Recent infection testing algorithm (RITA) applied to new HIV diagnoses in England, Wales and Northern Ireland, 2009 to 2011

A Aghaizu; G Murphy; J Tosswill; D DeAngelis; A Charlett; O N Gill; H Ward; S Lattimore; R D Simmons; V Delpech

doi:10.2807/1560-7917.ES2014.19.2.20673

Surveillance and outbreak reports Open Access

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Recent infection testing algorithm (RITA) applied to new HIV diagnoses in England, Wales and Northern Ireland, 2009 to 2011

A Aghaizu¹, G Murphy², J Tosswill², D DeAngelis³, A Charlett¹, O N Gill¹, H Ward⁴, S Lattimore¹, R D Simmons⁵, V Delpech¹
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Affiliations: ¹ HIV and STI Department, Centre for Infectious Disease Surveillance and Control, Public Health England, Colindale, London, United Kingdom ² Virus Reference Department, Microbiology Services Colindale, London, United Kingdom ³ MRC Biostatistics Unit, Institute of Public Health, Cambridge, United Kingdom ⁴ Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom ⁵ MRC Clinical Trials Unit, London, United Kingdom

Correspondence:
A Aghaizu
adamma.aghaizu phe.gov.uk
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Citation style for this article: Aghaizu A, Murphy G, Tosswill J, DeAngelis D, Charlett A, Gill O N, Ward H, Lattimore S, Simmons R D, Delpech V. Recent infection testing algorithm (RITA) applied to new HIV diagnoses in England, Wales and Northern Ireland, 2009 to 2011. Euro Surveill. 2014;19(2):pii=20673. https://doi.org/10.2807/1560-7917.ES2014.19.2.20673 Received: 25 Jul 2013

Abstract

In 2009, Public Health England (PHE) introduced the routine application of a recent infection testing algorithm (RITA) to new HIV diagnoses, where a positive RITA result indicates likely acquisition of infection in the previous six months. Laboratories submit serum specimens to PHE for testing using the HIV 1/2gO AxSYM assay modified for the determination of HIV antibody avidity. Results are classified according to avidity index and data on CD4 count, antiretroviral treatment and the presence of an AIDS-defining illness. Between 2009 and 2011, 38.4% (6,966/18,134) of new HIV diagnoses in England, Wales and Northern Ireland were tested. Demographic characteristics of those tested were similar to all persons with diagnosed HIV. Overall, recent infection was 14.7% (1,022/6,966) and higher among men who have sex with men (MSM) (22.3%, 720/3,223) compared with heterosexual men and women (7.8%, 247/3,164). Higher proportions were among persons aged 15-24 years compared with those ≥50 years (MSM 31.2% (139/445) vs 13.6% (42/308); heterosexual men and women 17.3% (43/249) vs 6.2% (31/501)). Among heterosexual men and women, black Africans were least likely to have recent infection compared with whites (4.8%, 90/1,892 vs 13.3%, 97/728; adjusted odds ratio: 0.6; 95% CI: 0.4-0.9). Our results indicate evidence of ongoing HIV transmission during the study period, particularly among MSM. .