HIV Does Not Worsen H1N1-Related Complications (and Vice Versa), Study Finds
A Discussion With Esteban Martinez, M.D.
February 24, 2010
Below is the transcript of a press conference held at CROI 2010 on Feb. 19, in which Esteban Martinez, M.D., from Hospital Clinic in Barcelona, Spain, discusses a study he presented about the risk and severity of H1N1 in HIV-infected people compared to the general population.
In addition to this transcript, be sure to read this summary of noteworthy research from CROI 2010 on H1N1 and HIV written by Anjali Sangvhi.
Esteban Martinez: You know about the importance in daily life, in travel, in general health, about H1N1 influenza. We were specifically worried at our institution in Barcelona and, for epidemiological and clinical reasons, wanted to know what happened with patients admitted in to the clinic with any respiratory illness.1
Within that frame, a specific protocol was developed in which clinical items, and radiological and laboratory, as well as pharyngeal swabs for diagnosing influenza, were scheduled. Within this specific protocol, we were able to follow the HIV-infected patients with confirmed H1N1 influenza. We looked at the characteristics of those patients, and also at the potential for higher risk of complications. We tried to do so by a case-control study, comparing each confirmed H1N1-infected adult with HIV with three non-HIV-infected adults diagnosed with H1N1 in the same calendar week. We tried to compare epidemiological, clinical and outcome characteristics.
Concerning the epidemiology, we saw that the epidemiological course in both populations, HIV positive and HIV negative, were parallel. That suggests that there was no specific temporal trend different in the HIV population from the general non-HIV population.
Concerning the characteristics of the patients, we were able to see differences between HIV positive and HIV negative. In terms of age, HIV positive were older. There were more males. There were more smokers. All of these characteristics are typical features of the general HIV population cared [for] at our institution.
Their median CD4+ cell count was about 550 per microliter, and the viral load was suppressed in more than 90% of the patients. Again, these characteristics are typical of the average HIV-infected patient at our institution.
That suggests that no specific HIV-infected patient, or group of patients, was at higher risk for H1N1 influenza, despite what could be expected. For instance, younger patients, or those with lower CD4+ cell counts, were similar to the general population.
Concerning the clinical features, there were similar features regarding the presentation at the emergency room. And there was even a lower rate of pneumonia and respiratory failure. When we took into account the potential for concomitant comorbities -- as HIV-infected patients may be more willing to go to the hospital in the first instance, and that might not be the case for the non-HIV-infected population -- we performed a super analysis, just to see if patients without comorbidities shared similar clinical and outcome presentations. We were not able to see any difference.
In conclusion, we were not able to see any significant change in CD4+ cell count, or in virological suppression. Thank you.
Reporter #1: In this population, the only real difference I saw, in your abstract, anyway, was a lower rate of respiratory failure and pneumonia. Why is that?
Esteban Martinez: I do not know. I would be very hesitant to say that the risk in HIV-infected people is lower than in the general population, but at least we cannot say that it is greater.
Reporter #1: The reason I ask that is that there has been a suggestion that this virus in some patients is associated with a cytokine storm, which is a function of an immune system. Is it possible that a suppressed immune system, or a slightly weaker immune system, would be protective in that instance?
Esteban Martinez: Absolutely. That's very interesting. For instance, we saw that lymphopenia -- a typical feature of seasonal influenza -- was not the case in HIV-infected people, despite these patients commonly having lymphopenia. And concerning the cytokine storm, I have to say that, as far as I know, the potential with concomitant bacteria infections is very important in determining the severity of the patient. For instance, even in patients treated with certain antibiotics that destroy the bacterial cellular wall, a release of material may increase the cytokine storm, as you mention. But the presence of concomitant bacteria was similar in both groups.
Reporter #2: Do you have any idea about the rate of H1N1 infection in HIV-positive patients, compared to the general population? Was it higher?
Esteban Martinez: We are not able to answer this issue. But I can tell you that HIV-infected patients represented about 10% of confirmed H1N1 cases. If we take into account the prevalence of HIV infection in Catalonia -- that's 0.6 per 1,000 persons -- the number of expected non-HIV-infected patients that should have been diagnosed with influenza, H1N1, should have been 15 times higher. We do not know the reason. One potential explanation may be that HIV-infected patients may be at more risk of contagion. That seems not to be the case, because the features were similar. Or maybe other non-HIV-infected patients did not come to the reference health center to be confirmed with influenza.
Reporter #3: Wouldn't it be because of the prophylaxis that a lot of patients would be on, or other medications, that can consider the lower incidence of respiratory illnesses, and so forth?
Esteban Martinez: That's interesting. But this did not seem to be the case, because a large proportion of patients were above 200 CD4+ cells. For those patients, no routine prophylaxis are recommended. We were not able to test that, so we are not confident that this may be the cause.
Reporter #4: With H1N1, the most severe disease is in younger people. Do you have any knowledge about young people and HIV infection and H1N1?
Esteban Martinez: Yeah, because we were aware of the H1N1 diagnoses in our area. But it was not part of the study. I can tell you that none of the severely ill children were HIV positive.
Reporter #5: Do you have any figures about the access to the vaccine in the HIV population in Spain, or in your center? Because I think that the figures are different from country to country. My guess is that in Spain, the access to the vaccine was low, not because of the campaigns -- they were very direct -- but maybe for some cultural differences in approach of vaccine use?
Esteban Martinez: You're right. Vaccination in Spain was available in mid-November. That's quite late. Most of the persons I describe in our work had been already diagnosed by that time, so vaccination was not affecting this diagnosis.
Concerning the potential for vaccination in HIV-infected patients, similar to seasonal influenza, and probably with different details, it was not popular. HIV-infected patients, in a large majority, did not get vaccinated similarly to other populations. I do not know why.
Reporter #6: You mentioned that your HIV patients might be more amenable to going to the hospital when they would have an infection, or a cold, and that might translate to earlier treatment. Could you elaborate a little bit on that?
Esteban Martinez: That could be the case. In terms of the time from the onset of symptoms, however, there were no differences between HIV positive and HIV negative, which argues against that contention. But at least in Spain, and maybe in other developed countries, it is not the general practitioner, but the institution -- the hospital institution, where they are cared for -- that's usually their reference health center. So it may be possible that for other people without any underlying illness, or with chronic illness, that it is treated outside the hospital. The first reference might not be the hospital. That could be a bias, and I cannot address farther to that point.
This article was provided by TheBodyPRO.com. It is a part of the publication The 17th Conference on Retroviruses and Opportunistic Infections.
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