title: Silica exposure is associated with an increased risk of developing ACPA-positive rheumatoid arthritis in an Asian population: evidence from the Malaysian MyEIRA case-control study.
abstract: OBJECTIVES: Silica exposure has been associated with an increased risk of developing rheumatoid arthritis (RA), especially among smokers. In this study, we aimed at examining the association between silica exposure (and its interaction with smoking) and the risk of RA in the Malaysian population. METHODS: In total, 149 cases and 213 matched controls, all men, were included between August 2005 and December 2009. A case was defined as a person with early diagnosed RA using the 1987 American College of Rheumatology criteria for RA. Controls were randomly selected matched on sex, age and residential area. Silica exposure was defined as exposure to stone dust, rock drilling or stone crushing, and smoking status was categorized as ever/never cigarette smoking. RESULTS: An increased risk of anti-citrullinated protein antibody (ACPA)-positive RA (OR = 2.4, 95 % CI 1.0-5.6) was observed among those exposed to silica. Ever-smokers exposed to silica had a particularly high risk of developing ACPA-positive RA (OR = 7.5, 95 % CI 2.3-24.2), compared with never-smokers not exposed to silica. No association was found regarding ACPA-negative RA. CONCLUSION: Our data demonstrate that exposure to both silica and cigarette smoke comprise risks for developing RA in the Malaysian genetic context. The findings expand a link between environmental lung exposures and ACPA-positive RA to Asian populations.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Nobel väg 13, Box 210, 17177, Stockholm, Sweden, abqariyah.yahya@gmail.com.
authors.forename: Abqariyah
authors.initials: A
authors.lastname: Yahya
authors.forename: Camilla
authors.initials: C
authors.lastname: Bengtsson
authors.forename: Per
authors.initials: P
authors.lastname: Larsson
authors.forename: Chun Lai
authors.initials: CL
authors.lastname: Too
authors.forename: Amal Nasir
authors.initials: AN
authors.lastname: Mustafa
authors.forename: Nor Aini
authors.initials: NA
authors.lastname: Abdullah
authors.forename: Nor Asiah
authors.initials: NA
authors.lastname: Muhamad
authors.forename: Lars
authors.initials: L
authors.lastname: Klareskog
authors.forename: Shahnaz
authors.initials: S
authors.lastname: Murad
authors.forename: Lars
authors.initials: L
authors.lastname: Alfredsson