Declines in Mortality Rates and Changes in Causes of Death in HIV-1-Infected Children During the HAART Era
J Acquir Immune Defic Syndr. 2010 Jan;53(1):86-94.
Brady MT, Oleske JM, Williams PL, Elgie C, Mofenson LM, Dankner WM, Van Dyke RB; for the Pediatric AIDS Clinical Trials Group219/219C Team.
CONTEXT: Introduction of highly active antiretroviral therapy has significantly decreased mortality in HIV-1-infected adults and children. Although an increase in non-HIV-related mortality has been noted in adults, data in children are limited.
OBJECTIVES:: To evaluate changes in causes and risk factors for death among HIV-1-infected children in Pediatric AIDS Clinical Trials Group 219/219C.
DESIGN, SETTING, AND PARTICIPANTS:: Multicenter, prospective cohort study designed to evaluate long-term outcomes in HIV-1-exposed and infected US children. There were 3553 HIV-1-infected children enrolled and followed up between April 1993 and December 2006, with primary cause of mortality identified in the 298 observed deaths.
MAIN OUTCOME MEASURES:: Mortality rates per 100 child-years overall and by demographic factors; survival estimates by birth cohort; and hazard ratios for mortality by various demographic, health, and antiretroviral treatment factors were determined.
RESULTS:: Among 3553 HIV-1-infected children followed up for a median of 5.3 years, 298 deaths occurred. Death rates significantly decreased between 1994 and 2000, from 7.2 to 0.8 per 100 person-years, and remained relatively stable through 2006. After adjustment for other covariates, increased risk of death was identified for those with low CD4 and AIDS-defining illness at entry. Decreased risks of mortality were identified for later birth cohorts, and for time-dependent initiation of highly active antiretroviral therapy (hazard ratio 0.54, P < 0.001). The most common causes of death were "End-stage AIDS" (N = 48, 16%) and pneumonia (N = 41, 14%). The proportion of deaths due to opportunistic infections (OIs) declined from 37% in 1994-1996 to 24% after 2000. All OI mortality declined during the study period. However, a greater decline was noted for deaths due to Mycobacterium avium complex and cryptosporidium. Deaths from "End-stage AIDS," sepsis and renal failure increased.
CONCLUSIONS:: Overall death rates declined from 1993 to 2000 but have since stabilized at rates about 30 times higher than for the general US pediatric population. Deaths due to OIs have declined, but non-AIDS-defining infections and multiorgan failure remain major causes of mortality in HIV-1-infected children.
Science 11 December 2009: Vol. 326. no. 5959, pp. 1476 - 1477
Dozens of studies have been examining people who fend off HIV despite repeated exposures in an effort to find genetic or immunologic factors that can help guide AIDS vaccine research. But all too often the leads point in contradictory directions, in part because investigators use different assays to probe their samples, and there is little coordination among them. Many labs also use wildly varying criteria to decide who qualifies as HIV-resistant, making it difficult to sort out which study subjects were truly exposed and uninfected, were exposed and have an occult infection, or were never exposed in the first place. At the first-ever meeting on natural immunity to HIV, held from 15 to 17 November, researchers attempted to hammer out these and other issues.
AIDS. 2010 Jan 2;24(1):123-37.
OBJECTIVE: To estimate the effect of combined antiretroviral therapy (cART) on mortality among HIV-infected individuals after appropriate adjustment for time-varying confounding by indication. DESIGN: A collaboration of 12 prospective cohort studies from Europe and the United States (the HIV-CAUSAL Collaboration) that includes 62 760 HIV-infected, therapy-naive individuals followed for an average of 3.3 years. Inverse probability weighting of marginal structural models was used to adjust for measured confounding by indication. RESULTS: Two thousand and thirty-nine individuals died during the follow-up. The mortality hazard ratio was 0.48 (95% confidence interval 0.41-0.57) for cART initiation versus no initiation. In analyses stratified by CD4 cell count at baseline, the corresponding hazard ratios were 0.29 (0.22-0.37) for less than 100 cells/microl, 0.33 (0.25-0.44) for 100 to less than 200 cells/microl, 0.38 (0.28-0.52) for 200 to less than 350 cells/microl, 0.55 (0.41-0.74) for 350 to less than 500 cells/microl, and 0.77 (0.58-1.01) for 500 cells/microl or more. The estimated hazard ratio varied with years since initiation of cART from 0.57 (0.49-0.67) for less than 1 year since initiation to 0.21 (0.14-0.31) for 5 years or more (P value for trend <0.001). CONCLUSION: We estimated that cART halved the average mortality rate in HIV-infected individuals. The mortality reduction was greater in those with worse prognosis at the start of follow-up.
