Bourne, David

English

South African Medical Journal (SAMJ)

December 2003, Vol. 93, No. 12  SAMJEDITORIALThe current HIV/AIDS pandemic is the worst plague ever toafflict humanity, and unfortunately it is at its most severe insouthern Africa. Approximately 5 million people are currentlyinfected in South Africa, and therein lies the rub, for ourestimates are always based on data that contain uncertainties.While the impact on health is undeniably profound, theuncertainties around the statistics create debate. Our main source of data on the epidemic is the annual reportof the Department of Health on HIV prevalence in a sample ofpregnant women attending antenatal clinics in the publicsector.1 This needs to be extrapolated to the general population,and to do this a series of assumptions (that may differ betweendifferent researchers) are needed. Even the population of SouthAfrica is uncertain. While the official population in the 2001census is 44 819 778,2 this figure is of questionable accuracy.There was an undercount of about 1 in 6 of the population,3 soassumptions and statistical models were required to arrive atthe final estimate.In an endeavour to obtain the critically important empiricalinformation on the prevalence of HIV in South Africa, theHuman Sciences Research Council (HSRC) conducted a surveyon the general population of South Africa.14 However, as withall sample surveys, there are still uncertainties which are quitelarge when stratified by age and gender. The HSRC will bedoing a similar survey again next year.In 2001 a group from the University of Cape Town and theMedical Research Council produced a report indicating thatHIV/AIDS had become the leading cause of death in SouthAfrica.5 It  was based on empirical data and demonstrated thattotal mortality had risen dramatically in recent years,particularly among young adults (and especially youngfemales). By a process of elimination, it was concluded thatHIV/AIDS was the major cause of the changing pattern, butthe proportion of AIDS deaths needed to be estimatedindirectly from the model, leaving some uncertainty about thestatistics. This was done using the AIDS and demographicmodel of the Actuarial Society of South Africa (ASSA).5Official mortality statistics for South Africa are several yearsout of date. The latest full published report which has causes ofdeath is for 1996, and a report on a sample of deaths isavailable for 1997 to 2001.6 Again the data are not conclusive. Aperson who is sick with AIDS will often die from anopportunistic coinfection such as pneumonia or tuberculosis,and the HIV status may not be reflected on the deathcertificate. Death certificates explicitly recording HIV as theunderlying condition are very much in the minority.Both the MRC/UCT7 and the HSRC8 groups have producedreports on future projections of the HIV/AIDS epidemic inSouth Africa. While they have utilised different models andhave different numerical estimates, the broad sweep of thenatural course of the epidemic is remarkably similar. Thecourse of the epidemic can best be described as a series ofwaves,9 each with a different time component. The first wave ofthe epidemic, that of incidence or new cases, peaked around1998 and has since declined. The second wave of the epidemic,that of prevalence or the numbers infected with HIV, is peakingaround now, and will drop even if there are no interventions.The third wave of the epidemic is that of deaths, now thedominant phase, which will peak around 2009, and finally thewave of children orphaned by AIDS will peak in around 2015at several millions (the precise figure depends on the definitionadopted).9It is important to understand the natural course of epidemicsand understand the interplay between incidence, deaths andprevalence. It should be noted that the HIV/AIDS epidemic,like any epidemic, will become self-limiting and start todecline, even without intervention. The level at which itstabilises will be influenced by the effectiveness ofinterventions. Too much emphasis on causality should not beplaced on the link between behavioural change and thestabilising of the prevalence; and in the future, on theintroduction of  antiretroviral therapy. Paradoxically asuccessful ART programme would initially lead to a rise in thenumbers of those who are HIV-positive, compared with whatwould otherwise be the case, as death is delayed. Mostimportantly the numbers of orphans will be drastically reducedas the lives of their parents are extended, and many people willhave a longer, healthier life.In order to reduce our future uncertainties regarding thecourse  of the epidemic, we will need to develop newsurveillance tools and data sets as the ART programme isrolled out, such as direct measurement of years of life saved,and more and regular population-based seroprevalencesurveys. Given the health crisis this country faces, there is aspecific obligation that whatever statistical systems aredeveloped the data need to be rapidly available, at the finestlevel compatible with confidentiality, and be subject to criticalevaluation and analysis by all.David BourneSchool of Public Health and Family MedicineUniversity of Cape Town, andBurden of Disease Research UnitMedical Research Council916Whither the AIDS epidemic — or lies, damned lies andstatistics?Editorial Dec   11/25/03  3:15 PM  Page 916EDITORIAL1. Department of Health. Summary Report. National HIV and Syphilis Antenatal SeroprevalenceSurvey in South Africa 2002. Pretoria: Dept of Health, 2003.http://www.doh.gov.za/docs/index.html (accessed 11 Nov 2003).2. Statistics South Africa. Census in Brief. Report 03-03-03. Pretoria: Statistics South Africa, 2003.http://www.statssa.gov.za/Specialprojects/Census2001/Census2001.htm (accessed 11 Nov2003).3. Statistics Council (2003).  Statement by the South African Statistics Council on Census 2001.http://www.statssa.gov.za/Specialprojects/Census2001/HTML/Stats_Council_Statement.pdf(accessed 11 Nov 2003).4. Nelson Mandela/Human Sciences Research Council Study of  HIV/AIDS (2002). SouthAfrican National HIV Prevalence, Behavioural Risks and Mass Media Household Survey 2002. CapeTown: Human Sciences Research Council, 2002.http://www.hsrcpublishers.co.za/index.html?hiv.html~content (accessed 11 Nov 2003).5.  Dorrington R, Bourne D, Bradshaw D, Laubscher R and Timæus IM. The impact of  HIV/AIDSon adult mortality in South Africa (Technical Report). Cape Town: South African MedicalResearch Council, 2001. http://www.mrc.ac.za/bod/bod.htm (accessed 11 Nov 2003).6. Statistics South Africa. Causes of Death in South Africa 1997-2001. Advance Release of RecordedDeaths (P0309.2). Pretoria: Statistics South Africa, 2002.http://www.statssa.gov.za/Archives/ArchivesReleases.htm (accessed 11 Nov 2003).7. Dorrington R, Bradshaw D, Budlender D. HIV/AIDS Profile in the Provinces of South Africa,Indicators for 2002 (Technical Report). Cape Town: Medical Research Council, 2002.http://www.mrc.ac.za/bod/bod.htm (accessed 11 Nov 2003).8. Rehle TM, Shisana O. Epidemiological and demographic HIV/AIDS projections: SouthAfrica. Afr J Aids Res 2003; 2: 1-8.9. Bradshaw D,  Johnson L, Schneider  H, Bourne D, Dorrington R. Orphans of the HIV/AIDSEpidemic — The Time To Act is Now. (MRC  Policy  Brief No 2). Cape Town, Medical ResearchCouncil, 2002.  http://www.mrc.ac.za/bod/bod.htm (accessed 11 Nov 2003).917December 2003, Vol. 93, No. 12  SAMJEditorial Dec   11/25/03  3:15 PM  Page 917

Whither the AIDS epidemic - or lie, damned lies and statistics?

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Whither the AIDS epidemic - or lie, damned lies and statistics?

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South African Medical Journal (SAMJ)