Table 3. Comparison of the different case definitions.

	2009	2011	2009 (with values of thrombocytopenia specified as less than 150 000)	With backache included in the criteria of any 2 in the 2011 definition	With backache included in the criteria of any 2 in the 2009 definition
Sensitivity	76.4 (69.6–82.1)	87.9 (82.2–91.9)	85.1 (79.0–89.6)	97.7 (94.2–99.1)	96.6 (95.4–97.8)
Specificity	42.5 (38.9–46.3)	20.1 (17.2–23.3)	32.5 (29.1–36.1)	9.3 (7.3–11.7)	14.3 (11.9–17.1)
LR+	1.3 (1.2–1.5)	1.1 (1.0–1.2)	1.3 (1.2–1.4)	1.1 (1.0–1.1)	1.1 (1.0–1.2)
LR−	0.6 (0.4–0.7)	0.6 (0.4–0.9)	0.5 (0.3–0.7)	0.3 (0.1–0.7)	0.2 (0.1–0.5)
DOR	2.4 (1.6–3.5)	1.8 (1.1–3)	2.7 (1.7–4.3)	4.4 (1.6–12.2)	4.7 (2.0–10.9)

DOR: diagnostic odds ratio.