Case Study

Medical labs address measurement differences and improved patient tracking through AHRQ grant

BPI was involved in a government grant to study how to apply Lean and Six Sigma to an anticoagulation clinic back in 2006. The project was focused on reducing adverse events in the Cedar Rapids (IA) community. One of the largest contributors to adverse events were patients taking anticoagulants like Warfarin and Coumadin. Patients need to be closely monitored with weekly blood tests to ensure they are within the proper test ranges.

To tackle this problem, we helped setup the project using the DMAIC model (Six Sigma methodology), and initially focused on the quality of the data coming from the different labs within the area. The blood test applied to anticoagulation patients is called International Normalized Ratio (INR). When the patient has INR values too high or too low, it puts them at risk for an adverse event.

One of the first steps when studying data is to determine if it is valid (not just assumed to be good), as poor measurements could be causing some of the variation in the INR readings and potentially causing difficulties for patients and medical staff keeping the patient in a safe range.

Most of the blood tests were performed at a few different medical labs in the community. We used the Six Sigma tool called Gage Repeatability and Reproducibility (R&R) to determine if there were significant differences between two different labs when measuring the same blood samples.

To test this out, we took 10 randomly selected patients. Each patient had his/her blood drawn from Lab A, and the blood was then separated into six tubes. Three tubes remained at Lab A for testing, and three tubes were immediately sent to Lab B for testing.

Table 2 below shows the results of the study

Results showed a statistically significant difference among labs.

Root cause analysis revealed that the normalizing number (mean normal prothrombin time, MNPT) utilized in one of the labs varied greatly from other area labs. The team determined a new qualification process for MNPT to keep results consistent across all the labs.

The study also evaluated opportunities to apply Lean concepts to a clinic. The goal of any clinic is to reduce the total time from when the patient is tested, until they receive communication back from the clinic reviewing their results. Batching was observed when handling results, which delayed getting feedback to patients and medical staff.

One of the biggest improvements was the creation of the INR Pro web-based program. It was developed and launched by us to better track and analyze patient INR results, and manage patient visits to prevent patients from missing appointments.

The read a longer summary of this project, you can go to

A 4-volume series of articles from AHRQ was released, titled Advances in Patient Safety: New Directions and Alternative Approaches.

The full paper on this project is accessible from the AHRQ website, titled Using Lean Six Sigma Tools to Compare INR Measurements from Different Laboratories within a Community.

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