Graph SHCS
» Evolution of recruitment
» Current status
In the following section, descriptive statistics of the population recruited and still participating in the SHCS are presented. This information is part of a more general and on-going effort to provide regular feed back to participating centers and clinicians on the evolution of the SHCS population.
Evolution of recruitment
The Swiss HIV Cohort Study (SHCS) is a large cohort study enrolling patients prospectively since 1988. Some data going back to 1981 have been collected retrospectively. As of May 2011, a total of 16'832 persons have been enrolled in the SHCS. Since 1997, the annual number of newly registered patients has been decreasing from 834 in 1997 to about 500 in 2002 and has slightly increased afterwards until 2009 (Figure 1). The largest proportion of patients were recruited in Zurich (37.7%) (Figure 2).
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 Figure 2 |
A unique feature of the SHCS is the large proportion of women (30% of women followed up in 2010) and the fact that the main three transmission groups IDU (Intravenous Drug User), MSM (Men having Sex with Men) and HET (heterosexual contacts) are well represented. Among patients belonging to the transmission group IDU we further distinguish patients where the most probable cause of infection was intravenous drug use from those where the transmission might have occurred sexually. The originality of this representation remains over time as indicated in Figures 3 and 4. In 2010, the two main transmission groups of patients newly registered in the SHCS were HET patients 35.1% (183/522) and MSM patients 54.4% (284/522).
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 Figure 4 |
The mean age of patients at the time of registration has increased over the years : for males, it was 34 in 1990 and 40 in 2010; for females, it was 30 in 1990 and 40 in 2010 (Figure 5). Figure 6 indicates that the median CD4 cell count at the time of registration, first decreased over time for both sex until 1995, then increased up to nowadays though with some fluctuations.
 Figure 5 |
 Figure 6 |
With the advent of combined Antiretroviral Therapy (cART) in 1995-1996 and the hope to eradicate the virus by early treatment, the median CD4 cell count at the initiation of the therapy raised very rapidly. However, due to the likely impossibility to eradicate completely the virus we observed a down-turn in the curve indicating that the guidelines for initiating a treatment evolved toward lower values of the CD4. Noteworthy, however, is that since 2002 an up-turn of the curve is generally observed with cART therapy started at higher levels of CD4, particularly regarding MSM (Figure 7). Mortality has substantially decreased since cART became available in 1996 and is still steadily decreasing (Figure 8).
 Figure 7 |
 Figure 8 |
Since the inception of the SHCS (in 1988), 30.6% (5'157) of study participants died, and 4'256 (25.3%) were reported lost from follow-up (drop-outs), because they did not answer, left the country or did not want to participate any more in the study. Among the patients who dropped out 629 were eventually reported to have died. The number of patients currently followed up in the SHCS is 8’120, whereas this number was 6’393 in 2005 (Figure 9).
With an average of 1.74 follow-up visits per patient in 2010, the evolution of the number of patients’ visits paralleled well with the number of patients followed up each year (Figures 9 and 10). The number of patients followed up by other outpatient clinics (e.g. Bienne, Burgdorf, Neuchâtel, etc.) and by private practitioners increased the last few years.
 Figure 9 |
 Figure 10 |
Current status
In Geneva, for example, over 60% of participating patients were under the care of private physicians during the year 2010, whereas this figure was less than 20% for Bern (Figure 11).
The presumed mode of HIV acquisition of patients currently followed is depicted according to gender in Figure 12 (males) and Figure 13 (females), as well as by clinical center in Figure 14. The majority of persons active in the SHCS acquired infection sexually (at least 80%).
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 Figure 12 |
 Figure 13 |
 Figure 14 |
Figure 15 illustrates the increasing use of multiple (i.e. triple or more than 3 drugs) combinations therapies in the SHCS. The proportion of non treated patients has continuously decreased the last few years and amounts, currently, to approximately 10%.
As of July 2010, more than 85% of the patients were receiving at least three drugs (Figure 16).
 Figure 15 |
 Figure 16 |
Figure 17 depicts the situation of treatment status according to the CD4 cell count and by presumed mode of HIV acquisition. The proportion of patients with CD4 value below 350 cells/mm3 who have never been treated is relatively small in all risk groups (<3%).
Figure 18 summarizes the complex history of antiretroviral prescriptions in the SHCS.
 Figure 17 |
 Figure 18 |
The last twenty years, the age structure of the cohort has drastically changed as depicted by Figure 19.
The coverage proportion of the SHCS regarding HIV infected patients living in Switzerland is illustrated in Figure 20. We compared the number of patients ever registered in the SHCS with the number of confirmed positive HIV-tests reported by the Federal Office of Public Health (FOPH), as well as the number of patients with a documented AIDS diagnosis in the SHCS with the number of AIDS cases reported by the physicians to the FOPH. We see that compared to HIV infected patients, AIDS patients are better-represented in the SHCS.
 Figure 19 |
 Figure 20 |