Maximize HbA1c Testing and Diabetes Control


January-February 2015 - Vol.4 No. 1 - Page #2

As most health care professionals can attest, the prevalence of diabetes in the United States is increasing at a disconcerting rate. In 2012, 29.1 million Americans—approximately 9.3% of the total population—were diagnosed with diabetes, compared to 25.8 million or 8.3% of the population in 2010.1 These staggering statistics are of great concern given the significant complications and comorbidities associated with diabetes, including heart attack, stroke, eye problems and blindness, kidney disease, and amputation. 

In addition, diabetes and its associated complications exact a significant economic toll on society. In the same 2012 study, the national price tag of direct medical costs was calculated to be $176 billion, with an additional $69 billion attributed to reduced productivity.1 For these reasons, the diagnosis and proper management of patients with diabetes is of great importance.

Influence of HbA1c
Hemoglobin A1c (HbA1c), also referred to as glycated hemoglobin or glycohemoglobin, results from adding glucose to the hemoglobin molecule through a non-enzymatic process. Unlike a serum or plasma analysis of a sample taken from routine venipuncture, which provides only a snap shot glucose level from the specific time of the blood draw, the measurement of HbA1c represents the average blood glucose level over the previous three months (a period of time that correlates to the average life span of a normal red blood cell). HbA1c measurements are used to monitor a diabetic patient’s compliance with prescribed therapy or to predict a patient’s risk of developing diabetes and/or its associated complications.2 Today’s methods for HbA1c testing include core laboratory and point-of-care testing (POCT) options, both of which have operational advantages and disadvantages.

St. Vincent’s Medical Center in Bridgeport, Connecticut—a 473-bed, acute care community hospital—serves both inpatient and outpatient populations. The Family Health Center (FHC) and Seton Women’s Center offer a wide variety of health care services to the uninsured and underinsured members of the community. When considering which type of HbA1c testing—core lab or POC—to make available, we took into account our overall testing volume, available laboratory resources, and the makeup of our patient population.



Co-opting POC and Core-based HbA1c Testing
When we first adopted HbA1c testing, we offered it through our core laboratory only. Our original methodology required that specimens being tested for HbA1c have a hemolysate prepared prior to analysis. This was a time-consuming, manual step that necessitated the batching of patient testing three times per week during the day shift, Monday through Friday. Our laboratory had limited staffing on weekends, evening and night shifts, and holidays, so manual specimen hemolysate preparation could not be performed during these times. But with the advent of an improved methodology from our assay manufacturer, our core lab method no longer requires manual hemolysate preparation; this activity is now performed using instrument automation, thus making HbA1c testing available seven days a week, 24 hours a day. The resulting 24/7 availability more than adequately meets the needs of our inpatients. 

Next, we turned our attention to our outpatient population. Within the past two years, after consultation with FHC’s medical staff, our laboratory explored and implemented a POCT method for HbA1c at the FHC site. The driving factor behind this decision was that the delivery logistics and turnaround time associated with sending the offsite FHC specimens to the core lab were untenable; invariably, results were not available to FHC staff prior to patients leaving the clinic. This was particularly problematic because some of the FHC’s patient population tends to be transient, making communication regarding treatment after a patient leaves the clinic a significant challenge. The adoption of POCT testing in the FHC setting provided physicians with immediate HbA1c results, enabling appropriate treatment decisions while patients remained at their appointments.

Important POCT Considerations
Implementing POCT for HbA1c (or any other test) should entail several important considerations. First, if the POCT will be performed by non-laboratory personnel, the method must be designated as CLIA waived, and the laboratory must apply for a CLIA certificate before initiating patient testing. Second, personnel must be thoroughly trained on instrument maintenance and troubleshooting, the running and interpretation of quality control (QC) materials, the running of patient samples, and the documentation of both patient results and QC. The third consideration involves ongoing assessment of operator competency for as long as the POCT method is in use. 

According to regulations—POCT requirements from the College of American Pathologists (CAP) and the Joint Commission—operators must have initial training and demonstrate competency, followed by a competency reassessment at six months, and then annually thereafter. Furthermore, the regulations require that competency be proved through two methods; at St. Vincent’s, we use a written test and direct observation of specimen testing. We also subscribe to the CAP proficiency survey program, allowing our FHC staff to run unknown, whole-blood specimens for HbA1c followed by CAP assessing the acceptability of the analyzed results. Through participation in CAP’s proficiency survey program, we are provided with a third avenue for assessing operator competency. With this in mind, an organization may want to consider limiting the number of operators for a POCT method, as doing so will help to reduce the challenges of maintaining an operator-competency assessment program that meets rigorous regulatory standards.

