Task shifting in primary eye care: how sensitive and specific are common signs and symptoms to predict conditions requiring referral to specialist eye personnel?

Table 2 Sensitivity, specificity and predictive value for two other referral criteria

	Right eyes
Referral Criteria	Serious	Not serious	Total	Sensitivity	Specificity	PPV	NPV
VA<6/18 or pain Neither of above Total	504 283 787	202 308 510	706 591 1297	64.0	60.4	71.4	52.1
VA<6/18 or pain or red eye None of above Total	544 243 787	252 258 510	796 501 1297	69.1	50.6	68.3	51.5

Row and column totals are in italics. Data are missing for some eyes. PPV = predictive value of a positive test (abnormal sign). NPV = predictive value of a negative test (absence of the abnormal sign).

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