Parkinson's Disease, Multiple Sclerosis and Changes of Residence in Alberta

BACKGROUND: Our objective is to examine how persons diagnosed with Multiple Sclerosis (MS) and Parkinson's disease (PD) change residence following disease onset. We hypothesize that persons choose to change residence (locally or regionally) in different ways depending on whether or not they have been diagnosed with MS/PD. We also estimate the effects of residence change on measures of disease prevalence made at several different levels of geography. METHODS: Using fee-for service and hospitalization data, we identify cases of MS and PD between 1994 and 2004. Both of these case groups are matched to controls based on age, sex, socioeconomic status and municipality of residence. We tabulate and compare the changes of residence among persons in the case and control groups. We also use these data to estimate the effects that changes in residence have on disease prevalence at three different levels of geography. RESULTS: Both MS and PD patients were more likely to change residence following disease onset compared to groups of matched controls (p<=0.001). Most changes of residence occur within the same municipality. The total magnitude of these changes is small, however, and is unlikely to affect estimates of disease prevalence; over our study period, the largest change in geographical prevalence estimates due to individual changes in residence was about 1%. CONCLUSIONS: Persons diagnosed with MS and PD both have mobility characteristics that differ from those of their respective control groups, and in general, are more likely to move to or between Edmonton and Calgary, and less likely to move out of province. However, the balance of mobility characteristics of persons with PD and MS appear unlikely to greatly affect the patterns observed on maps of disease prevalence.