Many people have invested millions of hours trying to find a cure for AIDS and it has been discouraging to find each step so difficult. Often the progress described in the scientific literature is masked in lingo and statistics that fail to encourage us as it should; perhaps a picture will help.

Figure I is a bar chart of AIDS survival statistics for King County, Washington. It shows the percentage of those diagnosed in various years who have then survived for varying lengths of time. The presentation is not meant to be rigorous or to identify the mechanisms leading to improved survival. To create it, we counted individuals diagnosed in various years and recorded their status in subsequent years from databases maintained by the Health Department's HIV/AIDS Epidemiology Unit. In total 5089 cases are represented, although the 1983 data represent only eleven individuals. Calendar years - a somewhat gross sieve for estimating annual survival - are used. (Someone diagnosed in December and dying in January is thus counted as surviving a year - but another person diagnosed in January and dying in December of the following is also counted as surviving only one year. The count is long on some and short on others.)

Discussion

The figure shows that only 55% of those diagnosed in 1983 survived for a year or more while over 90% of those diagnosed ten years later now apparently do so. The number of those surviving three or more years beyond diagnosis has increased from about 10% - 60%. Perhaps most encouraging is the final jump in each series of bars. For example, 36% of those diagnosed in 1992 survived after five years compared with only 25% from the 1991 diagnosis class. These increases across the other bars are consistent with the dramatic drop in deaths in 1996 compared with previous years. This drop was 43% from 1995 for King County and was announced in February (Seattle-King County, 1997.) Similar significant drops were also announced at about the same time for New York.

Protease inhibitors will hopefully prolong these trends although the recent drops in death rate had began last year before these new drugs became readily available. A number of other medical improvements over the years are significant factors leading to the results shown in Figure 1. Complicating factors in understanding AIDS survival include continually changing definitions of the disease itself. The survival literature attempts to explain some of these impacts.

Lemp et al. (1990) reported a five year survival rate of only 3.4% of 4300 early San Fransisco cases and significantly improved survival especially in those diagnosed with PCP. They also found in the 1986-87 era that over 50% of those not receiving AZT as compared to ~80% of those receiving it survived beyond a year. Median survival for patients included in their study was only 12.5 months.

Lafferty et al. (1991) reported similar median survival in the state of Washington but then found it to have risen to about 20 months by 1987-89.

Blum et al. (1994) discussed survival in New York City after examining some 23,000 cases through mid 1989. They reported 55% for 12 months or longer and 23% survival for 36 months or longer. They suggested that the higher proportion of white MSM (men who have sex with men) cases in Western States may partly explain higher survival than was found in New York. They further tried to examine the effect of the late 1987 change in the definition of AIDS and found it to have reduced survival because only those meeting the new definition had a higher percentage of first diagnosis dementia or wasting, both of which have short survival and were not included in the prior definition.

Osmond et al. (1994) studied a smaller group of San Francisco patients. They reported 55-68% survival for a year or more using the 1987 clinical diagnosis criteria but 90+% using a 200 CD4 count criterion with some variation but no clear trend over the years from 1983-93. For survival of three years or more they reported 7-15% using clinical criteria and 40-57% with the CD4 criterion. They concluded that the increased survival observed most likely results from PCP prophylaxis and treatment than from antiretroviral therapy.

Vella et al. (1994) attempted to further examine the effect of the changing AIDS case definition considering 3500 Italian patients enrolled from 1987-91 in their study. They showed survival for a year or more to be about 73% using the earlier definition and about 88% with the later definition. Those surviving five or more years increased from approximately 25% to 50%. The new 1993 definition increased the number of AIDS cases in their population by 188%.

Finally, Chaisson et al. (1995) sought survival differences among 1370 HIV+ patients treated at a single urban center, the Johns Hopkins HIV Clinic, from 1989-94. They found no survival differences due to sex, race, injection-drug use, or socio-economic status. Greater survival did result for those using PCP prophylaxis, those using AZT after enrollment (but not before), and those employed when they enrolled (thought to be in better health.) They believe that AZT use before enrollment had a negative effect on survival because of the limited duration of the efficacy of antiretroviral therapy and the fact that these patients had received the benefit before enrolling. Of the demographic variables examined, only age appeared related to survival (negatively), and they concluded that other demographic differences that have been observed in other papers are probably explained by access to adequate medical care. Of those enrolled with CD4 counts of less than 200, 70-85% survived for a year or more while 15-27% survived for three or more years. CD4 count was the most important predictor of survival in their study, as other studies have also found. For those entering the study with counts above 200, about 90-97% survived for a year or more while 75-90% survived for three or more years.

All of these factors, and perhaps others not yet understood, affect the bars of the figure. Gross though it may be, it seems an interesting chart, and an optimistic view of the progress that has been made so far in the medical fight against AIDS.

Ken Fowler, PhD., is a member of STEP's Scientific Review Committee

References:

Blum S. Tejinder PS, Gibbons J, Fordyce EJ, Lessner L, Chiasson MA, Weisfuse IB, Thomas PA. "Trends in Survival among Persons with AIDS in New York City", Am J Epidemiol 1994 Feb 15;139(4):351-61.

Chaisson RE, Keruly JC, Moore RD. "Race, Sex, Drug Use, and Progression of HIV Disease", N Engl J Med 1995 Sep 21;333(12):751-6.

Lafferty WE, Glidden D, Hopkins SG. "Survival Trends of People with AIDS in Washington State", Am J Public Health 1991 Feb;81(2):217-9.

Lemp GF, Payne SF, Neal D, Temelsco T, Rutherford GW. "Survival Trends for Patients with AIDS", JAMA 1990 Jan 19;263(3):402-6.

Osmond D, Charlebois E, Lang W, Shiboski S, Moss A. "Changes in AIDS Survival Time in Two San Francisco Cohorts of Homosexual Men, 1983 to 1993", JAMA 1994 Apr 13;271(14):1083-7. Published erratum appears in JAMA 1996 Nov 13;276(18):1472.

Seattle-King County Dept. of Public Health, AIDS Sentinel Newsletter, 1997; 8 (1): 1.

Vella S, Chiesi A, Volpi A, Giuliano M, Florida M, Daily LG, Binkin N. "Differential Survival of Patients with AIDS According to the 1987 and 1993 CDC Case Definitions", JAMA 1994 Apr 20;271(15):1197-9.

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