Trending Data Over Time: Run Charts

Although summary tables performed before and after implementation of your insulin order set/protocol might be helpful to some degree, trending over time using run charts is preferred. Run charts have several advantages over before-and-after summaries: it’s easier to see the effect of different aspects of your interventions as they occur, you get a quicker picture of whether something is working, it is easier to separate out the impact of your intervention from secular trends, and our brains simply interpret run chart graphical displays more innately than they do tables or columns.

The following table of results from the UCSD glycemic control effort demonstrate the advantages of run charts over tabular reporting. The study population was patients in adult, non–critical care wards, with pregnant patients excluded. An individual mean glucose was calculated for all patients with 8 or more bedside glucose meter readings. Only the first 14 days of monitoring were included to prevent skewing of the mean in those with outlier length of stays. Glucose values ≤ 60 mg/dL were excluded from calculations of the mean. The baseline period went through September 2003, a standardized insulin order set was implemented in October 2003, and an algorithm supporting the order set was successfully piloted in May 2005.

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Results of UCSD Glycemic Control Effort

Do you feel inspired by the numerous data points listed in this table? Are you convinced the order set or algorithm made a difference in increasing the percentage of patients with a mean < 180 mg/dL? The run chart below shows essentially the same data in a different format.

Run Chart with Statistical Process Control (SPC) Limits Showing
Percentage of Patients at UCSD with a Mean Glucose ≤ 180 mg/dL

CPOE = computerized physician order entry.

Time is shown on the X axis, and the percentage of patients achieving a mean of ≤180 mg/dL is shown on the Y axis. The red horizontal line represents the mean percentage of patients achieving this goal. The vertical line represents the beginning of the first intervention (the subcutaneous insulin order set), whereas the star indicates when the pilot of an algorithm guiding prescribers through insulin ordering in different patient situations took place. The improvement in glycemic control is highly statistically significant. The human eye can often detect statistically and clinically relevant change before you could ever pick it up in a table.

You can build your run charts using Excel, statistical packages, or even use the IHI’s tool for run charts, the Improvement Tracker.

The following chart is a presentation of summary data from the same institution. It shows the percentage of patients with a mean patient-stay glucose in the indicated ranges over three periods (baseline, intervention 1 [order set], intervention 2 [algorithm]).

View several examples of run charts, data summaries, and other methods of tracking and trending glucometrics and other important parameters.