May 8, 2017
Compared with HIV-negative people, people with HIV had a 13 times higher rate of invasive pneumococcal disease, a possibly serious infection with the bacterium Streptococcus pneumonia (Strep) (Figure 1).1 The rate of new pneumococcal (new-mo-KOK-al) infection in HIV-positive people dropped over the 1996-2011 study period. But in the most recent years analyzed, people with HIV still had more than a 6 times higher rate of invasive pneumococcal disease than a similar group of people without HIV.
Figure 1. The bacterium Streptococcus pneumonia can cause invasive pneumococcal disease, a serious group of illnesses more common in people with HIV infection than in HIV-negative people. (Photo from CDC/Dr. Richard Facklam.)
Invasive pneumococcal disease can appear as pneumonia, blood infection (bacteremia or sepsis), meningitis, or middle-ear infection.2 These possibly life-threatening infections can be prevented by vaccination. In 2012 U.S. experts recommended that people with HIV receive the PCV13 vaccine, followed by the PPSV23 vaccine.2,3
Studies suggest that invasive pneumococcal disease rates are falling in people with HIV, but these studies lack an HIV-negative comparison group similar to the HIV group analyzed. Researchers in the Kaiser Permanente Northern California group conducted a new study to provide this kind analysis within this single healthcare system.
The research team identified everyone at least 18 years old and in care for HIV at Kaiser Permanente Northern California on or after January 1, 1996. For each HIV-positive person, the researchers selected 10 HIV-negative people the same sex and age (within 5 years) who started care in the same year as the HIV-positive person at the same medical center. The investigators checked medical records of each person until invasive pneumococcal disease developed, or until December 31, 2011, or until the person left the Kaiser system or died. Pneumococcal vaccines are given in the Kaiser system at no extra charge.
The main study outcome was lab-confirmed development of invasive pneumococcal disease in blood, brain and spinal fluid, bone, or joints. The researchers also collected other health data from the file of each study participant. Then they calculated the rate of invasive pneumococcal disease per 100,000 person-years, that is, how many cases of invasive pneumococcal disease developed in 100,000 people each year. They used a standard statistical method to compare pneumococcal disease rates in people with versus without HIV. This kind of analysis considers many invasive pneumococcal disease risk factors at the same time so the comparison between people with and without HIV is more accurate. They used a similar statistical method to identify individual factors that affect risk of invasive pneumococcal disease regardless of whatever other risk factors a person has.
The study involved 13,079 people with HIV and 137,643 without HIV. Each group averaged about 40 years in age, and about 90% of each group were men. The HIV group included a higher proportion of whites (61% versus 51%) and blacks (18% versus 9%), and lower proportions of Hispanics and others. A significantly higher proportion of people with than without HIV smoked (47% versus 31%). HIV-positive people had HIV infection for an average 4.7 years, and only 48% of them had taken antiretroviral therapy for their HIV.
During the 1996-2011 study period the invasive pneumococcal disease rate was much higher in people with HIV (160 cases per 100,000 person-years) than in people without HIV (8 cases per 100,000 person-years). For the whole study period, people with HIV had a 19-fold higher risk of invasive pneumococcal disease than people without HIV. An analysis that accounted for the impact of age, sex, race, smoking, diabetes, and other risk factors determined that HIV-positive people had a 13-fold higher risk of invasive pneumococcal disease than HIV-negative people.
Over the 5 study periods listed in Figure 2, invasive pneumococcal disease incidence (the new-detection rate) dropped by 71% among people with HIV, from 305 cases per 100,000 person-years in 1996-1999 to 88 per 100,000 in 2010-2011. An analysis figuring the impact of other pneumococcal disease risk factors found that risk fell from 18.5 times higher in people with HIV in 1996-1999 to 6.6 times higher with HIV in 2010-2011 (Figure 2). But even in 2010-2011, risk of invasive pneumococcal disease was significantly higher in the HIV group. In other words, a statistical test determined that chance did not explain the higher pneumococcal disease rate in the HIV group.
Figure 2. From 1996-1999 through 2010-2011, HIV-positive people in California always had a higher rate of invasive pneumococcal disease than HIV-negative people. But the higher rate with HIV infection grew smaller over the years.
In people with HIV three factors raised the risk of invasive pneumococcal disease regardless of whatever other risk factors a person had: being black (versus white), ever smoking, and having cancer in the past each more than doubled the risk of invasive pneumococcal disease (Figure 3). Two factors lowered the risk of invasive pneumococcal disease in people with HIV: being in higher wealth brackets and having a lower recent HIV viral load. PPSV23 vaccination had no impact on risk of invasive pneumococcal disease in this analysis. Neither did age, sex, or year entering the study.
Figure 3. In people with HIV three factors independently raised the risk of invasive pneumococcal disease 2.3 times: black versus white race, ever smoking, and cancer in the past. Three factors lowered pneumococcal disease risk in people with HIV: being in the highest two of five wealth brackets (versus the lowest) and having a latest HIV viral load (VL) under 500 copies or from 500 to 9999 copies (versus 10,000 copies or higher).
Invasive pneumococcal disease is a serious and possibly deadly infection that affects adults and children.4 Every year about 900,000 people in the United States get pneumococcal pneumonia (one form of invasive pneumococcal disease), and 5% to 7% die from it. About 3700 people in the United States die every year from two other forms of this disease, pneumococcal meningitis (brain and spinal fluid infection) and bacteremia (blood infection).
This study found that adults with HIV had much higher rates of invasive pneumococcal disease than adults of similar age without HIV. Overall, the HIV group had a 13 times higher rate of invasive pneumococcal disease than people without HIV. The good news is that invasive pneumococcal disease rates have dropped over recent years in people with HIV. But even in the most recent study period, 2010-2011, people with HIV had more than a 6 times higher rate of invasive pneumococcal disease.
You can greatly lower your risk of invasive pneumococcal disease by getting the correct vaccinations. For people with HIV, this study found that the PPSV23 vaccine alone did not protect HIV-positive people from invasive pneumococcal disease. U.S. health authorities recommend PCV13 vaccination followed by PPSV23 vaccination for HIV-positive adults who have never received a pneumococcal vaccine.3 HIV-positive adults who have already received a dose of the PPSV23 vaccine should get a dose of the PCV13 vaccine 1 year or more after the last PPSV23 dose.
The study pinpointed individual risk factors for invasive pneumococcal disease in people with HIV. Blacks, smokers, and people who had cancer all had higher rates of invasive pneumococcal disease. People with a recent viral load below 10,000 copies and people in higher wealth brackets had lower rates of invasive pneumococcal disease. These findings underline the importance of avoiding or quitting smoking. Quitting smoking is not easy, but 20% of all HIV-positive people in the United States are people who have quit smoking. See "Smoking May Shorten Life More Than 6 Years in U.S. Men and Women With HIV" in this issue for advice on quitting smoking.
Reaching and maintaining an undetectable viral load is the main goal of antiretroviral therapy. This study provides another reason for starting anti-HIV therapy and continuing treatment to keep an undetectable viral load: preventing invasive pneumococcal disease. The researchers believe falling viral loads over the years in HIV-positive people explain the falling invasive pneumococcal disease rate they found over time.
|PCV13 Pneumococcal Vaccine Boosts Immunity in Adults With HIV and Prior PPSV23 Vaccination|
No comments have been made.
The content on this page is free of advertiser influence and was produced by our editorial team. See our content and advertising policies.