"Dial-an-ROI?" changing basic variables impacts cost trends in single-population pre-post ("DMAA type") savings analysis.

Abstract Disease management (DM) programs claim to achieve cost savings by reducing clinical adverse events. While measuring changes in adverse events is straightforward, plausibly demonstrating savings has been contentious, especially absent an external comparison population. In this situation, a single-population methodology is often used, in which the cost trend for those with no program conditions (“non-chronics”–NC) forms the expected trend for those who have at least 1 program condition (“chronics”–C). The methodology's fundamental assumption is that—absent DM—C and NC trends would be identical (or bear a constant relationship over time). We assessed this assumption by altering the values of key variables used to identify C and NC, and to calculate trend. We compared C and NC baseline trends for a 23-condition telephonic DM multiemployer program representing nearly 300,000 members. Trends were calculated for 16 combinations of values for 4 key variables: identification look-back frame (12 vs. 24 mon...