Survival of Children with HIV in the United States Has Improved Dramatically Since 1990s, New Analysis Shows
Mortality Rate Still Higher Than for Children without HIV
The death rates of children with HIV have decreased ninefold since doctors started prescribing cocktails of antiretroviral drugs in the mid-1990s, concludes a large-scale study of the long-term outcomes of children and adolescents with HIV in the United States. In spite of this improvement, however, young people with HIV continue to die at 30 times the rate of youth of similar age who do not have HIV, found researchers from the National Institutes of Health and other institutions.
Earlier studies have shown that adults with HIV are living longer because of improved multi-drug antiretroviral regimens known as highly active antiretroviral therapy (HAART). However, limited information has existed about the effectiveness of HAART in improving the survival of children with HIV. The current analysis, published in the Dec. 15 issue of the Journal of Acquired Immune Deficiency Syndromes, delineates the effects of HAART on the rates and causes of death for HIV-infected children and adolescents. Read more »
Six-month gain in weight, height, and CD4 predict subsequent antiretroviral treatment responses in HIV-infected South African children
AIDS. 2010 Jan 2;24(1):139-46.
Yotebieng M, Van Rie A, Moultrie H, Meyers T.
OBJECTIVES: Construct percentile curves for 6-month gain in weight, height, CD4 cell count, and CD4 percentage (CD4%) in children initiating ART, and to assess the association between lower percentiles and subsequent ART responses. DESIGN: Cohort of 1394 HIV-infected children initiating ART between April 2004 and March 2008, Johannesburg, South Africa METHODS: The generalized additive model for location, scale, and shape was used to construct percentile curves for 6-month gain in weight, height, CD4 cell count, and CD4%. Cox proportional models were used to assess the association between lower percentiles of each distribution and death, virological suppression, and treatment failure between 6 to 36 months post-ART initiation. RESULTS: Lower percentiles for gain in weight, CD4, and CD4% count after 6 months of ART, but not height, were associated with poor subsequent treatment outcomes independent of baseline characteristics, with increasing strength of association as percentiles decreased. Age-specific 6-month post-ART weight gain in our cohort was substantially higher compared with 6-month weight gain in non-HIV-infected American children of the Fels Institute cohort and the attained weight-for-age at 6 months post-ART plotted on WHO weight-for-age growth charts were not associated with subsequent treatment outcomes. CONCLUSION: Gain in CD4% in the first 6 months of ART was the best predictor of poor subsequent ART outcomes. In areas with limited access to CD4%, weight gain post-ART using our newly developed reference distributions for HIV-infected children on ART is a good alternative to CD4%, and clearly superior to the commonly used 'Road-to-Health' weight-for-age charts.
Fact: Studies in vitro, ex vivo and in vivo all support HIV's ability to deplete CD4+ T-cells.
There are some denialists that argue that HIV does exist but that it is merely a harmless passenger virus and that no evidence exists to claim otherwise. In fact, there are thousands of studies that support the cytopathic properties of HIV. While some aspects of how HIV destroys cells that are not fully understood, that it does so it beyond doubt. This is not unique to HIV, of course, as the effects of many diseases are known despite the mechanisms not being completely elucidated. Some of what is known (and supporting evidence will be cited) is the documented here. Since there are literally thousands upon thousands of papers on HIV, a representative few are cited here. This is by no means an exhaustive list.
Evidence shows us that AIDS the CD4+ T-cell depletion is due to HIV. This can be observed 1) in vitro (in cell cultures), 2) ex vivo (in tissues removed from animal models or patients), and 3) in vivo both in animal models and in infected individuals.
A new study has found poorer adherence to antiretroviral therapy among African-American men with HIV who hold conspiracy beliefs, e.g. that HIV is a man-made virus designed to kill Africans.
JAIDS. 2009 Dec 09.
