Respiratory Infection in HIV: A Dysfunctional Marriage
ABSTRACT & COMMENTARY
Synopsis: Respiratory infection is common in HIV infection. Upper respiratory infection is most common initially but, unlike bacterial pneumonia and PCP infection, does not increase with declining CD4 counts. Antibiotic prophylaxis reduces the incidence of PCP but not bacterial pneumonia.
Source: Wallace JM, et al. Am J Respir Crit Care Med 1997; 155:72-80.
Acquired immunodeficiency syndrome is a chronic and ultimately fatal disease, with a latent period of between eight and 10 years. From its earlier description, respiratory infection has been identified as a major barrier to improved survival, and much emphasis has been placed on preventive therapy specifically aimed at Pneumocystic carinii pneumonia (PCP) and, more recently, bacterial pneumonia.1 To understand the patterns and spectrum of respiratory infection complicating HIV disease, an NIH-sponsored prospective cohort study was undertaken involving six different urban centers and three HIV risk groups (homosexual/bisexual men, intravenous drug users, and heterosexual female partners of HIV-infected men). A total of 1297 (1130 HIV-positive) individuals were studied over five years (1989-1993). Over the course of the study, the proportion of patients with CD4 counts less than 200 cells/cc, increased from 19% to 34%. By year five, both anti-retroviral and PCP prophylaxis was employed in 70% and 80% of patients, respectively. Both upper and lower respiratory illness was more common in HIV seropositive individuals, especially acute bronchitis and pneumonia. In the HIV-positive individuals, the incidence of respiratory illness increased from year one to five, with lower respiratory tract illness increasing most prominently. Although upper respiratory tract illness was more common, the incidence remained stable over the study period. The most common lower respiratory tract infections were acute bronchitis, bacterial pneumonia and PCP. Among the categories of HIV infection, pneumonia was more common in the intravenous drug users compared to homosexual/bisexual men. Tuberculosis was also more common in drug abusers, but the incidence was low (3 episodes/100 person years) in both transmission groups. Death rates paralleled the decline in CD4 counts over the five-year observation period. In those who had more than 500 CD4 cells on admission, acute bronchitis was the most common lower respiratory tract infection. Bacterial pneumonia and PCP were more common in those with CD4 counts less than 200 cells/cc compared to those with higher counts. While trimethoprim-sulfamethoxazole prophylaxis (as opposed to aerosolized pentamidine) reduced the incidence of PCP pneumonia, it had no effect on the acquisition of bacterial pneumonia once CD4 cell counts fell below 200 cells/cc.
COMMENT BY ALAN M. FEIN, MD
It is clear that respiratory infection remains a major cause of morbidity and mortality in patients with HIV infection. While this study is broadly based geographically, its cohort is heavily weighted toward white homosexual and bisexual men and, thus, may not entirely be generalizable. There are, however, some important insights that Wallace et al provide. First, respiratory infection is extremely common in all HIV patients, but only lower respiratory tract infection increases, as CD4 count progressively declines. Although tuberculosis occurs in AIDS patients with increased frequency,2 it remains, along with pulmonary neoplasm, a relatively uncommon cause of respiratory tract disease in the HIV-infected group as a whole (< 3 episodes/100 patient years). Acute bronchitis is the most common respiratory infection in this population, a fact that is relatively unappreciated in the general medical community. Acute bronchitis in contrast to bacterial and PCP did not increase over the time of observation or with declining CD4 counts. Specific AIDS risk groups had unique patterns of infection with bacterial pneumonia more common in the intravenous drug users. Despite a very high rate of chemoprophylaxis, PCP infection was frequent, and preventive antibiotics did not seem to reduce acute bronchitis or bacterial pneumonia.
As a clinician, one must ask: Is the glass half empty or half full? Patients with HIV infection are living longer, with improved quality of life. While respiratory tract infection continues to plague these patients, tuberculosis is uncommon in the group overall. Although most patients are receiving appropriate PCP prophylaxis, both PCP and bacterial pneumonia are common. The fact that these infections continue with high frequency, despite these preventive measures, reflects advanced immunosuppression, which characterizes HIV infection.
References
1. Pulmonary Complication of HIV Infection Study Group. The prospective study of pulmonary complications of human immunodeficiency virus infection. J Clin Epidemiol 1993;46:497-507.
2. Incidence of tuberculosis in the United States among HIV- infected persons. Ann Intern Med 1997;126: 123-132.
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