Trends in HIV care cascade engagement among diagnosed people living with HIV in Ontario, Canada: A retrospective, population-based cohort study

Abstract

Background: The HIV cascade is an important framework for assessing systems of care, but population-based assessment is lacking for most jurisdictions worldwide. We measured cascade indicators over time in a population-based cohort of diagnosed people living with HIV (PLWH) in Ontario, Canada.

Methods: We created a retrospective cohort of diagnosed PLWH using a centralized laboratory database with HIV diagnostic and viral load (VL) test records linked at the individual-level. Individuals enter the cohort with record of a nominal HIV-positive diagnostic test or VL test, and remain unless administratively lost to follow-up (LTFU, >2 consecutive years with no VL test and no VL test in later years). We calculated the annual percent of diagnosed PLWH (cohort individuals not LTFU) between 2000 and 2015 who were in care (≥1 VL test), on ART (as documented on VL test requisition) or virally suppressed (<200 copies/ml). We also calculated time from diagnosis to linkage to care and viral suppression among individuals newly diagnosed with HIV. Analyses were stratified by sex and age. Upper/lower bounds were calculated using alternative indicator definitions.

Results: The number of diagnosed PLWH increased from 8,859 (8,859-11,389) in 2000 to 16,110 (16,110-17,423) in 2015. Over this 16-year period, the percent of diagnosed PLWH who were: in care increased from 81% (63-81%) to 87% (81-87%), on ART increased from 55% (34-60%) to 81% (70-82%) and virally suppressed increased from 41% (23-46%) to 80% (67-81%). Between 2000 and 2014, the percent of newly diagnosed individuals who linked to care within three months of diagnosis or achieved viral suppression within six months of diagnosis increased from 67% to 82% and from 22% to 42%, respectively. Estimates were generally lower for females and younger individuals.

Discussion: HIV cascade indicators among diagnosed PLWH in Ontario improved between 2000 and 2015, but gaps still remain-particularly for younger individuals.

Fig 1. Flow diagram for the creation of the Ontario HIV Laboratory Cohort from the Public Health Ontario Laboratory HIV datamart.

Non-nominal forms of testing include the use of coded or completely anonymous identifiers. Evidence of being an HIV-negative person = record of a nominal HIV-negative diagnostic test after, on the same day as, or within 30 days before last undetectable viral load test. VL = viral load.

Fig 2. Trends in the number of diagnosed PLWH and the percent who were in care, on ART, and virally suppressed, Ontario HIV Laboratory Cohort, 2000–2015.

A) Number of diagnosed PLWH. B) Percent of diagnosed PLWH who were in care. C) Percent of diagnosed PLWH who were on ART. D) Percent of diagnosed PLWH who were virally suppressed. Solid lines represent “main” estimates and shaded areas represent “upper” and/or “lower” bounds. See Table 1 for indicator definitions. PLWH = people living with HIV. ART = antiretroviral treatment.

Fig 3. Trends in conditional cascade indicators, Ontario HIV Laboratory Cohort, 2000–2015.

A) Percent of diagnosed PLWH in care who were on ART. B) Percent of diagnosed PLWH in care who were virally suppressed. C) Percent of diagnosed PLWH on ART who were virally suppressed. Solid lines represent “main” estimates and shaded areas represent “upper” and/or “lower” bounds. See Table 1 for indicator definitions. PLWH = people living with HIV. ART = antiretroviral treatment.

Fig 4. Trends in time from HIV diagnosis to linkage to care and viral suppression among individuals newly diagnosed with HIV in Ontario, 2000-2013/2014.

A) Percent of newly diagnosed individuals who linked to care within a certain number of months after HIV diagnosis. B) Median (IQR) number of days from HIV diagnosis to linkage to care. C) Percent of newly diagnosed individuals who achieved viral suppression within a certain number of months after HIV diagnosis. D) Median (IQR) number of days for HIV diagnosis to viral suppression. In Fig B and D, yellow bar indicates interquartile range and black line indicates median.

Fig 5. Trends in viral suppression indicators by sex and age category (main estimates only), Ontario HIV Laboratory Cohort, 2000-2014/15.

A) Percent of diagnosed PLWH who were virally suppressed by sex. B) Percent of newly diagnosed individuals who achieved viral suppression within 6 months of HIV diagnosis by sex. C) Percent of diagnosed PLWH who were virally suppressed by age category. D) Percent of newly diagnosed individuals who achieved viral suppression within 6 months of HIV diagnosis by age category. In Fig D, percents averaged over three years to reduce year-to-year variation due to small counts. In Fig 5B and 5D, individuals with no VL are included in the denominator.