Table 3. Performance of measles 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	42	199	17.4	97.2	79.2	65.7
Negative	11	381
By age (years)
0–1			20.6	100.0	100.0	63.5
1–19			12.8	97.9	79.2	64.2
20–39			26.5	92.1	64.3	69.9
40+			29.2	97.7	87.5	71.7
Any reported fever
Yes			28.0	94.6	78.4	65.2
No			2.0	100.0	100.0	66.2
Any reported rash
Yes			26.5	95.6	78.8	67.5
No			1.2	100.0	100.0	62.9
Any measles immunization
Yes			11.1	95.9	60.0	66.0
No			19.3	97.6	83.7	65.6

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