PROGNOSTIC FACTORS IN COPD PATIENTS RECEIVING LONG-TERM OXYGEN-THERAPY - IMPORTANCE OF PULMONARY-ARTERY PRESSURE

Prognostic factors in COPD patients receiving long-term oxygen (LTO) t herapy were recently analyzed, but very few studies considered the pro gnostic value of pulmonary artery pressure (PAP) in these patients. We investigated 84 patients who had undergone a right heart catheterizat ion just before the onset of LTO. There were 75 men and 9 women, with a mean age of 63.0 +/- 9.9 (SD) years, at the onset of LTO. When PaO2 was persistently less than 55 mm Hg, LTO was initiated. This therapy w as started in some patients with PaO2 in the range of 55 to 60 mm Hg i f they had signs of cor pulmonale or a resting PAP of 25 mm Hg or grea ter at right heart catheterization. The daily duration of LTO was 16 h /d or more. Oxygen now was adapted to achieve a PaO2 of 65 mm Hg or mo re. The patients were subdivided into subgroups according to the media n value of age (cutoff value=63 years); vital capacity (2,250 mL); FEV (1) (800 mL); residual volume-total lung capacity ratio (58%); PaO2 va lue (52 mm Hg), PaCO2 level (45 mm Hg); and PAP (25 mm Hg). The cumula tive 5-year survival rate was 48% for the group as a whole. Actuarial survival curves were plotted for the two subgroups of patients subdivi ded according to the initial median value of the variables just listed . There was no significant difference in survival rate between subgrou ps except when taking into account the level of PAP and age. In patien ts with an initial PAP of 25 mm Hg or less (n=44), the 5-year survival was of 62.2 vs 36.3% in the remainder (n=40) [p<0.001]. We performed a multivariate analysis of survival using Cox's model of the proportio nal hazards regression including sex and the variables with the same c ategorization in the stepwise procedure: PAP and age were the only var iables included in the final model. We conclude that the best prognost ic factor in COPD patients receiving LTO is not the FEV(1), nor the de gree of hypoxemia or hypercapnia, but the level of PAP.