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Prognostic Factors Associated with Survival in 860 PAH Patients Treated With Subcutaneous Treprostinil Over a 3 Year Period

C. Arneson

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Conference: 2008 International PHA Conference and Scientific Sessions

Release Date: 06.20.2008

Presentation Type: Abstracts

Arneson C.

United Therapeutics Corporation, Silver Spring, MD, USA

BACKGROUND: Parenteral prostacyclins are a mainstay in the treatment of pulmonary arterial hypertension (PAH). Current treatment guidelines suggest parenteral prostacyclins as options for patients across the spectrum of disease, and as recommended first line agents in patients with most advanced disease. An assessment of treatment outcomes across different markers of disease severity can guide optimal use of therapies. Previous studies have assessed factors associated with survival in patients receiving prostanoids: [Sitbon et al 2002 (n=178), Miyamoto et al 2000 (n=38), and Paciocco et al 2001 (n=27)].  There were 860 patients enrolled in a long term SC treprostinil trial in a period forming the largest prostanoid database from which factors associated with survival can be ascertained.

METHODSBaseline variables that were assessed in univariate and multivariate analyses included: etiology, NYHA, PAPm, RAPm, SvO2, PCWPm, CI, PVRI, duration of PAH, time at current FC, HIV status, age, sex, race.  Of these, only etiology, NYHA functional class, SvOand PVRI were found to be associated with survival.  Kaplan Meier estimates for survival at years 1, 2, and 3 were generated in addition to relative risk within each prognostic factor across each of the categories compared to a reference parameter.

RESULTSThe Results are summarized in the table below: 

Prognostic Factor

Categorization

Relative Risk (95% CI)

(vs. reference)

3 year survival

Etiology

Congenital Heart Defect (CHD)

0.552 (0.336, 0.908)

87%

IPAH

reference

73%

Connective Tissue Disease (CTD)

1.92 (1.35, 2.74)

50%

NYHA Class

FC II

0.781 (0.496, 1.232)

79%

FC III

reference

72%

FC IV

2.29 (1.50, 3.50)

52%

SvO2 

Quartile 4 Q4: >69 %

0.297 (0.170, 0.520)

84%

Quartile 3: >64-69 %

0.328 (0.192, 0.559)

82%

Quartile 2: >55-64 %

0.430 (0.271, 0.684)

73%

Quartile 1: ≤55 %

reference

54%

PVRI

mmHg/L/min/m2

Quartile 1: ≤16

reference

81%

Quartile 2: >16-22

1.21 (0.655, 2.23)

77%

Quartile 3: >22-30

1.26 (0.701, 2.28)

75%

Quartile 4: >30

2.49 (1.47, 4.21)

59%

COMMENTS AND CONCLUSIONS: Patients who begin SC treprostinil therapy with moderate symptoms of disease (eg. FC III) are twice as likely to survive over three years as compared to those with severe symptoms of disease (eg FC IV).  Similarly, patients with lower PVRI also were approximately 2 fold more likely to survive than those with worse hemodynamics.  These data suggest that patients receiving treatment earlier in disease are less likely to experience disease progression over three years.