Outcomes associated with modern treatment paradigms in connective tissue disease (CTD)-associated pulmonary arterial hypertension (PAH): a meta-analysis of randomized controlled trials (RCTs)
Authors: McLaughlin V , Zhao C , Coghlan J.G , Chung L.S , Mathai S.C , Saggar R , Shah M , Hartney J , Khanna D 
Published: November 2020

Abstract

Background
CTD-PAH has historically represented a PAH subtype with poor prognosis. New therapies, as well as combination therapy approaches targeting multiple pathways have been approved for PAH based on RCTs. CTD-PAH patients comprise a subgroup of the RCT populations and efficacy analyses are based on subgroup analyses which can be less reliable than the overall analysis. We conducted a meta-analysis of RCTs of approved PAH therapies to evaluate outcomes of patients with CTD-PAH.

Purpose
To use meta-analysis to determine response to treatment in patients with CTD-PAH.

Methods
The PubMed and EMBASE databases were searched for English-only articles published between January 1, 2000 and November 25, 2019. Inclusion criteria were multicenter RCTs that enrolled adults with WHO group 1 pulmonary hypertension (PAH); enrollment in 2000 or later; long-term clinical morbidity and/or mortality event or 6-minute walk distance (6MWD) as an efficacy endpoint reported for ≥30 patients with CTD-PAH; and evaluation of a US Food and Drug Administration-approved PAH therapy. The primary outcomes were treatment effect as measured by the study time to first morbidity or morality event and change in 6MWD from baseline to between 3–6 months, per the data provided in each article. Results from individual studies were combined using a random-effects model for overall study population (PAH patients) and the subgroup of CTD-PAH patients.

Results
Ten RCTs (N=4329 PAH patients; n=1263 (29%) with CTD-PAH) met inclusion criteria and were included in the meta-analysis. At baseline, PAH patients had a mean age of 50 years, approximately 78% were female, and approximately 58% had functional class III or IV disease. These characteristics were balanced between treatment and control groups. Baseline 6MWD was 356 m for the overall population and 337 m for patients with CTD-PAH. Five RCTs (N=3172; n=941 with CTD-PAH [30%]) reported hazard ratios (HRs) for time to a morbidity or mortality event by drug treatment and PAH etiology: overall population HR=0.63 (95% confidence interval [CI], 0.56–0.72; P&lt;0.001); CTD-PAH population HR=0.64 (95% CI, 0.51–0.80; P&lt;0.001) (Figure). Nine RCTs reported mean change with drug treatment from baseline to 3 to 6 months in 6MWD for PAH and CTD patients: 33.9 m (95% CI, 21.9–45.9; P&lt;0.001) in the overall population; 20.2 m (95% CI, 10.8–29.7; P&lt;0.001) in CTD-PAH patients.

Conclusions
The improvement in 6MWD in patients with CTD-PAH is smaller than in those with other types of PAH, perhaps reflecting comorbidities and CTD-induced mobility constraints, independent of their cardiopulmonary capacity. Data from long term clinical morbidity/mortality endpoint studies in this large group of patients with CTD-PAH demonstrate that these patients derive significant benefit from currently available PAH therapies which, in many patients, comprised the addition of a drug targeting a second or third pathway involved in the pathophysiology of PAH.
Treatment effect on morbidity/mortality

Funding Acknowledgement
Type of funding source: Private company. Main funding source(s): Actelion Pharmaceuticals US, Inc.