Factors that prognosticate mortality in idiopathic pulmonary arterial hypertension: a systematic review of the literature

Rationale: There is a lack of consensus on factors that predict mortality in idiopathic pulmonary arterial hypertension (IPAH). Tests that can accurately predict prognosis are needed to guide treatment and counsel patients.

Methods: We conducted a systematic review to identify factors that prognosticate mortality in IPAH. Study design, cohort size, comparison method, measured value, and statistical significance was extracted for eight pre-selected parameters [pulmonary vascular resistance (PVR), mean pulmonary arterial pressure (mPAP), mean right atrial pressure (mRAP), cardiac output, right ventricular end diastolic pressure, functional class, 6 min walk distance (6MWD), and diffusing capacity of carbon monoxide].

Results: 107 factors have been associated with mortality in IPAH. A reproducible predictive association with mortality was demonstrated for only 10 factors: functional class (14 studies), heart rate (10 studies), 6MWD (8 studies), pericardial effusion (5 studies), mPAP (10 studies), mRAP (17 studies), cardiac index (13 studies), stroke volume index (4 studies), PVR (10 studies), mixed venous PaO(2) or saturations (4 studies). Of the 8 factors chosen for detailed evaluation, there were at least half as many studies that evaluated the variable and did not find an association with mortality compared to those that did.

Conclusions: There is a large body of literature describing numerous factors that predict mortality in IPAH. Most factors have been assessed in very few studies. There are conflicting reports on the prognostic value of many factors. These discrepancies highlight the need to evaluate the literature in total when considering the utility of variables as prognostic factors in IPAH.