Selected 2010 WHO Early Warning Indicator definitions (Numerator/Denominator) and targets.

ART - Antiretroviral therapy.ARV - Antiretrovirals.LTFU - Lost to follow-up.EWI - Early Warning Indicator.*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.†EWI sample start date: The date designated as the start of the sampling. The sample start date is fixed by the HIVDR Working Group.§Lost to follow-up: 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 were classified as LTFU. Transfers of care to another site and deaths were excluded from the numerator and denominator. Stopping therapy without restarting was classified as not LTFU if the patient continued to attend clinic appointments.∞Transfers of care to another site, deaths, and ART stop without a restart were excluded from the denominator.‡On-time pick-up of ARV drugs: A patient pick-up of ARV drugs on or before the date the previously dispensed drugs would have run out if they had been taken according to schedule.!The following patients were excluded from the denominator: Patients who transferred out, died, or stopped ART without a restart between baseline pick-up date and baseline pick-up run-out date.#For EWIs: Patients LTFU at 12 month, Patients switched to a second-line regimen 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.∧Stock-out: Any occurrence of zero stock of a routinely-used ARV drug at the site at which the patient routinely picks up ARVs.Table adapted from WHO HIV Drug Resistance EWI guidance document [16].