Implementing effective test utilization via team-based evaluation and revision of a family medicine laboratory test requisition.

Introduction

Revision of laboratory test requisitions is a simple utilisation strategy that can reduce unnecessary testing.1 2 The goal of this study was to improve test utilisation via a collaborative team-based evaluation and revision of a standardised lab requisition used by six large family medicine units.

Methods

Revising the family requisition form

A historical laboratory requisition used by the Family Medicine Department at Unity Health, St. Michael’s Hospital site, Unity Health Toronto, Toronto, Canada, was reviewed and modified by a steering committee comprised of family medicine clinicians (physicians and a nurse practitioner), lab medicine specialists and a quality improvement specialist. Decisions were made by consensus, and input was sought from the entire Department of Family Medicine via departmental rounds before changes were finalised. Laboratory tests were removed from the requisition if there was evidence in the literature of overuse (eg, Aspartate Aminotransferase (AST), folate, urea, Erythrocyte Sedimentation Rate (ESR),3 4 if they were outdated (eg, amylase, Creatine Kinase (CK)),3 or if there was consensus that they were infrequently needed in a family practice (eg, rheumatoid factor, direct bilirubin). The requisition was also revised to improve readability, and education was imbedded regarding some special tests such as urine toxicology screening and coagulation testing (changes in online supplemental table 1). Tests that were removed from the requisition remained orderable with longhand.

Data analyses

The primary outcome was the monthly volume of targeted tests ordered by the family medicine clinic 6 months pre- and 6 months post-requisition changes (September 2018 to September 2019). The proportion of abnormal test results and the ratio of Alanine Aminotransferase (ALT) (not targeted) to AST (targeted) were used as balance measures. Outpatient monthly laboratory test volumes for 20 tests were extracted from the laboratory information system. Process Control charts were generated using GraphPad Prism V.8.2.0. The proportion of abnormal results was calculated using R studio program V.1.2.5033. A two-tailed t-test was used to explore whether testing volumes were significantly different pre-requisition changes compared to post-requisition changes. Non-targeted tests (eg, ALT, total bilirubin, creatinine, haemoglobin) were used as negative controls. Cost analysis was performed using the Ontario Health Insurance Plan laboratory service fees as an estimate of true cost. The project was formally reviewed by institutional authorities at Unity Health Toronto and deemed to neither require research ethics board approval nor written informed consent from participants. Patients and/or the public were not included in the design, conduct, reporting, or dissemination of our research.

Results

Ninety-nine thousand four hundred and thirteen laboratory tests were included in this analysis. Modifying the family medicine lab requisition resulted in a significant reduction in volume of targeted tests on AST (−50.8%), direct bilirubin (−68.2%), CK (−31.9%), amylase (−61.2%), urea (−79.9%), ESR (−31.3%), serum folate (−87.2%) and Red Blood Cell (RBC) folate (−76.8%) as depicted in figure 1 and online supplemental table 2. Although there was a trend towards an increase in ordering ALT, total bilirubin, creatinine, haemoglobin over time, this change was not significant, except in the case of sodium (online supplemental table 2), and could reflect seasonal variation in overall clinic volume. The decrease in ordering resulted in cost savings each month. Online supplemental table 3 shows that the monthly cost of AST dropped by 50.8%, direct bilirubin by 68.7%, CK by 31.9%, amylase by 61.0%, urea by 80.0%, ESR by 30.9%, serum folate by 87.1% and RBC folate by 76.9%. On average, the cost of unnecessary testing used to be CAD 4687.41 per month prior to our quality improvement initiative and was reduced to CAD 2738.41 per month, amounting to an average of CAD 1949.00 in savings per month.

Figure 1

Decline in ordering of tests removed from the family medicine laboratory test requisition form over time. (A) AST and ALT, (B) amylase, total and direct bilirubin, (C) urea and creatinine and (D) ESR and negative controls, Haemoglobin and CBC (platelets and white blood cells). Dotted lines show the point of QI intervention. Asterisk denotes tests removed from the requisition. AST, Aspartate Aminotranferase; ALT, Alanine Aminotransferase; ESR, Erythrocyte Sedimentation Rate; CBC, Complete Blood Count.

We performed a focused analysis on AST to evaluate whether the removal of AST from the family medicine lab requisition impacted the AST to ALT ordering ratio. A lower ratio of AST to ALT suggests more appropriate or targeted testing.5–7 The AST:ALT ratio prior to our intervention was 0.6 whereas the average AST:ALT ordering ratio post intervention was 0.3 (p<0.05) (figure 2). The proportion of abnormal results in AST and ALT tests was then calculated as the proportion of results that were outside the reference intervals (ALT: 10–45 U/L, AST: 7–40 U/L) used for the tests. AST showed a significant increase of 40% (p value <0.05) in the percentage of abnormal results after it was removed from the requisition potentially indicating more targeted usage of this test. ALT, our negative control in this analysis, did not show any significant change in the percentage of abnormal results. This finding suggests that modifying the family medicine requisition only impacted the utilisation of the targeted tests removed.

Figure 2

AST to ALT ordering ratio before and after removal of tests from family medicine laboratory tests requisition. A significant drop in AST:ALT ordering ratio was observed (p value <0.05) after removing AST from the family medicine test requisition. Dotted lines show the point of QI intervention. AST, Aspartate Aminotransferase; ALT, Alanine Aminotransferase; QI, Quality Improvement.

Conclusions

Revision of a family medicine lab requisition was a simple, but effective strategy to decrease unnecessary laboratory testing and improve appropriate testing at our hospital. We recommend reviewing and revising historical requisitions and/or order sets as a way to encourage appropriate lab testing practices.