Chronic obstructive pulmonary disease is one of the leading causes of mortality and morbidity worldwide. Thus, it was found to be the eight greatest cause of health loss in the 2016 Global Burden Disease Study. The prevalence in the adult population in Finland has been estimated at between 3% and 9%. COPD is an extremely complex condition and the severity of the disease can be classified according to symptoms, history of exacerbations and airflow limitation assessed using spirometry.
The economic burden associated with with the disease is substantial and is likely to continue to rise in the future. The aim of this study was to describe healthcare resource utilization (HCRU) and associated costs in patients with COPD in Finland, according to disease severity and eosinophil level. In addition, we aimed to determine all-cause and COPD-related mortality in these patient groups.
This retrospective registry study utilized real world evidence (RWE) data from the Hospital District of Southwest Finland collected from 2004 to 2015. Based on the latest guidelines, patients with ever recorded post-bronchodilation fixed ratio of forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) of <0.70 were classified as having non-severe (FEV1 >50 % predicted) or severe (FEV1≤50 % predicted) COPD. Patients who were initially non-severe but progressed to severe were classified as having progressing COPD. Patients were also categorized according to blood eosinophil counts (under or over 300 cells/µl). The total and COPD-related HRCU, including hospital inpatient days, outpatient visits, emergency room visits, hospital laboratory tests and procedures, was determined and compared between the different levels of disease severity. All-cause and COPD-related times of death were obtained through Statistics Finland.
A total of 9052 patients with chronic obstructive pulmonary disease were included in the analysis, which of complete spirometry history was available for 1060 patients. Out of those, 340 had non-severe, 326 progressing and 394 severe COPD. Patients without spirometry data were classified as clinically verified COPD (n=7982). Eosinophil measurements were available in 31.8 % of patients, which of 31.3 % had had increased blood eosinophil counts (≥300 cells/μL). Patients with severe COPD had a slightly higher rate of HCRU compared to those with the non-severe disease. Total HCRU costs per patient year were similar across COPD severity groups, however, COPD-related HCRU costs were higher in patients with severe disease compared with those with the non-severe disease. All-cause mortality was 45.9 % during the study period and the overall survival was reduced in patients with severe COPD and clinically verified COPD compared to patients with the non-severe disease. When patients were classified by blood eosinophil count, those with a blood eosinophil counts ≥300 cells/μL had had higher overall HRCU but improved overall survival compared with those with a blood eosinophil counts >300 cells/μL.
The present RWE study demonstrates that chronic obstructive pulmonary disease represents a substantial healthcare burden in Finland, which appears to be particularly high in patients with severe COPD and probably also in patients with severe eosinophilic COPD. The association of eosinophilia with better survival needs to be confirmed in future studies. Importantly, this study supports that blood eosinophil counts may be a useful biomarker for assessing disease burden in patients with COPD and identifying those who may benefit from alternative treatment strategies.