M. T. Schechter

Lower socioeconomic status and shorter survival following HIV infection

We studied the association between socioeconomic status and survival in a prospective study of 364 HIV-infected homosexual men who were recruited during 1982-84. The participants were divided by annual income; those earning above Canadian

Rectal gonorrhoea as an independent risk factor for HIV infection in a cohort of homosexual men.

10,000 (high-income; n = 274) and those below

Progression to AIDS and predictors of AIDS in seroprevalent and seroincident cohorts of homosexual men.

10,000 (low-income; n = 90) at recruitment. The latter threshold closely approximated to the poverty level for this population. Low income men were significantly younger than high income men but the groups were similar with respect to baseline CD4 counts, subsequent use of anti-retrovirals and prophylaxis against Pneumocystis carinii pneumonia (PCP), and number of visits attended during follow-up. Subjects were followed for a median of 9.5 years (range 1.8-13.1). By Dec 31, 1993, there were 135 deaths yielding a cumulative mortality rate of mean 45% (SD 4.0) at 11.5 years. Men aged 30 or more at infection had poorer survival than those under 30 (mortality risk ratio 1.56; 95% CI 1.09-2.24; p = 0.015), and longer survival was significantly associated with a higher CD4 count at the earliest seropositive visit. The age-adjusted mortality risk ratio for low income men compared with high income men was significantly increased at 1.63 (95% CI 1.11-2.40; p = 0.013). The significant risk of death for low income men persisted despite adjustment for age at infection, CD4 count, use of zidovudine, dideoxyinosine, and dideoxycytidine, use of PCP prophylaxis, and year of infection. We cannot attribute our findings to income loss as a result of more rapid HIV progression because the same effect was present in people who provided income data before seroconversion. Similarly, our findings are not due to differential access to care because the study was done within the context of a universal health care system, and the two income groups received treatments equally. This finding is consistent with the association of lower socioeconomic status with increased morbidity and mortality observed within large populations and in other diseases.

The changing spectrum of AIDS index diseases in Canada

OBJECTIVE--To determine whether certain sexually transmitted diseases are independent risk factors for HIV transmission in a cohort of homosexual men. METHODS--Eligible cases were identified as those who had seroconverted between November 1982 and November 1990. Two persistently HIV-seronegative control participants were randomly selected for each case from all participants who remained seronegative in November 1990. For cases, risk factor data were taken from an index visit which was defined as the first seropositive visit, while for controls these data were obtained from a matched visit which occurred within two months of the index visit for the corresponding case. Mantel-Haenszel methods and logistic regression were used to compare differences in risk factors for seroconversion between cases and controls. RESULTS--A total of 125 cases and 250 controls were eligible for this study. Cases were significantly more likely to have had reported any gonorrhoea (17% versus 6%; OR = 2.94; 95% CI: 1.51-5.73) or syphilis (7% versus 2%; OR = 3.78; 95% CI: 1.33-10.79) than controls during the seroconversion period. Multivariate logistic regression revealed rectal gonorrhoea to be independently associated with risk of seroconversion (odds ratio = 3.18; p = 0.044), whereas urethral gonorrhoea (p = 0.479) and pharyngeal gonorrhoea (p = 0.434) were not after inclusion of rectal gonorrhoea. In addition, the following variables were also shown to exert an independent effect on seroconversion: frequency of anal intercourse, use of illicit drugs, number of male sexual partners, and lack of a post-secondary education. CONCLUSIONS--In this observational study, rectal gonorrhoea was found to be associated with HIV seroconversion after adjustment for a number of HIV risk factors. We cannot rule out that rectal gonorrhoea was not directly associated with HIV infection but rather with other residual lifestyle factors not fully adjusted for in the analysis. However, the relationship with gonococcal involvement of a specific anatomic site lends support to a biological association between gonorrhoea and HIV infection, rather than to alternative non-biologic explanations. Our findings are consistent with previous studies reporting an association between HIV infection and non-ulcerative sexually transmitted diseases. Such a direct association might be explained by postulating that gonorrhoea results in inflamed rectal mucosa and compromised epithelial integrity, thereby predisposing an individual to subsequent HIV infection.

HIV-1 and the aetiology of AIDS

As part of an ongoing prospective study of seropositive homosexual men in Vancouver, Canada, a seroprevalent cohort of 246 subjects (i.e. duration of infection unknown) and a seroincident cohort of 102 subjects (i.e. duration of infection known) were followed a median of 63 and 45 months, respectively. Follow-up with validation utilizing record linkage with the Canadian Federal Centre for AIDS registry revealed 58 and nine cases of AIDS in the seroprevalent and seroincident cohorts, respectively, through July 1988. These data yield product limit estimates of the cumulative progression rates to AIDS at 60 months of 23.0% for the seroprevalent cohort, 13.0% for the seroincident cohort, and 21.0% for the combined groups. Univariate analyses revealed the following to be statistically and clinically significant predictors of AIDS progression: low CD4 counts, low CD4/CD8 ratios, elevated immune complexes, elevated immunoglobulin G (IgG) and immunoglobulin A (IgA) levels, and low platelet counts. Cox regression revealed that elevated IgA levels, low CD4 counts, elevated immune complexes, two or more symptoms, and more than 20 male sexual partners in high-risk areas in the 5 years prior to enrollment were independent predictors of progression to AIDS over the subsequent 5 years. A multivariate risk function based on the latter five variables delineated low-, medium- and high-risk groups whose 5-year progression rates to AIDS were 6.7, 15.6 and 64.4%, respectively. The high-risk group contained 75% of all subjects who progressed to AIDS. Only 6% of the high-risk group would have qualified for zidovudine therapy under current guidelines at the beginning of the observation period.(ABSTRACT TRUNCATED AT 250 WORDS)

