Abstract
BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a relatively rare disease with increasing incidence trends. Cardiovascular disease is a significant complication in IPF patients due to the role of common proatherogenic immune mediators. The prevalence of coronary artery disease (CAD) in IPF and the association between these distinct pathologies with overlapping pathophysiology remain less studied. RESEARCH QUESTION: We hypothesised that IPF is an independent risk factor for CAD. METHODS: We conducted a retrospective case-control study using the national inpatient sample (2017-2019). We included adult hospitalisations with IPF after excluding other interstitial lung diseases and other endpoints of CAD, acute coronary syndrome and old myocardial infarction. We examined their baseline characteristics, such as demographic data, hospital characteristics and socioeconomic status. The prevalence of cardiac risk factors and CAD was also compared between hospitalisations with and without IPF. Univariate and multivariate regression analysis was further performed to study the odds of CAD with IPF. The cases of IPF in the study population were propensity-matched, after which generalised linear modelling analysis was performed to validate the findings. RESULTS: A total of 116 010 admissions were hospitalised in 2017-2019 with IPF, of which 55.6% were men with a mean age of 73 years. Adult hospitalisations with IPF were found to have a higher prevalence of diabetes mellitus (29.3% vs 24.0%; p<0.001), hypertension (35.6% vs 33.8%; p<0.001), hyperlipidaemia (47.7% vs 30.2%; p<0.0001) and tobacco abuse (41.7% vs 20.9%; p<0.001), while they had a lower prevalence of obesity (11.7% vs 15.3%; p<0.0001) compared with hospitalisations without IPF. Multivariate logistic regression analysis revealed 28% higher odds of developing CAD in IPF hospitalisations (OR -1.28; CI 1.22 to 1.33; p<0.001). Postpropensity matching, generalised linear modelling analysis revealed even higher odds of CAD with IPF (OR -1.77; CI 1.54 to 2.02; p<0.001) CONCLUSIONS: Our study found a higher prevalence of CAD in IPF hospitalisations and significantly higher odds of CAD among IPF cases. IPF remains a terminal lung disease that portends a poor prognosis, but addressing the cardiovascular risk factors in these patients can help reduce the case fatality rate due to the latter and potentially add to quality-adjusted life years.