MODELIZATION OF LONG-STAY AND HIGH COST P ATIENT DISTRIBUTION WITHIN BRONCHOPNEUMOPATHIES AND LEUKEMIA OR LYMPHOMA DIAGNOSIS RELATED GROUPS

After the implementation of the Medicare Prospective Payment System (P PS) in the USA, many European countries like France have introduced DR Gs to curb hospital overspending. However, there has been some relucta nce from hospital actors, especially because of the heterogeneous natu re of DRG's. To analyse this situation, we propose a method based on d istribution modelization of length of stays and costs within DRGs. For each DRG, the model is based on a mixture of Poisson and Weibull dist ributions identified as subgroups. The subgroups are characterized by their means and their proportions which are estimated by maximization of data likelihood. For a particular DRG, the proportion of long stay or high-cost patients can be explained by the introduction of clinical variables in the model. First the model was applied to the DRG ''leuk emia and lymphoma'' (HCFA V.3), using 133 discharge abstract files fro m the Dijon public teaching hospital which were classified into this D RG in 1993. Among the studied parameters only acute leukemia, neutrope nia < 500 PNN/mm(3), high dose aplastic chemotherapy, central venous c atheterization, parenteral nutrition, use of protected or laminar airf low room, septicemia, large spectrum intravenous antibiotherapy, and b lood transfusion had a significant influence on the distribution of th e patients in the long stay or costly subgroup. Second, for DRG ''chro nic bronchopneumopathies'' (n = 220) the significant parameters were m echanical ventilation, antibiotherapy, post hospitalization medicalize d care.