Conspiracy Beliefs About HIV Are Related to Antiretroviral Treatment Nonadherence Among African American Men With HIV
Bogart, Laura M PhD; Wagner, Glenn PhD; Galvan, Frank H PhD; Banks, Denedria MSW
Background: Medical mistrust is prevalent among African Americans and may influence health care behaviors such as treatment adherence. We examined whether a specific form of medical mistrust-HIV conspiracy beliefs (eg, HIV is genocide against African Americans)-was associated with antiretroviral treatment nonadherence among African American men with HIV.
Methods: On baseline surveys, 214 African American men with HIV reported their agreement with 9 conspiracy beliefs, sociodemographic characteristics, depression symptoms, substance use, disease characteristics, medical mistrust, and health care barriers. Antiretroviral medication adherence was monitored electronically for one month postbaseline among 177 men in the baseline sample. Read more »
AIDS. 2010 Jan 2;24(1):123-37.
The effect of combined antiretroviral therapy on the overall mortality of HIV-infected individuals
The HIV-CAUSAL Collaboration
Objective: To estimate the effect of combined antiretroviral therapy (cART) on mortality among HIV-infected individuals after appropriate adjustment for time-varying confounding by indication.
Design: A collaboration of 12 prospective cohort studies from Europe and the United States (the HIV-CAUSAL Collaboration) that includes 62 760 HIV-infected, therapy-naive individuals followed for an average of 3.3 years. Inverse probability weighting of marginal structural models was used to adjust for measured confounding by indication. Read more »
AIDSTruth contributor Nicoli Nattrass writes in AIDS and Behavior:
In his new book, Denying AIDS, Seth Kalichman observes that people are surprised by the persistence of AIDS denialists: “Are they still around?”[1, p. 1] he is often asked. And it is a good question. Given the large body of scientific and clinical evidence on HIV disease and treatment (expertly summarized by Chigwedere and Essex in this issue of AIDS and Behavior) it is indeed strange that Peter Duesberg and his followers still claim HIV is harmless and that antiretrovirals cause rather than treat AIDS. While such dissident views were intellectually respectable in the 1980s when HIV science was new, they make little sense today. Thus Joseph Sonnabend, a doctor who treated some of the earliest AIDS cases in New York and was well known for arguing that environmental factors may be more important than a virus in driving AIDS, was quick to change his mind once antiretroviral treatment was shown to act against HIV and transform the health of his patients [2, p. 25]. Peter Duesberg, by contrast, refused to accept the evidence, thereby earning the label ‘denialist’ rather than ‘dissident’ [1, 2].
The Lancet has hailed the new approach evident in South Africa in which the government has decisively turned away from the AIDS denialism associated with former President Thabo Mbeki.
HIV/AIDS: a new South Africa takes responsibility
On Dec 1 the usual activities surrounding World AIDS Day will take on a special significance for South Africans. In a high-profile event in Pretoria, the South African National AIDS Council (SANAC) is bringing together people who work in HIV/AIDS, those who have been affected by HIV, and government officials, including President Jacob Zuma, Deputy President and SANAC Chair Kgalema Motlanthe, and the Minister of Health Aaron Motsoaledi. Zuma will give a televised address on HIV/AIDS to the nation. Under the motto “I am responsible, we are responsible, South Africa is taking responsibility”, a new era in the country's response to HIV/AIDS is being publicly heralded. In a key-messages booklet, SANAC calls on everyone to know their HIV status by frequent testing; on communities to stop stigma and discrimination against people living with HIV; and on itself to ensure that the government is taking responsibility for people to receive counselling, provide condoms, and give access to treatment for tuberculosis and HIV.
Already on Oct 29, in what has been widely praised as a landmark speech, Zuma left no doubt about the decisive departure from the previous government's stance of denialism and indifference: “South Africa must work harder to implement the national strategy to tackle HIV/AIDS…all South Africans need to know their HIV status and be informed of the treatment options available to them…there should be no shame, no discriminations, and no recriminations”. The non-governmental organisation Treatment Action Campaign called Zuma's speech, which came almost 10 years after Thabo Mbeki made his HIV/AIDS denial clear before the same National Council of Provinces, as “one of the most important speeches in the history of AIDS in South Africa”. Read more »
by George N. Pavlakis, Rockville, MD USA
What do you do about someone who claims to be an expert, serving up half-truths, twisting the facts in credible-sounding sentences and misleading a patient? There must be some rules that apply to someone who professes to be an expert and induces patients to stop their doctor-prescribed medication. These must be applied to prevent harm to more patients. And what if these actions lead to the patient’s death?
