Readmissions Count: Should CMS Revise Its Calculations?

by Dr.  Joanne Lynn

When community coalitions apply for funding from the Community-Based Care Transitions program of the Centers for Medicare and Medicaid (CMS), they have to show that they will reduce hospital readmissions by 20% and will save money for Medicare. Funding recipients will be held to those two outcomes in evaluating the contract.

In general, CMS intends to evaluate these programs by applying the 20% reduction to the rate of rehospitalization: that is, rehospitalizations/[live discharges]. If a community’s baseline rate in 2010 was 15%, then 20% of 15% is 3% and they’d have to reduce rehospitalizations to 12%.

If hospitalization itself remains stable, these are the same goal numerically.

However, much of what is done to reduce 30-day rehospitalization also reduces hospitalizations beyond 30 days, and sometimes even hospitalizations without antecedent hospitalizations. If patients learn more self-care, use more hospice, obtain more support in the community, and so forth, then the use of hospitalization outside of that 30-day window may decline as well. And it does not take a lot of decline in that rate to mimic the decline in 30-day rehospitalization, making it a challenge to change the rate of rehospitalization/hospitalization.

Suppose, for example, that a community had 10,000 hospitalizations and 1,500 30-day rehospitalizations in 2010. Suppose the CCTP work changed the rehospitalization number by a full 20% – cutting it to 1200 per year by 2014. But that good work also cut down on hospitalization by 10% — yielding 9000 for the denominator. Then 1200/9000 would be just a 13.3% rate, and the team would have missed the goal of 12% — even though it had actually done a terrific job.

It is always risky to use a rate where the denominator is presumed to be stable but actually can respond to some of the same interventions as the numerator.

Using the N of 30-day rehospitalizations has its risks also – a bad flu year or a decline in community-based support could push it up, as could an influx of patients that increases the denominator. It can also have spurious improvement if many patients are moved from FFS to managed care.

For now, it seems that the prudent thing to do is to convince CMS that they should keep the question open and make it legitimate for CCTP and providers to pursue the reduction in numbers only rather than the reduction in the rate.

key words: CCTP, readmissions rates, CMS, care transitions