Asthma disease management: regression to the mean or better?

To assess the effectiveness of disease management as an adjunct to treatment for chronic illnesses, such as asthma, and to evaluate whether the statistical phenomenon of regression to the mean is responsible for many of the benefits commonly attributed to disease management.

This study evaluated an asthma disease management intervention in a Colorado population covered by Medicaid. The outcomes are presented with the intervention group serving as its own control (baseline and postintervention measurements) and are compared with a matched control group during the same periods.

In the intervention group, 388 asthmatics entered and 258 completed the 6-month program; 446 subjects participated in the control group. Facilities charges were compared for both groups during the baseline and program periods. Both groups were well matched demographically and for costs at baseline.

Using the intervention group as its own control revealed a 49.1% savings. The control group savings were 30.7%. Therefore, the net savings were 18.4% (P < .001) for the intervention group vs controls. Although the demonstrated savings were less using a control group to correct for regression to the mean, they were statistically significant and clinically relevant.

When using a control group to control for the statistical effects of regression to the mean, a disease management intervention for asthma in a population covered by Medicaid is effective in reducing healthcare costs.