Figure 1.

Study flow diagram. Out of a total of 827 records identified searching through five electronic databases, that is, Medline, EMBASE, Science Citation Index Expanded, Cochrane Central Register of Controlled Trials and Google Scholar, 645 records were screened by titles and abstracts after removing 182 duplicates. After excluding 320 records consisting of non-English reports (n=16) and articles of ineligible types (n=304) (conference proceedings (n=153), case reports (n=72), editorials or letters (n=10) and review articles (n=69)) and 265 irrelevant reports, 60 records were retrieved as full-texts. Out of these, 31 records were excluded due to no specific pulmonary disease (n=7), no ILD (n=5), no risk estimates (n=11), no anti-CCP antibody (n=7) and no RA (n=1). The remaining 29 reposts/studies were eligible for the review and additionally four reports were identified through a hand-search of references of eligible studies. As a result, a total of 33 reports/studies were considered for the review. Among them, four studies were excluded due to overlapped cohorts by other studies and finally a total of 29 studies/cohorts were focused for further analysis. CCP, cyclic citrullinated peptide; ILD, interstitial lung disease.