Such is the case of Lambros Papantoniou, a journalist living in Washington, a diplomatic correspondent for several Greek media institutions for more than 30 years and a man loved by all who met him. Even in the higher political echelons of Washington, he was affectionately known as “Mr Lambros”.
During a hospital stay approximately ten years ago, Lambros was diagnosed with AIDS and given anti-retroviral therapy. Following this, his interest in the AIDS problem skyrocketed, and he sought information on it. Although he was a diplomatic correspondent, he reported on AIDS issues several times. Read more »
by Nathan Geffen, 1 December 2009
Substantially updated by the author on 7 December 2009
In a piece published in Rapport newspaper and on politicsweb, Rian Malan claims:
[D]on't trust anything the Aids bwanas say - especially not Nathan Geffen of TAC. Earlier this week, he informed the world that Zuma's mistake "was of little consequence," because other data showed that SA's death rate has doubled since l997. Hmmm. It is true that annual death registrations rose from 316,000 in 1997 to around 600,000 in 2007, but it is absurd to claim, as Geffen did, that this was almost entirely the result of Aids.
Over the same period, completeness of registration rose from around 67 percent to 81 percent, according to Stats SA, while our population rose by close on seven million. If you adjust the raw numbers accordingly, Geffen's apparent doubling shrinks to an increase of around 15 to 20 percent.
He then published a correction:
Correction: I am informed that my mathematical skills leave much to be desired. If you run the numbers in the penultimate paragraph correctly, the real increase in SA death registrations since l997 comes out at around 30 percent - still a tragedy by any reckoning, but still way short of the doubling claimed by Geffen.
First let's deal with the numbers. Malan continues to get it wrong, even in his correction. AIDS deaths have conservatively increased 6-fold since 1997, from approximately 50,000 to well over 300,000 in 2006 as well as 2007 and maybe even over 350,000, meaning the real increase in deaths -which is way more than 30%- recorded or otherwise, was mainly due to AIDS. The ASSA2003 interventions model calculates under 150,000 AIDS deaths in 2000 and about 360,000 in 2007. Approximately 45% of deaths in 2006 and 2007 were due to AIDS. The model probably overestimates AIDS deaths but not substantially enough to give any material support to Malan's argument. But even a 30% increase in mortality, as Malan acknowledges, is a tragedy. Read more »
Rob Sharp reports in The Independent on the presistence of AIDS denialism
A middle-aged man walks into an East London café and apologises for being late. With his clipped hair and bus-driver's uniform of thick overcoat, shirt, and branded tie, he looks like any other public service employee. But soon he delivers a speech of startling ferocity against the medical establishment.
Mike explains that he runs a London-based health website on which he posts articles and links to information that questions whether HIV causes Aids, disputes the existence of HIV, and denies the fact that unprotected sex helps to spread it. He offers support for those who, he says, are "negotiating with medical authorities over taking a different approach to dealing with their circumstances." He claims to get thousands of hits on his site and has helped advise several people who have been diagnosed with HIV and are launching legal action against their local health authorities, in the belief that they have been unfairly treated by the doctors who are trying to help them.
Stephanie Law writes in the McGill Daily:
Christina Maggiore died of an AIDS-related illness on December 27, 2008. She was a successful businesswoman who started a multimillion-dollar import/export clothing company, and a freelance consultant for U.S. government export programs. Maggiore is most notorious for her role as an HIV-positive activist who promoted the idea that HIV is not the real cause of AIDS. She was an HIV-denialist.
Maggiore was diagnosed with HIV in 1992. In 1994, she met Peter Duesberg, a molecular biology professor at the University of California at Berkley. Duesberg convinced Maggiore that HIV does not lead to AIDS. A year later, Maggiore started one of the largest networks of HIV-denialists and skeptics, called Alive & Well AIDS Alternatives.
Maggiore refused antiretroviral treatment for HIV because she did not think HIV would lead to AIDS and AIDS-related illnesses. She did not take the recommended treatment for pregnant HIV-positive women to prevent mother-to-child transmission. Her child died at the age of three from Pneumocystis jirovecii pneumonia. The Los Angeles County coroner and various other independent pathology experts concluded that the death was a direct result of her untreated HIV that had progressed into AIDS.
