Contribution
of Diabetes to SF Burden of Disease
Coronary heart
disease is the leading cause of death in nearly every zip code and
among every ethnic
group in San Francisco. Diabetes--along with other risks such as age,
smoking, high cholesterol, and hypertension--contributes to heart
disease
mortality. The
Population Attributable Fraction (PAF) for mortality is the proportional
reduction in a specific cause of death that would have been expected
if the population had no exposure to a specific determinant.
It is calculated from the relative risk from exposure (RR) to the
determinant
and the prevalence of exposure to the determinant in the population
(P), expressed as PAF = P(RR-1)/[P(RR-1) + 1]. Though
it has limitations, PAF is an important measure for public health
planning.
A reasonable first
estimate of the PAF for heart disease mortality among adults age
40 and older associated with diabetes is as follows:
Based on the
2001 California Health Interview Survey, a convervative estimate
of the prevalence of diabetes among adult San Franciscans (age 40
and older)
is approximately
7.3%
Assume the RR
for heart disease mortality from diabetes is 2.5 (a recent
meta-analysis
of eight prospective studies found it to be 2.3 for men and 2.9
for women).
PAF = P(RR-1)/[P(RR-1) + 1] = 0.073(2.5 - 1)/0.073(2.5
- 1) + 1 = 0.109/1.109 = 0.9.8 = 9.8%
This estimate is
very conservative, because it excludes unidagnosed diabetics (nearly
a third of all diabetics) and it ingores the fact that the prevalence
of type 2 diabetes is increasing (following the increase in obesity).
