Optimization of Laboratory Ordering Practices for Complete Blood Count With Differential

Jeffrey Z. Shen; Benjamin C. Hill, MD; Sherry R. Polhill, MBA, MT(ASCP); Paula Evans, MT(ASCP); David P. Galloway, MD; Robert B. Johnson, RRT, MS; Vishnu V.B. Reddy, MD; Patrick L. Bosarge, MD; Lisa A. Rice-Jennings, MT(ASCP); Robin G. Lorenz, MD, PhD


Am J Clin Pathol. 2019;151(3):306-315. 

In This Article

Materials and Methods

UAB Hospital is a 1,022-bed tertiary care academic medical center with eight intensive care units, including trauma burn (TBICU), medical (MICU), neurosciences (NICU), and surgical (SICU) intensive care units. The number of beds in TBICU is 25, NICU 26, SICU 20, and MICU 19 and the occupancy rate is approximately 100%. TBICU was chosen because it was found to have the highest number of CBC w/diff tests ordered out of all inpatient units. SICU and NICU were chosen as controls because both are units that, like the TBICU, have a high frequency of ordering CBC and CBC w/diff tests. These both are also surgical ICUs like the TBICU. MICU was chosen as a nonsurgical ICU unit control, ordering the highest number of CBC and CBC w/diff tests out of the nonsurgical ICU units, and higher than most other inpatient units. The clinical laboratory at UAB Hospital performs laboratory testing for all inpatients at UAB Hospital.


The study design included four steps. First, we collected data from Power Insight and Cerner on UAB Hospital-wide laboratory ordering patterns to determine the most ordered tests from January 2015 to April 2015. It was found that the CBC w/diff test was the most ordered test at 97,515 and the CBC the eighth most ordered test at 9,871. It was unexpected that the CBC w/diff test was ordered about 10 times more frequently than the CBC, so we decided to focus our investigation on the ordering practices for these two laboratory tests.

Second, we collected data about total CBC and CBC w/diff orders from comparator hospitals by asking several questions (listed in Table 1 ) of hospitals that are part of the University Health System Consortium, a national organization comprising most of the nation's leading academic medical centers. Third, we determined the hospital unit that ordered the most CBC w/diff tests, which was the TBICU. We met with TBICU staff to present the initial data on CBC test and CBC w/diff test ordering practices and to gather information on specific ordering patterns. Utilizing this information, a process map was created for how clinical laboratory tests were ordered for patients on the TBICU and this process map was utilized to generate a Pareto chart to identify "reasons for ordering" data that impacted overutilization of CBC w/diff tests Figure 1 . Finally, because of previous success of educational interventions at other academic medical centers, we decided to implement an educational intervention and then analyze the effects of that intervention on laboratory ordering practices during the time of the intervention and 2 months after (to see whether any improvements were retained).

Figure 1.

Pareto chart listing "Reason for ordering" for CBC with differential (w/diff) test overutilization. The top failure was "CBC w/diff test is default." At University of Alabama at Birmingham (UAB) Hospital in early 2016, there were 2104 different ordering PowerPlans that had the CBC w/diff test as a component of their orders and approximately 20% had the CBC w/diff test as a routine order more frequently than once/day. The UAB Hospital units with the most PowerPlans with these frequent CBC w/diff test orders were the trauma burn intensive care unit and the surgical intensive care unit.

Data Collection

This study was approved by the institutional review board (IRB) of University of Alabama Birmingham (IRB-160826009). We first collected data on laboratory ordering patterns of CBC tests and CBC w/diff tests at UAB hospital through the Cerner database during January of 2016. This included information of all inpatient units, quantity of each test ordered, the time they were collected, the time they were ordered, who ordered the test, and the patient for whom they were ordered. These data were used for the rest of our analyses, as the majority of the CBC w/diff test orders in an inpatient setting are due to repeat testing over the duration of the patient's stay in the hospital. We next determined the intervals between CBC w/diff test orders over the entire UAB Hospital and the most frequent intervals for repeat testing.


We implemented a three-step approach to reducing repetitive or unnecessary CBC w/diff testing in the TBICU. First, team members met with the entire TBICU staff to introduce the project and show the initial analysis. This initial encounter demonstrated several unanticipated barriers and ordering practices that were then considered in the second phase of the project (March 14, 2016, to March 28, 2016), where the TBICU providers and staff agreed to follow the flowchart guiding CBC ordering practices shown in Figure 2A. The most significant changes in ordering recommendations was a switch from ordering the CBC w/diff test every 4 to 6 hours for all new trauma patients to ordering a CBC test (no diff) every 4 to 6 hours. If the patient was considered stable at 48 hours after admission, then the repeat orders were changed to a CBC w/diff test every 12 hours for the rest of the hospitalization. Additionally, a pocket educational tool was developed and given to all TBICU providers and staff, in order to have an additional method to remind them of the new ordering protocol Figure 2B.

Figure 2.

Educational guides designed to reduce overutilization of CBC with differential (w/diff) testing in the trauma burn intensive care unit (TBICU) setting. A, Flow sheet ordering tool placed on clip boards and given to frontline staff. B, Pocket ordering tool given to frontline staff.

After the 2-week trial of these new ordering practices, data were analyzed through the use of both control and run charts for effectiveness of the intervention and the key stakeholders were surveyed for their input on the process and its implications for patient care and outcomes. Repeat tests were defined as a test of the same type collected for the same patient within 22 hours; this time was chosen to avoid categorizing routine daily tests as repeat tests. This data analysis was repeated 2 months after the educational intervention (on data collected May 14, 2016, to May 28, 2016) to determine if the changes seen in CBC w/diff test ordering patterns were retained.

In discussions with TBICU providers, one reason stated for ordering frequent CBC w/diff tests for patients was to use the differential as an early biomarker for sepsis. Therefore, we designed a component of our study to determine if the educational intervention (and the switch to CBC tests instead of CBC w/diff tests during the first 48 hours of hospitalization) had the negative effect of delaying identification of sepsis. We took 20 patients in the TBICU during January 2016 (before the intervention) who had the most repeat testing done and reviewed their charts to see whether they fit the criteria of having: (1) no clinical signs of infection, as well as (2) CBC w/diff test result shows greater than 10% bands. Then we did the same for 20 patients in the TBICU who had the most repeat tests done for them during the March intervention period.

Statistical Analyses

Excel XSTAT was used to perform statistical analyses of the data. For comparing ordering patterns across different units and across different months, we used a two-sample t test for unequal variances. CBC ratios were calculated by taking the fraction of CBC w/diff ordered over the CBC without differentials. We then calculated the percentage reduction by taking the difference in ratio between 2 months and dividing over the original number (CBC ratio in January).