Statements by Professor Niel Constantine and Professor Robin Weiss about the Misrepresentation of their Interviews in “House of Numbers.”
Posted November 23, 2009, to HouseofNumbers.org
The sections on HIV antibody tests in “House of Numbers” contain fragments of interviews with a number of different people, put together in a way that confuses viewers rather than clarifying what HIV testing protocols are and how they work. The editing of the interviews to try to create doubts about the worth of HIV diagnostic assays is surely intentional. Questioning HIV diagnostics is one of the main tactics of HIV denialism.
The talking heads in these sections of the video include an eager-to-please but inexpert woman working in a temporary testing tent in a South African mall, several legitimate scientists, and HIV denialist Liam Scheff and filmmaker Brent Leung. The section jumbles together bits of speech about the use of HIV antibody testing for different purposes—for screening the blood supply, for screening individuals for HIV infection and confirmatory testing, for diagnosis and for prognosis. It also scrambles remarks about different generations of tests; about tests of different qualities—those manufactured under FDA oversight and those produced in uncontrolled conditions; about different types of HIV antibody tests—conventional and rapid tests, ELISA and Western Blot; and about the use of these tests under different countries’ government protocols—Germany, South Africa, Britain, the USA. The resulting mess of words creates confusion – as it was intended to.
The history, variety, and protocols of HIV antibody testing can be confusing to non-experts. Leung and his team have exploited this in the film. But any of the legitimate scientists or clinicians in the film, asked a clear question by an ethical interviewer who would try to present their views accurately, could easily explain how HIV antibody testing works, what protocols are used to maximize accuracy in different places and at different times, the distinctions between screening and diagnostic assays, the differences between ELISAs and Western Blots, and so on. But Brent Leung sought to confuse, not clarify. He wanted to make it seem like the tests are unreliable and that the scientists he interviewed didn’t know disagreed with each other about HIV tests. The reality is very different. HIV antibody tests are extremely accurate, and various confirming protocols (two or three different types of tests) are used in different places. Read more »
by Dr John Moore, PhD (Originally published by health-e)
Surveys have consistently shown that over 40% of Americans do not believe in evolution. It is not surprising, then, that our society is vulnerable to being fooled by people who misrepresent scientific or historical facts.
We are now all too familiar with the crazed activities of the 'Birthers', an ad hoc, right wing political group refusing to accept President Obama was born in the United States. Earlier this year, we saw media coverage of the insane views of a clique that refuses to accept American astronauts walked on the moon 40 years ago. The "9/11 Truth Movement" flourishes on the internet, arguing that the World Trade Center and the Pentagon were not hit by hijacked jetliners, but were blown up by the CIA at the behest of Israeli intelligence. Conspiracy groups like these usually do little real damage to society, although the activities of the "9/11 Truth Movement" foster anti-Semitism and insult the memories of the nearly 3000 Americans who died on 9/11. Unfortunately, other equally bizarre and factually unfounded, internet-based conspiracy groups can, and do, harm, even kill, significant numbers of people. This is not just an American problem, as the ripple effects of conspiracy theories spread worldwide via the internet. Indeed, the most serious consequences of one such group’s actions have been felt in Africa. Read more »
We endorse this call for mandatory disclosure.
Mandatory Disclosure of Pharmaceutical Industry-Funded Events for Health Professionals
Robertson J, Moynihan R, Walkom E, Bero L, Henry D (2009) PLoS Med 6(11): e1000128. doi:10.1371/journal.pmed.1000128
- There are moves internationally to ensure greater disclosure of gifts and educational events for doctors paid for by pharmaceutical manufacturers. However, there is no agreement on appropriate standards of disclosure. In Australia, since mid-2007, there has been mandatory reporting of details of every industry-sponsored event, including the costs of any hospitality provided.
- Examination of the Australian data shows that although expenditure at individual events is often modest, cumulative expenditure is high, particularly in the case of medical specialists prescribing high cost drugs—oncologists, endocrinologists, and cardiologists.
- Although a significant advance, the new Australian reporting standards do not allow assessment of the educational value of sponsored events, and do not include details of speakers or educational content for most events. However, doctors in training are often present at these events.
