Document ID: Mo.C.205
Title: AIDS UNDER-REPORTING MAY DISTORT THE EPIDEMIC: THE QUEBEC
EXPERIENCE
Authors: Remis, Robert S, Meunier L, Vandal AC, Palmer RWH, Desrochers D.
STD/AIDS Prevention and Control
Program, Regional Public Health Department, Montreal, Quebec, Canada
ABSTRACT:
Objectives:
To determine the impact of retrospective active case-finding on trends in AIDS
incidence in Quebec.
Methods:
Based on a study of the completeness of AIDS reporting in 1994, we identified acute care hospitals
with the largest number of previously unreported AIDS cases. Using predictive ICD-9 codes, we
identified and validated the medical files of persons treated at these hospitals from 1983 to 1994.
AIDS cases so identified were compared with cases reported through the passive surveillance
system. AIDS incidence for each risk category adjusted for reporting delays was compared with and
without the cases identified in the active surveillance project.
Results:
Completeness of AIDS reporting in Quebec was 75% (total AIDS cases to end 1995: 3943).
Five hospitals with a high level of under-reporting and a substantial AIDS caseload
were identified, all in Montreal. As a result of case-finding to end 1995 in 3 hospitals,
an additional 285 AIDS cases were identified; 133 cases had been previously reported by
these hospitals. The distribution of risk category for the active cases differed from that
of passive cases: 27.7% were among persons born in HIV endemic countries (PHEC) compared
to 9.4% for the passive cases (p<10-6); for injection drug users, it was 7.0% versus 3.9%
(p=0.02). Relative AIDS incidence in Montreal compared to the rest of Quebec increased from
8.7 to 9.2 with the inclusion of the active cases. Finally, the shape of the AIDS incidence curve
among PHEC changed with the addition of the active cases (see graph).
Conclusions:
In our study, we observed differential under-reporting of AIDS cases, in particular among
persons born in HIV endemic countries and among injection drug users. Under-reporting of
AIDS may not only underestimate the magnitude of the HIV epidemic, it may also distort the
trends in AIDS and HIV incidence.
Address:
R.S. Remis, 1616 René-Lévesque ouest, Suite 300A, Montréal, Qc., Canada H3H 1P8
Tel: (514) 932-3305 Fax: (514) 932-1502 E-mail: md22@musica.mcgill.ca
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