▪ Objective: To characterize mortality in persons diagnosed with primary pulmonary hypertension and to investigate factors associated with survival.

▪ Design: Registry with prospective follow-up.

▪ Setting: Thirty-two clinical centers in the United States participating in the Patient Registry for the Characterization of Primary Pulmonary Hypertension supported by the National Heart, Lung, and Blood Institute.

▪ Patients: Patients (194) diagnosed at clinical centers between 1 July 1981 and 31 December 1985 and followed through 8 August 1988.

▪ Measurements: At diagnosis, measurements of hemodynamic variables, pulmonary function, and gas exchange variables were taken in addition to information on demographic variables, medical history, and life-style. Patients were followed for survival at 6-month intervals.

▪ Main Results: The estimated median survival of these patients was 2. 8 years (95% Cl, 1.9 to 3.7 years). Estimated single-year survival rates were as follows: at 1 year, 68% (Cl, 61% to 75%); at 3 years, 48% (Cl, 41% to 55%); and at 5 years, 34% (Cl, 24% to 44%). Variables associated with poor survival included a New York Heart Association (NYHA) functional class of III or IV, presence of Raynaud phenomenon, elevated mean right atrial pressure, elevated mean pulmonary artery pressure, decreased cardiac index, and decreased diffusing capacity for carbon monoxide (DL_CO). Drug therapy at entry or discharge was not associated with survival duration.

▪ Conclusions: Mortality was most closely associated with right ventricular hemodynamic function and can be characterized by means of an equation using three variables: mean pulmonary artery pressure, mean right atrial pressure, and cardiac index. Such an equation, once validated prospectively, could be used as an adjunct in planning treatment strategies and allocating medical resources.