Screening of Osteoporosis in Menopausal Women using OSTA index , ORAI index and OSIRIS index

Abstract

Screening of Osteoporosis in Menopausal Women using OSTA index , ORAI index and OSIRIS index

Budsaba Wiriyasirivaj MD, MSc (Clinical epidemiology), LSHTM, UK

Department of Obstetrics and Gynecology, BMA Medical College and Vajira Hospital

Objective: To determine the diagnostic performance of the Osteoporosis Self-Assessment Tool for Asians (OSTA), Osteoporosis Risk Assessment Instrument index (ORAI index) and Osteoporosis Index of Risk (OSIRIS) for identifying osteoporosis in menopausal women.

Study design: Diagnostic study.

Subjects: A total of five hundred and fifty-six menopausal women attending menopause clinic at BMA Medical College and Vajira Hospital between January 2004 and May 2007 were selected.

Methods: The data was retrospectively collected from the medical records of women who had lumbar and femoral neck BMD T-score measurement by dual energy X-ray absorptiometry (DEXA). Data on age, body weight, estrogen usage, and history of low impact fracture were collected and calculated for OSTA index, ORAI index, and OSIRIS index. Diagnostic performance of each index comparing with standard DEXA were determined.

Main outcome measures: Sensitivity, specificity, positive predictive value, negative predictive value, and 95% confidence interval.

Results: Prevalence of osteoporosis (T-score < -2) at lumbar spine and femoral neck were 13.9% and 3.8%, respectively. OSTA index at cutoff ≤ -1 had a sensitivity and specificity of 52.0% (95% CI, 47.8-56.1) and 87.5% (95% CI, 84.7-90.2) respectively for lumbar spine and 61.9% (95% CI, 57.9-65.9) and 83.7% (95% CI, 80.7-86.8) respectively for femoral neck. ORAI index at cutoff ≥ 9 had a sensitivity and specificity of 94.8% (95% CI, 93.0-96.7) and 31.3% (95% CI, 27.5-35.2) respectively for lumbar spine and 90.5% (95% CI, 88.0-92.9) and 28.4% (95% CI, 24.7-32.2) respectively for femoral neck. OSIRIS index at cutoff ≤ 1 had a sensitivity and specificity of 87.0% (95% CI, 84.2-89.8) and 45.5% (95% CI, 41.4-49.7) respectively for lumbar spine and 85.7% (95% CI, 82.8-88.6) and 42.1% (95% CI, 38.0-46.2) respectively for femoral neck. In this setting, OSTA index at cutoff ≤ 0 is the most appropriate value for osteoporosis screening with the sensitivity and specificity of 74.0 (95% CI, 70.4-77.7) and 67.9% (95% CI, 64.0-71.7) respectively for lumbar spine and 81.0% (95% CI, 77.7-84.2) and 63.7% (95% CI, 59.7-67.7) respectively for femoral neck.

Conclusion: OSTA index is a simple and effective clinical risk assessment tool for identifying either lumbar spine or femoral neck osteoporosis in Thai post menopausal women. In this setting, individuals with OSTA score ≤ 0 were high risk for osteoporosis and should be targeted for BMD measurement by DEXA.

Vajira Med J 2007 ; 51 : 75 - 85