Geographical variations in the use of three elective surgical procedures in the elderly

1. Geographical variations in the use of three elective surgical procedures in the elderly J Jacques1, D Gillain1, J Petermans2, P Kolh1, P Gillet3 1Medico-Economic Informations Department (Simé), University Hospital (CHU) of Liège Belgium ; 2Geriatric department CHU Liège Belgium ; 3 University of Liège Objective : To study the incidence of three three surgical procedures in the old person : Total Hip Replacement (THR), Total Knee Replacement (TKR) and Cataract Intervention and to assess the geographical disparities in Belgium Methodology : Based on administrative data of all hospital admissions between 1997 and 2002 in Belgium, a perimeter of definition was built by combination of criteria of inclusion (APR-DRG, ICD-9-CM procedures) and exclusion (diagnosis and procedure ICD-9-CM codes). A standardized admission ratio (SAR) for each of the 589 belgian municipalities was obtained (method of indirect standardization). In a second time, multiple regression is used to explain the SAR by district by several explanatory variables reflecting the demand and the supply of care. To observe the effect of the different variables, we proceed in two steps : firstly, a regression model where the explanatory variables are a set of demand variables; secondly, introducing into the equation supply variables. Results : The multivariate linear regression model shows, for cataract, that demand and supply variables explain each of them approximately 10% of geographical disparities. Comorbidity is not a significant variable of the explanatory model. Income and educational level, in the demand model, and living alone, in the complete model, are significant. In the supply variables, we notice that high substitution rate to day hospital may reflect a degree of attractiveness of the procedure. Finally, physician density is not decisive. In the cases of TKR and THR, the developed model explains moderately variation between the SAR by district. Less than 10% of the variability of standardized rates of intervention can be explained by selected variables. Regarding supply, the density of orthopedists and of hospital beds are associated with high levels of TKR. However, in the literature, there is no evidence to explain the meaning of this correlation. Thus, for certain authors, a greater offer would make it possible to meet a request which is not besides assured (underuse hypothesis). In England, 5 to 7% of population over 65 years presents a need of TKR which is not met. On the contrary, for others, this best accessibility of the offer would imply an induced demand (overuse hypothesis). [ Yong PF, et al. Inequalities in access to knee joint replacements for people in need. Ann.Rheum.Dis. 2004;63(11):1483 ] Conclusions : Geographical disparities are observed in Belgium for the three procedures. Multiple regressions used explained only a little part of those. Cataract Total knee replacement (TKR) Total hip replacement (THR) Contact: jessica.jacques@chu.ulg.ac.be