Abstract
OBJECTIVE: Zero risk of linked HIV transmission in serodiscordant couples when the HIV-infected partner had viral load less than 200 copies/ml ('U status') was found in observational studies. We aimed at estimating the proportion of time in which 'U status' was maintained and identifying factors associated with the risk of losing it. DESIGN: Observational cohort study. METHODS: We included participants in the ICONA cohort who had reached an established 'U status' (viral load ≤200 copies/ml for >6 months) as of December 2010. The outcome was the number of person-days of follow-up (PDFU) above a viral load greater than 200 copies/ml, relative to the total number of PDFU observed. A logistic regression model was used to identify factors independently associated with the risk of losing 'U status'. RESULTS: Eight thousand, two hundred and forty-one persons living with HIV were included in the analysis who contributed 2 670 888 PDFU. Of these, 1648 (20%) were women, 768 (9%) were people who inject drugs (PWID), and 2066 (25%) were foreign-born. The median of viral load measurements was 9 (IQR: 4-15). Overall, only 3.1% of PDFU were observed when viral load was above 200 copies/ml. The proportion of PDFU with viral load more than 200 copies/ml was higher than average in women (5.3%), unemployed (5.4%), PWID (4.7%), and in people with more than three previous virologic failures (6.3%). These variables were significant predictors of losing 'U status' in the multivariable logistic regression. CONCLUSION: Our results reinforce the validity of the U=U message in real-world setting. However, we identified subsets of our study population at higher risk of losing the 'U status' for whom additional efforts are needed.