Table 1.

Decision support interventions designed to implement an institutional magnesium testing protocol^*

Intervention	Dates	Target and Description
Baseline	1/1/98 – 12/4/99	No protocols restricting the frequency, context, or volume of magnesium testing
First intervention†	12/5/99 – 3/21/00	Targeted all laboratory testing instances. Instances scheduled for more than 72 hours into the future flagged; users prompted to discontinue them.
Second intervention†	6/20/00 – 11/30/01	Targeted magnesium, calcium, & phosphorus testing instances. Included a graphical display of recent serum magnesium, calcium, and phosphorus results; educational material outlining indications for magnesium testing and interpretation; and restrictions on the volume of magnesium, calcium, and phosphorus testing
Third intervention‡	12/1/01 – 12/31/03	Targeted magnesium testing orders. Included the most recent serum magnesium result; graphical display of a calculated corrected magnesium value; restriction testing volume to one test per order; and requirement to select a magnesium testing indication

^*For the purpose of this study, orders are finalized interactions with the CPOE system that lead to one or more actions on patients (such as laboratory testing). Instances are the individual actions that occur on patients as the result of an order (e.g., one order for twice-daily magnesium testing to occur over 5 days leads to 10 magnesium testing instances).

^†Broad-based tools, globally addressing multiple laboratory tests simultaneously.

^‡Focused tool targeting only serum magnesium testing orders.