The usefulness of implementing minimum retest intervals in reducing inappropriate laboratory test requests in a Dutch hospital

Introduction

Over the past decades, a rise in healthcare costs have been observed and international campaigns have been launched to discourage low-value care. Although in vitro diagnostics (IVD) only accounts for a maximum of 2% of the total health care budget worldwide, laboratory testing represents the largest volume of diagnostics in current use, and an estimated overuse of approximately 20% has been described [1, 2]. Apart from the financial consequences, a decrease in unnecessary testing would be more patient friendly and would lower the risk of false positive results and additional potentially harmful downturn diagnostics [3]. Despite different campaigns and studies to reduce inappropriate use of laboratory testing, it is still a challenging problem. We recently demonstrated in the RODEO project that a reduction of 11% in laboratory test volume could be achieved by using a combination of different interventions, such as education, feedback and modifications in order entry systems such as minimum retest intervals (MRI) [4]. However, the effect of the individual components of these combined interventions on this reduction is not clear. In the primary care setting, education and computerized physician order entry (CPOE) strategies such as order sets and reflex testing seem most effective while feed-back reports and cost display as single interventions have minimal effects [5].

A MRI is an intervention to reduce inappropriate laboratory retesting and can be implemented as a CPOE intervention if a local laboratory system can provide this facility. A MRI is a defined time period in which a test cannot be repeated, the test order will be blocked. Retesting in this time interval is considered to have limited clinical value and should therefore be avoided unless a physician has specific reasons for overruling the MRI. Besides MRI, other terms used to describe this intervention include frequency filtering, spare periods, redundancy checks, electronic gatekeeping and demand management in general [4, 6], [7], [8]. Choosing the right time interval is important in the prevention of missing clinical relevant results due to too restrictive MRIs, and still let the MRI be effective in blocking inappropriate repeated tests. There is no international guideline on standard time periods for MRIs, but The Association for Clinical Biochemistry and Laboratory Medicine has published recommendations for the use of MRIs in clinical biochemistry and these recommendations have frequently been used in previous studies [9], [10], [11].

The effectiveness of broadly implemented MRIs to reduce inappropriate repeat testing is still unclear. A recent review described, based on 31 identified studies between 2000 and 2020, a cancellation of 10.6% of the test requests after MRI implementation [11]. However, these studies have described this intervention for a variety of laboratory tests with different time intervals and mostly in a limited number of the laboratory tests. An earlier study in the Netherlands reported a slighter effect where the proportion of barred tests was only 0.56% [7].

The aim of this study is to evaluate the effectiveness of broadly implemented MRIs to reduce inappropriate laboratory test requests, after implementation in a general care hospital in the Netherlands as a part of combination of interventions.

Materials and methods

Results

After excluding tests with less than 100 requests during July 13th 2017 and December 31st 2019, 28 laboratory tests remained. In total, 218,511 requests of these tests were ordered during the study period by the department of internal medicine. Most of these requests were made in the outpatient clinics (72.98%), and a smaller amount at the emergency department (18.87%) and inpatient clinics (8.15%). The day care unit is included in the inpatient clinics, and dialysis unit included in the outpatient clinics. In the day care unit, patients are treated with chemotherapy, blood transfusion or other medications during the day and are discharged in the evening.

MRI alerts were reported in 4,159 tests, corresponding with 1.90% of the test requests. Physicians overruled these MRI alerts in 21.76% of the alerts and 78.24% of the MRI alerts were honored. 3,254 test requests out of a total of 218,511 (1.49%) were barred due to MRI implementation. Table 1 shows the MRI alerts and barred tests sorted by specific laboratory test, combined with the financial costs. Immunoglobulins, LDH and NT-proBNP had the highest percentage of blocked tests, whereas liver biochemical tests had the lowest percentage. Figure 1 presents an histogram with the percentage of blocked tests for all evaluated tests. Most of the barred test requests were ordered at the outpatient clinics (59.99%, 1952 test orders), compared to 16% (521 orders) at the emergency department and 24% (781 orders) at the inpatient clinics. The distribution of barred tests over the different locations in the hospital is illustrated in Figure 2.

