Pulmonary Complications of HIV Infection Study (PACS)

BACKGROUND:

Pulmonary infections as a group are the most commonly recognized life threatening disorders in patients with the AIDS. Although Pneumocystis carinii was the predominant pulmonary pathogen found in these patients, other organisms were clearly of importance as well, not with early years of the HIV epidemic only in patients with AIDS and ARC but in individuals with asymptomatic HIV infection.

In the mid-1980s, physicians who examined many AIDS patients had the impression that a shift was occurring in the types and incidence of pulmonary complications associated with HIV infection. For example, there appeared to be an increased incidence of serious infections caused by pyogenic bacteria and pulmonary and extrapulmonary infection with M. tuberculosis had been noted with increased frequency. Furthermore, lymphoid interstitial pneumonitis (LIP), which is diagnostic of AIDS in children under 13 years old who are HIV antibody positive, was diagnosed with increased frequency in adults. Nonspecific interstitial pneumonitis also appeared to be on the rise. Legionella pneumonia, in contrast to its increased incidence during 1981-83, was now seldom encountered. However, apart from the increased incidence of tuberculosis, a reportable disease, these other shifts in the incidence of pulmonary complications had not been verified.

Because diagnostic strategies in the development of new treatment regimens and new approaches for clinical research were dependent upon knowledge of the incidence and natural history of pulmonary complications associated with HIV infection, the collection of such information was important.

The Request for Proposals for this initiative was released in January 1987. Awards were made in September 1987. The study was funded jointly by the NHLBI and the NIAID. The study was extended by the cooperative agreement mechanism in FY 1993.

DESIGN NARRATIVE:

The cohort consisted of 3 groups: Group A HIV seropositive, no symptoms attributable to HIV and CD4+ Cells >= 400 per microliter; Group B HIV seropositive chemical manifestations of HIV in past 6 months or CD4+ Cells < 400 per microliter; and Group C HIV seronegative controls. The pulmonary status of individuals in each of the categories was evaluated by such methods as chest radiography, pulmonary function tests, nuclear medicine studies, and histological and/or microbiological evaluation. The prospective cohort study described the incidence and course of lung diseases at all stages of HIV infection. Six clinical centers from different geographic areas in the United States began enrolling participants in 1988, and the resulting cohort comprised 1,369 members. HIV seropositive participants were randomized to "intensive" (pulmonary disease screening and follow-up at three-month intervals) or "routine" (six-month follow-up intervals with annual screening) follow-up to assess the impact of these strategies on patient outcomes. The contract-supported phase of the study was jointly funded by the NHLBI and the NIAID.

In 1992, the NHLBI decided to extend follow-up for another five years. The contractors applied for research grants which were approved by the National Heart, Lung, and Blood Advisory Council in May 1992 and awarded in October, 1992. In the renewal, particular attention was given to identifying patterns of complications among demographic subgroups that had not been extensively studied, such as women and Blacks, and to defining differences between HIV transmission groups. The study ended in May, 1997.