# Systematic evaluation of subgroup analyses of inhaled treprostinil in pulmonary hypertension due to interstitial lung disease

## TL;DR

This study evaluates subgroup analyses from a trial on inhaled treprostinil for pulmonary hypertension in interstitial lung disease, finding limited credibility in the reported subgroup effects.

## Contribution

The study systematically assesses the credibility of subgroup effects in the INCREASE trial using multiple methodological tools and identifies a previously unclaimed significant subgroup effect.

## Key findings

- Five claimed subgroup effects did not achieve statistical significance when tested with interaction tests.
- A statistically significant subgroup effect was found for improved exercise capacity in patients with higher pulmonary vascular resistance.
- The credibility of subgroup claims from the original trial authors was found to be very low.

## Abstract

The INCREASE trial introduced a novel therapeutic option for Pulmonary Hypertension caused by Interstitial Lung Disease. Subsequently to this trial, several subgroup analyses were conducted, aiming to explore specific effects within subgroups.

This study aimed to evaluate the subgroup analyses performed in the INCREASE trial and to identify potentially reliable subgroup effects.

A methodological assessment of the subgroup analyses was performed. Claims of subgroup effect were evaluated using three different tools: Sun, X et al. 2012, Gil-Sierra, M.D et al. 2020, and Schandelmaier, S et al. 2020. Additionally, all statistically significant subgroup effects that were not claimed by the authors were evaluated.

Five claims of subgroup effect were identified; none of them achieved statistical significance when assessed using an interaction test. The evaluation conducted with the three tools consistently yielded very low credibility for all the claims. During the assessment, a statistically significant subgroup effect of moderate credibility was identified, which the authors did not claim: iTre appeared to improve exercise capacity exclusively in patients with Pulmonary Vascular Resistance ⋝ 4 WUs.

Due to methodological limitations, the credibility of subgroup claims from the authors of the INCREASE was lacking and, therefore, should not be relied upon to inform decisions on an individual basis.