Aims Repeat serum C-reactive protein (CRP) measurements on the same day or on consecutive days are of limited clinical value. Minimum retesting intervals are recommended for managing unnecessary repeat testing. As not previously reported, we studied the effect of minimum retesting interval test rejection on laboratory workload and expenditure and on clinician-requesting behaviour.
Methods In a prospective study, we evaluated the effect of an automated 48 h CRP minimum retesting interval rule on inpatient and outpatient CRP workload and costs. Control data on inpatient and outpatient serum urea and electrolytes (UE) workload were collected during the study.
Results Over 1 year, there was a 7.0% and 12.3% decrease in CRP requests and CRP tests analysed, respectively, following the introduction of the minimum retesting interval rule when compared to the 1 year baseline period. This equated to an estimated annual reduction in revenue costs of £10 500, but cash savings in consumable costs of £3000. There was no significant change in UE requests.
Conclusions We report, for the first time, that automated minimum retesting interval rejection rules as a stand-alone strategy are a cheap and sustainable method for reducing unnecessary repeat CRP tests, resulting in small laboratory cash savings, more efficient use of laboratory resources and standardisation of patient care pathways. The minimum retesting interval rejection rule also altered clinician test-requesting behaviour towards more appropriate requesting.
- Laboratory Tests
- Laboratory Management
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Clinical laboratories are under increasing pressure to reduce costs and maintain quality despite increasing workloads.1 A major reason for the dramatic increase in laboratory costs is the increased number of laboratory investigations, many of which are perceived to be a waste of time and money including excessive and unnecessary repeat testing.2 ,3 As a consequence, the Association for Clinical Biochemistry and Laboratory Medicine, supported by the Royal College of Pathologists, has published recommendations for minimum retesting intervals for use in clinical biochemistry.4 ,5 A minimum retesting interval is the minimum time before a test should be repeated, and is based on the properties of the test and the clinical situation in which it is used.4 National guidelines on appropriate testing frequency, however, appear to have little impact on inappropriate test requesting.6 Although there may be many possible reasons for this, labour intensive methodologies and the inability to sustainably influence clinicians’ laboratory requesting are probably the most important.3 An automated IT-based minimum retesting interval rejection rule has the potential to overcome these hurdles, but there is no data on the effect of minimum retesting interval test rejection on laboratory workload and costs or on clinician test requesting patterns.
Repeat C-reactive protein (CRP) measurements on the same day or on consecutive days are of limited clinical value.4 Guidelines recommend CRP should not be repeated within a 24 h period with the exception of requests in neonates.4 ,7 In a 2-year prospective study we, therefore, evaluated the effect of an automated IT-based 48 h minimum retesting interval rejection rule for managing repeat CRP requests.
Activity data for CRP requests were collected between June 2006 and May 2013 to identify annual trends in workload. An audit of CRP requests between 1 March 2011 and 7 March 2011 was initially carried out to identify the number of repeat (within 48 h) CRP requests. Subsequently, in July 2011, an automated 48 h minimum retesting interval rejection rule for repeat serum CRP was introduced, with an over-ride facility only by direct consultation with a consultant microbiologist, within hours and out-of-hours. The rule, recommended by our consultant microbiologists, was applied to all patients with the exception of neonates ≤7 days old. A letter communicating the change was distributed to all consultants, nurse practitioners and junior doctors just prior to implementation of the minimum retesting interval rule.
Audit and activity data were collected retrospectively via the laboratory IT system. The intervention was implemented using the Trust's electronic requesting (TD-Web, Technidata Medical Software, Montbonnot, France) and laboratory IT systems (TD-Synergy, Technidata Medical Software, Montbonnot, France). Although the Trust's e-requesting system alerts the clinician to a repeat request, there is no facility to block the request at this stage, so test rejection is facilitated by the laboratory IT system alone. The requestor is alerted to a blocked test via an automated comment appended to the results report. Serum CRP and serum urea and electrolytes profile (UE; a surrogate marker of laboratory workload) data for inpatients and outpatients were compared 1 year before (July 2010–June 2011), and for 1 year after (July 2011–June 2012) the intervention. Changes in laboratory costs for CRP were calculated as total and consumable expenditure.8
Data, as assessed by the Kolmogorov and Smirnov test, were parametric. Changes in laboratory workload for 1 year before and 1 year after the minimum retesting interval intervention were, therefore, assessed using the unpaired t test. Data are expressed as means with SD in parentheses. Data processing and statistical analyses were performed using GraphPad Instat V.3.00 for Windows 95 (GraphPad Software, San Diego, California, USA).
CRP activity data (CRP tests analysed) since June 2006 showed a mean annual (year-on-year) increase of 13 (5) % until the 48 h minimum retesting interval rule intervention (figure 1). The audit prior to the intervention identified that 343 of 2646 (13%) CRP requests were repeated within 48 h. These repeat requests originated from inpatients (81%) and, to a lesser extent, outpatients (19%). Since no repeat requests were received from primary care, the effect of the minimum retesting interval rule was evaluated by studying laboratory workload data on CRP and UE from inpatients and outpatients only.
