medwireNews: A positive fecal immunochemical test (FIT), indicating the presence of hemoglobin, may point to an increased risk for developing rheumatoid arthritis (RA) in the general population, researchers report.
“Our result underscores that in those with a positive FIT, articular symptoms should be vigilantly monitored,” say Sung Soo Ahn (Yonsei University College of Medicine, Yongin, Republic of Korea) and colleagues.
As reported in BMC Medicine, the analysis included over 1 million people with an average age of 62 years who participated in the Korean nationwide colorectal cancer screening program in 2009–2013 and were categorized according to whether they had a positive (n= 229,594) or negative (n= 815,361) FIT result for fecal hemoglobin in the absence of gastrointestinal bleeding. People with a history of colorectal cancer, inflammatory bowel disease, or immune-mediated inflammatory diseases were excluded from the study.
During an average follow-up of 7.6 years, RA was diagnosed in 0.83% of individuals positive for fecal hemoglobin and 0.70% of those with a negative result. The age- and sex-adjusted incidence rate per 10,000 person–years was numerically higher in those with versus without fecal hemoglobin (10.11 vs 8.96), albeit without reaching statistical significance.
However, people with FIT positivity had a significant 16% higher risk for RA than those with a negative result in a multivariable analysis accounting for factors including comorbidities, lipids, BMI, and lifestyle factors.
The researchers also carried out propensity score matching to account for differences in baseline characteristics between the two groups, finding that the presence of fecal hemoglobin was associated with a significant 18% increased RA risk in the matched population (n=437,250).
Ahn and team note that RA incidence was highest in the first year of a positive FIT test and decreased over time, which they say indicates “that early referral to a rheumatology department is imperative when there is persistent, multiple joint pain, or those showing signs suggestive of RA.”
In contrast to the findings with RA, the researchers observed no such associations between fecal hemoglobin and the risk for psoriatic arthritis or systemic lupus erythematosus.
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