Case Control Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 21, 2016; 22(15): 4002-4008
Published online Apr 21, 2016. doi: 10.3748/wjg.v22.i15.4002
Socio-economic status and lifestyle factors are associated with achalasia risk: A population-based case-control study
Helen G Coleman, Ronan T Gray, Kar W Lau, Conall McCaughey, Peter V Coyle, Liam J Murray, Brian T Johnston
Helen G Coleman, Ronan T Gray, Kar W Lau, Liam J Murray, Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen’s University Belfast, Belfast BT12 6BJ, United Kingdom
Conall McCaughey, Peter V Coyle, Regional Virus Laboratory, Royal Victoria Hospital, Belfast, Belfast BT12 6BJ, United Kingdom
Brian T Johnston, Department of Gastroenterology, Royal Victoria Hospital, Belfast, Belfast BT12 6BJ, United Kingdom
Author contributions: Coyle PV, McCaughey C, Murray LJ and Johnston BT were involved in the study design; Lau KW oversaw the recruitment of patients and controls; Coleman HG conducted the statistical data analysis; Coleman HG and Gray RT drafted the first version of the manuscript; all authors contributing to the editing of the final manuscript and approved its submission.
Institutional review board statement: This study was ethically approved by the Office for Research Ethics Committees Northern Ireland (ORECNI: 05/NIR02/132).
Informed consent statement: Written informed consent was obtained from all study participants.
Conflict-of-interest statement: No potential conflicts of interest relevant to this article were reported.
Data sharing statement: For data sharing queries, please contact the corresponding author.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Helen G Coleman, Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen’s University Belfast, Grosvenor Rd, Belfast BT12 6BJ, United Kingdom. h.coleman@qub.ac.uk
Telephone: +44-2890-978953 Fax: +44-2890-635900
Received: December 11, 2015
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
Abstract

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.

Keywords: Achalasia, Risk factors, Epidemiology, Lifestyle, Socio-economic status

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.