Early infant HIV-1 diagnosis programs in resource-limited settings: opportunities for improved outcomes and more cost-effective interventions

Table 2 Index of participation through each step in the early infant diagnosis (EID) cascade

Step in cascade	Highest value from Table 1	Lowest value from Table 1	Cumulative index of participation through step in cascade (range, lowest to highest values from Table 1)
Proportion of exposed infants undergoing EID testing	98% [62]	6% [81]
Specimen collection and processing	99.7% evaluable [61]	84% evaluable [64]	5.9% to 97.7%
Proportion of EID results returned	90% [3]	37% [62]	1.9% to 87.9%
Proportion of infected infants linking to care (of infected infants receiving results)	78% [62]	65% [3]	1.2% to 68.6%
Proportion of infected infants initiating ART (of infected infants receiving results and linking to care)	77% [3]	38% [65]	0.5% to 52.8%

For each step in the EID cascade, the highest and lowest reported values from Table 1 are highlighted. The index of participation is calculated as the product of successful uptake through each step in the cascade. For example, the highest value of uptake through 'specimen collection and processing' is calculated as the product of the highest value for the prior step ('proportion of exposed infants undergoing EID testing', 98%) and the highest value for the current step (99.7%); 0.98 × 0.997 = 0.9771. Results highlight that even with the highest reported uptake values, the total proportion of infected infants successfully accessing all steps in the care cascade is low, at 52.81%. As noted in the text, prior to 2008, fewer than 100% of HIV-infected infants would have been recommended to initiate ART, and the estimate of 1.4% to 68.6% of infected infants linking to care may be a better reflection of cascade completion. These calculations are conducted for purposes of discussion only, and require the assumption that the prevalence of HIV-infected infants among those not accessing each step in the cascade is equal to the prevalence among infants accessing care.
ART = antiretroviral therapy.

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