Unexpected Single-year-of-age Changes in the Elderly Mortality Rate in England and Wales During 2012

Abstract

Aims: To evaluate single-year-of-age specificity in deaths in England and Wales associated with a large, unexpected and unexplained increase in 2012. To demonstrate that this type of event has occurred previously across the entire UK. To demonstrate that infectious-like spread at a regional level in England may be involved. Study Design: Longitudinal study of annual (calendar year) deaths (all-cause mortality) in the United Kingdom and England and Wales using publically available statistics available from the Office for National Statistics (ONS). Place and Duration of Study: United Kingdom, England & Wales, local authorities within England & Wales covering a variety of time spans designed to illustrate various key points. Methodology: Deaths between 1974 and 2012 in the United Kingdom. Live population and deaths for residents of England and Wales and of English local authorities. Calculation of single-year-of-age death rates in 2011 and 2012 which are the years before and after the large and unexpected increase in deaths. Results: A recurring series of infectious-like events can be demonstrated which prior to 2000 had been largely assumed to be due to influenza epidemics. The event in 2012 shows specificity for the elderly particularly above age 75, which is somewhat expected given increased susceptibility to the environment as we age. The single year of age mortality rate shows saw tooth behavior for deaths in 2011 and even more exaggerated saw tooth behavior is seen in the difference between 2011 and 2012. Similar saw tooth behavior is seen in the difference between single-year-of-age standardized admissions via the emergency department in England between 2008 and 2012. The infectious spread across England behind this phenomenon is illustrated at regional level and probably results in a 40% underestimation of the saw tooth behavior. Conclusion: The saw tooth behavior is known to be associated with what is called ‘original antigenic sin’. Hence the saw tooth behavior appears to indicate that the unexpected high elderly mortality in 2012 was due to an outbreak of an infectious agent which has multiple strains. This behavior confirms the results of other studies investigating simultaneous increase in medical admissions to hospital during the time that the deaths increase. The ubiquitous herpes virus, cytomegalovirus may be involved, although at the moment this virus provides a prototype for the sort of immune modulating agent that may be responsible. The use of five year age bands to age standardize mortality and medical admission rates may be subject to misleading outcomes where the periodicity behind these outbreaks and their cumulative effect on immune mediated responses is out of synchrony with the basic saw tooth behavior seen in both mortality and admission rates. This has major implication to the calculation of hospital standardized mortality rates (HSMR).