Arthritis diagnosis and early-life exposure to air pollution

Evaluate the relationship between arthritis diagnosis in those over 50 and exposure to extreme air pollution in utero or infancy (<1 year of age).

Compare rates of arthritis diagnosis between groups that experienced differential air pollution exposure in early-life due to quasi-random variation in birth location and date relative to the 1952 Great Smog in London. We use regression-estimated difference-in-differences analyses based on English Longitudinal Study of Aging (ELSA) data.

In the 2816 respondent sample, aged 51-62, the arthritis diagnosis rate is 22.8%, with 16.4% reporting osteoarthritis and 4.6% reporting rheumatoid arthritis. We estimate that exposure to the Great Smog in infancy increases the arthritis diagnosis rate by 23.4 percentage points (95% CI: 1.97 to 44.8). Decomposing these results by type of arthritis reveals that the rheumatoid arthritis diagnosis rate increases due to infant exposure are larger and more significant than those for osteoarthritis: 14.9 percentage points (95% CI: 0.495 to 29.4) versus 9.5 percentage points (95% CI: -11.9 to 30.8). In utero exposure is not associated with significant increases in arthritis diagnosis rates.

Our results are the first to link early-life air pollution exposure to later-life arthritis diagnoses, and suggest a particularly strong link for RA. These findings are consistent with those of shorter-term, correlational studies, and indicate that health effects of air pollution exposure can span decades and extend beyond cardiopulmonary systems.