Mortality and Disease Prevalence among the Oldest Old

Area of Science:

• Gerontology
• Epidemiology
• Biostatistics

Background:

• Despite overall mortality improvements, the oldest-old (90+ years) face extremely high mortality rates.
• Existing demographic models and rules of thumb may not accurately reflect mortality dynamics in this extreme age group.

Purpose of the Study:

• To analyze mortality patterns in the oldest-old population.
• To investigate the relationship between chronic conditions and survival at advanced ages.

Main Methods:

• Analysis of mortality data for individuals aged 90 and above.
• Modeling the interplay of incidence, recovery, death, and prevalence of chronic diseases.

Main Results:

• Mortality rates in the 90+ age group are high enough to invalidate common demographic assumptions.
• The prevalence of certain chronic conditions might decrease at extreme ages due to survival biases, irrespective of medical advancements.

Conclusions:

• Standard demographic rules of thumb are insufficient for the oldest-old.
• The "bathtub" effect in disease dynamics influences prevalence in extreme aging populations, highlighting the need for age-specific epidemiological models.