Reduced carbon monoxide transfer factor (TLCO) in human immunodeficiency virus type I (HIV-I) infection as a predictor for faster progression to AIDS

Abstract

Background: In addition to the acute fall in carbon monoxide transfer factor (TLCO) associated with Pneumocystis carinii pneumonia (PCP) or other opportunistic lung infections, reduced TLCO occurs in HIV-I seropositive individuals without active pulmonary disease. Abnormal TLCO, in the absence of lung disease, may be a surrogate marker of HIV-I induced immunosuppression and, therefore, a predictor for a more rapid progression to AIDS.

Methods: Eighty four individuals with AIDS, who had regular pulmonary function tests before the diagnosis of AIDS was made, were identified from a cohort of patients with HIV-I infection. None had evidence of active pulmonary disease at the time of initial pulmonary function testing. The relation between the time taken to progress to AIDS and initial pulmonary function tests was examined with life table survival analysis.

Results: Patients with a TLCO value of < 80% of predicted normal (n = 46) progressed significantly faster to AIDS, with a median time of 8.0 months compared with 16.5 months for those with a TLCO value of > or = 80% (n = 38). When stratified by AIDS defining diagnosis (PCP or non-PCP), median time to PCP was also significantly related to initial TLCO values (TLCO of < 80% = 9.0 months, TLCO of > or = 80% = 19.0 months). Reductions in other measurements of lung function (FEV1, FVC, KCO) were not temporally associated with the development of AIDS.

Conclusions: HIV-I seropositive individuals with TLCO values of < 80% predicted and no evidence of lung disease progress more rapidly to AIDS than those with TLCO values of > or = 80%.