Managing Inappropriate Requests of Laboratory Tests: From Detection to Monitoring

This study shows automatic, practical, simple, and effective strategies designed in the laboratory, in consensus with requesting clinicians, to improve laboratory test appropriateness.
Published Online: September 07, 2016
Maria Salinas, PhD; Maite López-Garrigós, PhD; Emilio Flores, PhD; Maria Leiva-Salinas, MD, PhD; Alberto Asencio, MD; Javier Lugo, MD; and Carlos Leiva-Salinas, MD, PhD

Objectives: The main objectives of this study were to show a simple approach to detect inappropriate requests of laboratory tests and to monitor success after establishing interventions. These objectives were monitored through process and outcome indicators customized according to the type and phase of the appropriateness strategy.

Study Design: Quasi-experimental design.

Methods: Based on evidence regarding laboratory test utilization differences among different geographical areas of Spain, we identified serum calcium (s-Ca) testing to be underrequested and total bilirubin (tBil) testing to be overrequested in primary care patients who undergo testing at the Public University Hospital of San Juan, in San Juan de Alicante, Alicante, Spain. Additionally, the ratio of free thyroxine (FT4) tests to thyrotropin (also called thyroid-stimulating hormone [TSH]) tests was well above the published 0.25 goal in primary care. Finally, numerous laboratory tests were overrequested in hospitalized patients due to repetitive testing. We designed and implemented a variety of strategies to correct such inappropriateness and designed different indicators to monitor the intervention success over time.

Results: After implementation of the different strategies, the absolute number of s-Ca tests increased. The number of tBil tests in primary care, and numerous other tests repeated too frequently in hospitalized patients, decreased. The FT4/TSH indicator goal was reached and maintained over time. Regarding the outcome indicators, the strategy of reducing tBil tests in primary care and reducing the aggregate of unnecessary tests in hospitalized patients resulted in savings of $3543.80 and $9825.50, respectively, from January 2012 to December 2014. The s-Ca strategy, from November 2011 to December 2014, detected 62 subjects’ primary hyperparathyroidism at a cost of $137.80 per case.

Conclusions: The study demonstrates a simple approach to detect inappropriate requests of laboratory tests, and how to assess the potential success of interventions using process and outcome indicators.

Am J Manag Care. 2016;22(9):e311-e316
Take-Away Points
  • Addressing inappropriate laboratory orders is a great challenge for laboratory professionals. 
  • The aim of this study was to show a simple approach to detecting inappropriate laboratory orders. 
  • Indicators customized according to the type and to the phase of the appropriateness strategy are essential to being able to measure the potential impact on the patient’s diagnosis.
Addressing inappropriate requests of laboratory tests is a great challenge for healthcare professionals; yet, due to the significant adverse effects of such requests, it is worth tackling.1-6 Although underrequesting may result in missing a diagnosis, overrequesting may generate as many as 3 major adverse effects: 1) economic costs—although the individual cost of a single test may seem low, the cumulative effect of unnecessary tests is high, as they generate high costs due to their high request7; 2) adverse effects of false-positive results—these can produce additional side effects, including the costs of additional medical consultations and diagnostic tests, and the collateral effects of Ulysses8 and Imaginary Invalid syndromes9; and 3) increasing commoditization of the laboratory—the laboratory may be seen more as a “data vending machine” than as a provider of knowledge,10 and it might deliver results that are possibly misinterpreted or create a scenario in which those results with high clinical value are “hidden.”11 Given these issues, it is crucial to reduce variability of laboratory testing in clinical practice.12 Indeed, establishing interventions in collaboration with all the stakeholders involved in healthcare is a key element for better efficiency in clinical decision making.13,14

The first objective of this study is to propose an intervention that can detect inappropriate requests of laboratory tests. The second is to monitor the course of the intervention over time through process and outcome indicators, customized according to the type and phase of the appropriateness strategy.



Through the National Health System, every citizen of Spain has access to public health services. The system divides Spain into health departments, each of which covers the healthcare necessities of a population living in a particular geographic area through several primary care centers and a hospital. The laboratory located at each hospital attends to the needs of every inhabitant of that health department.

The study was conducted from January 1, 2010, to December 31, 2014, in the clinical laboratory at the Public University Hospital of San Juan, a suburb of Alicante, Spain. This 370-bed suburban community hospital serves a population of 234,551 who utilize 9 different primary care centers (PCCs). It receives samples from hospitalized patients, outpatients, and primary care patients (PCPs).

Hospitalized patients’ samples are collected in every ward by nurses and then transported to the laboratory. The hospitalized patient and outpatient orders are entered manually in the laboratory information system (LIS); however, PCPs’ requests are ordered electronically by the general practitioners (GPs). Blood is drawn for PCPs in the PCC. Samples are transported by couriers following scheduled routes covering the PCCs and are delivered to the laboratory sample reception desk. Subsequent reports are sent electronically from the LIS to the PCP’s electronic health record.

