Finding is disheartening

Editor—Sinicco et al reported a worse prognosis for patients who became HIV positive between 1991 and 1995 compared with those who seroconverted before 1991.1 Their findings are unexpected, and caution must be exercised to avoid overinterpreting them in the light of results from several studies, including that by the UK Register of HIV Seroconverters (XI international conference on AIDS, Vancouver, 1996), which have not detected a change in the time from seroconversion to AIDS or death. Indeed, a slight improvement in prognosis was reported in one study from the Netherlands of homosexual men who seroconverted between 1985 and 1993.2 Encouraging results from clinical trials suggest that the use of dual antiretroviral treatment, which began in the mid-1990s, is likely to prolong survival34;depending on the rate of uptake, this would be expected to lead to a better prognosis in the more recent time periods. Further improvements are anticipated with increasing use of drug regimens that include two nucleoside analogues and a protease inhibitor.

Although data on CD4 cell count, which were much used by Sinicco et al, are useful markers of progression of disease, they are highly dependent on the frequency of clinical follow up and of the collection of specimens and may be increased temporarily by antiretroviral drugs. Time to death and AIDS are end points independent of the protocol for monitoring the CD4 cell count and bear the most relevance to patients with HIV infection.

Methodological and statistical issues that influence the eligibility criteria for inclusion in a study, such as frequency of attendance and follow up, changes in the rate of loss to follow up over time, as well as the possibility of preferentially including patients whose disease progressed rapidly in the later time period may wholly or partly explain why Sinicco et …