Cause-specific mortality associated with HIV and HTLV-II infections among injecting drug users in the USA.
BACKGROUND
Human T-lymphotropic virus type II (HTLV-II) is widespread among injecting drug users (IDU) and may contribute to the risk of leukemia/lymphoma, neurodegenerative disease, and perhaps pneumonia, especially with HIV co-infection.


METHODS
In 1987--1991, 6570 IDU were tested for HIV and HTLV-II antibodies. In 1998, they were matched to the National Death Index. Numbers of observed deaths of each cause were compared by standardized mortality ratios with the numbers expected, using sex-, race-, age-, and year-specific rates in the general population. Relative risk (RR) associated with each virus, compared to uninfected drug users, was estimated by Poisson modeling.


RESULTS
There were 1351 deaths, including 683 (15%) of 4604 participants who enrolled seronegative for both viruses; 328 (47%) of 701 who had HIV but not HTLV-II infection; 220 (21%) of 1033 who had HTLV-II but not HIV infection; and 120 (52%) of 232 who were infected by both viruses. Compared to the general population, mortality for participants with neither virus was increased 4.3-fold [95% confidence interval (CI), 4.0--4.7] and was significantly elevated for virtually every cause of death. With HIV, mortality from medical causes, but not external causes, was increased 3.7-fold (95% CI, 3.3--4.2), particularly with AIDS and related conditions. With HTLV-II, all-cause mortality was reduced (RR, 0.8; 95% CI, 0.7--0.9), with no statistically significant reduction or elevation for any specific cause. A non-significant excess of tuberculosis deaths (RR, 4.6; 95% CI, 0.8--25.2) was noted with HTLV-II, but there was no excess mortality from leukemia/lymphoma, other malignancies, or neurodegenerative disease.


CONCLUSIONS
Without HIV or HTLV-II, IDU had profoundly increased mortality from medical and external causes. HIV was specifically associated with death due to AIDS and related conditions. HTLV-II infection was not significantly associated with mortality from any cause, suggesting that it is not a significant human pathogen, even when present with HIV infection.
Goedert
J J
JJ
Viral Epidemiology Branch, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA.
Fung
M W
MW
Felton
S
S
Battjes
R J
RJ
Engels
E A
EA
D002423:Cause of Death; D015331:Cohort Studies; D015658:HIV Infections / Q000453:epidemiology / Q000401:mortality*; D015528:HIV Seroprevalence; D015491:HTLV-II Infections / Q000401:mortality*; D006801:Humans; D012307:Risk Factors; D015819:Substance Abuse, Intravenous; D014481:United States / Q000453:epidemiology