Detection of Inappropriate Requests

In 2010, based on test utilization differences among Spanish geographical areas,15 overrequests of free thyroxine (FT4) tests were noted in primary care via the indicator that measures the ratio between the tests requested of FT4 and of thyrotropin (also known as thyroid-stimulating hormone [TSH]). The ratio of FT4/TSH equaled 0.42, which did not reach the published <0.25 indicator goal.16 We also detected a significant underrequest of serum calcium (s-Ca) tests and an overrequest of total bilirubin (tBil) tests in PCPs, through the indicators, “test requests per 1000 inhabitants” (37 and 56 tests per 1000 inhabitants for s-Ca and tBil, respectively).

For hospitalized patients, redundant requests of brain natriuretic peptide (BNP); ferritin; folate; glycated hemoglobin (A1C); high-density lipoprotein cholesterol (HDL-C); immunoglobulin G, A, and M (IgG, IgA, IgM, respectively); iron; and prostatic specific antigen (PSA); as well as rheumatoid factor, transferrin, triglycerides, and vitamin B12, were identified. We considered a test redundant when it was requested before an established interval; for instance, requesting a rheumatoid factor test when one had been performed just 2 days earlier was considered redundant.


Implementation of Strategies

To address the problem, we designed and established 4 strategies in consensus with GPs and the test-requesting hospital physicians. The first strategy, implemented in PCCs, is that the LIS discards FT4 when the TSH value is in reference range, unless the FT4 measurement is specifically requested by the GP. The second strategy, also implemented in PCCs, is that the LIS automatically adds s-Ca to the GP requests made for patients 45 years or older who have not had the test in the previous 3 years.17

GPs agreed with these 2 interventions during various meetings; patients provided verbal consent for conducting a biochemical examination at the moment of the request by the GP. However, if, for some particular reason, a clinician justifies the relevance of an automatically cancelled FT4 test for a specific patient, this test is registered again.

The third strategy consists of measuring tBil only when the icteric index is above 2 mg/dL (34.2 µmol/l).18 The icteric index is a very accurate semi-quantitative surrogate of tBil. When the index is below 2 mg/dL (34.2 µmol/l), tBil is reported through a comment, such as “with a confidence interval of 99%, tBil result is below 1.2 mg/dL (20.5 µmol/l).” This strategy was applied to every type of patient.

The fourth strategy involved hospitalized patients. If previously requested and completed in the past 7 days, the LIS would automatically negate requests for tests of total cholesterol, HDL-C, or A1C. If previously requested and completed in the past 3 days, the LIS would automatically negate requests for tests of BNP, ferritin, folate, IgG, IgA, IgM, iron, PSA, rheumatoid factor, transferrin, triglycerides, or vitamin B12.

eAppendix Table A (eAppendices available at illustrates the different steps of the proposed approach to identify and correct potential inappropriate use of laboratory tests. The strategies to reach appropriate request levels of FT4, s-Ca, and tBil in primary care, and the intervention for the aforementioned tests in hospitalized patients, were established in May 2011, November 2011, January 2012, and March 2012, respectively. From October 2012 to January 2013, the s-Ca strategy stopped for preliminary evaluation, then the strategy was reinstituted in January 2013. The rest of the measures were continuous.

This study was approved by the Hospital Research Committee of the Public University Hospital of San Juan.

Monitoring Through Process and Outcome Indicators

The strategy that discards FT4 when the TSH value is in the reference range was monitored through the ratio of requests of both tests. The strategy to increase the measurement of s-Ca in PCPs was monitored through the process indicator: the absolute number of s-Ca tests that were added. This strategy was also monitored through the indicator that relates s-Ca to serum glucose (s-Glu) requests. To control that the predicted increase in s-Ca requests was indeed due to the intervention and not a general trend, we also calculated the ratio of serum creatinine to s-Glu requests. The intervention to request tBil testing through a comment, when the icteric index is below 2 mg/dL (34.2 µmol/l), was monitored through the process indicator of number of patients whose tBil was not measured.

The strategy that eliminated the aforementioned tests (total cholesterol, BNP, etc) in hospitalized patients when requested too soon (as described) after previous identical measurements was evaluated monthly, utilizing the counts of tests that were cancelled.

We calculated the following outcome indicators: number of new cases of primary hyperparathyroidism (HPT) detected; the economic cost per new HPT diagnosis derived from an s-Ca test added from the clinical laboratory (calculated by dividing the total amount of s-Ca reagent costs by the number of new HPT cases); and economic savings that resulted from the decrease in tBil measurement and from cancelling the hospitalized patients’ tests that were deemed redundant because identical ones had recently been performed. To calculate these savings, the tBil and redundant tests that would have been performed were counted, and the total was multiplied by the price of the reagent that would have been used (other “saved” laboratory fees were not included). eAppendix Table B summarizes the different indicators that were used to track and monitor the different interventions after their establishment.


The Table shows the number of requests and tests received annually on behalf of PCPs and hospitalized patients from January 1, 2010, to December 31, 2014.

Figure 1 shows the evolution of the FT4/TSH indicator value for primary care on a monthly basis. The indicator goal was reached in May 2011 and has been maintained ever since.

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