Wednesday, July 25, 2007

Classic Dissident Viral Load Misunderstandings

I read a "quote" today from the good old denialists Andrew Maniotis

"...viral load is only able to predict progression to disease in 4% to 6% of HIV-positives studied, challenging much of the basis for current AIDS science and treatment policy" [Rodriquez B, Sethi AK, Cheruvu VK, et al. Predictive value of plasma HIV RNA level on rate of CD4 T-cell decline in untreated HIV infection. JAMA 296(12):1498-506, 2006;Cohen J. Study says HIV blood levels don't predict immune decline. Science 313(5795):1868, 2006. "

Of course this is related to the paper I referred to in an earlier post. As is typical for AIDS denialists, Maniotis is either unable to understand the science, or deliberately misrepresents it. He certainly "quotes" from the paper when in fact no such quote exists (it's one of his own!).

As Mellors and others have shown, viral load is actually predictive of progression to AIDS and death extremely well. In fact, in their original paper the researchers showed that this link was present regardless of baseline CD4 count. In full support of this, the Rodriguez article confirmed that in general viral load measurements were a good predictor of CD4 cell decline.

But, and listen closely, they said that absolute viral load only predicted 4-6% of the RATE of CD4 cell DECLINE. They didn't say that it only predicted it in 4-6% of patients, nor 4-6% of the CD4 cell count, and certainly didn't look at risk of AIDS or death.

In laymans' terms, if someone's CD4 cell count dropped by 100 over a year and someone else's CD4 count dropped by 200 over a year, only 4-6 of that difference of 100 could be statistically explained by having a higher viral load.

This is nothing new, as Rodriguez made clear - all the work did was quantitate the impact of one variable (viral load). Other factors would include the level of immune response, proviral load, nutritional status and even mental health (depression has been known to be linked to an increased risk of AIDS for years - similar to cancer).

No doubt this "4-6%" myth will propogate and mutate - which is why I'm posting. As I've said many times before - by all means criticize and debate, but don't do so from a position of pseudoscience.