Eosinophilic esophagitis: Escalating epidemiology?

To the Editor:

Eosinophilic esophagitis (EE) is a chronic, inflammatory disorder of the esophagus.1 The leading symptom in adults is dysphagia for solids with the imminent risk of food impaction.2 The diagnostic criterion is a dense eosinophilic infiltration of the esophageal epithelium.1 The inflammation may induce esophageal tissue damage and subsequent fibrosis with ensuing narrowing and stricture.1, 3, 4 Some demographic data exist for pediatric patients,5 but none for adults, the primary target population of this study.

We report on 23 adult cases selected from a continuing database begun in 1989 that enrolled EE patients prospectively. All patients presented here lived in Olten County, Switzerland, an area that had 1 gastroenterology and pathology center serving approximately 100,000 inhabitants and that had undergone no relevant demographic changes within recent decades. Database inclusion criteria were typical history, consistent endoscopic abnormalities, and histologic infiltration of the esophageal epithelium with ≥24 eosinophils per high-power field. Gastroesophageal reflux disease was excluded clinically and endoscopically.

The dominant symptom was dysphagia. Other symptoms were food impaction with the necessity of endoscopic intervention, heartburn, and retrosternal discomfort. Twenty-one of 23 patients (91.3%) were male. The average age at diagnosis was 34.3 years (range, 13-55 years). At diagnosis, patients had experienced dysphagia for an average of 4.8 years (range, 0-22 years; Table I). Strikingly, 1 patient was completely asymptomatic and diagnosed only during a work-up for chronic diarrhea. Typical EE signs (scalelike white exudates) were endoscopically noted and histologically confirmed.

Table I. Characterization and prevalence of adult EE

		Frequency (%)∗
	Symptom
	Dysphagia	21 (91.3)
	Food impaction	7 (30.5)
	Heartburn	4 (17.4)
	Retrosternal discomfort	1 (4.3)
	Patient and family history
	History of rhinoconjunctivitis	12 (52.2)
	History of wheezing	7 (30.4)
	History of possible food allergy†	2 (8.7)
	Family history of atopic disease‡	8 (34.8)
	Family history of EE‡	3 (13.0)

	Incidence and prevalence	89	90	91	92	93	94	95	96	97	98	99	00	01	02	03	04§
	Incidence║	2	0	1	1	2	1	1	0	2	0	1	2	0	3	1	6
	Prevalence║	2	2	3	4	6	7	8	8	10	10	11	13	13	16	17	23

∗ Presenting symptoms as well as patient and family history of 23 adult EE patients. The frequency is indicated by both absolute and relative numbers. Cases may have had more than 1 symptom. † History of positive SPT result, RAST, or anaphylaxis to specific dietary antigens. ‡ First-degree relative. § Prevalence of adult EE in Olten County between 1989 and September 2004. ║ Frequency estimates per 100,000 total population.

There was a strong association with atopic disease among patients and their families. In 3 patients, the father had confirmed EE, and we identified 1 family in which the father and both his children (boy and girl) had EE but, interestingly, only the boy suffered from atopy. These data suggest a familial form of EE not necessarily associated with atopy. That atopy-independent genes may predispose to EE is further supported by EE's high male:female ratio (Table I).

Throughout an almost 16-year observation period, an average annual incidence of 1.438 cases per 100,000 inhabitants was noted (range, 0-6) with a marked increase in newly diagnosed cases during the last years. On the basis of the documented chronicity of EE,4 the steady incidence resulted in a constantly increasing prevalence (Table I). Given the stability of the demographic and recording conditions, it is very likely that this remarkable trend reflects a real increase in EE and not just enhanced awareness. Furthermore, that our frequency calculations should be considered at minimum the tip of the iceberg has been recognized; many oligosymptomatic or asymptomatic cases may remain undiagnosed. Our data indicate that in adults, EE, once believed to be an extremely rare anomaly, occurs at a considerable frequency and may soon reach that of chronic inflammatory bowel diseases.