From January 1, 1990 to December 31, 2006, 424 clinical AIDS-defining events were diagnosed among 2,121 men during 14,483 person-years of follow-up. Of the AIDS events, 82 were AIDS-defining cancers, of which 64 (79%) were KS, 16 (20%) were NHL and one (1%) was a central nervous system lymphoma. The 343 other AIDS-defining illnesses consisted predominantly of opportunistic infections (n=281, 82%), but also included wasting syndrome (n=46, 13%) and HIV-related dementia (n=16, 5%).
Fifty-one percent of the men were white/non-Hispanic. The median date of seroconversion, age at seroconversion, and years of follow-up time from seroconversion to AIDS or censoring were November 1991 (IQR=June 1988, July 1997), 28 years old (IRQ=23, 34), and 6.6 years (IQR=4.0, 10.5), respectively. MACS participants had an earlier median date of seroconversion, a greater median age at seroconversion, a longer follow-up and a greater proportion of white/non-Hispanic men than the TACC participants. No notable differences were seen between those with AIDS-defining cancers and other AIDS-defining illnesses ().
Descriptive characteristics of seroconverters in the Tri-service AIDS Clinical Consortium and the Multicenter AIDS Cohort Study
Antiretroviral therapy use (no therapy, monotherapy, combination therapy and HAART) among participants from both TACC and MACS is presented in by calendar year, demonstrating the rationale for the definition of the monotherapy/combination therapy calendar period as 1990-95 and the HAART calendar period as ≥1996.
Antiretroviral therapy use by calendar year among participants in the Tri-service AIDS Clinical Consortium and the Multicenter AIDS Cohort Study, 1987-2006.
With the monotherapy/combination therapy calendar period as the referent group, the rates of both AIDS-defining cancers (rate ratio (RR) =0.26; 95% CL 0.15, 0.46) and non-cancer AIDS diagnoses (RR=0.28; 95% CL 0.21, 0.36) were reduced in the HAART calendar period (). HAART, measured by calendar period, was observed to be equally effective at reducing the incidence of both cancer AIDS and non-cancer AIDS (interaction ratio=0.95 (95% CL 0.51, 1.74). Allowing for modification by cohort with the inclusion of an interaction term, the rate ratios for cancer AIDS in the HAART versus monotherapy/combination therapy period were similar in the TACC (RR=0.27) and MACS (RR=0.24) studies; likewise, the rate ratios for non-cancer AIDS in the HAART versus monotherapy/combination therapy period were similar in the TACC (RR=0.29) and MACS (RR=0.25) studies.
Table 2 Rate ratios for AIDS-defining cancer and other AIDS-defining events in the HAART versus the monotherapy/combination therapy eras, and the interaction ratio between HAART and type of AIDS event among 2,121 male seroconverters in the Tri-service AIDS Clinical (more ...)
It may not be reasonable to assume the effect of HAART on preventing AIDS begins immediately at HAART initiation, or at the beginning of the HAART calendar period (i.e. 1996), particularly for KS or NHL, which may have long latency periods. We therefore assessed the sensitivity of the results to the calendar period definition, using lag periods of one, two and three years for each calendar period (i.e. monotherapy/combination therapy period redefined as ≥1991, ≥1992 and ≥1993 and HAART calendar period redefined as ≥1997, ≥1998 and ≥1999, respectively). Of the 24 AIDS-defining cancers in the HAART calendar period, 8 occurred in 1996-98, 8 occurred in 1999-2002 and 7 occurred in 2003-2006. With a one-year lag period, rate ratios of 0.23 (95% CL 0.12, 0.42) and 0.23 (95% CL 0.17, 0.30) were observed for AIDS-defining cancers and other AIDS-defining events, respectively (interaction ratio=1.00 (95% CL 0.51, 1.97). With a two-year lag period, rate ratios of 0.24 (95% CL 0.13, 0.45) and 0.22 (95% CL 0.16, 0.31) were observed for AIDS-defining cancers and other AIDS-defining events, respectively (interaction ratio=1.10 (95% CL 0.55, 2.19). With a three-year lag period, rate ratios of 0.29 (95% CL 0.15, 0.55) and 0.23 (95% CL 0.16, 0.33) were observed for AIDS-defining cancers and other AIDS-defining events, respectively (interaction ratio=1.26 (95% CL 0.61, 2.58).