Variation In Age-specific Rates Research Articles

Head Injury Incidence and Mortality in New Zealand over 10 Years

Background: Although reducing the burden of head injuries is an important focus of several injury prevention initiatives, they remain a large proportion of injury-related deaths. In New Zealand, trends over time and the socio-economic distribution of the cause-specific incidence of head injuries have received little attention. Methods: We analyzed primary hospitalizations (2000-2009) and deaths (1999-2008) due to head injury using national mortality and hospital discharge databases, specifically exploring variations in age-specific rates by major causes over time and by socio-economic deprivation. Population-based incidence rate estimates were calculated using census denominators. Results: Children aged <5 years and adults aged ≥65 years had the highest rates of hospitalization and mortality, respectively. Transport-related incidents and falls were the leading causes, with most fatal injuries occurring on roads and most hospitalized injuries occurring at home. There was a significant increase in mortality rates among older adults over the decade, and in most age groups, mortality rates increased with increasing levels of socio-economic deprivation. Conclusions: The findings of this review alongside the significant risks of premature death and disability reinforce the need to explore policies that address the specific causes as well as socio-economic inequalities in their distribution in New Zealand.

On the role of aging in carcinogenesis

Correlation coefficients for age-standardized incidence rates between cancers of the stomach, colon, rectum and lung over place (worldwide) and time (in Connecticut) vary from positive to negative values, indicating that these cancers are not caused by common environmental agents. Correlation coefficients for age-incidence patterns (the variation in age-specific rates with age) between these cancers, on the other hand, are all highly positive for both sexes. We conclude that the carcinogenic determinants that vary with age are common to the cancers studied and to both sexes, and distinct from the carcinogenic determinants that vary with place and time. For the cancers studied, incidence rates are negligible until age 30, at which time they increase dramatically and continue to increase at least until age 75. The rate of increase, however, diminishes continuously with advancing age after 30. We suggest that the role of aging in cancer incidence is determined by two components, one responsible for the dramatic rate increase beginning near age 30 and one responsible for the gradual diminution in that rate increase. The former may correspond to the activation of quiescent cells with damaged DNA or to the deactivation of DNA surveillance or repair or to impaired apoptosis, while the latter may correspond to the loss of cell division potential.

The role of aging in cancer incidence: an epidemiological study.

Age-specific and age-standardized incidence rates for cancers of the bronchus, stomach, colon, rectum, pancreas, skin, male bladder, and female breast, uterus, and ovary in 1975 were studied in populations throughout the world, and, for bronchus and stomach cancers, over time from 1960 to 1975. The variation in age-specific rates with age was similar for all cancers, as demonstrated by large positive correlation coefficients between age-incidence patterns averaged over all populations. In addition, the age-incidence patterns for bronchus and stomach cancer were similar and essentially invariant over time. The variation in age-standardized rates among the populations was not similar for all cancers, as demonstrated by correlation coefficients that were small in some cases and negative in others. Between bronchus and stomach cancer, age-standardized rates varied in opposite directions from 1960 to 1975. It is obvious, therefore, that the cause for the variation in age-specific rates with age is not related to the cause for the variation in age-standardized rates among populations or over time. The shape of age-incidence patterns for the cancers studied must be determined by a factor that is common to the tissues of tumor origin, and invariant among populations and over time. The intrinsic aging process is the most reasonable candidate for this role.