Association of ambient air pollution with hospital admissions for major osteoarthritis diseases: A national case-crossover study in China

Objectives: To investigate the acute effects of short-term exposure to ambient air pollution on the risk of hospital admissions for osteoarthritis (OA) and its major subtypes. Methods: Hospital admission data on OA and its major subtypes were sourced from two major urban medical insurance systems in China, covering the period from 2013 to 2017. A two-stage, time-stratified case-crossover design was used to investigate the acute effects of short-term exposure to ambient air pollutants on hospital admissions for OA across 278 Chinese cities with available hospital admission data over 50 cases. The conditional logistic regression model was utilized to assess city-specific associations, which were subsequently pooled by employing a random-effects model. Results: A total of 1,404,095 OA-related hospital admissions were included. At the main time windows, per interquartile range increases in PM_2.5 (particulate matter with an aerodynamic diameter of ≤ 2.5 μm), PM₁₀ (particulate matter with an aerodynamic diameter of ≤ 10 μm), NO₂ (nitrogen dioxide), SO₂ (sulfur dioxide), O₃ (ozone), and CO (carbon monoxide) were associated with significant increases in OA-related admissions by 0.70 % (95 % CI: 0.12 %, 1.28 %), 1.08 % (95 % CI: 0.47 %, 1.69 %), 4.50 % (95 % CI: 3.36 %, 5.65 %), 2.75 % (95 % CI: 1.79 %, 3.72 %), 1.33 % (95 % CI: 0.57 %, 2.10 %) and 1.77 % (95 % CI: 0.76 %, 2.79 %), respectively. Short-term exposures to ambient air pollutants were also associated with increased hospital admissions for major OA subtypes, especially gonarthrosis. The attributable fractions of OA admissions ranged from 0.87 % for PM_2.5 to 6.22 % for NO₂. Conclusions: Short-term exposure to ambient air pollution is significantly associated with an increased risk and burden of OA admissions.