Han 2013.

Methods	Double‐blind, placebo‐controlled trial 12 weeks duration
Participants	Inclusion criteria: Consensus criteria‐defined IPF and CO diffusing capacity < 35% predicted Evidence of right ventricular hypertrophy or right ventricular dysfunction. Exclusion criteria: Resting oxygen saturation < 92% on 6 L of supplemental oxygen Aortic stenosis Idiopathic hypertrophic subaortic stenosis Severe heart failure (left‐sided VEF < 25%) (WHO Group 3) N = 119
Interventions	Oral sildenafil (20 mg 3 times a day) (N=56) compared with placebo (N=63)
Outcomes	6MWD SGRQ SF‐36 EuroQol visual analogue scores
Notes	This was a substudy of the STEP‐IPF study which examined all participants with IPF and compared sildenafil with placebo This substudy examined only those with pulmonary hypertension and IPF Industry‐funded Trial conducted at 14 centres in the USA, dates of enrolment not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants meeting eligibility criteria were randomly assigned in a 1:1 ratio to receive sildenafil or matched placebo with the use of a permuted‐block design, with stratification according to clinical centre
Allocation concealment (selection bias)	Low risk	Placebo‐controlled
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Placebo‐controlled
Blinding of outcome assessment (detection bias) All outcomes	Low risk	All echocardiograms were performed prior to randomisation and scored independently and in a blinded fashion by two cardiologists with advanced expertise in echocardiography.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Quote: "Sixty‐one echocardiograms could not be transferred to the study centre, thus ineligible for inclusion".
Selective reporting (reporting bias)	High risk	This is a substudy
Other bias	Low risk	Other bias is unlikely