2.3 Epidemiology & Skeletal Morbidity of Fractures

Identify the population, time and outcome

Incidence counts new events in a specified population and period. An incidence rate can use person-time as the denominator. Prevalence describes how many people have a condition at a point or during a period. An annual count of fracture hospitalizations describes encounters. It does not give the number of people living with osteoporosis or an individual's chance of fracture. Specify whether an encounter measure counts ED visits, admissions, or both.

Rates and counts can move in different directions as a population changes. In the 2019 global analysis, the number of new fractures increased compared with 1990 while the age-standardized incidence rate decreased. Comparing rates standardized to a common age structure addresses a different question from estimating total service demand.

Recognize common outcomes after fracture

Hip fracture can lead to reduced mobility, need for rehabilitation or help with daily activities, and increased mortality. A U.S. Medicare analysis reported adjusted 360-day mortality after hip fracture in 2004 of 32.5% in men and 21.9% in women. These are estimates for that year and population. The study does not establish that the fracture caused every death or that those proportions apply today. In an analysis of underlying health and mortality, baseline health status helped explain some of the observed excess. Follow-up interval, patient characteristics and method matter when comparing estimates.

Vertebral fractures may be found on images acquired for another reason. A study counting radiographic vertebral fractures can identify events absent from clinical diagnoses. Standard FRAX major osteoporotic fracture probability includes clinical spine, hip, forearm and proximal humerus. It does not count all morphometric vertebral deformities as clinical spine events. Vertebral fractures can be associated with pain, height loss and functional limitations. Kyphosis can be associated with impaired lung function, but new breathlessness or weight loss requires evaluation for other causes. Wrist and proximal humerus fractures can limit activities requiring hand or shoulder function.

Interpret early risk of another fracture

A previous fracture is a risk factor, and the timing of that fracture adds information. In the Reykjavik study, one year after a first major osteoporotic fracture, the risk of another was about 2.7 times the population risk at that point. That comparison does not provide an absolute probability for a particular patient.

Lindsay and colleagues studied placebo participants from osteoporosis trials. Among women who developed a radiographically identified vertebral fracture, 19.2% had another in the following year. The paper's separate relative-risk estimate of 5.1 compared initial-year risk in participants with versus without a vertebral fracture at study entry. The two estimates answer different questions. Neither establishes a fixed recurrence probability for every patient with a new symptomatic fracture.

A recent fracture can justify timely evaluation of bone health, the injury mechanism, fall risks and treatment options. In the BHOF setting, a hip or vertebral fracture supports considering pharmacologic treatment regardless of BMD. Other sites are handled in context. Use the applicable clinical guidance and avoid converting a measured T-score into a different densitometric category. Arrange follow-up and communicate the fracture event even when a scan will be performed later. The short-term risk pattern supports timely care, while the specific regimen depends on the patient.

CDC NCHS osteoporosis and low bone mass · U.S. hip fracture encounters · Global fracture analysis · Medicare mortality analysis · Underlying health and hip fracture outcomes · Functional recovery cohort · Kyphosis and lung function cohort · Reykjavik cohort · Vertebral recurrence analysis · FRAXplus · BHOF Clinician’s Guide