Previous research suggests an association of celiac disease (CD) with anorexia nervosa (AN), but data are mostly limited to case reports. We aimed to determine whether CD is associated with the diagnosis of AN.
Register-based cohort and case-control study including women with CD (n = 17 959) and sex- and age-matched population-based controls (n = 89 379). CD (villous atrophy) was identified through the histopathology records of Sweden’s 28 pathology departments. Inpatient and hospital-based outpatient records were used to identify AN. Hazard ratios for incident AN diagnosis were estimated by using stratified Cox regression with CD diagnosis as a time-dependent exposure variable. In the secondary analyses, we used conditional logistic regression to estimate odds ratios for being diagnosed with AN before CD.
Median age of CD diagnosis was 28 years. During 1 174 401 person-years of follow-up, 54 patients with CD were diagnosed with AN (27/100 000 person-years) compared with 180 matched controls (18/100 000 person-years). The hazard ratio for later AN was 1.46 (95% confidence interval [CI], 1.08–1.98) and 1.31 beyond the first year after CD diagnosis (95% CI, 0.95–1.81). A previous AN diagnosis was also associated with CD (odds ratio, 2.18; 95% CI, 1.45–3.29). Estimates remained largely unchanged when adjusted for socioeconomic characteristics and type 1 diabetes.
The bidirectional association between AN diagnosis and CD warrants attention in the initial assessment and follow-up of these conditions because underdiagnosis and misdiagnosis of these disorders likely cause protracted and unnecessary morbidity.
Comments
Surveillance bias, celiac disease and anorexia
I read this article on celiac disease (CD) and anorexia nervosa (AN) with great interest (1). The author studied patients with biopsy diagnosed CD for development of AN and compared this to the occurrence of anorexia nervosa in the general population. They found the incidence rate for AN after a CD diagnosis was 27/100 000 person-years compared with 18/100 000 person-years among matched controls. They have also interrogated data of patients with anorexia nervosa to look for development of celiac disease and compared it to the general population (A total of 33 individuals with CD (0.18%) and 76 matched controls (0.09%) had a record of AN before CD diagnosis).
I worry about the validity of their conclusions. Both AN and CD are chronic disease with long term follow-up. Patient with either disease would be subjected to close medical follow-up and patients coming frequently in contact with medical services are likely to have other diseases diagnosed more frequently than the general public not subjected to such close medical scrutiny. If instead of anorexia nervosa, we looked for frequency of renal stone detected by ultra sound examination in patients with celiac disease and compare it with frequency in general population we may well detect more renal stone among those with CD because patient with CD are investigated more frequently and asymptomatic stones are picked up. Based on this data it will not be prudent to suggest, there is an association of CD with renal stones just as it would not be correct to conclude there is an association of CD with AN. The findings of the author of increased CD developing after AN is also to be looked at with caution as it is subject to the same type of surveillance bias.
The author rightly refer to the possibility of surveillance bias in their discussion but in this case, surveillance bias can invalidate their conclusions. Appearing in Pediatrics, this article has the potential to distort the literature if this is not acknowledged/corrected.
Deepak Mittal
St. Stephen’s Hospital
Delhi India
[email protected]
Reference
1. Mårild K, Størdal K, Bulik CM, Rewers M, Ekbom A, Liu E, Ludvigsson JF. Celiac disease and anorexia nervosa: a nationwide study. Pediatrics. 2017;139(5):e20164367
RE: Celiac Disease and Anorexia Nervosa
It would be interesting to know if it is atypical celiac symptoms that are being seen in these patients. Also since Anorexia Nervosa is associated with bradycardia, malnutrition, POTS, and rapid weight loss; is Anorexia Nervosa really an atypical presentation of what is called a celiac crisis? There is not much research on celiac crisis and what is present seems to show major gastrointestinal complaints that are not present in atypical celiacs.