Testing Blood Glucose at the Bedside in a Chronic Care Hospital

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1 CHEMISTRY Robert M. Greendyke, MD F. Ronald Gifford, MT(ASCP) Testing Blood Glucose at the Bedside in a Chronic Care Hospital We can provide tests that are fast, inexpensive, or accurate. Pick two. Anonymous Most authors agree that bedside or point-of-care testing for blood glucose (BG) provides results quickly, usually in 5 to 8.5 minutes.1,2 Indeed, the most often-heard justification for this method is that it shortens turnaround times for reporting of urgently required results. Winkelman et al2 and Nosanchuk and Keefner,3 however, have demonstrated that pneumatic tube systems that rapidly transport specimens to the central laboratory offer a viable, cost-effective alternative when combined with special laboratory provisions that expedite reporting. A number of investigators have studied the costs of BG testing at the bedside and in the centralized laboratory for both large- and smallvolume applications. They concluded that bedside testing is substantially more costly in most settings. One of the authors found each test for BG cost $11.5 at the bedside whereas it cost $3.19 in the laboratory in a small Veterans Administration (VA) hospital.1 Winkelman and others reported bedside testing to cost $6.62 while laboratory testing cost $3.3 in a large teaching hospital.2 In a similar institution, LeeLewandrowski and others reported $4.19 for a bedside test and $3.84 for the test performed in the laboratory.4 (They did not include indirect costs for bedside BG testing while assessing central laboratory costs of 3%.) At the same time, Lee-Lewandrowski and colleagues separately calculated costs of $13.48 for bedside BG testing in an affiliated hospital. Somewhat disconcerting is the report from the College of American Pathologists' Q-Probe study on bedside BG testing5 analyzing data from 569 ABSTRACT A prospective study was carried out in a chronic care hospital to determine the clinical indications for testing blood glucose (BG) levels at the bedside and to assess the degree of correlation between the clinical impression of the patients' BG status and the results of these tests. Most (94%) BG tests performed on inpatients at the bedside were done to monitor routine treatment and did not require the rapid turnaround time afforded by this type of testing. Clinical estimation ofbg status was highly inaccurate, which presents the argument for routine monitoring but not for the immediate turnaround provided by this method. The cost ofbg testing at the bedside in low-volume settings is high, and the method is periodically unreliable. These disadvantages must be weighed against the undocumented advantages of the method: shorter hospital stays and more rapid stabilization ofbg levels. institutions. In this study, almost 9% of bedside results varied from those obtained in the central laboratory by more than 25%; 1.4% varied by more than 1 mg/dl (5.6 mmol/l) and several (.4%) by more than 2 mg/dl (11.1 mmol/l). In this study,5 14% to 16% of errors in bedside BG testing resulted in inappropriate treatment. The authors cited a report stating that 17 deaths and 871 patient injuries related to bedside BG testing had been reported to the Food and Drug Administration by March It seems fair to infer from the almost universal clinical acceptance and enthusiasm for bedside BG testing that this method has merits. Factual data to support this position are, however, currently unavailable.1'6'7 As Rainey and Jatlow have written, "We do not know whether bedside testing in the hospital, when compared to centralized testing with rapid turnaround, results in more rapid stabilization of glucose concentration or reduced hospital stay."7 Downloaded from JANUARY 1997 VOLUME 28, NUMBER 1 From the Pathology and Laboratory Medicine Service, Department of Veterans Affairs Medical Center, Canandaigua, NY. Presented at the ASCP/CAP Fall Meeting, New Orleans, September 18, Reprint requests to Dr Greendyke, Pathology and Laboratory Medicine Service, Department of Veterans Affairs Medical Center, 4 Fort Hill Ave, Canandaigua, NY LABORATORY MEDICINE

