Pulmonary Complications of HIV Infection

The HIV/AIDS epidemic has led to an unprecedented worldwide response that has involved global partnerships and collaborations among clinicians and educators; patients and patient advocacy groups; researchers and funding sources; and governments, multinational organizations, and corporations. As a result, on World AIDS Day, December 1, 2015, the UNAIDS proclaimed that “The world has halted and reversed the spread of HIV. The epidemic has been forced into decline. New HIV infections and AIDS-related deaths have fallen dramatically since the peak of the epidemic.” In support, the UNAIDS estimated that there has been a 35% decrease in new HIV infections since 2000, a 42% decrease in AIDS-related deaths since its peak in 2004, and an 84% increase in access to potentially life-saving antiretroviral therapy since 2010. And yet, the UNAIDS also estimates that there are 36.9 million people worldwide living with HIV, 2 million people became newly infected with HIV, and 1.2 million people died from AIDS-related causes in 2014. Thus, in the absence of an effective HIV vaccine and without a definitive cure for those already infected with HIV, clinicians throughout the world will continue to encounter persons living with HIV/AIDS.

This issue of Seminars in Respiratory and Critical Care Medicine is devoted to “Pulmonary Complications of HIV Infection.” Since the beginning of the epidemic, the lungs have been one of the major targets of HIV and its associated opportunistic infections and neoplasms; and therefore, an understanding of the spectrum of lung diseases in persons with HIV/AIDS is an important aspect in the care of these individuals. Leaders in the field of HIV-associated lung diseases have authored each of the 13 articles in this issue.

The first article reviews the pathogenesis of HIV infection and impairments in host defense in the lungs that predispose HIV-infected individuals to opportunistic respiratory pathogens. The second article details the beneficial effect of combination antiretroviral therapy on pulmonary immune function, and also the potential detrimental impact of immune reconstitution inflammatory syndrome. Together, these articles provide an important foundation to understand the individual HIV-associated lung diseases discussed in subsequent articles.

The global HIV/AIDS epidemic shares similarities, but also has important differences from the HIV/AIDS epidemic in the United States. The third article summarizes the global epidemiology of HIV-associated pulmonary complications with a special focus on potential factors that explain the global variation in HIV-associated respiratory disease, while the fourth article focuses on the epidemic in the United States. Now more than 20 years into the era of combination antiretroviral therapy in the United States, this article also provides important U.S. data comparing the earlier era with the current one. The high prevalence of cigarette smoking in persons with HIV/AIDS is an important, modifiable risk factor for nearly all of the HIV-associated respiratory diseases, and the limited data on smoking cessation in HIV-positive persons are reviewed. The fifth article discusses key aspects of the evaluation and diagnosis of HIV-associated lung diseases and details features that may distinguish these lung diseases from each other. Several examples of the characteristic chest radiographic and chest computed tomographic appearances of the main HIV-associated lung diseases are presented.

The spectrum of HIV-associated lung diseases is broad and includes HIV-associated opportunistic infections and neoplasms and, increasingly, noninfectious and nonneoplastic conditions such as chronic obstructive pulmonary disease (COPD) and pulmonary arterial hypertension. Worldwide, tuberculosis (TB) remains the leading cause of death among people living with HIV/AIDS, while in the United States bacterial respiratory infections are a major cause of HIV-associated morbidity. In populations with access to combination antiretroviral therapy, HIV infection has become a chronic disease and the life expectancy of persons living with HIV/AIDS is nearly comparable to that of individuals without underlying HIV. As a result, comorbid conditions such as COPD have increased in prominence. The next four articles review HIV-associated bacterial respiratory infections; mycobacterial lung diseases; Pneumocystis pneumonia; and fungal, viral, and parasitic pneumonias. The tenth article reviews HIV-associated malignancies, while the eleventh and twelfth articles review obstructive lung diseases and other noninfectious and nonneoplastic conditions. To conclude this issue, the thirteenth article discusses key aspects of the critical care of persons with HIV/AIDS, with an emphasis on the aspects of management that are specific or unique to HIV/AIDS.

We thank all of the authors who contributed their experience and expertise to this issue of Seminars in Respiratory and Critical Care Medicine, and we trust that readers will gain a better understanding of these many pulmonary complications of HIV infection.