Zeng Pingling, Bengtsson Camilla, Klareskog Lars, Alfredsson Lars
Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
Rheumatology Unit, Department of Medicine, Karolinska University Hospital, Karolinska Institute, Stockholm, Sweden.
RMD Open. 2017 Aug 16;3(2):e000488. doi: 10.1136/rmdopen-2017-000488. eCollection 2017.
To investigate (1) whether working in cold environment (WCE) is associated with an increased risk of developing rheumatoid arthritis (RA) (overall), anticitrullinated protein antibody (ACPA)-positive RA and ACPA-negative RA and (2) whether WCE interacts with occupational physical workload in conferring RA risk.
Data from the Swedish population-based case-control study Epidemiological Investigation of Rheumatoid Arthritis involving 3659 incident cases and 5925 controls were analysed. Study participants were asked whether they had ever worked in cold/outdoor environment along with their exposure duration and frequency. Occurrence of RA among exposed and unexposed subjects were compared by calculating ORs with 95% CI using logistic regression. Additive interactions between WCE and six types of physical workload were assessed using the principle of departure from additivity by calculating attributable proportion due to interaction (AP).
The OR associated with having ever worked in cold environment was 1.5 (95% CI 1.4 to 1.7) for RA (overall), 1.6 (95% CI 1.4 to 1.8) for ACPA-positive RA and 1.4 (95% CI 1.2 to 1.6) for ACPA-negative RA. The risk of developing RA increased with increasing cumulative dose of working in cold indoor environment (p value <0.001), but not working in cold outdoor environment. Positive additive interaction was observed between WCE and repetitive hand/finger movements (AP 0.3 (95% CI 0.1 to 0.5)).
WCE is associated with increased risk of developing both ACPA-positive and ACPA-negative RA. A dose-response relationship was found between working in cold indoor environment and risk of developing RA. Moderate additive interaction was observed between exposure to cold environment and exposure to repetitive hand/finger movements.
调查（1）在寒冷环境中工作（WCE）是否与类风湿关节炎（RA）（总体）、抗瓜氨酸化蛋白抗体（ACPA）阳性RA和ACPA阴性RA发病风险增加相关，以及（2）WCE在赋予RA风险方面是否与职业体力负荷相互作用。
分析了瑞典基于人群的病例对照研究——类风湿关节炎流行病学调查的数据，该研究涉及3659例新发病例和5925名对照。研究参与者被问及他们是否曾在寒冷/户外环境中工作及其暴露持续时间和频率。通过使用逻辑回归计算95%可信区间（CI）的比值比（OR），比较暴露组和非暴露组中RA的发生情况。利用偏离相加性的原理，通过计算交互作用归因比例（AP），评估WCE与六种体力负荷类型之间的相加交互作用。
曾在寒冷环境中工作与RA（总体）的OR为1.5（95%CI 1.4至1.7），ACPA阳性RA为1.6（95%CI 1.4至1.8），ACPA阴性RA为1.4（95%CI 1.2至1.6）。在寒冷室内环境中工作的累积剂量增加时，患RA的风险增加（p值<0.001），但在寒冷户外环境中工作则不然。在WCE与重复性手部/手指运动之间观察到正向相加交互作用（AP 0.3（95%CI 0.1至0.5））。
WCE与ACPA阳性和ACPA阴性RA发病风险增加相关。在寒冷室内环境中工作与患RA风险之间存在剂量反应关系。在寒冷环境暴露与重复性手部/手指运动暴露之间观察到中度相加交互作用。