- At present, the standards of disclosure are inadequate and should not be tied to an arbitrary monetary value of gifts or sponsorship. Reporting standards should require the names of the speakers presenting, whether sponsors played a role in suggestion or selection of speakers or the development of the content of presentations, and the nature of any direct or indirect financial ties between the speakers and the sponsors.
Michael Carter writes on aidsmap:
Results of US research “challenge the notion that nevirapine is uniquely associated with hepatotoxicity during pregnancy.” The study did however show that pregnancy itself increased the risk of liver toxicities in women with HIV. The research is published in the November 27th edition of AIDS.
AIDS. 2009 Nov 27;23(18):2425-30.
Increased risk of hepatotoxicity in HIV-infected pregnant women receiving antiretroviral therapy independent of nevirapine exposure.
Ouyang DW, Shapiro DE, Lu M, Brogly SB, French AL, Leighty RM, Thompson B, Tuomala RE, Hershow RC.
OBJECTIVE: To estimate whether the association between nevirapine (NVP) and hepatotoxicity differs according to pregnancy status in HIV-infected women. METHODS: The present analysis included HIV-infected pregnant women on antiretroviral therapy (ART) from two multicenter, prospective cohorts - the Women and Infants Transmission Study and the International Maternal Pediatric Adolescent AIDS Clinical Trials protocol P1025 - and HIV-infected nonpregnant women from one multicenter, prospective cohort - the Women's Interagency HIV Study. Using multivariate Cox proportional hazards regression, the interaction between NVP and pregnancy status in terms of hepatotoxicity was investigated. NVP use was dichotomized as use or no use and was further categorized according to ART exposure history. We investigated two outcomes: any liver enzyme elevation (LEE; grade 1-4) and severe LEE (grade 3-4). RESULTS: Data on 2050 HIV-infected women taking ART were included: 1229 (60.0%) pregnant and 821 (40.0%) nonpregnant. Among the pregnant women, 174 (14.2%) developed any LEE and 15 (1.2%) developed severe LEE as compared with 75 (9.1%) and 5 (0.6%), respectively, of the nonpregnant women. In multivariate adjusted models, NVP was not significantly associated with risk of LEE, regardless of pregnancy status; however, pregnancy was associated with an increased risk of any LEE (relative risk 4.7, confidence interval = 3.4-6.5) and severe LEE (relative risk 3.8, confidence interval = 1.3-11.1). The association of pregnancy and LEE was seen, regardless of prior ART and NVP exposure history. CONCLUSION: No significant association between NVP and LEE was observed, regardless of pregnancy status, but pregnancy was significantly associated with increased hepatotoxocity in HIV-infected women.
by Nathan Geffen, 19 November 2009
In 2001, Rian Malan wrote an article in Rolling Stone questioning the accuracy of HIV tests in order to disparage the evidence of a growing HIV epidemic in South Africa. In 2003 he published similar articles in the Spectator and Noseweek. All these articles were replete with errors. I subsequently debunked the latter two in a January 2004 article.
One of Malan's errors was particularly serious. He presented miscalculated, massively understated estimates of AIDS deaths which he falsely attributed to Stats South Africa. As I wrote then, the mistake was so serious and obvious that it raised questions about Malan's basic competence as a research journalist -or more disturbingly- about his motives and integrity.
In Mbeki's 2004 State of the Nation speech he quoted from Malan and spoke warmly about him. It was not explicitly about HIV, but to anyone following the debate at the time, it was clear that Mbeki was grateful for Malan's support on AIDS. Read more »
By Nathan Geffen, 16 November 2009
On 2 November 2009, Statistics South Africa released the latest mortality data, which goes up to 2007 (Stats SA, 2009). This table gives the number of recorded deaths per year:
Number of recorded deaths by Stats SA
You do not need to be a statistician to be astounded by this. Recorded deaths have increased over 90% in a decade. Improved death registration and population growth can account for only a small portion of this increase. The vast majority of additional deaths are due to the HIV epidemic. A huge body of evidence shows this. For example, there has been a three-fold increase in TB deaths over the same period and TB is the leading cause of death in people with HIV. Also the age pattern of the deaths --younger instead of older adults comprise the bulk of them-- and the drop in the median age of death from 51 in 1997 to 44 in 2007 are consistent with the way AIDS works. (For more detailed evidence see Dorrington et al. 2006, Dorrington et al. 2001 and Stats SA, 2002). Read more »