Lung Involvement Increases Patients’ In-hospital Risk of Death, Costs

Having lung involvement increases the risk of in-hospital mortality, the length of hospital stays, and the costs related to hospitalization in people with scleroderma, a study of U.S.-based data finds.

The study, “Lung involvement in systemic sclerosis is associated with adverse hospital outcomes: insights from the National Inpatient Sample,” was published in the Journal of Investigative Medicine.

Scleroderma is mainly divided into two subtypes, limited or diffuse, depending on the extent of skin thickening and the degree of internal organ damage. The lungs are frequently affected in both, however, with pulmonary manifestations such as pulmonary arterial hypertension and pulmonary fibrosis (scarring) representing leading causes of death.

Co-existing conditions can have a great impact on prognosis, treatment, and disease outcome, and are related with worse health status.

As such, knowing the risk factors for mortality is a key step toward a potential improvement in disease outcomes. However, large-scale studies in the U.S. population to clarify if lung involvement is associated with worse outcomes in scleroderma patients are still lacking.

To address this gap, a team of researchers used the National Inpatient Sample (NIS) database, the largest publicly available inpatient registry in the U.S., to find information spanning 2016 to 2017.

The study’s primary goal was to compare in-hospital mortality between patients with and without lung involvement. As secondary goals, the study assessed the length of stay at the hospital and the total hospital expenses in both groups of patients.

The team analyzed 62,930 hospitalizations of adults with scleroderma — 5,095 (8.1%) with lung involvement and 57,835 (91.9%) without.

Overall, the group with lung involvement had a lower proportion of women (79.96% vs. 84.97%) and was younger (mean age of 59.1 vs. 62.95). These patients also were more likely to be followed in teaching and/or large bed-size hospitals than the group whose disease did not affect the lungs.

In addition, the proportions of Blacks also was higher among those with lung involvement (22.51% vs. 15.17%).

A total of 2,980 hospitalizations (4.74%) resulted in death. The group with lung involvement showed a higher proportion of deaths when compared with the other patients (9.04% vs. 4.36%), which corresponded to a nearly two times greater risk of mortality.

Over the study period, patients with lung disease had longer mean hospital stays (8.38 vs. 5.97 days), as well as higher total hospital-related costs: $109,565 vs. $65,187.

Additionally, patients with pulmonary involvement were more likely to have co-existing conditions such as atrial fibrillation/flutter, a type of abnormal heart rhythms (15.8 vs. 13.3%), and congestive heart failure (33.79 vs. 24.7%). Smoking habits also were more frequent in this group of patients (27.38 vs. 23.44%).

These findings did not surprise the researchers given that those conditions and habits are more frequent in patients with pulmonary conditions, they said.

According to the team, the higher presence of co-existing diseases is related with the increased risk of mortality and longer hospital stays. Consequently, healthcare-related expenses in these patients are expected to be higher as well.

“This has a great impact on hospital resources such as healthcare costs, as patients with SSc [scleroderma] are most likely to incur high costs in subsequent years of treatment,” the team wrote.

As such, the scientists believe that co-existing disorders are important factors to consider in the construction of health-related quality of life models in scleroderma.

A multidisciplinary collaboration in improving disease outcomes also is important. “Interdisciplinary approach involving the pulmonologist and the rheumatologist is important in optimizing outcomes of SSc hospitalizations with lung involvement,” the investigators wrote.