The hospitalisation rate in people who were undetectable on ART
was 10.5 per 100 patient-years. In elite controllers it was 22.3 per 100 patient-years. Even people with detectable viral loads had lower rates of hospitalisation than ECs: in people with viral loads under 1000
copies/ml it was 12.6 per 100 patient-years and in people with viral loads of 1000 copies/ml or more
it was 16.9 per 100 patient-years.
After adjusting for gender, race and some other variables such
as health insurance status, in multivariate analysis ECs spent 77% more time in
hospital than patients undetectable on ART. The difference between ECs and patients with viral loads over 1000 copies/ml became non-significant, but the cardiovascular disease risk was still raised in ECs compared with patients with detectable HIV.
For some categories of illness, being an elite controller was
an advantage. For instance, 24% of hospital admissions were accounted for by
non-AIDS-defining infections, which would mean things like bacterial sepsis;
but in ECs non-AIDS-defining infections accounted for only 2.7% of admissions.
The researchers comment that the reasons for this are unknown and that more
research is needed to see what immune responses protected against these
However these were more than outweighed by the fact that there
were more than twice as many admissions for cardiovascular disease (CVD) in ECs
than there were in other patients: CVD
admissions accounted for 31% of the total in ECs compared with 13.5% in other
In multivariate analysis, the risk of admission for CVD was 3.2 times
greater in ECs than in people with undetectable viral loads on ART, 2.9 times greater than in people with viral loads between 50 and 1000 copies/ml, and 2.7 times greater than in people with viral loads of 1000 copies/ml or more.
It was already known that ECs have higher levels of certain
inflammatory proteins in their blood and more hardening of the arteries, so the
finding of more CVD in ECs at least had a mechanism to explain it.
What is less easy to explain is that ECs, in multivariate
analysis, had a nearly four times greater rate of admission for psychiatric
conditions than patients undetectable on ART.
In an editorial comment on the study, Maile Karris and Richard
Haubrich of the University of California, San Diego speculate that the same inflammatory
processes that cause CVD could also cause inflammation in the central nervous
system; the fact that the psychiatric admission rate in people was three times
higher in people with viral loads over 1000 copies/ml than people on ART with undetectable viral loads could also support this
idea. But this is just a hypothesis, and Karris and Haubrich point out that other
possible causes of psychiatric illnesses, such as drug use and psychiatric history, were not controlled for.
It also initially looked as if admissions for lung disease were higher
in ECs, with 22% of admissions in ECs for pulmonary conditions compared with
4.8% overall. However the researchers found that one particular EC patient had
had 21 admissions for asthma and chronic obstructive pulmonary disease (COPD)
during the study. If this patient was excluded, the rate of admission for pulmonary
disease was similar in ECs to other patients. Omitting this patient also reduced
the 77% higher rate of admissions in general in ECs down to 56% higher, though
this was still significant, and the higher rate of CVD in ECs was unaffected.