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Evaluating the use of reactivity levels to inform risk communication and improve service user experience in an HIV
Jennifer Taylor1,2, Sally O'Brien3,2, Jamie Fagg1,2
1Royal Free London NHS Foundation Trust, London, UK.
Objectives:
This service improvement study scoped the value of using quantitative reactivity levels (RL) to introduce a two-tier counselling approach in HIV self-sampling services. The objectives were to (1) use self-reported confirmatory test results to estimate the positive predictive value (PPV) of the first-line assay and (2) to calculate the impact on the PPV and theoretical negative predictive value of a range of proposed RL thresholds, which could be used to differentiate between higher and lower reactive results.
Methods:
We studied HIV testing data from a UK-based online sexual health service from 1 December 2018 to 15 July 2020. Routinely collected, anonymised data on RL and self-reported confirmatory testing outcomes were used to calculate PPV at a range of RL thresholds.
Results:
116 474 adequate HIV tests were reported during the study period, of which 889 were reactive (0.76%, 95% CI 0.71% to 0.82%). Confirmatory testing outcomes were self-reported by 572 (64.34%) reactive service users, of whom 43 (7.52%) had a new HIV diagnosis, 412 (72.03%) were negative and 117 (20.45%) already had a known HIV diagnosis. PPV was 9.45% at an RL threshold of >1. Quantitative RLs were reported for 30 281 results, of which 200 were reactive. PPV increased to 80% at an RL threshold of >30. No confirmed HIV diagnoses were reported among service users with RL <30.
Conclusion:
RLs could be used to support a more nuanced approach to counselling, potentially reducing anxiety prior to confirmatory testing.
