Table III.

Test characteristics for adherence measures identifying patients with virological failure.

Indicator	Sensitivity (95% CI)	Specificity (95% CI)	PPVa (95% CI)	NPVb (95% CI)
Came after scheduled refill date	0.19 (0.18,0.20)	0.84 (0.83, 0.85)	0.18 (0.17, 0.19)	0.86 (0.85, 0.86)
Came 5 or more days late	0.12 (0.11, 0.13)	0.91 (0.91, 0.92)	0.19 (0.18, 0.21)	0.85 (0.85, 0.86)
Came more than 30 days late	0.05 (0.04, 0.06)	0.98 (0.98, 0.98)	0.30 (0.27, 0.34)	0.85 (0.85, 0.86)
Less than 100% pill coverage (pill count)	0.14 (0.13, 0.15)	0.89 (0.88, 0.89)	0.18 (0.17, 0.19)	0.85 (0.84, 0.86)
Less than 90% coverage (pill count)	0.07 (0.06, 0.08)	0.96 (0.95, 0.96)	0.23 (0.20, 0.25)	0.85 (0.85, 0.86)
Less than 80% coverage (pill count)	0.06 (0.05, 0.06)	0.97 (0.97, 0.97)	0.24 (0.22, 0.27)	0.85 (0.85, 0.86)
Fewer than 90% of doses taken (self-report)	0.13 (0.12, 0.14)	0.88 (0.88, 0.89)	0.19 (0.17, 0.21)	0.83 (0.82, 0.84)

^aPositive predictive value

^bNegative predictive value; the NPV and PPV only apply to this population or one with an identical prevalence