Summary:
Introduction: A great amount of studies involves the comparison between PLHIV according to various characteristics, such as sex, mode of infection and CD4 cell counts at diagnosis. Within this context, the role of migrants consists one of the main priorities. In fact, relatively recently some studies have shown an increased probability of post – migration HIV acquisition. However, this estimate varies by country of origin. Thus, this creates the need for comparison between various characteristics between PLHIV, temporal trends, as well as of the probability of infection in the country of destination by geographical region of origin.
Objective: The comparison of PLHIV in Greece according to clinical and demographic characteristics, temporal trends, as well as the estimation of post – migration HIV acquisition probability by geographical region of origin.
Materials and Methods: Data were derived from the prospective multicentre HIV cohort study AMACS, in which 14 out of the 16 HIV clinics that follow PLHIV in Greece, participate. Last data merger was on 31/12/18. For the first part of the analysis, subjects with diagnosis age of 15 years or above, with first recorded HIV – positive sample after 1/1/1996 and valid CD4 measurements within 3 months of diagnosis were included. For the comparison of CD4 cell counts before ART initiation by region of origin, an adjusted Kaplan – Meier method was used, according which, time to event (i.e. ART initiation) had been replaced by a reversed CD4 scale. For the statistical significance assessment, a logrank test was performed. Additionally, for the investigation of statistical associations between other characteristics and participants region of origin, the Pearson’s X2 test and Kruskal – Wallis test were used (in the case of categorical or continuous variables accordingly). Finally, for changes over time by region of origin, graphical depictions of the relevant distributions were presented. For the second part of the analysis, individuals of non – Greek nationality, with known country entry dates, available values of critical variables for the analysis and diagnosis age of 15 years or above, were included. For the estimation of seroconversion time and the probability of post – migration infection, biomarkers data of HIV progression, such as CD4 and viral load changes over time, as well as information on whether the patient had been diagnosed with clinical AIDS, were combined. CD4 and viral load temporal trajectories had been estimated by bivariate linear mixed models fitted to natural history data. All of the above data were combined using Bayes’ rule in order to extract subject specific posterior distributions of infection times. For the assessment of the probability of post – migration HIV acquisition risk factors, a logistic regression analysis was fitted combined with a multiple imputation approach using Rubin’s rules.
Results: For the sample of the 7335 individuals that were included in the first part of the analysis, statistically significant relationships were observed between region of origin and sex, mode of infection, late presentation, advanced disease, diagnosis year, loss to follow – up, AIDS status at diagnosis, CD4 measurement at diagnosis, as well as CD4 value at ART initiation (P value < 0.001). Mode of infection that dominates among Greek and Western Europeans is through sexual contact between men (above 60%). On the contrary, the prevalent route of transmission for Asians and Africans is through heterosexual contact, for the last being above 80%. Whereas within all origin groups, rates for men were higher versus women, within Africans, the proportion of women that live with the virus is higher than that of men. Also, for subjects of African origin, an increased percentage of PLHIV presented with advanced disease was observed (over 50%). Median CD4 count at ART initiation for Greek participants was 232 cells/μl. For PLHIV from Western and Central Europe accordingly it was 245 cells/μl, while the rest geographical groups tended to initiate therapy after their CD4 levels dropped below 200 cells/μl (P value < 0.001).
From the sample of 221 subjects of non – Greek nationality with known country entry dates that contributed in the second part of the analysis, the highest percentage was originated from South and Eastern Europe (41.2%). In addition to this, the highest percentage seemed to have been infected through heterosexual contact (44.3%). Median length of stay in Greece was 13 years (IQR: 5 – 21). Differences by diagnosis year were observed for sex, diagnosis age and educational level (P value < 0.05), as well as for mode of infection (P value < 0.01). Overall, post – migration infection probability differed significantly by region of origin (P value < 0.001), and, that significance remained (P = 0.005), after adjusting for sex, transmission mode and age at arrival. The longer the length of stay in the destination country, the highest the risk of acquiring the infection after migration. On the other hand, the younger the age at arrival, the highest the post – migration HIV acquisition risk. Overall probability of infection after migration was estimated at 51% (95% CI: 43% - 59%). For Europeans from North and Western Europe the estimated post – migration probability of infection was 56% (26%, 82%), whereas for Asia and Africa (or other origin), the same probability and the corresponding 95%CI were accordingly at 54%(39%,68%) and 22%(12%,38%). Finally, for South and Eastern Europe the corresponding estimates were 65%(54%,76%). For IDU were 60%(36%,80%), for women MSW 39%(26%,55%), and for men MSW higher and equal to 60%(41%,76%). Lastly, for MSM the estimate was 50%(37%,63%). Mean time from infection to diagnosis was roughly 4 years, with small variations by geographical origin.
Conclusions: Among PLHIV in Greece, individuals originated from Greece and West and Central Europe tend to initiate therapy before their CD4 cell counts drop to lower levels, in comparison with other geographical groups, such as those of African origin. Also, the increased post – migration HIV acquisition levels in Greece, overall and by region of origin, highlights the necessity for the implementation of appropriate public health strategies. Finally, further investigation regarding the above findings is encouraged.
