Epidemiology

of Osteoporosis

By : P.MOTTAGHI MD

Associate Professor of Medicine – Rheumatology Department

• Bone accretion occurs during adolescence, when there is a large

increment in bone mass.

• Peak bone density is normally achieved after puberty and into the

third decade of life.

• However, by age 22, most individuals have achieved their peak

bone mass.

• At menopause, an acceleration of bone loss usually occurs over

approximately 5 to 8 years, with an annual 2% to 3% loss of

trabecular bone and a 1% to 2% loss of cortical bone.

• Both men and women lose bone with age. Over a lifetime, women

lose approximately 50% of trabecular and 30% of cortical bone;

men generally lose two thirds of these amounts.

Genetics, gender, and racial differences

• There are few data on ratio or gender differences in age related bone

loss ,although limited evidence suggests that bone loss at the hip is

greater in women than in men.

• Lifestyle factors and level of economic development also contributes to

the geographic variability in facture risk.

• Peak bone mass determined largely by genetics .

• Genetic factors account for about 70 to 80% of interdividual

variation in peak bone mass in both gender.

• Environmental factors , especially diet and mechanical loading ,also

play a role in determining peak bone mass .

• There are few data on racial or gender differences in age- related bone

loss .

BONE REMODELING

Brief summery

animation

• Osteoporosis was previously thought to be a silent disease that

was part of the normal aging process.

• However, the advent of bone densitometry has made it possible

to accurately and reproducibly identify patients at risk for

osteoporosis so that prevention and treatment strategies can be

instituted to reduce fractures.

•

• Osteoporosis, the most common metabolic bone disease, affects 200 million

individuals worldwide.

• Osteoporosis, or “porous bone,” is a “disease characterized by low bone mass

and structural deterioration of bone tissue, leading to bone fragility and an

increased susceptibility to fractures, especially of the hip, spine and wrist.

• Initial studies of the epidemiology of osteoporosis was based on bone mineral

content ,but no international agreement on the interpretation of the results

made. Some groups rely on age- and sex-specific ‘normal’ ranges; others

interpret their data in the light of the biomechanical concept of an absolute

fracture threshold.

• Therefore, the epidemiology of osteoporosis is still predominantly identical

with the epidemiology of its major consequence, i.e. certain types of bone

fractures claimed to be associated with osteoporosis

Epidemiology

• 40% of women over 50 have osteopenia

7% of women over 50 have osteoporosis

• Presence of osteoporosis carries 4-fold

increase in fracture rate

(over 50 years old)

• Among those who live to 90 years old, 1/3 of women and 1/6

of men will have sustained osteoporotic fracture

• After 50 years of age, there is an exponential rise in fractures, such

that 40% of women and 13% of men develop one or more

osteoporotic fractures in their lifetimes.

• In the United States alone, there are more than 1.5 million

osteoporotic fractures annually, including 250,000 hip, 250,000

wrist, and 500,000 vertebral fractures.

• Hip fractures are associated with a 12% to 24% mortality rate in

women and a 30% mortality rate in men within the first year of

fracture, and 50% of patients are unable to ambulate independently

and require long-term nursing home care.

• These numbers will continue to grow exponentially as the elderly

population of industrialized nations increases.

Clinical Crisis

• 25 million women with osteoporosis or osteopenia in US in

2003

• At 50 years, 10% population

• At 65 years, 20-25% population

• At 75 year, 40% population

• $13 billion for care of patients with osteoporotic spinal

fracture in 1997

Vaccaro 2003

Epidemiology of osteoprosis in IranEpidemiology of osteoprosis in Iran

Risk factors for osteoporosis

Female gender

Age (post-menopausal or > 70 years)

Asian or Caucasian

Smoking, alcohol consumption

Thin body shape

Inactivity/immobility

Diet low calcium, high protein, caffeine, sodium

Some drugs glucocorticoids, chemotherapy, etc.

Some systemic diseases gastrectomy, chronic liver or renal disease, etc.

