The demographic and clinical characteristics of patients with idiopathic pulmonary fibrosis (IPF) in Spain are similar to those of IPF patients in other countries, allowing for comparison with other registries and cohorts, a study has found.
The study, “Demographic and Clinical Profile of Idiopathic Pulmonary Fibrosis Patients in Spain: the SEPAR National Registry,” was published in the journal Respiratory Research.
IPF is a chronic disease characterized by pulmonary scarring (fibrosis), and a progressive and irreversible decline in lung function.
“Little is known on the characteristics of patients diagnosed with IPF in Spain,” the researchers said. Therefore, they decided to investigate the demographic and clinical profiles of patients included in the IPF National Registry of the Spanish Respiratory Society (SEPAR).
The investigation involved 608 patients included in the SEPAR IPF Registry between 2012 and 2017, and who received any treatment for their disease. A total of 28 public hospitals throughout Spain participated in the study.
Results showed that IPF patients were predominantly male (80.8%), ex-smokers (63.7%), and in their 70s. Time from the onset of symptoms to diagnosis was 20.4 months.
At the time of diagnosis, the patients showed signs that were indicative of IPF. A total of 89.6% of the patients had inspiratory bibasilar crackles (abnormal sounds from the base of the lungs), 84.7% experienced dyspnea (difficulty breathing), 62.8% had non-productive cough, and 29.4% had digital clubbing (deformity of the fingertips or toes).
The mean predicted forced vital capacity of the patients was 77.6%. Forced vital capacity (FVC) measures the total volume of air that can be blown forcefully following a full inhalation. The normal range is between 80% and 120%.
The diffusing capacity for carbon monoxide (DLCO) of the patients was 48.5%. DLCO measures the ability of the lungs to transfer gas from inhaled air to red blood cells in pulmonary capillaries. The normal range is 80%–120%.
The 6-min walk distance (6MWT) was 423.5 meters. This test of exercise capacity measures the distance an individual is able to walk on a hard, flat surface in six minutes. In healthy subjects, this ranges from 400 to 700 m.
Of note, while some IPF features are common to all countries — such as male predominance, mean age in the 70s, and smoking history — the mean FVC, DLCO, and 6MWD have been found to vary widely in different studies. The team suggested that this may depend on the different methodologies and types of centers used.
The median survival time of the patients analyzed was 5.8 years after diagnosis. DLCO at diagnosis was the only factor significantly associated with mortality in this study — 39.1% lower risk of death per 10 units of DLCO (%) increase.
Patients with IPF have a higher risk of developing comorbidities. In this study, 15.8% of the patients had diabetes, 15.6% had other chronic respiratory disease, 12.8% had gastroesophageal reflux, 12.1% had pulmonary emphysema, 8.6% had coronary artery disease, and 6.2% had pulmonary hypertension.
The IPF diagnosis was established mainly based on high-resolution computed tomography in the proper clinical context (55% of patients), while 21.2% of patients required invasive procedures (surgical lung biopsy) for a definitive diagnosis.
Patients receiving Esbriet showed a stable lung function based on FVC (71.5% of predicted) and DLCO (47.2% of predicted) after 12 months of treatment. The mean 6MWT distance was similar after 12 months of treatment (429.9 meters).
Eight patients (3.5%) receiving Esbriet died during the first 12 months of treatment, while 55 patients (23.8%) died during the follow-up period. Their median survival time was 5.8 years after diagnosis, which is similar to the median survival rate of the total patients analyzed.
This finding did not agree with other studies, such as the European Registry, which reported a significant improvement in survival rate in patients receiving anti-fibrotic treatment after seven years of follow-up, when compared with patients not receiving it.
“Although no definitive explanation can be provided, we suppose it is because pirfenidone [Esbriet] has been only available to patients with FVC lower than 80% for a long time in most of Spanish hospitals,” the team said.
Based on the results, the overall “demographic characteristics of patients from the SEPAR IPF National Registry are in accordance with other national registries,” the researchers said.
“The SEPAR IPF Registry should help to further characterize current characteristics and future trends of IPF patients in Spain, and compare/pool them with other registries and cohorts,” the team said.