Over 1 year, there was a 7.0% and 12.3% decrease in CRP requests (p<0.005) and CRP tests analysed (p<0.0001), respectively, following the introduction of the 48 h CRP minimum retesting interval rule when compared to the 1-year baseline period (table 1). In the year following the intervention, 6.2% (462 (70)) of requests were rejected per month, but 2.6% (12 (5)) of rejected requests were reinstated in agreement with a consultant microbiologist (table 1). No complaints were received, and the intervention was acceptable to clinicians and laboratory personnel. The 12.3% reduction in serum CRP test analysed, over 1 year, equated to an estimated reduction in total costs of £10 500 (derived using a full cost per test of £0.84) and a cash saving of £3000 (based on a consumables cost per test of £0.24). There was no significant change in UE requests following the minimum retesting interval intervention (table 1).
The 48 h CRP minimum retesting interval rejection rule was effective since 97.4% of CRP requests repeated within 48 h were not analysed. Very few (2.6%) rejected CRP requests were reinstated suggesting that most repeat CRP requests were unnecessary. We suggest that the reduction in CRP requests and tests analysed was directly due to the automated minimum retesting interval intervention. Data were collected for 12 months before and after the intervention eliminating any influence of seasonal variation on CRP workload. The automated minimum retesting interval intervention had no significant effect on UE requests and tests analysed, suggesting the reduction in CRP requests was not due a non-specific general reduction in laboratory workload. Additionally, the sharp decrease in CRP requests and tests analysed was against a background of a year-on-year increase in CRP requests and tests analysed (figure 1).
Other studies have reported a reduction in laboratory workload and expenditure with a combination of several strategies including repeat test rejection.9 ,10 Janssens and Wasser reported a reduction in laboratory workload and costs using a combination of clinician education and discussion followed by a laboratory computer ‘barring’ repeat tests.9 Hutton and colleagues successfully used a sequential combination of disease-related protocols, consultant only requesting and a 24 h minimum retesting interval protocol to manage CRP over-requesting on two acute wards, including the Accident and Emergency Department and the Medical Admissions Unit.10 Their 24 h CRP minimum retesting interval rule, however, did not appear to have a significant impact on CRP request analysis10 possibly because CRP requesting had already reached a nadir following previous interventions. In these studies, it is unclear which single strategy, if any, from the combination of several (some labour intensive) strategies was effective.9 ,10 We report, for the first time, that automated minimum retesting interval rejection rules as a stand-alone strategy are effective in reducing unnecessary repeat tests.
Although several strategies for curtailing clinicians’ inappropriate laboratory over-usage have been proposed, none has been universally successful.3 There may be several reasons for this, but the most important is most likely labour intensive methodologies which are difficult to implement, expensive and difficult to sustain.3 Although cost savings were relatively small in our study, the 48 h CRP minimum retesting interval rejection rule was inexpensive (easy to implement and not labour intensive) and easily sustainable.
The 48 h minimum retesting interval rejection rule also altered clinician-requesting behaviour, since there was a reduction in CRP requesting following the minimum retesting interval intervention. Ideally, test rejection should be at the point of request for maximum feedback impact and also the potential to reduce unnecessary venepunctures, but this is not possible with our electronic requesting system. Our current electronic requesting system alerts to repeat tests but cannot prevent tests being requested and, therefore, tests may only be rejected after sample receipt in the laboratory. Since repeat CRPs continued to be unnecessarily requested, education on appropriate requesting may still be required, in addition to automated approaches, to more fully tackle inappropriate requesting.
In conclusion, we report for the first time that automated minimum retesting interval rejection rules as a stand-alone strategy are an inexpensive, sustainable and effective method for reducing analyses of inappropriate repeat CRP tests, resulting in small laboratory cost savings but more efficient use of laboratory resources and standardisation of patient care pathways. The automated minimum retesting interval rejection rules also altered clinician test-requesting behaviour towards more appropriate requesting.
Take home messages
Stand-alone automated minimum retesting interval rejection rules for repeat C-reactive protein (CRP) requests are an inexpensive and sustainable method for reducing analyses of unnecessary repeat CRP tests.
Automated minimum retesting interval rejection rules result in small laboratory cash savings, more efficient use of laboratory resources and standardisation of patient care pathways.
Automated minimum retesting interval rejection rules influence clinician test-requesting behaviour towards more appropriate requesting.
Contributors JLW researched the literature, analysed the data and wrote the first draft of the manuscript. RH designed, implemented and tested the IT rule base. AR extracted the data. CF, DD, GD and RG contributed to the data. RG is the guarantor. JLW and CF conceived the study. All authors reviewed and edited the manuscript and approved the final version of the manuscript.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.
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