Recent infections among newly diagnosed cases of HIV infection in Spain, 2015-2016. National estimates using cohort data

Background: To estimate the prevalence of recent infection (RI) among people newly diagnosed with HIV in Spain using a representative sample collected by the AIDS Research Network cohort (CoRIS) during 2015-2016. Methods: Stratified sampling of CoRIS data was used with proportional allocation by mode of transmission of new HIV diagnoses notified to National Surveillance System. Samples used were from patients in the CoRIS cohort with available stored plasma collected within 6 months after diagnosis. Weighted methods were used to estimate the prevalence of RI and multivariate logistic regression models were used to determine associated factors. Results: Of the 669 individuals included, 55.1% were men who had sex with men (MSM), 24.6% were heterosexual, and 20.3% were non-MSM non-heterosexual. The weighted prevalence of RI was 11.8% (95% Confidence interval [CI] 9.4-14.8%) overall, 15.5% (12.2-19.4%) among MSM, 6.3% (3.9-10.0%) among heterosexual, and 8.6% (3.2-20.9%) in non-MSM non-heterosexual persons. Factors associated with prevalence of RI were: MSM (OR 2.05; 95% CI 1.02-4.14) vs. heterosexual, being Spanish (OR 2.92; 1.36-6.26) or European (OR 3.42; 1.28-9.13) vs. Latin American, having a secondary or higher education level (OR 3.08; 0.95-1.00) vs. primary, and having a CD4 count of 350-499 (OR 3.26; 1.46-7.30) or >500 (OR 6.26; 2.92-13.39) vs. <350 cells/mm(3). Conclusions: In the absence of direct data from surveillance systems, the use of cohort data is a very valuable option for identifying the prevalence of RI at national level. This is the first nationwide study carried out in Spain to determine the prevalence of RI using an avidity assay.

Automated summary

This study used data from the AIDS Research Network cohort (CoRIS) in Spain to estimate the prevalence of recent infection (RI) among people newly diagnosed with HIV. The results showed that factors associated with RI prevalence include being MSM, Spanish or European, having a higher education level, and having a CD4 count above 350 cells/mm3. This is the first nationwide study in Spain to determine RI prevalence using an avidity assay.