|Resistance Testing, A Reason to Delay Treatment?
Jun 18, 2010
I am aware of the current national and international guidelines that suggest that genotype testing be done to determine resistance to therapies before starting patients on HAART and I can see where this should be the case when dealing with patients who have had some form of HAART therapy previously.
However, in treatment naive patients, is the risk of starting an HAART regimen to which the patient is resistant enough reason to delay therapy? With only a 10% likelihood that a patient will develop HIV that is resistant to a single therapy and with only a 1% chance of multi-drug resistance, isn't it irresponsible to delay treatment as much as four weeks (presumably to wait for the genotype results) when the patient has CD4 cell counts as low as 13 and a rate of decline that indicates a loss of nearly 8 CD4 Cells* in as little as one week?
Since multidrug therapy would invariable prove beneficial on at least two fronts for treatment naive patients in 90% of the cases and since less than 1% of patients will show multi-drug resistance, what is the benefit of delaying treatment?
Your prompt reply is greatly appreciated. Thanks in advance for your help.
| Response from Dr. McGowan
Thanks for your thoughtful question. For most peole, if they are diagnosed by routine HIV testing, there would be no serious harm in waiting a couple of weeks for a genotype. In a person with a very low CD4 count, or active opportunistic infection such as PCP, assuming they are prepared to take medication and have active insurance to continue taking it (many people newly diagnosed in the US have to wait to get coverage or ADAP) we would want to start as soon as possible. Also, if someone has acute HIV infection, there may be some urgency to start treatment to interrupt the early stages of infection.
The risk of having acquired a drug resistant strain is about 10-15% depending on where you live. The type of resistance that is spread tends to be mostly against NNRTIs and NRTIs, with a much much less chance of picking up resistance to a boosted protease inhibitor. So, if we want to start treatment ASAP, before getting a genotype (which we sometimes do), we would avoid NNRTI based therapy and favor a "boosted PI" type of treatment. This removes the simple "one pill a day" option, which could be switched to later if genotype results do confirm susceptibility.
Thanks and good luck.
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