TABLE 1.

Selected WHO Early Warning Indicator Definitions and Targets

Indicator	Definition
ART Prescribing Practices*	Percentage of patients initiating ART at the site who are initially prescribed, or who initially pick up from the pharmacy, an appropriate first-line ART regimen.
	Target: 100%
Patients lost to follow-up at 12 months§#	Percentage of patients initiating ART at the site who are lost to follow-up during the 12 months after starting ART.
	Target: ≤20%
Patient retention on first-line ART at 12 months#∞	Percentage of patients initiating ART at the site who are still on ART after 12 months, and whose initial ART regimen was changed during the first 12 months to a regimen with a different drug class.
	Target: 0%
On-time ARV drug pick-up#	Percentage of patients picking up all prescribed ARV drugs on time, before the previous prescription would run out if taken according to schedule.
	Target: ≥90%
ARV drug-supply continuity	Percentage of months in a designated year in which there were no ARV drug stock-outs (determined at the level of site dispensary).
	Target: 100%

^*

Appropriate first-line ART regimen: An ART regimen that meets one or both of the following definitions:

• Standard regimen listed in national ART guidelines and used according to those guidelines
• Regimen recommended in the WHO treatment guidelines

^§Patients who had not returned to the pharmacy or clinic ≤90 days after the last ART run-out date during the 12-months after the date of ART initiation and who were not known to have transferred their care to another site, stopped therapy without restarting, or died, were classified as LTFU.

^#For EWIs: Patients LTFU at 12 month, Patient retention on first-line ART at 12 months, and On-time ARV drug pick-up, if no ARV pick-up date, regimen, and number of pills dispensed was not recorded in the records, it was assumed that no pick-up had occurred, resulting in the most conservative estimate of each indicator.

Table adapted from WHO HIV Drug Resistance EWI guidance document [19]