TABLE 4.

Composite estimate of sensitivity, specificity and positive predictive value from the overall screening process using data from the first three low back pain visits

Screening status	True status		Total
	Low cost	High cost
Low cost	13,119*	1528*	27,334
	4862†	669†
	4536‡	2620‡
High cost	1802*	1776*	7261
	1289†	1086†
	681‡	627‡
Total	26,289	8306	34,595

Sensitivity = 42.0%; Specificity = 85.7%; positive predictive value = 48.1%.

^*Obtained from first visit;

^†Obtained from second visit;

^‡Obtained from third visit