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BACKGROUND: Rheumatoid arthritis may be an emerging condition among 9/11-exposed populations. Silica and other constituents of the dust resulting from the collapse of the World Trade Center (WTC) on September 11, 2001, and posttraumatic stress disorder (PTSD) have been previously linked to an increased risk of rheumatoid arthritis (RA). The objectives of this study are to better characterize self-reported post-9/11 autoimmune diseases (AD), specifically RA, and to determine if 9/11-specific exposures or PTSD are associated with incident disease.
METHODS: The WTC Health Registry is a cohort of 71,431 persons who were exposed to the September 11, 2001 attack on the WTC and its aftermath. The Registry has conducted three major health surveys, Wave 1 (2003-2004), Wave 2 (2006-2007), and Wave 3 (2011-2012). In 2014, enrollees who reported on their Wave 3 survey that they had been diagnosed with RA or another AD after 9/11 (n=2786) were sent an AD survey that queried their symptoms, medications, family history, and general health status. The Connective Tissue Disease Screening Questionnaire (CSQ) was included to screen participants for a number of ADs, including RA. Probable RA was defined as meeting ≥4 of the following 6 CSQ criteria: morning joint stiffness for ≥1 hour for ≥ 6 weeks; swelling of ≥3 joints for ≥ 6 weeks; swelling of the wrists, metacarpophalangeal or proximal interphalangeal joints for ≥ 6 weeks; symmetric joint swelling; rheumatoid nodules; or a positive blood test for RA. RA cases were compared to Wave 3 participants who did not report an AD (i.e., controls), using chi-square tests of association and multivariable logistic regression.
RESULTS: A total of 1977 (71%) enrollees responded to the AD survey. Among those who reported post-9/11 RA at Wave 3 (n=1498, 76%), we identified 596 (40%) who screened positive for probable RA based on the CSQ criteria in the AD survey. 39% of RA cases screened positive for PTSD at Wave 1, compared with 13% of controls (p<.0001). In a multivariable analysis controlling for age, race, and sex, probable PTSD at Wave 1 and exposure to the dust cloud on 9/11 were associated with incident RA (p-values <.0001 and 0.0366, respectively.)
CONCLUSIONS: Results of this study are preliminary, though they suggest that RA may be associated with 9/11 exposures and its aftermath, including PTSD. Physician confirmation of self-reported RA and other AD diagnoses is planned as the next phase.