2 The study presented here was designed to gather information on the use of bedside BG No. of Tests Indication testing in a long-term1,621 Therapy management care VA hospital with Suspected hyperglycemia 55 emphasis on clinical indications for testing 34 Suspected hypoglycemia and correlations bebehavioral change 1 tween the clinical imunknown 5 pression of the patient's BG level and the results of bedside BG testing. Although the data do not bear directly on the merits of bedside BG testing, they do permit certain inferences about the monitoring of the type of diabetic patient population served and the unreliability of the clinical assessment of BG levels from subjective evaluation. TABLE 1. WHY CLINICIANS ORDERED BEDSIDE BLOOD GLUCOSE TESTS Plan of Study The study was conducted at the Department of Veterans Affairs Medical Center in Canandaigua, NY. The institution is a 66-bed chronic care facility with a predominantly geriatric and chronic psychiatric population. The center has no surgical, obstetric, or pediatric services; no emergency department; and an intensive care unit of only five beds. In this hospital, testing for BG levels has been conducted at the bedside for the past 5 years using the Boehringer-Mannheim Accu-Chek Ilm meter (Indianapolis). To operate this instrument, the nurse-operator must be credentialed, demonstrate proficiency quarterly, and be recertified Fig 1. Frequency distribution of 1,725 blood glucose test results obtained at the bedside on four clinical units during a period of 18 days. LABORATORY MEDICINE VOLUME 28, NUMBER 1 JANUARY 1997 Downloaded from annually. The performance of the instrument is checked weekly, and a laboratory technologist monitors quality control. The number of instruments in use and the number of operators certified is restricted on medical wards that use the instrument at a high rate. The prospective study was conducted on one acute-care and three intermediate-care medical units for 18 consecutive days, beginning March 18, No newly diagnosed cases of uncontrolled diabetes mellitus were in the study. For all orders for bedside BG testing during the study period, clinicians were required to state the indication for testing, eg, suspected hypoglycemia or hyperglycemia, management of therapy, behavioral change, etc. All orders were entered into the hospital's computerized central data management system with the test results and demographic information. At the conclusion of the study, the data were collected and subjected to review. Hospital policy requires that conventional laboratory analysis confirm all abnormal results of bedside BG testing (ie, less than 6 mg/dl [3.3 mmol/l] or greater than 4 mg/dl (22.2 mmol/l]). When conventional laboratory analysis was performed, the results were available for comparison. Results During the study, 1,725 bedside BG tests were performed on 6 patients. Each patient was subjected to an average of 29 tests; patients were tested 1 to 28 times. Excluding patients with 4-r

3 only one or two tests, 1,77 tests were performed on 48 patients. (A mean of 36 tests was performed per patient in this group.) A plot of the frequency distribution for the bedside BG testing results is shown in Fig 1. The reasons why practitioners ordered the tests are shown in Table 1. The indication listed most often (94%) was management of treatment. Particular attention was paid to correlation between patients with clinically suspected hypoglycemia or hyperglycemia or with clinically unexplained behavioral change and the results of the bedside BG testing. Results are shown in Table 2, where it is apparent that the clinical suspicion of possible hypoglycemia was confirmed in only 24% of cases. The suspicion of possible hyperglycemia was confirmed for 69% of patients; 13% of patients had BG levels of greater than 4 mg/dl (22.2 mmol/l). Only 1 of 1 patients whose behavioral change was evaluated was found to have abnormal BG levels. Data regarding patients who were hypoglycemic or hyperglycemic when tested at the bedside correlated with their clinicians' impressions are presented in Table 3. Clinicians suspected hypoglycemia in only 17% of patients found hypoglycemic and suspected hyperglycemia in only 5% of patients found with hyperglycemia. In light of the potential clinical consequences of inaccurate results and the reportedly low 5 but definite occurrence of such errors in BG testing at the bedside, the results were examined to determine how often abnormal bedside BG testing results were confirmed immediately by laboratory testing. Despite a hospital rule requiring such confirmation, only 52 (33%) of 16 abnormal test results were verified. Of the 27 confirmed tests reporting BG levels of greater than 4 mg/dl, 1 (37%) of 27 were in error by more than 15%; such patients were not as hyperglycemic as the bedside results indicated. Of 15 results of BG levels of less than 6 mg/dl, 8 (53%) were in error by more than 25% TABLE 2. CLINIC AL IMPRE! 