Figure 1:

Blocked tests due to MRIs (percentage of requested tests).

Figure 2:

Distribution of tests between outpatient clinics, inpatient clinics and the emergency department (ED). Day care units are included in the inpatient care, and dialysis unit is included in the outpatient care.

The percentage of overruling MRIs was scattered between 0.00 and 91.10%, as shown in Table 1. Overruling MRIs was most common with regards to triglycerides, T4, PSA and HDL.

During the almost 30-month period evaluated in this study, the financial savings for the department of internal medicine due to the implementation of MRIs for 28 laboratory tests (see Table 1) was 11,880 euros on a total amount of 636,598 euros for all performed tests.

Discussion

This study evaluates the effect of implementing minimum retest intervals to reduce inappropriate laboratory test requests. Overall, the benefits of these MRI alerts on the amount of tests and financial savings are small. Only 1.49% of the test requests were barred as a result of implementing MRI alerts.

Contrary to previous studies, we observed only a small effect on the amount of tests by implementing MRIs. A 2020 review reported an average of 10.6% cancelled tests in 31 included studies in the period 2000–2020 [11]. However, a few other studies reported a limited effectiveness of MRIs. Pema et al. described a 3.18% cancellation rate of requested tests and Lapic et al. a 1.9% reduction of requested tests [13, 14]. A previous study in the Netherlands, the only Dutch study about this topic in the past, reported a proportion of 0.56% barred tests and 0.33% financial saving of total testing costs in line with our study [7]. These concurrent smaller effects of MRIs in the Netherlands may be explained by an already existing awareness of appropriate laboratory test utilization in the Netherlands. Compared to approximately 2% worldwide, only 0.5% of total health care budget is spend on IVD in the Netherlands and this is one of the lowest ratings in the world [2]. A striking difference between the Netherlands and other countries is the organization of laboratory diagnostics. In contrast to other countries, medical laboratories in the Netherlands are relatively small, mostly located in the hospital and collaborate with hospital staff on a daily basis. Therefore, clinical chemists are accessible for consultation by physicians and actively participate in multidisciplinary consultation. These interactive organization of clinical chemistry presumably leads to more awareness of appropriate laboratory test utilization, a diagnostic process that is more adjusted to an individual patient and is less driven by financial motives.

Another possible explanation for the different effects of MRIs compared to previous studies, is the various time intervals that are used for implementation of MRIs. The recommendations of the Association of Clinical Biochemistry and Laboratory Medicine for MRIs depend on the (suspected) diagnosis and previous results of an individual patient [9]. We implemented MRIs for all patients, inpatient and outpatient clinics separately. Therefore, comparison with these recommendations is complex. The various time intervals in previous studies, as reported in the review of Lang, impede the interpretation of these study results in context to each other [11]. Lapic et al. observed the effects of MRIs implemented in inpatient clinics and reported similar results as our study, but they defined overall longer time intervals than in our study (range of 1–30 days longer). Only IgG and lipogram test profile had longer time intervals in our study [14].

Overall, some laboratory tests have a shorter time interval while other tests have a longer interval. When narrowing this time interval, the proportion of barred tests will probably increase. However, when implementing MRIs, narrowing this time interval could also lead to more overruling of the MRIs. In our study, 21.76% of the MRI alerts were overruled by the physicians. These findings suggest smaller time intervals may not lead to positive effects on appropriate laboratory test utilization and may cause irritation to physicians and alert fatigue. Moreover, MRIs should prevent unnecessary test repeats and when overruling occurs frequently, the question is in which extent these were unnecessary test requests.