BOOSTER IMMUNISATION FOR DIPHTHERIA AND TETANUS: NO EVIDENCE OF NEED IN ADULTS

ObjectiveTo describe the changing spectrum of AIDS index diseases in Canada over a 10-year period from 1981 to 1991. DesignA descriptive, population-based study. SettingCanada. PatientsAll cases of AIDS in Canada reported by the Division of HIV/AIDS Epidemiology of the Department of National Health and Welfare. Main outcome measuresAge-standardized rates of initial AIDS manifestations (1987 Centers for Disease Control and Prevention case definition), by year of diagnosis among adults in Canada. ResultsA total of 6641 adult AIDS cases were examined. The rate of Pneumocystis carinii pneumonia (PCP) peaked in 1989 with a rate of 3.18 per 100000, declining to 2.74 per 100000 in 1991 (P= 0.894). Similarly, the rate of Kaposis sarcoma (KS) stabilized during this interval from 1.06 per 100 000 in 1987 to 1.14 per 100000 in 1991 (P=0.189). In contrast, the rates of all other AIDS-defining illnesses increased from 1.48 per 100 000 in 1987 to 3.43 per 100000 in 1991 (P= 0.001). For these other AIDS index diseases, significant rate increases were observed for esophageal candidiasis, cytomegalovirus (CMV) diseases, wasting syndrome, toxoplasmosis, and Mycobacterium avium complex (MAC) disease. ConclusionsOur study shows a leveling and decline in incidence of KS and PCP, respectively, and a concomitant increase of other diagnoses, especially esophageal candidiasis, CMV, wasting syndrome, toxoplasmosis, and MAC disease in Canada. These findings highlight the importance of developing specific strategies to prevent emerging AIDS index diseases and serve as a cautionary note to practicing clinicians, indicating the relative widening of the spectrum of HIV index diseases.

INDIRECT COSTS OF HIV/AIDS MORTALITY IN CANADA

The belief that HIV-1 infection causes AIDs has been questioned, and the suggestion made that to know the correct cause of AIDS the incidence of disease in patients with and without risk behaviours and with and without antibody to HIV-1 must be known. We describe findings in such a cohort. In 715 homosexual men followed for a median of 8.6 years, all 136 AIDS cases occurred in the 365 individuals with pre-existing HIV-1 antibody. Most men negative for HIV-1 antibody reported risk behaviours but none developed any AIDS illnesses. CD4 counts fell in anti-HIV-1-positive men but remained stable in antibody-negative men, whether or not risk behaviours were present. The hypothesis that AIDS in homosexual men is caused not by HIV-1 infection but by drugs and sexual activity is rejected by these data. HIV-1 has an integral role in the pathogenesis of AIDS.

Increasing age is associated with faster progression to neoplasms but not opportunistic infections in HIV-infected homosexual men.

Recommendations to give adults diphtheria and tetanus toxoid every ten years have been based on serological surveys that have shown lower antibody levels in older populations. The purpose of an immunisation programme, however, is to prevent disease and not merely to produce antibodies. In Canada, although an immunisation programme against diphtheria has been in operation for nearly sixty years, age-specific morbidity and mortality rates for diphtheria do not show an increase with age. Similarly, age-specific death rates from tetanus do not show any increase. From Canadian surveillance data, there is no evidence to suggest that people are leaving the immune pool and entering the susceptible pool. Immunisation programmes do not need to include routine administration of booster doses of diphtheria and tetanus toxoids to adults since the benefits of the procedure do not justify the risks or costs. Continuing case-surveillance will bring to light any increase in incidence of disease justifying a need for an adult programme.

The effect of cigarette smoking on lymphocyte subsets and progression to AIDS in a cohort of homosexual men

ObjectiveTo estimate and compare the societal impact of HIV infection and AIDS with other selected causes of male mortality in terms of the indirect costs of future production lost. DesignDescriptive, population-based economic evaluation study. PatientsAll men aged 25–64 years for whom HIV/AIDS or another selected disease was listed as the underlying cause of death in Canada from 1987 to 1991, as reported to Statistics Canada. SettingCanada. Main outcome measuresPresent value of future earnings lost for men using a human capital approach based on potential years of life lost in men aged 25–64 years. ResultsAssuming a 2% annual growth in earnings and a 3% annual real discount rate, the present value of the total loss of future production for all men aged 25–64 years who died in Canada during 1987–1991 was estimated to be 39.74 billion 1990 US. Deaths due to HIV/AIDS accounted for 5.3% of this total loss or 2.11 billion in 1990 US

The Vancouver Lymphadenopathy-AIDS Study: 6. HIV seroconversion in a cohort of homosexual men

. Future production loss due to HIV/AIDS more than doubled during the period from 1987 to 1991, from 0.27 to 0.60 billion 1990 US