The significance of laboratory testing for the German diagnosis-related group system--the systematic evaluation of comorbidities of relevance to case reimbursement and continued development of the DRG Watchdog software.

The launch of the G-DRG system version 2004 made it necessary to update our former studies on the importance of laboratory testing (Clin Lab 2002;48:327-333). Using a systematic search algorithm, we established a total of 2,828 comorbidities, the ICD coding of which has a positive effect on case reimbursement, thus helping to secure hospital revenue. 62% of these comorbidities were found to depend exclusively or predominantly on laboratory testing. On average, one such comorbidity can be said to influence approximately 100 DRGs (range 2 to 226). In order to gain a clearer idea of the practical benefit of such "hits", amounting to several 100,000s, we selected about 5% of them for illustration with a computer program called DRG Watchdog. This program shows just how much additional reimbursement can be achieved for a specific DRG upon the ICD coding of a specific comorbidity. The program is freely available on the Internet at www.trillium.de and enjoys more than 100 search runs per day.