In addition, the possibility to overrule a MRI also affects the cancellation rate of requested tests. MRIs can be implemented as a soft block or hard block intervention, based on the additional effort necessary to overrule the MRI. An example of a soft block intervention is an alert which notifies the ordering physician that the test is probably not necessary, but the physician can still order the test. In case of a hard block intervention, the ordering physician can only overrule the MRI by making a phone call to the laboratory, for example. Procop et al. compared these two kind of interventions and concluded that a hard block was significantly more effective than an alert only [15]. According to this definition, we implemented hard blocking MRIs in our study. Lapic et al. also described limited effectiveness of MRIs, but they implemented soft blocking MRIs [14]. However, two of the other studies which reported limited effectiveness of MRIs had also implemented hard blocking MRIs [7, 13].

Differences between the outcome of our study and other studies could also be related to the clinical setting. Both our and the previous Dutch study were conducted in a general care and teaching hospital and showed similar results. Studies on MRI in primary or tertiary care may show different results. Pellicer et al. described a successful effect of hard blocking MRIs as a gate keeping system to reduce test requests for anti-thyroblobulin and anti-thyroid peroxidase antibodies in primary care, while no change in trend was achieved in specialized care [16]. It could also be assumed that longer time intervals could be more effective in the primary care, without a rise in overruling MRIs or an increase in underutilization, based on a different patient population with less complex diseases than in a hospital setting. Different clinical settings require different time intervals of MRIs.

A major strength of this study is that we analyzed the effect of MRI implementation for several frequently ordered laboratory tests, in combination with a long study period of almost 30 months. In addition, we evaluated the effect of MRIs in a general care and teaching hospital. The combination of these factors distinguishes this study from several previous studies and is therefore relevant for many hospitals in different settings.

This study has a few limitations. First, the MRIs were implemented as part of a study to reduce unnecessary laboratory testing and was combined with other interventions like education and feedback. After implementing this combination of interventions an average reduction of 11% in laboratory test volume was accomplished in the four participating hospitals [4]. Therefore, it was not possible to measure the effect of MRIs alone. By reporting only in proportions, a decrease in total laboratory testing due to these interventions had no influence on our outcomes. Nevertheless, an increased awareness of appropriate testing could have caused less test repeats during the time period of the MRIs and less barred test requests. For example, during this previous study awareness was created through education and changes in order systems for AST testing and this resulted in a significant decrease in AST orders. The indications of other laboratory tests like CRP and ESR were also discussed during this previous study. Consequently, it is possible that this created awareness have led to a relatively low effect of MRIs in this hospital.

Second, we only analyzed the department of internal medicine due to various implementation dates in each individual department. The effect of MRIs was potential bigger in other departments, because in other departments there were no other interventions carried out. On the other hand, most of the laboratory tests are ordered by the department of internal medicine. An earlier study about the differences in inappropriate repeat testing between specialties, described the highest ratio of inappropriate repeat testing in surgical science specialties while the highest volume of inappropriate repeat testing was ordered by specialties from clinical medical science (internal medicine included) [17].

Future research on this topic is necessary to study the effect of MRIs on creating awareness of appropriate laboratory testing. This awareness is difficult to measure due to different factors that can affect behavior, but the influence of MRIs is potentially much bigger than on the amount of test requests and cost savings. The previously described RODEO project, focusing on reducing inappropriate laboratory testing, also led to a significant decrease in volume of radiology, nuclear medicine or microbiology tests in three of the four participating hospitals [4]. This finding underscores our hypothesis that interventions such as MRIs have potential more effect than we can measure in retrospective studies due to changes in the behavior of physicians induced by the implementation of MRIs. Furthermore, we only calculated the direct cost reduction related to the number of barred tests measured. Less false-positive test results could have much bigger impact besides the direct laboratory-related costs.

In conclusion, the effect of implementing MRIs on the amount of laboratory testing and direct financial savings is limited in our study. However, MRI alerts offer a continue reminder for physicians to use diagnostics appropriately and can be used to create awareness. The use of MRIs should be considered to improve the appropriate use of laboratory tests, but the potential impact of these alerts in each hospital strongly depends on the overuse of laboratory testing before implementation, the position of the laboratory in the hospital and the clinical care setting.