Technical notes: HIV care cascade, 2018
Indicator definitions
Diagnosed
| Estimate | “Diagnosed” definition |
| Main | Nominal or non-nominal HIV-positive diagnostic test and/or HIV viral load test*, and not administratively lost to follow-up after two years for viral load tests and unlinked non-nominal diagnoses, seven years for unlinked nominal diagnoses |
| Upper | Nominal or non-nominal HIV-positive diagnostic test and/or HIV viral load test*, and not administratively lost to follow-up after four years for viral load tests and unlinked non-nominal diagnoses, seven years for unlinked nominal diagnoses |
*Individuals with no nominal HIV-positive diagnostic test and all undetectable VL tests were not included if they had evidence of being HIV-negative (i.e. record of a nominal HIV-negative diagnostic test after, on the same day as, or within 30 days before their last undetectable VL test).
Newly diagnosed
| Estimate | “Newly diagnosed” definition |
| Main | Nominal HIV-positive diagnostic test and no evidence of being previously diagnosed (i.e. first VL after diagnosis not suppressed, or first suppressed VL test was not within 30 days after diagnosis) |
In care (among people with diagnosed HIV)
| Estimate | “In care” definition | “Diagnosed” denominator used for calculating percent of individuals in stage per year |
| Main | At least one VL test in two calendar years | Diagnosed (Main estimate) |
| Lower | At least one VL test in two calendar years | Diagnosed (Upper estimate) |
Linkage to care (among people newly diagnosed with HIV)
| Estimate | “Linkage to care” definition | “Newly diagnosed” denominator used for calculating percent of individuals in stage per year |
| Main | Number of months from HIV diagnosis to first VL test | Newly diagnosed (Main estimate) |
On ART (among people with diagnosed HIV)
| Estimate | “On ART” definition | “Diagnosed” denominator used for calculating percent of individuals in stage per year |
| Main | Documented on ART or VL less than 200 copies/mL last VL test | Diagnosed (Main estimate) |
| Upper | Documented on ART or VL less than 200 copies/mL any VL test | Diagnosed (Main estimate) |
| Lower | Documented on ART or VL less than 200 copies/mL all VL tests | Diagnosed (Upper estimate) |
On ART (among people in care)
| Estimate | “On ART” definition | “In care” denominator used for calculating percent of individuals in stage per year |
| Main | Documented on ART or VL less than 200 copies/mL last VL test | At least one VL test |
| Upper | Documented on ART or VL less than 200 copies/mL any VL test | At least one VL test |
| Lower | Documented on ART or VL less than 200 copies/mL all VL tests | At least one VL test |
Virally suppressed (among people with diagnosed HIV)
| Estimate | “Virally suppressed” definition | “Diagnosed” denominator used for calculating percent of individuals in stage per year |
| Main | VL less than 200 copies/mL on last VL test | Diagnosed (Main estimate) |
| Upper | VL less than 200 copies/mL on any VL test | Diagnosed (Main estimate) |
| Lower | VL less than 200 copies/mL on all VL tests | Diagnosed (Upper estimate) |
Virally suppressed (among people with diagnosed HIV in care)
| Estimate | “Virally suppressed” definition | “In care” denominator used for calculating percent of individuals in stage per year |
| Main | VL less than 200 copies/mL on last VL test | At least one VL test |
| Upper | VL less than 200 copies/mL on any VL test | At least one VL test |
| Lower | VL less than 200 copies/mL on all VL tests | At least one VL test |
Virally suppressed (among people with diagnosed HIV on ART)
| Estimate | “Virally suppressed” definition | “On ART” denominator used for calculating percent of individuals in stage per year |
| Main | VL less than 200 copies/mL on last VL test | Documented on ART or VL less than 200 copies/mL last VL test |
| Upper | VL less than 200 copies/mL on any VL test | Documented on ART or VL less than 200 copies/mL any VL test |
| Lower | VL less than 200 copies/mL on all VL tests | Documented on ART or VL less than 200 copies/mL all VL tests |
*Percent of those on with diagnosed HIV on ART that were virally suppressed is calculated differently than percent of those with diagnosed HIV and the percent of those with diagnosed HIV in care.
Time to viral suppression (among people newly diagnosed with HIV)
| Estimate | “Time to VL suppression” definition | “Newly diagnosed” denominator used for calculating percent of individuals in stage per year |
| Main | Number of months from HIV diagnosis to first suppressed VL (less than 200 copies/mL) | Newly diagnosed (main estimate) |
Definitions
Administrative lost to follow-up (LTFU)
An individual in the Ontario HIV Laboratory Cohort is considered to be a person with diagnosed HIV who is living in Ontario until administratively lost to follow-up, defined as having had no viral load test for more than two consecutive years and no viral load test in later years. Individuals lost to follow-up are assumed to have died or migrated out of the province, and are removed from the cohort. Based on the constraints of this definition, a diagnosed individual who is actually living in Ontario would be removed from the cohort if they haven’t had a VL test in more than two years. If this individual goes on to have a viral load test in the future, they are re-entered into the cohort. In additional analyses, the lost to follow-up criteria is increased to four years.
HIV datamart
An integrated data platform composed of Public Health Ontario Laboratory’s diagnostic and viral load testing databases. Within the datamart, diagnostic and viral load test records are linked together for the same person (however, linkage is not possible for non-nominal HIV-positive diagnostic tests).
HIV-positive diagnostic test
Defined as a blood sample that has initially tested reactive on a screening test (either at the laboratory or on a point-of-care / rapid test), and has been confirmed as HIV-positive by a separate test (lateral flow immunoassay, Western Blot, p24 antigen confirmatory test, or polymerase chain reaction for children <18 months). HIV-positive diagnostic tests in the HIV Datamart include people who were diagnosed with HIV for the first ever time in Ontario, as well as people who were diagnosed HIV-positive elsewhere and moved to Ontario and tested again.
Newly HIV diagnosed
Individuals in the HIV Datamart who received their first ever HIV-positive diagnosis in Ontario (i.e. were not diagnosed elsewhere and then moved to Ontario and tested again). Individuals are considered newly diagnosed in Ontario if they have record of a nominal HIV-positive diagnostic test and no evidence of being previously diagnosed (i.e. no indication of a repeat test, no detectable viral load test or CD4 count before their diagnosis date, first VL after diagnosis not suppressed).
Nominal HIV testing
A type of HIV diagnostic testing where the test requisition form contains the name of the individual being tested. Nominal HIV tests can be linked to viral load tests in the HIV datamart using patient identifiers.
Non-nominal HIV testing
A type of HIV diagnostic testing where the test requisition form does not contain the name of the individual being tested. There are two types of non-nominal testing in Ontario: anonymous and coded. The lack of identifying information means that it is not possible to link non-nominal HIV-positive diagnostic tests to previous diagnostic tests and viral load tests within the HIV datamart.
Test requisition
Along with each HIV diagnostic and viral load test, a test requisition form is completed. It is filled out by the provider who conducted the test and collects information on the individual being tested. The viral load test requisition form collects information on whether the individual is on antiretroviral treatment at the time of testing and most recent CD4 cell count.