5SION OF GLUCOSE Al 3NORMALITY VS BEDSIDE BLI DOD GLUC OSE TEST RESULTS Clinical Impression Hypoglycemia (N=34) Hyperglycemia (N=55) Blood Glucose Level (mg/dl) <6 >6 >4 <4 >2 <2 No. of Patients TABLE 3. CORRELATION BETWEEN CLINICAL IMPRESSION AND ABNORMAL BLOOD GLUCOSE RESULTS Blood Glucose Level < 6 mg/dl (N=58) Hypoglycemia clinically suspected 1 Patients Hypoglycemia not clinically suspected 48 Patients Blood Glucose Level > 4 mg/dl (N=94) Hyperglycemia clinically suspected Hyperglycemia not clinically suspected A secondary goal of the study was to see what impact the introduction of bedside BG testing had on glucose testing in the laboratory (see Fig 2). The number of BG tests performed at the bedside doubled between 1992 and 1995, while the length of patient stay decreased by 17%. The volume of BG tests in the laboratory did not change. Thus, the postulated savings in labora tory testing of BG levels offered as an argument yf * & # # N c^ & & J? Blood Glucose Levels Tested at the Bedside ( 1 ) Blood Glucose Levels Tested in the Laboratory < 1 ) Cumulative Patient Days ( 1") 5 Patients 89 Patients Fig 2. Length of patient stay, glucose tests performed in the laboratory, and blood glucose testing performed at the bedside on four clinical units, Note: bedside testing began in 199. (1995 data: 9 months annualized.) c o 8» u e 3 E E o i 1 i Downloaded from JANUARY 1997 VOLUME 28, NUMBER 1 LABORATORY MEDICINE

4 for bedside BG testing has not materialized, nor do these data support the claim that the nationwide decrease in patient bed days can be attributed to BG testing at the bedside. Discussion Previous work from our institution 1 has shown that a bedside BG test costs the facility roughly three times as much as conventional laboratory glucose determination ($11.5 vs $3.19). With a modest annual volume of 6, tests, our institution's costs approximate $69, for testing BG at the bedside. The cost is wholly incremental, inasmuch as the volume of plasma glucose testing in the laboratory has not been reduced since bedside BG testing was introduced to this facility 5 years ago. Similar observations have been made previously by Lee-Lewandrowski and others. 4 Although $69, seems a modest sum by current standards, this figure becomes impressive when multiplied by the thousands of institutions testing BG at the bedside. Justifications for expenditures of this magnitude are required, but as pointed out by several authors, 5 ' 6 few factual data have been provided to demonstrate improved patient outcomes or decreased hospital stay. The usual arguments in favor of testing BG at the bedside focus on the rapidity with which test results are available. Great variability in laboratory test turnaround time arguably exists (partially because the way to determine the beginning and ending of turnaround time varies), yet a survey of 365 hospital laboratories conducted in 1993 reported a mean turnaround time of 76 minutes for routine laboratory testing for glucose. 8 Improvements, such as transporting specimens by pneumatic tubes, computerized reporting, specimen bar-coding, and improved automation were among factors cited in reducing turnaround time for routine testing by half between 198 and Winkelman and others 2 have achieved remarkable turnaround times for stat glucose tests in a major teaching hospital, reducing the mean turnaround time to 9.5 minutes. Because this method's cost-effectiveness and benefits to the patient have not been demonstrated, the authors have tried to obtain applicable data by indirect means. An attempt was made to find out why each BG test was done at the bedside. Clearly, allowances must be made for inaccurate orders by clinicians, but the data suggest two conclusions. First, management of therapy (ie, adjustment of insulin dosage) was the most common indication, and second, the clinical impression of the patient's BG status poorly correlated with the test results. It may not be appropriate to generalize about indications for bedside BG testing from the experience in a geriatric, chronic care institution to all hospitals. At least in this facility, however, it seems reasonable to say that even an hour's delay in the adjustment of daily or twice-daily insulin orders is not critical in most cases. The fact that 36 tests were performed on the average patient over 18 days, roughly one test every three days, strongly suggests that BG testing was performed at the bedside usually to monitor insulin administration, not to manage uncontrolled diabetic ketoacidosis. The greatest usage was for a single patient who had 28 tests in 18 days. The urgency of much of our bedside BG testing thus comes into doubt. The inability of our clinical staff to predict BG levels on subjective grounds is understandable