Investigators Explore Seasonal Trends for Interstitial Lung Disease Hospitalizations

Trend data on interstitial lung disease (ILD) show declining hospitalizations rates, but stable mortality rates.

A team, led by An Thi Nhat Ho, MD, Saint Louis University Hospital, investigated trends and seasonal variations in hospital admissions and mortality rates of interstitial lung disease from 2006-2016.

There currently is abundant data on the trends and seasonal variation of chronic obstructive lung disease and asthma. However, more recent data for interstitial lung disease still needs to be elucidated.

In the study, planned for presentation at the American Thoracic Society (ATS) 2020 International Conference this year,, the investigators examined all cases with the International Classification of Diseases (ICD)-9 or ICD-10 codes of interstitial lung disease of any cause from the Nationwide Inpatient Sample database.

The team also calculated hospitalization rates of each year based on US Census population data and analyzed monthly hospitalization rates and in-hospital mortality rates by seasonal and trend decomposition.

Between 2006-2016 there was a downtrend in all-cause hospital admissions. However, in-hospital mortality rates did not change, with or without the presence of pneumonia.

The investigators found the highest hospital admission rates for the disease per 100,000 people were from January to May, where the average number of hospitalizations in spring, summer, fall, and winter months were 7447.9 ± 932.0, 6643.0 ± 840.5, 6551.3 ± 922.6 and 7110.3 ± 866.1, respectively.

The all-cause in-hospital mortality rates ranged from 7.13% ± 0.79% in the summer to 8.13% ± 0.60% in the winter with winter months having the highest mortality rate (P = 0.018).

In addition, the seasonal variations of hospital admission rates and mortality rates were not changed by infectious pneumonia cases being ruled out.

In 2018, researchers found the presence of nearly any gram-negative bacteria is likely a risk factor for worse clinical outcomes in patients with interstitial lung diseases.

A team of investigators from Beaumont Health Systems in Michigan reported that patients hospitalized with ILD face worse outcomes in mortality, intensive care unit (ICU) admission, and vasopressor use rates in the event of any gram-negative bacteria infection, excluding Pseudomonas Aeruginosa (PA).

Led by Hira Iftikhar, MD, MBBS, investigators were working with the already evidenced fact that respiratory microbiome alterations are a predisposing factor for ILD. They instead sought to uncover the influence of bacteria’s virulence on such patients’ clinical outcomes, particularly in a hospital setting.

Across the 472 patients, 789 inpatient visits were assessed, and 170 different cultures were collected. Respiratory culture specimen included sputum, bronchioloalveolar lavage fluid, pleural fluid, endotracheal aspirate, and lung biopsy tissue.

The most common diagnoses among the admitted patients were idiopathic pulmonary fibrosis (40.6%) and Sarcoidosis (27.6%). The plurality of observed respiratory isolates were PA (38.8%), MRSA (26.5%), and other non-PA Gram-negative pathogens (17.6%). Investigators noted that the use of immunosuppressant medications or anti-fibrotics did not influence the development of resistant pathogens.

In consideration to rates of ICU admission, more than half (53.6%) of patients observed with non-PA Gram-negative pathogens were admitted. Though the greatest prevalence of intubation was observed in patients with MRSA (62.2%), a majority of non-PA Gram-negative patients (53.6%) also reported intubation.

However, the new data shows some positive annual data in this patient population.

“From 2006 to 2016, admission rates of ILD declined but in-hospital mortality remained unchanged,” the authors wrote. “All-cause hospital admissions and mortality of ILD have a strong seasonal variation. Hospital admissions are highest in the period from January to May, in-hospital death was highest in the winter.”

The abstract, “Trends and Seasonal Variation of Hospitalization and Mortality of Interstitial Lung Disease in the United States from 2006 to 2016,” was published online by the ATS International Conference.