The prognostic value of baseline erosions in undifferentiated arthritis

Table 5 Predictive value for the progression from UA to RA within one year using different cut-off values for erosions in feet

Number of erosive joints	n	PPV	(95% CI)	NPV	(95% CI)	Specificity	(95% CI)	Sensitivity	(95% CI)	LR+	LR-	AUC (SEM)
≥1	89	49	39-60	73	69-77	87	84-91	28	21-34	2.2	0.83	0.57 (0.028)
≥2	42	60	48-74	72	68-76	95	93-98	16	10-21	3.3	0.89	0.55 (0.028)
≥3	18	67	45-88	70	66-74	98	97-100	8	3-12	4.5	0.94	0.53 (0.028)
≥4	9	67	36-98	70	66-74	99	98-100	4	1-7	4.5	0.97	0.52 (0.028)
≥5	5	80	45-115	70	66-74	100	99-100	3	0-5	8.9	0.98	0.51 (0.028)

n = number of UA patients positive for this cutoff.
AUC = area under the curve; CI = confidence interval; LR+ = positive likelihood ratio; LR- = negative likelihood ratio; NPV = negative predictive value; PPV = positive predictive value; RA = rheumatoid arthritis; SEM = standard error of measurement; UA = undifferentiated arthritis.

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