Table 4. Performance of rubella IgM serology test using linked dataset, Ontario, Canada, 2009–2014.

IgM serology result	iPHIS Classification		Positive predictive value (%)	Negative predictive value (%)	Sensitivity (%)	Specificity (%)
	Confirmed	Not-confirmeda
Positive	5	135	3.6	100.0	100.0	25.8
Negative	0	47
By age (years)
0–1			0.0	100.0	-	40.0
1–19			4.3	100.0	100.0	60.0
20–39			3.9	100.0	100.0	9.8
40+			3.0	100.0	100.0	5.9
Any reported fever
Yes			15.0	100.0	100.0	54.1
No			1.7	100.0	100.0	18.6
Any reported rash
Yes			15.4	100.0	100.0	57.7
No			0.9	100.0	100.0	13.1
Any rubella immunization
Yes			7.1	100.0	100.0	45.8
No			3.2	100.0	100.0	22.8

^a- includes ‘Does not meet’, ‘suspect’ and ‘Person under investigation’ classifications, excludes ‘probable’ classification