Published online Apr 21, 2016. doi: 10.3748/wjg.v22.i15.4002
Peer-review started: December 14, 2015
First decision: December 30, 2015
Revised: January 14, 2016
Accepted: January 30, 2016
Article in press: January 30, 2016
Published online: April 21, 2016
Processing time: 114 Days and 1.7 Hours
AIM: To evaluate the association between various lifestyle factors and achalasia risk.
METHODS: A population-based case-control study was conducted in Northern Ireland, including n = 151 achalasia cases and n = 117 age- and sex-matched controls. Lifestyle factors were assessed via a face-to-face structured interview. The association between achalasia and lifestyle factors was assessed by unconditional logistic regression, to produce odds ratios (OR) and 95% confidence interval (CI).
RESULTS: Individuals who had low-class occupations were at the highest risk of achalasia (OR = 1.88, 95%CI: 1.02-3.45), inferring that high-class occupation holders have a reduced risk of achalasia. A history of foreign travel, a lifestyle factor linked to upper socio-economic class, was also associated with a reduced risk of achalasia (OR = 0.59, 95%CI: 0.35-0.99). Smoking and alcohol consumption carried significantly reduced risks of achalasia, even after adjustment for socio-economic status. The presence of pets in the house was associated with a two-fold increased risk of achalasia (OR = 2.00, 95%CI: 1.17-3.42). No childhood household factors were associated with achalasia risk.
CONCLUSION: Achalasia is a disease of inequality, and individuals from low socio-economic backgrounds are at highest risk. This does not appear to be due to corresponding alcohol and smoking behaviours. An observed positive association between pet ownership and achalasia risk suggests an interaction between endotoxin and viral infection exposure in achalasia aetiology.
Core tip: Little is known about achalasia aetiology, with roles suggested for genetic conditions, auto-immune diseases and infectious agents. This population-based case-control study investigated lifestyle and household factors in adulthood and childhood in relation to achalasia risk, for the first time. Results indicate that achalasia is a disease of inequality, and individuals from low socio-economic backgrounds are at highest risk. The burden of achalasia in lower socio-economic groups cannot be explained by smoking or alcohol intake. Pet ownership was associated with a two-fold increased risk of achalasia. Further studies of environmental factors and achalasia risk are warranted.