Abstract
In order to realize the informatizaton of health system, it is indispensible to standardize the data format. That is, a set of standard code of diagnoses and procedures is necessary. In Japan, there are little problems for coding of procedures, because the coding system of procedures has been already introduced into the claim processing computer system. On the contrary, the coding of diagnosis has problems for its correctness. The two mains reasons are immature ability of clinical coders and intrinsic ambiguity of ICD structure. In order to solve these problems, we have investigated the coding quality based on the Japanese casemix data, so called DPC data. Using the research results, we have categorized the pattern of mistakes and developed a set of additional code for accurate ICD indexing.
