Measuring Bone Mineral Density

Transcription

1 Measuring Bone Mineral Density Osteoporosis Screening by Pharmacists 9/20/06 Don Downing Institute for Innovative Pharmacy Practice Today s Topics What is osteoporosis? What causes osteoporosis? Screening importance Pharmacy based Bone Mineral Density Testing Definition of Osteoporosis A systemic skeletal disease, characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture 1

2 Bone Mineral Density (BMD) is related to bone mass at maturity (peak bone mass) and subsequent bone loss Peak Bone Mass Phases of Bone Loss Normal Bone: % of peak bone mass Osteopenia: 75-90% of peak bone mass Thinning bone, microarchitecture intact, slightly higher risk of fracture Osteoporosis: <75% of peak bone mass Thinning bone, microarchitecture disrupted, high risk of fracture 2

3 Causes of osteoporosis and risk fracture risk Personal history of fracture as an adult Family history of fracture (esp. 1 st -degree) Caucasian Advancing age Female Dementia Poor health/fraility Tobacco user continued Causes of osteoporosis and risk fracture risk Early menopause (<age 45) or bilateral ovartectomy Low body weight (<127 lbs) Prolonged premenopausal amenorrhea (>1 yr) Lifelong low calcium intake Alcoholism Impaired eyesight Recurrent falls Inadequate physical activity Absence of risk factors does not impart immunity Importance of Screening for Osteoporosis A silent disease with usually a yr lag period between onset of bone loss and 1st fracture 1.3 million fractures/yr in U.S. 400,000 hospitalizations 2.5million medical visits 180,000 nursing home admissions Decreased quality/quantity of life 3

4 Screening Candidates incl. NOF Guidelines* All women > 65 yrs of age* All postmenopausal women < 65 yrs of age with 1 or more risk factors* Postmenopausal women with fractures* Women considering tx for osteoporosis* Women on HRT for prolonged periods* Long-term use of glucocorticoids Strong family hx of osteoporosis or risk factors Primary hyperparathyroidism Risk of Fractures (Arch of Internal Medicine Vol. 164 No. 10, May 24, 2004) Tree-based prediction rule for women with T scores of 2.5 to 1.0. Additional testing thoughts Initially test during 30s or 40s Determines peak bone mass Provides reference point Early detection of problem Next test at menopause: If normal, repeat every 3-5 years If abnormal, repeat annually for 2-3 years, then periodically 4

5 Screening Sites NOF : Measurements of BMD at any skeletal site have value in predicting fracture risk. However, hip BMD is the best predictor of hip fractures and it predicts fractures at other sites as well as other measurements Intrepretation of Results Raw BMD value T Score Z Score Raw BMD Value Expressed as grams of calcium per square centimeter of bone cross section (g/cm 2 ) 5

6 T Score Describes the bone mass of the patient compared to the mean peak bone mass of a normal young adult sex-adjusted reference population using standard deviations (SD) Standard Deviation World Health Organization (WHO) T-Score Categories Normal = BMD >-1 SD Osteopenia = BMD >-1 SD but < -2.5 SD Osteoporosis = BMD > -2.5 SD Established osteoporosis = BMD > -2.5 SD and have 1 or more fractures 6

7 Z Score Compares the patient with a population adjusted for age and sex Osteoporosis is often defined as 1.5 SD below the age-matched mean bone density BMD Screening Devices accudexa (Norland Medical Systems, Inc.) Method: dual energy x-ray absorptiometry Site: hand Radiation dose: 0.3mRem Scan time: 30 sec Reference Population: female caucasians Components: scanner, optional printer BMD Screening Devices Achilles (Lunar) Method: Ultrasound Site: heel Radiation dose: none Scan time: 1 minute Ref. Pop.: female Caucasians Components: Scanner with built in microprocessor and printer, optional printer Weight: 55 lbs 7

8 BMD Screening Devices PIXI (Lunar) Method: dual-energy x-ray absorptiometry* Site: heel and forearm Radiation dose: 20mRem Scan time: 5 sec Ref pop.: female Caucasian Components: Scanner, computer, printer Weight: < 60 lbs * double beam from an x-ray source BMD Screening Devices Sahara (Hologic) Method: ultrasound Site: heel Radiation dose: none Scan time: < 10 sec Ref. pop.: female caucasians Components: Scanner, built-in microprocessor and printer Weight: 22 lbs BMD Screening Devices pdexa (Norland) Method: dual energy x-ray absorptiometry Site: forearm Radiation dose: <3 mrem Scan time: 5 min Ref. pop.: males and females of various ethnic groups Components: scanner, computer, printer Weight: 59 lbs 8

9 BMD Screening Devices ApolloDXA (Norland) Method: dual-energy x-ray absorptiometry Site: heel Radiation dose:,0.2 mrem Scan time: 15 sec Ref. pop.: male and female Caucasians Components: Scanner, control console, printer Weight: 71 lbs BMD Screening Devices Osteo-Analyzer (Norland) Method: Single-energy x-ray absorptiometry* Site: heel Radiation dose: < 1 mrem Scan time: 4 min Ref. pop.: male and female Caucasians/Asians Components: Scanner, control console, opt printer Weight: > 60lbs * Uses a single beam from an x-ray source Bisphosphonate therapy epocrates alert: 9/13/06 Efficacy of bisphosphonate therapy may be diminished by inadequate calcium intake As bisphosphonate use has increased recently (alendronate, ibandonate, risedronate) there has been a concurrent decrease in the use of calcium supplements Great opportunity for pharmacist intervention! 9

10 Questions? Lunch? Testing practice after lunch! 10