but also argues for regular BG monitoring. Although the studied population is small, the clinical suspicion of either hypoglycemia or hyperglycemia was incorrect in the great majority of cases (74 of 89 instances). Conversely, hypoglycemia or hyperglycemia was present in 152 cases but suspected in only 15. No one would argue reasonably that suspected abnormalities in BG levels should not be confirmed at once, but the bulk of cases of severely elevated or decreased BG were not clinically suspect. This being the case, regular assessment is clearly needed, if for no other reason. A question could be raised, however, about whether bedside BG testing is the proper vehicle for routine inhospital monitoring. Point-of-care testing frequently is justified in terms of potentially reducing length of the patient's stay and faster clinical decision-making as a result of reduced turnaround time. 4 Yet a recent study by Tsai and others in a large institution failed to show major benefits even in the emergency room setting. 9 The authors found that point-of-care testing for a seven-analyte chemistry panel and for a complete blood count would have resulted in earlier therapeutic action in only 19% of emergency-room patients studied. Further, treatment of three fourths of these patients required an additional step, such as a consultation or computerized tomography scan that lengthened the patients' stay. Downloaded 66 from LABORATORY MEDICINE VOLUME 28, NUMBER 1 JANUARY 1997

5 CYTOSPIN 3 Finally, the authors remain concerned about the potential for substantial error in bedside BG testing results, as documented by the Q-Probe study reported by Jones5 and confirmed in the present work. Such errors have been shown to be more frequent in the case of inexperienced or infrequent users of the test instruments. Errors of 1 to 2 mg/dl ( mmol/l) occur in reported values;5 mistakes in reports of hypoglycemia were common in our study. When the therapeutic aim of diabetes control is rigid management of blood sugar levels, such errors are unacceptable, if not life-threatening. It could be argued that complications engendered by incorrect bedside BG testing results easily could nullify the postulated benefits of rapid turnaround times in shortening length of patient stay. More work is clearly needed to justify the expense and to prove the clinical benefits of the surge of bedside testing before even greater expansion of the concept is embraced. In the meantime, rigid attention to performance monitoring of the bedside BG testing remains essential. Conclusion In the authors' institution, clinical assessment of patients' BG status at extreme levels poorly correlates with the results of bedside BG testing. Most bedside BG testing at that institution is performed for nonemergent, routine monitoring, which can be accomplished more accurately and less expensively using conventional testing in the laboratory CYTOCENTRIFUGE The Pathologist's Choice For Monolayer Cell Preparation LID STAYS LOCKED UNTIL PROGRAM COMPLETION SEALED HEAD FOR SAFETY APPROVED SPEED AND TIME REMAINING DISPLAY LOW, MEDIUM AND HIGH ACCELERATION RATES 9 PROG MEMORY References 1. Grecndykc RM. Cost analysis: bedside blood glucose testing. Am I Clin Pathol. 1992;97: Winkelman JW, Wybenga DR, Tanasijevic MJ. The fiscal consequence of central versus distributed testing of glucose. ClinChem. 1994;4: Nosanchuk IS, Keefner R. Cost analysis of point-of-care laboratory testing in a community hospital. Am J Clin Pathol. 1995;13: Lee-Lewandrowski E, Laposata M, Eschenbach K, et al. Utilization and cost analysis of bedside capillary glucose testing in a large teaching hospital: implications for managing point of care testing. Am ) Med. 1994;97: Jones BA, Bachner P, Howanitz PJ. Bedside glucose monitoring: CAP Q-probe study of the program characteristics and performance in 65 institutions. Arch Pathol Lab Med. 1993;117: Bickford GR. Decentralized testing in the 199s. A survey of United States hospitals. Clin Lab Med. 1994;14: Rainey PM, Jatlow P. Monitoring blood glucose meters. Am ] Clin Pathol. 1995;13: Editorial. 8. Jahn M. Turnaround time: part I. MLO. 1993;25: Tsai WW, Nash DB, Seamonds B, Weir GT. Point of care versus central laboratory testing: an economic analysis in an academic medical center. Clin Ther. 1994;16: New Meyafunnels Now prepare samples of up to 6 ml per chamber in your Cytospin. Call For a free sample. HWTTTM LXiPSHAW A LIFE SCIENCES INTERNATIONAL COMPANY US CUSTOMERS CALL: FAX: (412) EXPORT CUSTOMERS CALL: (412) FAX: (412) YOUR SINGLE JANUARY 1997 Downloaded from SOURCE FOR VOLUME 28, NUMBER 1 PATHOLOGY LABORATORY MEDICINE