OBJECTIVETo understand the overall HIV sero-conversion rate and its trend and risk factors of uninfected partners in sero-discordant couples.

METHODSA total of 3088 uninfected partners, whose HIV positive partners infected via former plasma donation or blood transfusion from July, 2006 to December 2010, were chosen as a fix cohort. They were tested for HIV antibodies twice a year using ELISA by local CDC from July, 2006 to December, 2010. Data regarding demographic, sexual behavior information of uninfected partners and infection, serologic characteristics of positive partners were retrospectively surveyed and collected to analyze possible risky factors.

RESULTSA total of 132 in 3088 uninfected partners were sero-converted, with a sero-conversion rate of 1.17/100 person years (95%CI: 0.99/100 person years -1.39/100 person years). Sero-conversion rate reached the peak (0.82%) in the following interval of January and June in 2008 and have a bottom conversion rate (0.13%) in the same month interval in 2010. Conversion rate outcome showed a downward trend in following(χ(2)trend = 8.907, P < 0.05). In the survey, 56.6% (1513/2673) uninfected partners were males, 56.2% (1501/2673) were with lower education level. Among uninfected partners, as reported by themselves, having sex in recently 6 months accounted for a proportion of 81.4% (2176/2673), sex frequency of less than 4 times per month accounted for 45.7% (1169/2558) and consistent using of condom accounted for 94.5% (2418/2558). The proportion of the index partners' most recently CD4 cell count less than 200 cells per µl was 17.4% (437/2505). Results from multivariate of Cox regression showed that male negative partners (RR = 1.58, 95%CI: 1.02 - 2.43), negative partners with lower education level(RR = 2.77, 95%CI: 1.68 - 4.57), having sexual activity in latest one year(RR = 4.39, 95%CI: 1.53 - 12.56) and CD4 count less than 200 cells per µl (RR = 2.36, 95%CI: 1.42 - 3.93) were associated with increased risk of HIV sero-conversion, while intercourse frequency less than 4 times per month(RR = 0.18, 95%CI: 0.10 - 0.32), consistent using of condom(RR = 0.07, 95%CI: 0.05 - 0.12) decreased the risk of conversion.

CONCLUSIONIn this city, the conversion rate of negative partners whose positive partner infected via former plasma donation or blood transfusion is relatively low and behave a downward trend. Serologic surveillance, education and intervention based on couple are needed to be enhanced.