Systematic review and meta-Analysis of clinical significance of autoantibodies for idiopathic pulmonary fibrosis

Objective To clarify clinical significance of the sole presence of autoantibodies for idiopathic pulmonary fibrosis (IPF) without any other symptoms or signs suggestive of autoimmune disease. Design Systematic review and meta-Analysis Data sources Medline, EMBASE, Science Citation Index Expanded and Google Scholar were searched from 1 January 2002 through 12 February 2019. Eligibility criteria for selecting studies Primary studies addressing all-cause mortality and the development of a defined autoimmune disease for IPF with autoantibodies were included for the review. Data extraction and synthesis Two reviewers extracted relevant data and assessed risk of bias independently. Meta-Analysis was conducted using a random-effects model if three or more studies reported the same outcome for a certain autoantibody. The quality of evidence was assessed by the Grades of Recommendation, Assessment, Development and Evaluation system. Results Out of 4603 records retrieved nine studies were included in this review. All studies contained some risk of bias. Based on pooled data myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) was significantly associated with microscopic polyangiitis incidence with risk ratio (RR) of 20.2 (95% CI: 7.22 to 56.4) and antinuclear antibody (ANA) was also significantly associated with the development of connective tissue diseases with RR of 7.11 (p=0.001) (10 cases in 157 patients with ANA) in one study. However, there was no significant association of autoantibodies with all-cause mortality aside from MPO-ANCA and proteinase 3-ANCA in one study each. MPO-ANCA was not demonstrated to be associated with all-cause mortality by meta-Analysis. The quality of evidence was deemed as either low or very low. Conclusions The presence of autoantibodies such as MPO-ANCA and ANA was demonstrated to be associated with the development of some autoimmune diseases for patients with IPF although there was no difference of all-cause mortality. However, the results should be interpreted with caution due to low evidence level. PROSPERO registration number CRD42017077336.