The variation of arthroplasty procedures in the OECD Countries: analysis of possible influencing factors by linear regression

Total hip and knee replacements (THR, TKR) are among the most common surgeries but incidence rates vary between OECD countries. Previous studies suggested economic factors to be most influential but did not take into account health care system related factors. Hence we analysed the possible influence of healthcare system related factors on the operation rate. We used OECD data for 27 countries and calculated Age-Standardized Incidence Rates (ASIR). In order to determine possible explanatory variables on the ASIRs we performed a stepwise blockwise linear regression. The ASIR of hip and knee replacement varies widely. We identified statistically significant determinants which influence the ASIR of THR in a positive manner: incidence and length of stay of coxarthrosis, ASIR of knee replacement, health expenditures, number of nurses and an etatistic social insurance. Diabetes prevalence, gross domestic product and number of doctor consultations, however, have a negative influence on the ASIR. TKR rate is positively influenced by health expenditures and incidence rate of gonarthrosis, negatively by the number of primary practitioners. We observed strong geographic disparities in the frequency of THR and THR that cannot be explained by age structure of the countries. Economic factors seem to play a secondary role while healthcare related factors have a greater influence.