By Michael Smith, MedPage Today Staff Writer
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco
October 17, 2006
Sweden, Oct. 17 — Having celiac disease is linked to nearly a fourfold increased risk of subsequently developing tuberculosis, researchers here found.
In a cohort study involving nearly 85,000 people in Sweden, those intolerant to the gluten proteins in wheat, barley, and rye were significantly more likely to develop TB than those without celiac disease, according to Jonas Ludvigsson, M.D., of Örebro University Hospital.
Conversely, a prior diagnosis of TB more than doubled the risk of later developing celiac disease, Dr. Ludvigsson and colleagues reported online in Thorax.
While the cause of the association remains unclear, it’s likely that “malnutrition in (celiac disease) leads to malabsorption of a number of nutrients including vitamin D, which increases the risk of TB infection,” the researchers said.
Using the records of the Swedish National Board of Health, Dr. Ludvigsson and colleagues identified 14,335 people diagnosed with celiac disease from 1964 through 2004. They were compared with up to five reference individuals, matched for age, sex, calendar year, and county of residence. The reference cohort consisted of 69,888 persons.
Follow-up began a year after the diagnosis of celiac disease. Neither the patients nor the reference individuals had TB at the beginning of follow-up, the researchers noted.
In a separate analysis, the researchers identified 15,398 persons with prior TB and a later diagnosis of celiac disease, as well as 76,857 reference individuals without later celiac disease.
The study found:
* Celiac disease was associated with an increased risk of subsequent TB. The hazard ratio was 3.74, with a 95% confidence interval from 2.14 to 6.53, which was statistically significant at P<0.001.
* Although celiac disease is more common in women than in men, the risk of subsequent TB was similar. The hazard ratios were 4.12 for men and 3.38 for women, which were significant at P<0.001 and P=0.003, respectively.
* The risk of later TB was also significantly increased both for those diagnosed before and after the age of 15.
* Given prior TB, the risk of developing later celiac disease was more than doubled. The hazard ratio was 2.50, with a 95% confidence interval from 1.75 to 3.55, which was significant at P<0.001.
Because of the study design — in which patients were compared only with matched reference individuals — “important potential confounding factors such as age, sex, calendar year, and geographical location within Sweden have little effect on our risk estimates,” the researchers said.
Also, the study has the advantage of a large sample size, which — combined with the Swedish public healthcare system — minimizes the effect of social class and economic status on the results, Dr. Ludvigsson and colleagues said.
Other studies have shown an increased risk of death for patients with both TB and celiac disease, the researchers noted, and it’s possible that gluten intolerance may complicate existing TB or even increase the severity of the disease.
Primary source: Thorax
Ludvigsson JF et al. “Coeliac disease and risk of tuberculosis: a population-based cohort study.” Thorax 2006; doi: 10.1136/thx.2006.059451.