Chart 1. Definition of the predominant follow-up system, according to the number of records of viral load (VL) tests and initiation of antiretroviral therapy (ART). Qualiaids-BR cohort, 2021.

Predominant follow-up system	Definition
SUS	People with two or more VL records People with more than one VL record – loss to follow-upa within 66 daysb from starting ART
Undefined	People without any VL record – loss to follow-up within 66 days from starting ART People with one VL record – loss to follow-up after 66 days from starting ART People without any record or with one VL record – starting ART after 10/26/2018c
Private	People without any record or with one VL record – starting ART prior to 10/26/2018 People without any record – with loss to follow-up after 66 days of starting ART

^a Loss to follow-up was defined as death or definitive abandonment of ART (which considers whether the last medication withdrawal was recorded up to 100 days before the final date of the cohort: 12/31/2018), in line with the criteria defined by the Ministry of Health¹⁷.

^b The 66-day interval is based on the definition in the Clinical and Therapeutic Guidelines Protocol²⁷ which states that, for people starting ART, the interval between VL exams should be up to 56 days. Another 10 days were added to this interval, including weekends and holidays.

^c The date was defined considering the end of the cohort (12/31/2018) and subtracted of 66 days.