Tea drinkers may be at risk for rheumatoid arthritis

Women who drink tea increase their risk of rheumatoid arthritis (RA), more than women who do not drink tea (P=0.04) or women who drink coffee, according to a US-based prospective cohort study.

“Given that we don’t really know why some people get RA and others do not, we are always searching for any potential causal effects,” said lead researcher Professor Christopher Collins, of the Washington Hospital Center and assistant professor of Medicine at Georgetown University in Washington, DC, US. “The relationship between coffee and tea and RA has, in fact, been looked at before in at least three other large epidemiologic studies, but with different results.”

Collins and colleagues examined data from 76,643 women, aged 50-79, participating in the Women’s Health Initiative Observational Study (WHI-OS), who reported whether they drank tea or coffee daily. RA diagnosis was determined by validated self-reporting and use of anti-rheumatic drugs.

At a 3-year follow up, 193 women had developed RA. After adjusting for race, education, smoking, alcohol use, body-mass index and hormone use, RA was positively associated with tea drinking in trend tests. Compared to women who did not drink tea, women who drank more than four cups of tea per day had a hazard ratio of 1.78 (confidence interval 0.83-3.82).

Women who developed RA in the cohort were not at risk for RA in other ways, after accounting for known potential risk factors, Collins said.

The researchers presented their results at the Annual Congress of the European League Against Rheumatism, held recently in Rome, Italy.

The study initially focused on potential associations between RA and coffee preparation and consumption, for which there were more detailed questions on the WHI-OS questionnaire.

However, the results showed no association between coffee consumption and RA (P=0.16), whether it was filtered, unfiltered, caffeinated or decaffeinated.

By contrast, the tea-related questions were vague, limited to ascertaining whether participants drank tea and if so how much. Data on type of tea and preparation were not available.

The researchers plan to re-evaluate the tea-drinking participants in the WHI-OS database for any unique or different attributes, but detailed information would be necessary to determine which types of tea are implicated in RA.

However, Collins said discontinuing tea consumption is not necessary at this point because the data is not specific.

“First, all we have is blanket terminology of ‘tea’ which encompasses a wide spectrum of beverages,” he said. “Second, other studies have either found no effects with tea or… a protective effect, so clearly this is a topic with a lot of variation in observed outcomes. Our study is more a piece of data in an attempt to better understand potential risk factors for disease.”

Source: mims.com