Background: Upcoding id defined by a systematic and deliberate shift in the case mix of a hospital in order to improve reimbursement. Upcoding is frequently mentioned as a reason for ineffective reimbursement under a DRG payment system.
Method: A systematic literature search identified relevant studies concerning the extent of the Upcoding. Results are used for estimating the magnitude of Upcoding in Germany.
Results: Studies showed different estimates for Upcoding. Transferred to Germany roughly up to 1% of the payments for inpatient care are estimated to Upcoding. After 4 to 5 years the level of Upcoding decreases. To what extent Upcoding could be taken into account when setting the DRG reimbursement fees, remains open. Regarding the creation of epidemiological time series Upcoding causes a abrupt change in statistics. However this disadvantage is offset by the more complete coding under a DRG payment system.
Consequences: When setting the DRG reimbursement fees the elimination of the contribution of Upcoding share to the total shift in case mix can only be done retrospectively. Thus a rule for compensation of subsequent years is likely. Likewise the possibly different distribution of Upcoding among hospitals and their departments requires further investigation.