Does the prevention of deaths from a particular disease increase overall life expectancy in direct proportion to its decreased mortality?

The assertion that the prevention of deaths from a particular disease increases overall life expectancy in direct proportion to its decreased mortality is false. While reducing mortality from a specific disease can contribute to increased life expectancy, the relationship is not strictly proportional. Various factors influence life expectancy, including the age distribution of the population, the presence of comorbidities, healthcare access, and the nature of the disease itself.

For example, if a disease primarily affects older individuals who may already have a shorter lifespan due to age-related factors, preventing deaths from that disease may have a limited impact on overall life expectancy. Additionally, if the disease prevention leads to prolonged life but not necessarily improved quality of life due to ongoing health issues, the increase in life expectancy may not reflect a significant improvement in health outcomes. Therefore, while preventing disease can lead to longer life, the effect on overall life expectancy is influenced by many other variables beyond just mortality rates from that specific condition.