Osteoporosis in pulmonary clinic patients: does point-of-care screening predict central dual-energy X-ray absorptiometry?

STUDY OBJECTIVES

Patients in a pulmonary clinic have disorders that predispose them to osteoporosis and may use glucocorticoid therapy, which has been associated with low bone mineral density (BMD) and increased fracture risk. Ideally, all patients at risk for osteoporosis would be screened using the best test available, which is central BMD by dual-energy x-ray absorptiometry (DXA). We proposed to stratify the risk for osteoporosis by the use of a simple questionnaire and point-of-care heel ultrasound BMD measurements.

DESIGN

Cross-sectional screening study.

SETTING

Pulmonary clinic in a single Veterans Affairs Medical Center.

PATIENTS

Approximately 200 male and female patients who had not had previous BMD testing were eligible for the study, and 107 gave consent.

INTERVENTIONS

One hundred seven men (white, 71 men; black, 35 men; and Asian, 1 man) underwent heel BMD testing and filled out a questionnaire. Ninety-eight men underwent a central DXA.

RESULTS

Of 98 subjects, 24.5% had a spine, total hip, or femoral neck (FN) T-score of <or= -2.5, which is the generally accepted definition of osteoporosis diagnosed using DXA, and 44.9% had a T-score of <or= -2.0. The best-fit models for predicting FN or total hip BMD included body weight, heel BMD, corticosteroid use for >or= 7 days, and race, which accounted for 52 to 57% of the variance. When a heel ultrasound T-score of -1.0 was tested to predict a central DXA T-score of -2.0, the sensitivity was 61% and the specificity 64%. Adding the questionnaire score and body mass index (BMI) to the heel T-score improved sensitivity but not specificity. Moreover, BMI and age predicted central BMD with similar sensitivity and specificity. Importantly, of 24 patients with a central DXA T-score of <or= -2.5, only 14 were identified by a heel T-score of <or= -1.0.

CONCLUSIONS

Although the findings from a heel ultrasound plus the answers to a questionnaire were reasonably good indicators for predicting the presence of low BMD, little predictability was gained over the use of BMI and age. In a group of pulmonary clinic patients, the prevalence of osteoporosis was clinically significant, and central DXA testing was the preferable technique for identifying patients who were at risk for fracture.