Risk FactorsRisk Factors

Female GenderFemale Gender

– 3X more likely to have hip or vertebral fracture than 3X more likely to have hip or vertebral fracture than

menmen

– 6X more likely to have forearm fracture6X more likely to have forearm fracture

Caucasian RaceCaucasian Race

– Higher than African-American, Asian raceHigher than African-American, Asian race

SmokingSmoking

Low Body Weight (less than 58 kilos)Low Body Weight (less than 58 kilos)

Risk Factors (cont’d)Risk Factors (cont’d) Sedentary LifestyleSedentary Lifestyle

Excessive Alcohol IntakeExcessive Alcohol Intake

– Ample suggestion that moderate alcohol intake Ample suggestion that moderate alcohol intake

may be protectivemay be protective

– No clear thresholdNo clear threshold

Nursing Home ResidentsNursing Home Residents

– 10X more likely to experience hip fracture than 10X more likely to experience hip fracture than

age-matched non-residents age-matched non-residents

Predisposing Medical ConditionsPredisposing Medical Conditions

Estrogen DeficiencyEstrogen Deficiency

Inflammatory Bowel DiseaseInflammatory Bowel Disease

Type 2 Diabetes Mellitus Type 2 Diabetes Mellitus

Celiac diseaseCeliac disease

Cystic fibrosisCystic fibrosis

HyperthyroidismHyperthyroidism

HyperparathyroidismHyperparathyroidism

HypogonadismHypogonadism

Liver DiseaseLiver Disease

Corticosteroid useCorticosteroid use

Heparin useHeparin use

Cyclosporine useCyclosporine use

Depo-Provera useDepo-Provera use

Risk Factors (cont’d)Risk Factors (cont’d)

No clear increase in risk with carbonated beveragesNo clear increase in risk with carbonated beverages

Although unclear risk association with excessive Although unclear risk association with excessive caffeinecaffeine

Bone mineral density and fracture

• The relationship between BMD and osteoporosis can be

compared with that between blood pressure and stroke.

• Although low BMD is not a prerequisite for osteoporotic

fracture, the risk for fracture is elevated considerably in the

presence of low bone mass.

• Therefore, as with blood pressure, appropriate cut-off values can

be defined to direct intervention toward ‘‘at-risk’’ individuals.

• BMD taken at different sites can be used to predict the future

risk for fracture at the same, or other, sites

Bone Mineral Density (BMD) and fracture rate

Siris et al. Arch Intern Med. 2004; 164:1108-1112

BMD does not fully explain increased fracture risk in the elderly

Age-related changes in bone quality are not fully captured

by BMD

– Bone structure

– Material properties of bone

Increased risk of falls

BMD Does Not Fully Explain the Effect of Age on Fracture Risk

50 80Age

BMD

Fracture risk

Determinants of Bone quality (1) Bone Structure

Macroarchitecture

Microarchitecture

Hip axis length

Cross sectional diameter

TrabecularPerforation

Cortical Porosity

Morbidity

• Overall, a 50-year-old white woman in the United States has a 13%

chance of experiencing attributable functional decline after any

fracture.

• The degree of functional recovery after this injury is age dependent;

in the United States, 14% of patients in the 50- to 55-year age group

who sustained a hip fracture were discharged to nursing homes,

compared with 55% of those aged older than 90 years.

• Hip fracture also has a significant effect on mobility; 1 year after hip

fracture, 40% were unable to walk independently, 60% required

assistance with at least one essential activity of daily living (eg,

dressing, bathing), and 80%were unable to perform at least one

instrumental activity of daily living (eg, driving, shopping)

• The impact of a single vertebral fracture may be low;

however, multiple fractures cause progressive loss of height

and kyphosis and severe back pain in the acute stages. The

resultant loss of mobility can exacerbate underlying

osteoporosis, which leads to the increased risk for further

fractures.

