H5, H7, and H9 influenza A viruses in humans have served as a vivid reminder of the potentially devastating effects that a novel pandemic could exert on the modern world. Those who have survived infections with influenza viruses in the past have been protected from subsequent antigenically similar pandemics through adaptive immunity. For example, during the 2009 H1N1 “swine flu” pandemic, those exposed to H1N1 viruses that circulated between 1918 and the 1940s were at a decreased risk for mortality as a result of their previous immunity. It is also generally thought that past exposures to antigenically dissimilar strains of influenza virus may also be beneficial due to cross-reactive cellular immunity. However, cohorts born during prior heterosubtypic pandemics have previously experienced elevated risk of death relative to surrounding cohorts of the same population. Indeed, individuals born during the 1890 H3Nx pandemic experienced the highest levels of excess mortality during the 1918 “Spanish flu.” Applying Serfling models to monthly mortality and influenza circulation data between October 1997 and July 2014 in the United States and Mexico, we show corresponding peaks in excess mortality during the 2009 H1N1 “swine flu” pandemic and during the resurgent 2013–2014 H1N1 outbreak for those born at the time of the 1957 H2N2 “Asian flu” pandemic. We suggest that the phenomenon observed in 1918 is not unique and points to exposure to pandemic influenza early in life as a risk factor for mortality during subsequent heterosubtypic pandemics. IMPORTANCE The relatively low mortality experienced by older individuals during the 2009 H1N1 influenza virus pandemic has been well documented. However, reported situations in which previous influenza virus exposures have enhanced susceptibility are rare and poorly understood. One such instance occurred in 1918—when those born during the heterosubtypic 1890 H3Nx influenza virus pandemic experienced the highest levels of excess mortality. Here, we demonstrate that this phenomenon was not unique to the 1918 H1N1 pandemic but that it also occurred during the contemporary 2009 H1N1 pandemic and 2013–2014 H1N1-dominated season for those born during the heterosubtypic 1957 H2N2 “Asian flu” pandemic. These data highlight the heretofore underappreciated phenomenon that, in certain instances, prior exposure to pandemic influenza virus strains can enhance susceptibility during subsequent pandemics. These results have important implications for pandemic risk assessment and should inform laboratory studies aimed at uncovering the mechanism responsible for this effect. IMPORTANCE The relatively low mortality experienced by older individuals during the 2009 H1N1 influenza virus pandemic has been well documented. However, reported situations in which previous influenza virus exposures have enhanced susceptibility are rare and poorly understood. One such instance occurred in 1918—when those born during the heterosubtypic 1890 H3Nx influenza virus pandemic experienced the highest levels of excess mortality. Here, we demonstrate that this phenomenon was not unique to the 1918 H1N1 pandemic but that it also occurred during the contemporary 2009 H1N1 pandemic and 2013–2014 H1N1-dominated season for those born during the heterosubtypic 1957 H2N2 “Asian flu” pandemic. These data highlight the heretofore underappreciated phenomenon that, in certain instances, prior exposure to pandemic influenza virus strains can enhance susceptibility during subsequent pandemics. These results have important implications for pandemic risk assessment and should inform laboratory studies aimed at uncovering the mechanism responsible for this effect.

Trends, patterns, and differentials in Canadian mortality over nearly a century (1921-2011)

In the past 90 years, remarkable progress was made in substantially improving survival and longevity in Canada, establishing it as a member of today’s group of very low mortality countries. We use several demographic indicators of all-cause and cause-specific mortality to illustrate the nature of these major advances throughout the life span. Reviewing the literature on trends in Canadian mortality, we also uncover various challenges for the next decades. Reducing or even eliminating important disparities in mortality that persist with regards to geography and several socioeconomic factors is one of the greatest challenges ahead. Keywords: Mortality, longevity, health, trends, Canada

The emergence of supercentenarians in Canada

As has happened in other developed countries with low mortality, Canada has seen a dramatic increase in the numbers of very old persons in its population, with a multiplication in the number of centenarians, and the concomitant emergence of supercentenarians. The extent of the phenomenon is, however, difficult to assess. On the one hand, because of a warped view of the protection of privacy, age data from Canadian censuses are available only in rounded figures, which renders them useless when reaching the small numbers associated with supercentenarianism. On the other hand, death statistics in general, and those from people born outside the country in particular, are suspect at the extreme ages, and the information necessary to validate the information is not accessible most of the time; with the Province of Quebec, representing some 23.5% of the Canadian population, being the only exception. Of the 25 reported deaths at an age of 110 or over in Quebec, careful validation has identified 10 true supercentenarians. Eight of them are women, but the earliest one, born in 1852, was a male. The oldest died in 2001 at the age of 112 years and four months, but this record will be soon shattered as a 115-year-old woman is currently living in Montreal. Eleven cases are known for the rest of Canada, but they necessarily represent a fraction of the total number of people who reached the 110-year milestone.

Road crashes and injuries in Quebec (1974): patterns among many variables

Data on 1008 Quebec road victims obtained from linkage of governmental records have led to different types of analyses. This article presents an application of correspondence analysis to these data. We have chosen one example with its specific results showing expected associations between variables and new, unexpected associations which are plausible. The resulting patterns indicate a clear distinction between hospitalized and non-hospitalized victims and between a rural and an urban type of road crash. This multidimensional approach gives an overall picture of the patterns among the variables studied, indicating which subsets of variables might be investigated further.