Assessing glucose monitor performance--a standardized approach.

BACKGROUND: Glucose monitor evaluations must be carefully designed and executed in order to control protocol-specific bias and random patient interferences. Although published guidelines and recommendations exist, investigators rarely incorporate consensus standards or quality guidelines into glucose monitor evaluation studies. METHODS: We performed a literature search for "best practice" quality guidelines for conducting and reporting glucose monitor evaluation studies. These guidelines included: Standards for Reporting Diagnostic Accuracy (STARD); Clinical and Laboratory Standards Institute (CLSI) C30-A2 and EP9-A2; U.S. Food and Drug Administration (FDA); International Federation of Clinical Chemistry (IFCC); Netherlands Organization for Applied Scientific Research (TNO); U.K. Medicines and Healthcare products Regulatory Agency (MHRA); Scandinavian evaluation of laboratory equipment for primary health care (SKUP); National Standard of the People's Republic of China (China GB/T 19634); and International Standards Organization (ISO 15197). RESULTS: We constructed a checklist that outlines a standardized approach to glucose monitor evaluations, along with associated references applicable to international standards and consensus recommendations. We expect that the checklist could be used as the basis for a protocol that is (1) evidence-based, (2) scientifically defensible, and (3) sufficiently descriptive to allow for test and result reproducibility. CONCLUSIONS: We propose a standardized 14-step checklist that facilitates the incorporation of international consensus standards, quality guidelines, and acceptance criteria into the design and reporting of glucose monitor evaluation protocols.

Palm glucose readings compared with fingertip readings under steady and dynamic glycemic conditions, using the OneTouch Ultra Blood Glucose Monitoring System.

OBJECTIVES: Past studies have suggested the absence of lag between palm glucose and fingertip glucose, even when glucose levels are changing rapidly. However, at any given time point, there may be differences between palm and fingertip glucose values because of glycemic instability and/or test methodology. The objectives of this study included assessing the variability in fingertip blood glucose test results between two fingers, and establishing whether the variability in blood glucose test results obtained from the palm was clinically equivalent to that observed in fingertip-to-fingertip comparisons. METHODS: This multicenter trial was conducted on patients under both steady-state glycemic conditions and after meal and exercise challenges (to promote rapidly changing glucose). Sequential capillary glucose testing, performed with the One Touch Ultra Blood Glucose Monitoring System (LifeScan, Inc., Milpitas, CA), was allocated to two of four fingertip sites and one of two palm sites in each subject using a randomized, balanced, incomplete block design. One of the fingertips was designated the reference site. Fingertip-to-fingertip variability and fingertip- to-palm variability were assessed under these steady-state and dynamic testing conditions using error grid analysis and by comparing the proportion of clinically acceptable blood glucose tests at the palm site versus the fingertip site. Clinically acceptable agreement was defined as pairs of values (fingertip to reference, or palm to reference) within 15 mg/dL when reference glucose was < or = 75 mg/dL or within 20% when reference glucose was >75 mg/dL. RESULTS: One hundred eighty-one subjects with type 1 [n = 74 (40.9%)] or type 2 [n = 107 (59.1%)] diabetes at eight clinical sites completed the study. Overall, the proportion of clinically acceptable agreement was high for both palm (95.1%) and fingertip (97.5%) testing. The mean difference between palm and fingertip clinically acceptable agreement when done by healthcare professionals was -1.3% and -4.4%, under steady-state and dynamic glycemic conditions, respectively. Error grid analysis showed >97% of all palm and fingertip measurements fell in Zone A. CONCLUSION: This study demonstrated that variability between fingertip-to-fingertip and palm-to-fingertip measurements was in the clinically acceptable range during steady-state conditions and when glucose was rapidly changing.

Rapid changes in postprandial blood glucose produce concentration differences at finger, forearm, and thigh sampling sites.

