19 Screening for Osteoporosis in Postmenopausal Women

19 Screening for Osteoporosis in Postmenopausal Women

Richard Neill,

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INTRODUCTION

The US Preventive Services Task Force recommends screening all women age 65 and over for osteoporosis using dual-energy X-ray absorptiometry (DXA) of the femoral neck. Neither the frequency of screening nor the age at which screening may stop are specified. Women at high risk should begin screening at age 60; however, the criteria for determining which women are at high risk are controversial. There is insufficient evidence to recommend for or against screening women younger than 60 or low-risk women aged 60–64. In making their recommendation, the US Preventive Services Task Force reviewed evidence related to five key questions, each of which is summarized next (1).

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From: Current Clinical Practice: Essential Practice Guidelines in Primary Care Edited by: N. S. Skolnik © Humana Press, Totowa, NJ

278 Neill

DOES RISK FACTOR ASSESSMENT ACCURATELY IDENTIFY WOMEN WHO MAY BENEFIT

FROM BONE DENSITY TESTING?

Multiple risk assessment tools were reviewed by the panel. The tools included varyingly complex scoring systems. Thus includes combination of the many risk factors with most including combinations of age, weight, estrogen use, eth- nicity history of fractures, and presence of rheumatoid arthritis. Age is the strongest predictor of osteoporosis risk, followed by weight of 70 kg or less.

The osteoporosis risk assessment instrument is a simple three-item scoring sys- tem that combines age, estrogen use status, and weight. A total osteoporosis risk assessment instrument score of 9 or more has 95% sensitivity for identifying women at high risk of osteoporosis (see Table 1).

DO BONE DENSITY MEASUREMENTS ACCURATELY IDENTIFY WOMEN WHO MAY BENEFIT

FROM TREATMENT?

There are several methods for measuring bone density, including computed tomography, ultrasound, and DXA. Each of these methods yields varying results depending on the skeletal site selected for study and the criteria used for establishing a diagnosis of osteoporosis. DXA scan of the femoral neck is the best predictor of hip fracture and is comparable to forearm measurements for predicting fractures at other sites. Osteoporosis risk assessment that relies on ultrasound or X-ray absorptiometry of peripheral skeletal sites (heel, forearm, or finger) predicts 1-yr risk of fracture, but these measurements have not been correlated with traditional DXA measurements.

WHAT ARE THE HARMS OF SCREENING?

Potentially unwarranted anxiety and perceived vulnerability are associated with positive screening tests. Because various screening methods yield results that cannot be compared directly, women undergoing testing using multiple methods overtime risk misclassification as normal or at risk. The time, effort, expense, and radiation exposure risk of repeated scans over a lifetime have not been determined.

WHAT ARE THE HARMS OF TREATMENT?

The harms of treatment depend on the treatment used. Medication use,

specifically with selective estrogen receptor modulators, is associated with gas-

trointestinal side effects in a significant number of patients. Increased weight is

associated with lower risk of osteoporosis but higher risk of cardiovascular

disease and diabetes.

Chapter 19 / Screening for Osteoporosis in Postmenopausal Women 279

DOES TREATMENT REDUCE THE RISK OF FRACTURES IN WOMEN IDENTIFIED BY SCREENING?

There are no published trials of the effectiveness of screening in reducing osteoporotic fractures. There are many studies that demonstrate the benefits of treatment in reducing fracture incidence, primarily using estrogen, bisphospho- nates, or selective estrogen receptor modulators. The benefits of exercise, smoking cessation, and adequate dietary calcium and vitamin D have also been demonstrated.

SOURCES

1. US Preventive Services Task Force (2002) Screening for osteoporosis in postmenopausal women: Recommendations and rationale. Ann Intern Med 137:526–528.

Table 1

Osteoporosis Risk Assessment Instrument

Risk factor Value Score

Age (yr) ≥75 15

65–74 9

55–64 5

≤54 0

Weight (kg) <60 9

60–69.9 3

≥70 0

Current estrogen use Yes 2

No 0

Total score ≥9 is high risk of osteoporosis.