Interstitial lung disease, higher risk of respiratory failure linked: Study

Other risk factors include pneumonia, pulmonary hypertension

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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An illustration of a person's lungs.

Systemic sclerosis (SSc) patients with interstitial lung disease (ILD), where the lungs become scarred, are more than three times more likely to be hospitalized due to respiratory failure, according to real-world data collected in the U.S.

Other strong risk factors for respiratory failure among hospitalized SSc patients included pneumonia and pulmonary hypertension, or high blood pressure in the vessels that supply the lungs.

“Outpatient optimization and inpatient recognition of these risk factors can lead to improved hospitalization outcomes for SSc patients,” the researchers wrote.

The study, “Risk Factors for Respiratory Failure in Patients Hospitalized With Systemic Sclerosis: An Analysis of the National Inpatient Sample,” was published in the journal Cureus.

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SSc, a type of scleroderma, can lead to fibrosis (scarring) and damage to not only the skin, but also several internal organs, such as the lungs, kidneys, and heart.

“Although scleroderma [kidney] crisis was previously identified as the leading cause of death in these patients, studies now show a shift to pulmonary complications,” the researchers wrote.

ILD, a group of lung conditions characterized by lung inflammation and fibrosis that often result in respiratory failure, is the leading cause of death in people with SSc.

While identifying potential risk factors of respiratory failure in people with SSc “can be used to improve hospital outcomes,” the researchers wrote, such risk factors remain poorly understood.

Analyzing data from hospitalized adults with SSC

To know more, a team of researchers at Rush University Medical Center in Chicago and the University of Illinois Chicago retrospectively analyzed clinical data from adults with SSc who were hospitalized with or without respiratory failure between 2016 to 2019.

The data were retrieved from the U.S. National Inpatient Sample database, a large, multi-year, population-based dataset.

During that three-year period, a total of 98,840 SSc patients were hospitalized, with respiratory failure being the main cause of hospitalization in 3,930 of them (4%). The remaining 94,910 SSc patients (96%) did not have a main diagnosis of respiratory failure on their hospitalization records.

There were no significant differences between the two groups in terms of age, but patients with respiratory failure were less likely to be women (81.6% vs. 84.7%) and more likely to be African American (20.7% vs. 14.8%).

SSc patients with respiratory failure were also hospitalized for longer (mean stay of 7.7 vs. 5.2 days) and had significantly greater mean total hospital charges ($95,282 vs. $59,257) than those without such event.

The Charlson Comorbidity Index (CCI), a measure of simultaneous health conditions (or comorbidities) was 3.4 in the respiratory failure group compared with 2.9 in those without it. This difference was statistically significant.

In addition, the in-hospital mortality rate was nearly 10 times higher among patients with respiratory failure than among those without (14.5% vs. 1.5%).

Risk factors analyzed

The researchers then conducted statistical analyses to identify the risk factors of respiratory failure-associated hospitalization among SSc patients. After adjusting for potential influencing factors, they found that ILD “was the strongest predictor of respiratory failure,” the team wrote.

Specifically, SSc patients with ILD were more than three times more likely to be hospitalized due to respiratory failure.

The presence of either pulmonary hypertension or pneumonia was also linked to a threefold higher chance of respiratory failure, just slightly less than ILD.

In addition, heart failure was associated with an 81% higher chance of pulmonary failure; smoking with a 42% greater likelihood; and a higher CCI score, indicating more comorbidities, with a 5% increased risk.

“This analysis represents the largest sample to date in assessing risk factors for respiratory failure among SSc inpatients,” the researchers wrote, adding that they “identified CCI, heart failure, ILD, pulmonary hypertension, smoking, and pneumonia to be associated with higher odds of inpatient respiratory failure.”

“Incorporating these variables in discussions with patients may assist with their understanding of the disease and the risks associated with potential inpatient respiratory failure,” they concluded.