• Although good functional recovery after distal forearm

fracture may be poor, reflecting complications (eg, reflex

sympathetic dystrophy, neuropathies, posttraumatic arthritis),

mortality after Colles’ fracture does not deviate from the

expected rate.

Clinical Features

Clinical manifestations

• Fracture

• Spine

• Hip

• wrist

Clinical manifestations

Kyphosis

Height loss

Symptoms

• Early

• Loss of bone mineral density

• Late • Spine (“Dowager Hump”) & Fx

• Hips Fx

• Colles’ (wrist) Fx

• Secondary Affects• Depression

• Pain

• Deformity

• Dependency

• Fear of falling

• Premature death

Fracture Incidence

Melton 1995

Hip Fracture

• Most commonly treated fracture with respect to osteoporosis

• Requires surgical intervention for future ambulation

• Risk of morbidity 5-20% increase

• The highest rates of hip fracture are seen in white populations that live

in northern Europe, where the age-adjusted 1-year cumulative

incidence in Norway in 1989 was 903/100,000 for women and

384/100,000 for men.

• The rates are intermediate in Asians, in China, and in Kuwait, and are

lowest in black populations.

• In Western populations, among individuals who are older than 50 years

of age, there is a female preponderance of hip fracture, with a

female/male incidence ratio of approximately 2:1.

Risk Factors for Hip Fracture Largely Independent of BMD

Previous fracture

Family history

Glucocorticoid therapy

Smoking

Alcohol intake

Rheumatoid arthritis

Seasonal Variations in Vitamin D and Hip Fracture (Paso et al, 2005, JBMR 19:752)

vertebral Fractures

• Thoracic

• Height loss (often of several inches) with multiple sites,

kyphosis, and secondary pain, discomfort related to altered

biomechanics of the back, restricted respiratory disease

• Lumbar

• Abdominal symptoms including distention, early satiety,

and constipation

• 60% of vertebral fractures remain undiagnosed during first

year of occurrence.

• Only about one third of all vertebral deformities that are

noted on radiographs come to medical attention, and less

than 10% necessitate admission to the hospital

Risk Factors for Vertebral Fracture

Age

Gender

Previous fracture

Low BMD

Premature menopause

Smoking

Use of a walking aid

• Recent data from the Epidemiology of Osteoporosis Study

yielded estimates of the prevalence of vertebral fractures to be

19% among women aged 75 to 79 years, 21.9% among

women aged 80 to 84 years, and 41.4% among those aged 85

years and older.

• Only one quarter of vertebral fractures result from falls. Most

are precipitated by routine daily activities (eg, bending or

lifting light objects),

Wrist fracture

• In white women, the incidence increases linearly between the

ages of 40 and 65 years, and then stabilizes.

• There is no apparent increase in the incidence of wrist fracture

with age in men.; in men, the incidence remains constant

between 20 and 80 years.

• United Kingdom showed that among women, the incidence of

distal radius fracture increased from a premenopausal baseline

of 10 per 10,000 population per year to a peak of 120 per

10,000 population per year over 85 years.

Other fractures

• The incidence of proximal humeral, pelvic, and proximal

tibial fractures also increase steeply with age, and are

greater in women than in men.

Osteoporotic fracture: Influence of Age and Gender

MenMen

35–39 85

Age group (years)

WomenWomen Hip

Vertebrae

Colles’4000

3000

2000

1000

20

35–39 85

Inci

den

ce/1

00,0

00 p

erso

n-y

ears

Survival Following Fracture >65

Years (GPRD) Van Staa et al, 2001, Bone 29:517

Femur/hip Vertebral

Observed Expected Observed Expected

Women

3 months 85.6% 97.7% 94.3% 98.4%

12 months 74.9% 91.1% 86.5% 93.6%

5 years 41.7% 60.9% 56.5% 69.6%

Men

3 months 77.7% 97.3% 87.8% 97.9%

12 months 63.3% 90.0% 74.3% 91.8%

5 years 32.2% 58.2% 42.1% 64.4%