Despite these limitations our study makes an important

Despite these limitations, our study makes an important contribution toward understanding the effect of increasing chronic condition burden on survival across neighborhood socioeconomic strata. Our use of health administrative data in a single-payer health care system yielded a representative Aminoallyl-UTP Supplier sample. We used validated algorithms to identify individuals\' chronic condition burden and had access to complete health care utilization and outcome data over the two-year follow-up period. Unlike past studies that have examined SES disparities in survival after a specific acute event (Alter et al., 1999; Kapral et al., 2012; Alter et al., 2013) our study is more broadly relevant to health care providers and policymakers grappling with the growing population of multimorbid older adults. Our sensitivity analyses using an alternate measure of neighborhood SES and a younger cohort of adults strengthen our conclusions by testing for potential misclassification and survival biases. We also demonstrate the insensitivity of our primary null finding to analytic assumptions about inclusion and exclusion of health care utilization variables from our models.
Conclusions
Contributors
Conflicts of interest
Funding The Ontario Ministry of Health and Long-Term Care and Vanier Canada Graduate Scholarship.
Acknowledgments This study was supported by a research grant from the Ontario Ministry of Health and Long Term Care (MOHLTC) to the Health System Performance Research Network (HSPRN#06034) and to the Institute for Clinical Evaluative Sciences. Natasha Lane is supported by a Vanier Canada Graduate Scholarship. The opinions, results and conclusions reported in this paper are those of the authors and are independent from the funding sources. No endorsement by ICES or the MOHLTC is intended or should be inferred.
Introduction The close relationship between the economy of individual countries and the extent of their medical activities has long been accepted as reality but has become a topic of research only in the last decade (Waitzkin 2003). The relevance of macroeconomics in health provision has recently been highlighted by the World Health Organization (WHO), with more solid organ and hematopoietic stem cell transplants (HSCT) performed in more affluent countries (White et al. 2014; Gratwohl et al. 2015). Allogeneic HSCT represents one role model of a low volume, high cost, but lifesaving medical procedure (Copelan 2006; Majhail et al. 2013; Khera et al. 2012). There is a strong association of country-specific economic factors with its use. Extensive studies have indicated significant correlations between transplant rates, e.g. the number of transplants compared to the number of inhabitants, and macroeconomic indices such as Gross National Income/capita (GNI/cap) or the availability of an unrelated donor registry. For a functioning national transplant network, a country must have a minimum size and a minimum of resources, teams require a minimum of support, donors must be available and patients have to have access to the transplant (Gratwohl et al. 2015; Gratwohl et al. 2010a; Gratwohl et al. 2010b). It is intuitive that country-specific macroeconomic factors could have an impact on outcome as well. The vast numbers of well recognized patient-, disease-, donor- and transplant technique associated risk factors hamper simple comparisons (Copelan 2006; Giebel et al. 2010; Gratwohl et al. 2009). There is as well a potential independent role of center-specific microeconomic factors at the level of the individual team. Complex medical procedures require the close cooperation of multiple persons and institutions, training, competency and experience; in short, team expertise. The role of “minimal center size” or “patient/hospital volume” has been discussed for many years, with conflicting data (Loberiza et al. 2005; Gratwohl et al. 1989; Frassoni et al. 2000; Matsuo et al. 2000; Giebel et al. 2013; Klingebiel et al. 2010; Horowitz et al. 1992; Taylor et al. 2013).The topic of “center experience” is not restricted to HSCT but a matter of debate in many fields of medicine. Data suggest that minimum numbers of specific practice are required to perform complex medical procedures safely; again, results have been conflicting (Hunsicker et al. 1993; Ozhathil et al. 2011; Guba 2014; Birkmeyer et al. 2003; Lüchtenborg et al. 2013). Hence, relatively arbitrary thresholds have been set in accreditation standards (Jones et al. 2006; http://www.jacie.org/standards/6th-edition-2015 n.d.). However, patient interest groups, health policy makers, competent authorities and other stakeholders are increasingly asking for objective measures of patient safety and outcome. They expect transparency and fair systems of comparisons between centers (Horowitz et al. 1992; Logan et al. 2008).