OBJECTIVE: To compare pre- and postmeal capillary blood glucose concentrations measured at the finger, forearm, and thigh in adults with diabetes. RESEARCH DESIGN AND METHODS: For phase 1, capillary blood glucose concentrations were measured at six time points (premeal and at approximately 60, 90, 120, 150, and 180 min postmeal) using a blood glucose monitoring system and technician-obtained samples collected from finger, forearm, and thigh sites of 42 adults with diabetes. The finger samples were also tested with a laboratory instrument. For phase 2, approximately 14 weeks later, the testing procedures were repeated with 38 subjects from the original study population. RESULTS: Meter finger results were accurate at all time points. Alternate sites tended to produce lower glucose readings compared to finger readings at times when glucose was increasing rapidly (60 and 90 min postmeal). Forearm-to-finger differences correlated with rates of glucose change (r = 0.56, P < 0.001), as did the thigh-to-finger differences (r = 0.52, P < 0.001). Other factors, such as subject age, BMI, diabetes type, and insulin dependence did not have a significant impact on site differences. When the testing procedures were repeated with the same subjects, the pattern of site differences was consistent, although individual results were variable. CONCLUSIONS: Changes in blood glucose immediately after a meal may be identified at finger sites before detection at forearm or thigh sites. Alternate site testing appears to be a useful option for routine self-monitoring before meals; however, patients and clinicians should recognize that results may be different from fingertip results when glucose levels are changing rapidly.

The impact of balloon catheter dilation on frequency of sinus surgery in the United States.

PURPOSE: Endoscopic sinus surgery for patients with chronic rhinosinusitis (CRS) unresponsive to medical therapy has traditionally been performed under general anesthesia and in the operating room. Balloons for catheter dilation of paranasal sinuses were introduced in 2005, allowing sinus surgery to be safely performed either in the operating room or the office care setting, under local anesthesia. This change in care setting has raised concerns of overuse or expanded indications for sinus surgery. This study was thus designed to evaluate changes in surgical volumes in the United States, for the period 2006-2011, and to evaluate the impact of the sinus balloons on surgical practice. METHODS: The MarketScan(®) Commercial Claims and Encounter Database was queried for the period 2006 to 2011 using CRS International Classification of Diseases, Ninth Revision codes (473.X) and sinus surgery US-based Common Procedural Terminology (CPT) codes (endoscopic sinus surgery: CPT codes 31254-31294 and 31299; balloon catheter dilation: CPT codes 31295-31297). MarketScan's projection methodology was applied to estimate the nationwide prevalence of CRS and the incidence of sinus surgery. Procedural case mix and total average payment per surgery were analyzed. RESULTS: From 2006 to 2011, the yearly prevalence of CRS and sinus surgery volume remained flat with ~430 patients with CRS per 100,000 in the employer-sponsored insured population, of which ~117/100,000 underwent surgery. In 2006, 2.69 paranasal sinuses (95% confidence interval [95% CI]: 2.65-2.71) were treated during each individual sinus surgery, with an additional 1.11 nasal procedures (95% CI: 1.08-1.13) performed concurrently. By 2011, the procedural case mix had expanded to 2.90 sinus (95% CI: 2.87-2.93) and 1.16 nasal procedures (95% CI: 1.14-1.85) per surgery. Payments increased from $7,011.06 (α=$6,378.30; ß=3.1490) in 2006 to $9,090.11 (α=$8,350.20; ß=2.9535) in 2011, in line with US medical inflation. CONCLUSION: In the study population, approximately 1 in 3.7 patients diagnosed with CRS underwent sinus surgery. This ratio remained constant from 2006 to 2011. There was no evidence that the number of distinct sinus surgeries per 100,000 people increased despite the introduction and utilization of balloon catheter dilation tools that enabled migration of sinus surgery to the office.

The effect of an instant hand sanitizer on blood glucose monitoring results.

