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Session 35
Oral Abstracts Infectious Complications: Prevention and Treatment Friday, 10 am - 12:30 pm Presentation Time: 10:45 am Ballroom A |
Background: The risk of
invasive pneumococcal disease (IPD) has been estimated to be more than 10 times
higher in HIV-infected individuals than in the general population. However,
little is known about the risk factors for IPD, or whether IPD incidence has
changed with the advent of HAART.
Methods: Episodes of IPD,
defined as recovery of S. pneumoniae
from a blood culture, were prospectively recorded in the Johns Hopkins HIV
Cohort since inception in 1990. The incidences of IPD in calendar periods that
correlated with the availability of increasingly potent ART were calculated as
events per 100,000 person-years. Risk factors for IPD were assessed with a
nested case-control design, in which 4 controls were selected for each case, using
conditional logistic regression and odds ratios (OR).
Results: During 19,022 person-years of observation, 72
episodes of IPD occurred in 67 individuals, for an overall rate of 379 cases
per 100,000 person-years. The incidence of IPD increased slightly (P=NS)
as increasingly potent ART became available (see the table). In a multivariate
model, factors significantly associated with IPD included having a CD4 < 200
cells/mm3 (OR 2.6), and having an HIV RNA > 50,000 copies/mL (OR 3.3 in the subset followed after this assay was adopted
into clinical practice). Interestingly, injection drug use was a strong risk
factor for IPD in women (OR 4.8, 95% CI 1.7 to 13.3), but not in men (OR 1.1,
95% CI 0.5 to 2.5; p = 0.023 for
interaction term). Age, use of HAART, and use of prophylaxis with
sulfasoxazole-trimethoprim or a macrolide were not significantly associated
with IPD risk.
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Pneumococcemia in HIV-infected individuals in different calendar periods |
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Calendar period |
Events (n) |
Observation time (person-years) |
Rate [events/100,000 person-years] (95% CI) |
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1990–1995 |
10 |
3581 |
279 (150–519) |
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1995–1998 |
15 |
3983 |
377 (227–625) |
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1998–2004 |
47 |
11,458 |
410 (308–546) |
Conclusions: IPD is a
common event, occurring in approximately 4 per 1000 HIV-infected individuals
annually. Despite being correlated with immunologic and virologic factors,
there is no evidence that widespread adoption of HAART has led to declines in
IPD. In fact, a trend to the contrary was observed, suggesting that modest
immune suppression leaves HIV-infected individuals susceptible to IPD.
Keywords: Invasive pneumococcal disease; S. pneumoniae; HAART
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