Geographical Variation of Incidence of Chronic Obstructive Pulmonary Disease in Manitoba, Canada

Mahmoud Torabi,Katie Galloway

doi:10.3390/ijgi3031039

Abstract

We aimed to study the geographic variation in the incidence of COPD. We used health survey data (weighted to the population level) to identify 56,944 cases of COPD in Manitoba, Canada from 2001 to 2010. We used five cluster detection procedures, circular spatial scan statistic (CSS), flexible spatial scan statistic (FSS), Bayesian disease mapping (BYM), maximum likelihood estimation (MLE), and local indicator of spatial association (LISA). Our results showed that there are some regions in southern Manitoba that are potential clusters of COPD cases. The FSS method identified more regions than the CSS and LISA methods and the BYM and MLE methods identified similar regions as potential clusters. Most of the regions identified by the MLE and BYM methods were also identified by the FSS method and most of the regions identified by the CSS method were also identified by most of the other methods. The CSS, FSS and LISA methods identify potential clusters but are not able to control for confounders at the same time. However, the BYM and MLE methods can simultaneously identify potential clusters and control for possible confounders. Overall, we recommend using the BYM and MLE methods for cluster detection in areas with similar population and structure of regions as those in Manitoba.

Highlights

Chronic obstructive pulmonary disease (COPD) is a lung disease defined by continuous airflow limitation caused by small airway disease and parenchymal destruction
Since the local indicator of spatial association (LISA) method does not depend on the expected number of observations, it could only be applied to cluster A as the other clusters require the adjustment of the expected number of disease cases for those regions inside the specified cluster
In the Bayesian disease mapping (BYM) method region 10 is most likely to be considered as a cluster and region 61 is least likely to be considered as a cluster under the criteria that the lower bound of relative risk (RR) is greater than one

Summary

Introduction

Chronic obstructive pulmonary disease (COPD) is a lung disease defined by continuous airflow limitation caused by small airway disease (obstructive bronchiolitis) and parenchymal destruction (emphysema). The small airways narrow in response to chronic inflammation. Inflammatory processes cause the deterioration of the lung parenchyma, which leads to a decrease in the elastic recoil of the lung. The biggest and most widely known risk factor of COPD is cigarette smoking [2]. Other risk factors of COPD include occupational or environmental exposure to dust and hazardous gases, for example when burning biomass fuel [3]. A family history (i.e., genetics), low socioeconomic status, poor nutrition, asthma, and recurrent lung infections can be risk factors for COPD [1,4]

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