Table 5

 Accuracy of clinic level diagnosis compared with double or triple read reference slides. Values are number/number in group (percentage) unless stated otherwise

VariablesNorth: new microscopyEast: established microscopyClinician in north*
False positive result39/193 (20.2)†329/1212 (27.1)412/413 (99.8)
False negative result47/451 (10.4)0/1
Sensitivity, % (95% CI)89.6 (88.1 to 91.1)100
Specificity, % (95% CI)79.8 (73.4 to 85.2)72.9 (70.7 to 75.0)0.2 (0 to 0.7)
Positive predictive value55.1 (52.7 to 57.5)0.2 (0 to 0.7)
Negative predictive value95.0 (93.9 to 96.0)100

*Against clinicians diagnosis based on signs and symptoms alone.

†New compared with established microscopy: Fisher’s exact, P=0.02.