SURVIVAL IN PRIMARY PULMONARY-HYPERTENSION - VALIDATION OF A PROGNOSTIC EQUATION

Background The prognosis of patients with primary pulmonary hypertensi on (PPH) remains a major problem for the planning and assessment of th erapeutic interventions. The objectives of this study were (1) to char acterize mortality in a Mexican population of patients with PPH and to investigate factors associated with survival and (2) to test the appl icability in this population of the prognostic equation proposed by th e US National Institutes of Health study on PPH.Methods and Results A dynamic cohort of patients with PPH at our institution were enrolled b etween June 1977 and August 1991 and prospectively followed at regular intervals through September 1992. Measurements at diagnosis included hemodynamic and pulmonary function variables in addition to informatio n on demographic data and medical history. The response to vasodilator treatment was also analyzed. The estimated median survival of the gro up was 4.04 years (95% confidence interval, 2.98 to 5.08 years). Varia bles associated with poor survival (univariate analysis) included an e levated mean right atrial pressure, a decreased cardiac index, and a d ecreased mixed venous Po,. A reduced forced vital capacity and the abs ence of vasodilator treatment were also associated with poor survival. A multivariate Cox proportional-hazards regression analysis was used to assess the adjusted hazard ratios, hence the relative contributions of the variables controlling for confounding. Reduced forced vital ca pacity and cardiac index and increased right atrial pressure were stil l significantly associated as risk factors for survival in patients wi th PPH. Survival as computed by the equation correlated with real surv ival of PPH patients with positive predictive values of 87%, 91%, and 89% at 1, 2, and 3 years, respectively. The equation, however, was rel atively unable to predict deaths in our population, in part because of the strict limits of poor prognosis. Conclusions Mortality in PPH is largely associated with hemodynamic variables that assess right ventri cular function. The proposed prognostic equation had a high sensitivit y and a relatively low specificity to predict survival in our PPH popu lation. To improve this specificity it may be necessary to increase th e limits of poor prognosis as defined by the equation.