Comparison of Treatment Response in Idiopathic and Connective Tissue Disease-associated Pulmonary Arterial Hypertension.
BACKGROUND
Studies suggest that patients with connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) have a poorer treatment response to therapies for PAH compared with patients with idiopathic PAH (IPAH), but individual randomized controlled trials (RCTs) have been underpowered to examine differences within these subgroups.


OBJECTIVE
To compare the effect of therapy for PAH in CTD-PAH versus IPAH.


METHODS
We obtained individual participant data from phase III placebo-controlled RCTs of therapies for PAH submitted to the U.S. Food and Drug Administration for drug approval. A treatment-by-diagnosis interaction term evaluated differences in treatment response between CTD-PAH and IPAH. Outcomes included change in 6-minute-walk distance (∆6MWD) from baseline to 12 weeks, clinical worsening, and all-cause mortality.


RESULTS
The study sample included 827 participants with CTD-PAH and 1,935 with IPAH from 11 RCTs. Patients with CTD-PAH had less improvement in 6MWD when assigned to active treatment versus placebo compared with patients with IPAH (difference in treatment effect on ∆6MWD in CTD-PAH vs. IPAH, -17.3 m; 90% confidence interval, -31.3 to -3.3; P for interaction = 0.043). Treatment was less effective in reducing the occurrence of clinical worsening in CTD-PAH versus IPAH (P for interaction = 0.012), but there was no difference in the placebo-adjusted effect of treatment on mortality (P for interaction = 0.65).


CONCLUSIONS
Treatment for PAH was less effective in CTD-PAH compared with IPAH in terms of increasing 6MWD and preventing clinical worsening. The heterogeneity of treatment response supports the need for identifying therapies that are more effective for CTD-PAH.
1 Division of Rheumatology.
Rennie L
RL
Rhee
2 Center for Clinical Epidemiology and Biostatistics, and.
Nicole B
NB
Gabler
1 Division of Rheumatology.
Sapna
S
Sangani
2 Center for Clinical Epidemiology and Biostatistics, and.
Amy
A
Praestgaard
1 Division of Rheumatology.|2 Center for Clinical Epidemiology and Biostatistics, and.
Peter A
PA
Merkel
2 Center for Clinical Epidemiology and Biostatistics, and.|3 Pulmonary, Allergy, and Critical Care Division, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
Steven M
SM
Kawut
D000959:Antihypertensive Agents / Q000627:therapeutic use*; D003240:Connective Tissue Diseases / Q000150:complications*; D005080:Exercise Test / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000627:therapeutic use*
D000959:Antihypertensive Agents; D014665:Vasodilator Agents
clinical trial; meta-analysis; pulmonary hypertension