ILD Linked to Worse Outcomes in Pulmonary Embolism

BOSTON — Patients with pulmonary embolism (PE) who also present with interstitial lung disease (ILD) have worse outcomes with respect to in-hospital mortality, length of hospital stay, hospital cost, and all-cause readmission, according to results from a new retrospective analysis.

“There’s a lot of evidence now that demonstrates that ILD, in general, leads to worse mortality, morbidity in hospital complications, and overall [outcomes]. It’s not hard to extrapolate this to pulmonary embolism outcomes, too. Unfortunately, there’s not a whole lot of evidence out there to really demonstrate it,” said Leah Yuan, MD, during a presentation of the results at the American College of Chest Physicians (CHEST) 2024 Annual Meeting.

The question is complicated by the nebulous nature of ILD, which includes a diverse set of diseases and etiologies, and different levels of inflammation and fibrosis. It has been employed in the Pulmonary Embolism Severity Index, but counts for only 10 points out of 210. “If you look at ILD and PE outcomes, there’s nothing really out there [in the literature],” said Yuan in an interview. She is a resident physician at Cook County Hospital System.

The new study suggested that ILD could have an important influence and perhaps should have greater weight in risk stratification of patients with PE, she said. “We looked at all-cause readmissions and we looked at in-hospital mortality, [both] of which are significant for increased odds ratio. One thing that I’m very curious to see is whether there is increased PE readmissions [associated with ILD], which is something that we couldn’t find to be significant in our study,” said Yuan

The researchers used data from hospitalizations for PE drawn from the National Readmission Database in 2019, using ICD-10 codes to identify admissions. Among a total of 105,133 patients admitted for PE, 158 patients also had ILD. The mean age was 63.6 years for those without ILD (SD, 0.1) and 66.5 years for those with ILD (SD, 1.3).

Admission with ILD was associated with all-cause readmission (odds ratio [OR], 4.12; P P = .01), a longer length of stay (+2.07 days; P P

In the Q&A period after the presentation, Parth Rali, MD, professor of thoracic medicine and surgery at Temple University, suggested phenotyping patients to better understand the location of the PE in relation to the ILD. “It may not fall into your classic PE classification. It may just depend on where the clot is in relationship to the interstitial lung disease. I think that’s where the field is going to evolve,” he later said in an interview.

“What is interesting is that patients with interstitial lung disease have a lot of fibrotic disease, and they do not need to have a large clot burden to make them sick. An example [is someone] who has undergone a lung transplant evaluation, and if their right lung is completely diseased from interstitial lung disease and if they get a big blood clot on the right side, it doesn’t affect them because the lung is already fibrotic, so the clot doesn’t matter. If they get a small clot [in the left lung], even though if you look at the standard PE classification they may qualify as a low-risk PE or even as an intermediate-low-risk PE, they are much sicker because that’s the functioning part of the lung,” said Rali.

He advised physicians to pay close attention to the location of PEs in relation to fibrotic tissue in patients with ILD. A PE in healthy lung tissue could have an outsized effect on hemodynamics, whereas a PE in fibrotic tissue may be clinically insignificant and not require treatment. “So it goes both ways: You don’t overtreat and you don’t undertreat,” Rali said.

Yuan and Rali disclosed no relevant financial relationships.

Jim Kling is a writer in Bellingham, Washington.