BACKGROUND: People with diabetes mellitus are instructed to clean their skin prior to self-monitoring of blood glucose to remove any dirt or food residue that might affect the reading. Alcohol-based hand sanitizers have become popular when soap and water are not available. The aim of this study was to determine whether a hand sanitizer is compatible with glucose meter testing and effective for the removal of exogenous glucose. METHODS: We enrolled 34 nonfasting subjects [14 male/20 female, mean ages 45 (standard deviation, 9.4)] years, 2 with diagnosed diabetes/32 without known diabetes]. Laboratory personnel prepared four separate fingers on one hand of each subject by (1) cleaning the second finger with soap and water and towel drying (i.e., control finger), (2) cleaning the third finger with an alcohol-based hand sanitizer, (3) coating the fourth finger with cola and allowing it to air dry, and (4) coating the fifth finger with cola and then cleaning it with the instant hand sanitizer after the cola had dried. Finger sticks were performed on each prepared finger and blood glucose was measured. Several in vitro studies were also performed to investigate the effectiveness of the hand sanitizer for removal of exogenous glucose.z RESULTS: Mean blood glucose values from fingers cleaned with instant hand sanitizer did not differ significantly from the control finger (p = .07 and .08, respectively) and resulted in 100% accurate results. Blood glucose data from the fourth (cola-coated) finger were substantially higher on average compared with the other finger conditions, but glucose data from the fifth finger (cola-coated then cleaned with hand sanitizer) was similar to the control finger. The data from in vitro experiments showed that the hand sanitizer did not adversely affect glucose meter results, but when an exogenous glucose interference was present, the effectiveness of the hand sanitizer on glucose bias (range: 6% to 212%) depended on the surface area and degree of dilution. CONCLUSIONS: In our study, use of an instant hand sanitizer was compatible with the results of a blood glucose monitor and did not affect finger stick blood glucose results. However, depending on surface area, hand sanitizers may not be adequate for cleaning the skin prior to glucose meter testing.

Review of adverse events associated with false glucose readings measured by GDH-PQQ-based glucose test strips in the presence of interfering sugars.

OBJECTIVE: To assess the implications of falsely elevated glucose readings measured with glucose dehydrogenase pyrroloquinolinequinone (GDH-PQQ) test strips. RESEARCH DESIGN AND METHODS: We conducted a review of the Food and Drug Administration's Manufacturer and User Facility Device Experience database and medical literature for adverse events (AEs) associated with falsely elevated glucose readings with GDH-PQQ test strips in the presence of interfering sugars. RESULTS: Eighty-two reports were identified: 16 (20%) were associated with death, 46 (56%) with severe hypoglycemia, and 12 (15%) with nonsevere hypoglycemia. In eight reports (10%), the AE was not described. Forty-two events (51%) occurred in the U.S. Although most events occurred in hospitalized patients, at least 14 (17%) occurred in outpatients. Agents most commonly associated with AEs were icodextrin-containing peritoneal dialysate and maltose-containing intravenous immune globulin. CONCLUSIONS: GDH-PQQ test strips pose a safety risk to insulin-using patients treated with agents containing or metabolized to interfering sugars.

Performance evaluation of a new blood glucose monitor that requires no coding: the OneTouch Vita System.

BACKGROUND: Improvements to blood glucose monitoring systems aim to simplify the testing process, reduce or eliminate errors, and provide additional information for patients with diabetes. New systems must continue to demonstrate high-quality analytical performance. The new OneTouch Vita System (LifeScan, Inc., Milpitas, CA) offers a no-code testing process and proven technology found in the OneTouch Ultra System. Comparative studies were conducted with the new and established systems to evaluate their precision and accuracy. METHODS: Within-run precision in blood, total precision with controls, and system accuracy were evaluated using three lots of OneTouch Vita Test Strips and one lot of OneTouch Ultra Test Strips. Accuracy was tested across a wide glucose range (38-520 mg/dl, 2.1-28.9 mmol/liter) using fingertip blood samples from 139 subjects. Reference plasma glucose values were obtained using the YSI 2300 STAT Plus Glucose & Lactate Analyzer (YSI Inc., Yellow Springs, OH). All studies were designed in accordance with requirements published by the International Organization for Standardization (ISO 15197). RESULTS: Precision testing (within-run and total) with both systems produced coefficients of variation (CVs) of <5% for all sample types and glucose levels. Within-run precision testing with blood showed CVs of <3.1% and <4.7% for the OneTouch Vita and OneTouch Ultra Systems respectively. Total precision with control samples gave CVs of <3.0% and <3.6% for the two systems. Consensus error grid analysis showed equivalent clinical accuracy with 98.4% (821/834) and 98.2% (273/278) of results within zone A. Both systems met the ISO acceptability requirements for system accuracy. CONCLUSION: The OneTouch Vita System provides a simple no-code testing process with performance comparable to the OneTouch Ultra and OneTouch Ultra2 Systems.