INITIAL ASSUMPTIONS CONSIDERED IN THE DETERMINATION OF OSTEOPOROSIS ATTRIBUTION PROBABILITIES

Gender

Females have a greater number of osteoporotic fractures than males.

Age

Approximately 10% of the population will have had a fracture by age 45. Increases above this are associated with osteoporosis.

Wrist fractures increase to age 65, then plateau.

Vertebral fractures and hip fractures increase exponentially with age.

Falls are more frequent in the elderly (>65), increasing the chance for hip fracture in this group.

Forearm fractures increase at age 50, spine at age 60, and hip at age 70. All other fractures increase at age 65.

Older patients (all genders and races) have more osteoporotic fractures than younger patients.

Race

Fracture rates are greater in Caucasians than blacks, with others in between.

Caucasians and Asians have lower bone mass and an increased risk of fracture than do blacks.

Little information is available for bone mass in Native Americans and Pacific Islanders.

The "other" racial category is intermediate between white and black.

Fractures of "other sites" in blacks and other races are approximately 50% of whites.

Insufficient data exist to suggest that there are significant differences of rates in other races than in whites.

Gender & Age

Most hip, spine, and wrist fractures in elderly women (>65) are associated with low bone mass.

Young males (<50) have more fractures due to severe trauma.

In men under 65, the rate of radial bone loss is slightly greater than half that of women.

Seventy percent of white women over age 50 will have a decrease in bone mass sufficient to warrant the diagnosis of osteoporosis. Therefore, the overall proportion of fractures at certain sites (hip, wrist, spine) due to osteoporosis will be at least 70% in the oldest group.

By age 80, three-fourths of white women have a decreased fracture threshold.

Gender & Race

The rate of hip fracture in black, Hispanic, and Asian females is about 40% that of whites. The rate of hip fracture in black males is 70% that of whites. The rate of hip fractures in Hispanic males is 50% that of whites. The rate of hip fractures in Asian males is 33% that of whites.

Percent due to osteoporosis is the same for males and females, blacks and whites although the number of fractures is less.

White males and black females will have about half the proportion of osteoporotic fractures as white females. Black males will have about one-fourth. However, secondary osteoporosis will contribute in all of these groups.

Osteoporotic hip fractures in white women are 3-4 times more common than in black women, and "others" are approximately three- fourths as common as whites.

Both male and female blacks have substantially greater bone mass at any age than whites.

Fracture Type

Fractures of the hip and wrist involve trauma; therefore their proportion attributable to osteoporosis will be lower than for the spine. Wrist fractures are usually not osteoporotic in men.

Traumatic vertebral fractures are relatively uncommon; therefore a higher proportion will be osteoporotic.

Other fractures are less likely to be osteoporotic. An average of 20% are associated with osteoporosis.

Fractures of the ankle, elbow, finger, and face are not associated with low bone mass.

An exponential relationship exists between decreasing bone mass and risk of fracture.

"Spine" refers to vertebral body and not posterior elements or transverse processes.

"Forearm" refers to all forearm fractures including distal radius.