• What is the Incidence of Achalasia?

What is the Incidence of Achalasia?

The incidence of achalasia is at least twice as high as previously believed, 2 studies (one from Chicago, the other from Australia) show in the March issue of Clinical Gastroenterology and Hepatology.

Achalasia is characterized by dysphagia, regurgitation of undigested food, and chest pain. Patients lose weight due to the absence of esophageal peristalsis and reduced relaxation of the lower esophageal sphincter, and require treatment. Advances in diagnostic techniques have led to better estimates of the incidence and prevalence of achalasia.

Salih Samo et al were interested in the seemingly low epidemiologic estimates of achalasia incidence, compared with the large number of motility disorders treated at their tertiary medical center in central Chicago. The authors therefore conducted a retrospective longitudinal study of achalasia cases, collecting data from Northwestern Medicine electronic health records on adult patients with a diagnosis of achalasia and/or idiopathic esophagogastric junction outflow obstruction from 2004 through 2014.

Age distribution of incident cases in Chicago (A) and the Northwester Memorial Hospital Neighborhood (B) during the entire study period.

Samo et al found yearly incidences to range from 0.77 to 1.35 per 100,000 citywide (average, 1.07 per 100,000) and from 1.41 to 4.60 per 100,000 in the Northwestern Memorial Hospital neighborhood (average, 2.92 per 100,000). The corresponding prevalence values increased progressively, from 4.68 to 14.42 per 100,000 citywide and from 15.64 to 32.58 per 100,000 in the hospital neighborhood.

These authors found an increase in incidence with age, especially from the age of 60 onward, reaching an incidence rate above 10/100,000 in the age range of 85–90 (see figure).

Jaime A Duffield et al collected data on cases of achalasia diagnosed by esophageal manometry from the 3 adult manometry laboratory databases in South Australia, from 2004 through 2013.

These authors identified 350 cases of achalasia and calculated an annual incidence of 2.3 to 2.8 per 100,000 persons. This is almost 50% higher than the highest reported incidence (1.6 per 100,000 persons) from studies of Italian and Canadian populations. Duffield et al also found that the incidence of achalasia increased with age.

In an editorial that accompanies the article, Guy E. Boeckxstaens wrote that these figures are surprisingly high and almost double those of previous studies. He says the difference most likely relates to the accuracy of identifying achalasia from the described databases. Previous studies used diagnostic codes collected from hospitals (patients have been hospitalized for treatment)— missing a large number of patients treated on an ambulatory basis.

Boeckxstaens points out that the incidence rate was only 1.07/100,000 when patients from the entire Chicago area were considered, rather than the authors’ main referral area (the neighborhood of Northwestern Memorial Hospital). He says that patients diagnosed in other hospitals of the Chicago area are likely to be missed in the numerator while the study population (denominator) increases, indicating the importance of accurate case collection.

It is interesting that incidence rates in the United States and Australia are comparable. This would argue against environmental, and perhaps even genetic, features as major risk factors.

Boeckxstaens says that both studies are of excellent quality and have used the most accurate possible data yet. Nonetheless, actual incidence rates could be even higher, because not all patients undergo manometry and some may have been misdiagnosed.

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