Table 3.

Sensitivity and specificity of heel ultrasounds in diagnosing bone mineral density defined osteoporosis or ruling it out.

	95% CI
Sensitivity a / (a+c) 53%	29-77
Specificity d / (b+d) 86%	75-96
Pre-test Probability (Prevalence): (a+c) / (a+b+c+d) 29%	17-40
Positive Predictive Value: a / (a+b) 60%	35-85
Negative Predictive Value: d / (c+d) 82%	70-93
Likelihood Ratio + sens / (1-spec) 3.71	1.56-8.81
Likelihood Ratio - (1-sens) / spec 0.55	0.33-0.92

CI, confidence interval. a, 9 (positive, osteoporosis); b, 6 (positive, no osteoporosis); c, 8 (negative, osteoporosis); d, 36 (negative, no osteoporosis).