In addition to the regulations covering testing personnel, there also are regulations that define the extent of the audit trail for POCT results, including the manner in which testing information (eg, lot numbers and expiration dates) and patient results must be posted to the medical record. Finally, a cost comparison is often necessary given that POCT methods may be more costly than core lab methods due to a higher cost per test unit. Keep in mind that the higher cost per test is due to the loss of economy of scale—a benefit of automation that POCT methods lack. If a POCT method is chosen for inpatient population testing, it is unlikely that reimbursement will offset the cost because of diagnostic-related groups (DRGs) bundling of services for reimbursement. Outpatient reimbursement for insured patients may be adequate, but recovery of costs for testing on underinsured or uninsured patients is unlikely.

Cost and reimbursement considerations aside, POCT methods allow health care providers to better serve patients, thereby resulting in improved patient outcomes. At St. Vincent’s, we chose to make POCT methods available to our clinicians caring for at-risk patient populations because we feel it is the right thing to do. In 1905, the Daughters of Charity opened the doors of St. Vincent’s Hospital on the same property where today’s Medical Center stands. The Daughters’ mission was to provide the best care to the sick and poor in the area, and we continue that mission today. Since 2006, St. Vincent’s has been a high-reliability organization (HRO); as such, we always put safety first. Implementation of POCT methods, which greatly improve the timeliness of diagnosis and treatment decisions, are one of the ways that we keep our patients safe.



Ensuring Testing Integrity
Before implementing a new POCT method or core lab assay for HbA1C, the laboratory should confirm that the method of choice is certified by the National Glycohemoglobin Standardization Program (NGSP) as being traceable to the Diabetes Control and Complications Trial (DCCT) reference method.2 The NGSP—which provides a comprehensive list of all core lab and POCT HbA1c methods that have been certified as having documented traceability to the DCCT reference method (available at www.ngsp.org/docs/methods.pdf)—recommends that manufacturers certify their method annually, as certification expires after one year. Another consideration is the potential for interferences from hemoglobinopathies in the patient population and whether the assay method is affected by the presence of variant hemoglobins or fetal hemoglobin. A comprehensive list of methods and interferences can be found at www.ngsp.org/interf.asp. 

In addition to the above due diligence, manufacturers provide information regarding their instrument’s accuracy and precision. It is generally accepted that core laboratory methods generate excellent results and that POCT methods entail greater variability, so it is adviseable to review the literature for assessments of current POCT market instruments.3 Other quality assurance considerations for both core lab and POCT methods include determining the critical value (CV) for the chosen method. Recommendations are that HbA1c have an intralaboratory CV of <2% and an interlaboratory CV of <3.5%.2 Finally, although manufacturers provide a defined reference range for their assay method, laboratories should establish their own reference range for their patient population based on the CSLI Guidelines found in document C28-A (available at www.clsi.org). 



Conclusion
The measurement of HbA1c is gaining an increasingly important role in patient care. It is now endorsed by the American Diabetes Association (ADA), the World Health Organization (WHO), and the Endocrine Society as being particularly useful in diagnosing diabetes (HbA1c >6.5%), being a quality predictor of the potential for developing diabetes, and for monitoring therapy compliance. Currently, only core lab methods are endorsed for use in diagnosis due to the variability of POC methods,2 but the delayed results associated with testing in the core lab may cause logistical problems with patient populations being cared for in off-site locations. Thus, the immediate results provided by POCT methods can help improve patient care. Regardless of which method is selected, the testing must be NGSP certified as traceable to the DCCT reference, and processes are required for quality assurance, including method comparison, determination of CV%, and establishment of reference range.

Disclosure
The comments and opinions expressed in this article are solely those of the author and not of the organization. Nor should they be considered anendorsement of a particular method, manufacturer, or product. 

References

  1. American Diabetes Association. Statistics about diabetes: Data from the National Diabetes Statistics Report, 2014. American Diabetes Association Web site; June 10, 2014. Available at: www.diabetes.org/diabetes-basics/statistics. Accessed August 7, 2014.
  2. Sacks DB, Arnold M, Bakris GL, et al. Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus. Diabetes Care. 2011;34(6):e61-e99.
  3. Lenters-Westra E, Slingerland RJ. Three of 7 hemoglobin A1c point-of-care instruments do not meet generally accepted analytical performance criteria. Clin Chem. 2014;60(8):1062-1072.

Susan E. Ferency, MS, MT(ASCP)C, is the manager of chemistry, phlebotomy, and POCT and is the education coordinator for the David H. Lobdell, MD Anatomic Pathology and Clinical Laboratory at St. Vincent’s Medical Center in Bridgeport, Connecticut. She has worked in the laboratory at St. Vincent’s for 26 years, spending the past ten years as a manager. Susan earned her BS in medical technology from Sacred Heart University in Fairfield, Connecticut, as well as an MS in organizational leadership at Quinnipiac University in Hamden, Connecticut. Also, she is an adjunct professor for the medical laboratory sciences (MLS) program at the University of Bridgeport.

Login

Like what you've read? Please log in or create a free account to enjoy more of what www.medlabmag.com has to offer.

Current Issue

Enter our Sweepstakes now for your chance to win the following prizes:

Just answer the following quick question for your chance to win:

To continue, you must either login or register: