Current issues of ACP Journal Club are published in Annals of Internal Medicine


Prognosis

Survival with primary pulmonary hypertension was associated with increased right arterial pressure and pulmonary arterial pressure and decreased with an increased cardiac index

ACP J Club. 1992 Jan-Feb;116:24. doi:10.7326/ACPJC-1992-116-1-024


Source Citation

D'Alonzo GE, Barst RJ, Ayres SM, et al. Survival in patients with primary pulmonary hypertension. Results from a national prospective registry. Ann Intern Med. 1991 Sep 1;115:343-9.


Abstract

Objective

To determine the mortality rate and to investigate factors associated with survival among patients with primary pulmonary hypertension.

Design

Inception cohort assembled at date of diagnostic catheterization and followed prospectively for at least 3 years.

Setting

32 centers referred data to the Patient Registry for the Characterization of Primary Pulmonary Hypertension at the National Heart, Lung, and Blood Institute.

Patients

194 patients with primary pulmonary hypertension were enrolled between July 1981 and September 1985 and were followed until the time of death, heart-lung transplantation, or until August 1988.

Assessment of prognostic factors

Baseline was established as the date of diagnostic catheterization. Follow-up visits were scheduled for every 6 months.

Main outcome measures

Baseline variables that were related to length of survival after diagnosis included demographic characteristics, medical history, pulmonary function test results, and hemodynamic and gas exchange data.

Main results

60 patients (31%) were alive when the study closed in August 1988. 106 patients (55%) had died and 13 (7%) had received heart-lung transplants. 15 were lost to follow-up and for purposes of analysis were considered survivors. Of the 106 deaths, 26% were unexpected or sudden and 47% were caused by right ventricular failure. The median survival from baseline catheterization was 39 months for men and 32 months for women, with 36% of patients followed ≥ 3 years. Univariate analysis showed an association between 3 hemodynamic variables and increased risk for mortality: increased mean right atrial pressure (odds ratio [OR] 1.99, 95% CI 1.47 to 2.69), increased mean pulmonary arterial pressure (OR 1.16, CI 1.05 to 1.28), and decreased cardiac index (OR 0.62, CI 0.46 to 0.82). A multivariate analysis showed similar odds ratios for these hemodynamic variables, which were the only ones that remained significantly associated with mortality.

Conclusion

Survival of patients with primary pulmonary hypertension was decreased with increasing right atrial pressure, pulmonary arterial pressure, and a decreased cardiac index.

Source of funding: National Heart, Lung, and Blood Institute.

Address for article reprint: Dr. C.E. Vreim, Division of Lung Diseases, National Heart, Lung, and Blood Institute, Westwood Building, Room 6A09, Bethesda, MD 20892, USA.


Commentary

Primary pulmonary hypertension has been a difficult disease to study prospectively. Because of the rarity of the disease, no group has previously been able to assemble a large cohort of patients with this problem. The investigators of this multicenter project assembled a well-defined group of patients and did a standard set of studies on them— a good example of how cooperation can improve medical care for the whole. The results of these studies were helpful in confirming that only a few variables predict survival in these patients.

Survival rates were lower in patients with cor pulmonale, as measured in this study by elevated right atrial and pulmonary arterial pressures and a decreased cardiac output. The authors noted that less invasive modalities such as history, physical examination, arterial blood gases, and pulmonary function tests including diffusing capacity did not predict survival. Because diffusing capacity is made up of alveolar volume and a transfer factor, it is possible that the latter two could be predictive individually but not when combined. It is difficult to imagine that gas exchange measurements both at rest and during exercise have no relation with survival.

The study followed patients who were not assigned to a specified regimen. The results could have been confounded by drug treatment because 83% of the patients received one or more drugs. Because no drug (including oxygen) has been shown to increase survival in these patients and, indeed, some drugs may be harmful, this may be important. Transplantation is becoming the treatment of choice.

General internists will occasionally see these patients in their practices. Based on this study, it appears they should be referring them to more specialized centers for appropriate diagnostic evaluation and follow-up.

John G. Mohler, MD
University of Southern CaliforniaLos Angeles, California, USA