Comorbidities in idiopathic pulmonary fibrosis patients: a systematic literature review

Idiopathic pulmonary fibrosis (IPF) is associated with a fatal prognosis and manifests in patients over 60 years old who may have comorbidities. The prevalence and impact of comorbidities on the clinical course of IPF is unclear. This systematic literature review examined the prevalence of comorbidities and mortality associated with comorbidities in IPF patients. Relevant observational studies published in English from January 1990 to January 2015 identified via MEDLINE and EMBASE were included; bibliographies of articles were also searched. Among the 126 studies included, prevalence of pulmonary hypertension (PH) was 3-86%, 6-91% for obstructive sleep apnoea, 3-48% for lung cancer and 6-67% for chronic obstructive pulmonary disease (COPD). Nonrespiratory comorbidities included ischaemic heart disease (IHD) (3-68%) and gastrooesophageal reflux (GER) (0-94%). Mortality was highest among patients with IPF and lung cancer. Most studies assessed relatively small samples of patients with IPF. PH, COPD, lung cancer, GER and IHD are significant comorbidities; differences in IPF severity, case definitions and patient characteristics limited the comparability of findings. The identification and prompt treatment of comorbidities may have a clinically significant impact on overall outcome that is meaningful for patients with IPF.