Di Giuseppe, Giancarlo, Sutradhar, Rinku, Pequeno, Priscila, Kwan, Marilyn L., Miglioretti, Diana L., Smith-Bindman, Rebecca, and Pole, Jason D.
Background: Medical imaging is an integral part of healthcare. Globalization has resulted in increased mobilization of migrants to new host nations. The association between migration status and utilization of medical imaging is unknown. Methods and findings: A retrospective population-based matched cohort study was conducted in Ontario, Canada from April 1, 1995 to December 31, 2016. A total of 1,848,222 migrants were matched 1:1 to nonmigrants in the year of migration on age, sex, and geography. Utilization of computed tomography (CT), magnetic resonance imaging (MRI), radiography, and ultrasonography was determined. Rate differences per 1,000 person-years comparing migrants to nonmigrants were calculated. Relative rates were calculated using a recurrent event framework, adjusting for age, sex, and time-varying socioeconomic status, comorbidity score, and access to a primary care provider. Estimates were stratified by migration age: children and adolescents (≤19 years), young adults (20 to 39), adults (40 to 59), and older adults (≥60). Utilization rates of CT, MRI, and radiography were lower for migrants across all age groups compared with Ontario nonmigrants. Increasing age at migration was associated with larger differences in utilization rates. Older adult migrants had the largest gap in imaging utilization. The longer the time since migration, the larger the gap in medical imaging use. In multivariable analysis, the relative rate of imaging was approximately 20% to 30% lower for migrants: ranging from 0.77 to 0.88 for CT and 0.72 to 0.80 for MRI imaging across age groups. Radiography relative rates ranged from 0.84 to 0.90. All migrant age groups, except older adults, had higher rates of ultrasonography. The indication for imaging was not captured, thus it was not possible to determine if the imaging was necessary. Conclusions: Migrants utilized less CT, MRI, and radiography but more ultrasonography. Older adult migrants used the least amount of imaging compared with nonmigrants. Future research should evaluate whether lower utilization is due to barriers in healthcare access or health-seeking behaviors within a universal healthcare system. Author summary: Why was this study done?: Globalization has led to an increasing number of migrants who must navigate a new healthcare system in the countries they migrate to. Migrants have been shown to use specific health services, such as cancer screening or general practitioner use, at a lower rate than those born in the host country. Limited studies have been performed which have evaluated the longitudinal usage patterns of medical imaging of migrants compared with nonmigrants. What did the researchers do and find?: A retrospective cohort study of 1,848,222 migrants to Ontario, Canada were matched to an equal number of nonmigrants and evaluated for the utilization rates of computerized tomography, magnetic resonance imaging, radiography, and ultrasonography medical imaging. Usage rates of medical imaging were 20% to 30% lower in migrants compared with nonmigrants. A longer time since migration resulted in larger disparities in imaging use, with the largest age-related differences in utilization patterns observed in older migrants. What do these findings mean?: Large disparities in the utilization of medical imaging within this universal healthcare system exist which warrants further investigation to uncover mechanisms of action. These data may be used by healthcare policymakers and practitioners in regions where migration plays a significant role in its population. [ABSTRACT FROM AUTHOR]