Venipuncture VS Finger Stick - eHealthScreenings

JANUARY 2013

Venipuncture VS Finger Stick

The Facts and the Fiction

Charles Foltz, Ph.D, M.P.H Introduction It’s no secret that biometric screenings are the foundation to successful wellness programs. “Good data in, good data out” is critical in quality, return on investment and effectiveness. Deciding on what type of a screening method to choose can be a complicated and often confusing choice. Factors such as testing methods, blood panel types, accuracy of results and overall company objectives are just some elements to consider. In this white paper, we will examine internal and external studies in a comprehensive evaluation of the differences, advantages, and myths of finger stick and venipuncture testing methods. Which Screening Method Is More Accurate? One question often debated in the wellness industry is whether finger stick is just as accurate as venipuncture blood testing for cholesterol screenings. “Accuracy of a Rapid, Finger Stick Lipid Profile Method is Comparable to Commercial Laboratory Methods,” a study commissioned by one of the largest manufacturers of finger stick equipment, is commonly referenced by many finger stick centric companies. The study concluded that the accuracy of finger stick and venipuncture screenings is comparable because of biases seen between both methods. The study‘s claims, combined with the fact that finger stick analyzers meet National Education Cholesterol Program (NCEP) analytical goals, lead people to believe the methods are comparable. However, if you take a comprehensive look at the commissioned study compared with other studies and measurements seen in a

1 Venipuncture VS Finger Stick – The Facts and the Fiction

practical setting, it becomes clear that there is NOT a true comparison and that venipuncture is clearly the most accurate method for cholesterol screenings. In the commissioned study, researchers examined the accuracy of the finger stick analyzer with three commercial laboratories by comparing them to true values determined by a Cholesterol Reference Method Laboratory Network (CRMLN) laboratory. The Center for Disease Control (CDC) has established the CRMLN to ensure the nationwide standardization of lipid measurements are consistent with the National Education Cholesterol Program (NCEP) analytical goals. The NCEP has established total error guidelines (Fig 1) for lipid tests and the NCEP guidelines apply to all testing methods regardless of instrument size or location. % range

Total cholesterol +8.9% HDL cholesterol

+13%

Triglyceride

+15%

LDL cholesterol

+12%

Figure 1. NCEP total error guidelines.

To meet the guidelines, blood results from a device or test must measure within a positive or negative range at least 95 percent of the time. For example, if total cholesterol is measured at 195 by a Cholesterol Reference Method Laboratory Network (CRMLN) laboratory, it has met the standard if 95 times out of 100, the finger stick results fall within a range of 213 to 178. The commissioned study claims that finger stick results are comparable to venipuncture results because of biases seen in both

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methods when compared to the standardized CRMLN lipid values. Upon closer examination of the study, the bias shown by LabCorp, the commercial laboratory used by eHealthScreenings, was approximately one percent or less for Total Cholesterol (TC), Triglycerides (TRG) and Low Density Lipoprotein Cholesterol (LDL). With such a small bias, the commissioned study’s claim that the accuracy of finger stick and venipuncture are comparable based on biases when compared to CRMLN values is FALSE if you only use the LabCorp values. What did we find when looking at noncommissioned studies? Non-commissioned studies reveal that finger stick blood testing does not consistently meet the NCEP total error guidelines for lipid tests. In the McKenney et al. study, the total error assessments indicated that triglycerides and LDL cholesterol measurements in individual patients did not meet the guidelines of the National Cholesterol Education Program and that more precise measurement technology for LDL cholesterol is needed. In another study by Volles et al., they report each device had an excessive number (12-22%) of individual results that exceeded NCEP recommended total error for a single cholesterol measurement (+/- 8.9%) and both devices failed to meet the NCEP recommendation for precision of 3% CV. The study also states that because of the variability in results, both devices had excessive numbers of individual subjects with total cholesterol results greater than the recommended total error limit of +/- 8.9% difference from the standardized method. At best, there are conflicting reports regarding whether finger stick blood testing even meets the NCEP total error guidelines. Even if the finger stick values read within the acceptable standards, the variation within the accepted range could have a significant impact on employees that are in programs with incentives and penalties based on results and progress.


Referencing the earlier example in which the Total Cholesterol is determined to be 195 by a Cholesterol Reference Method Laboratory Network (CRMLN) laboratory, the finger stick results need to fall within a range of 178 and 213 to meet NCEP standards. But a reading of 195 versus 213 for total cholesterol is the difference between low and moderate risk classification. Also, there are five screenings that may fall outside the acceptable NCEP standards of 95 out of 100 times that can lead to further misclassification of a person’s risk level. With such a potential for inaccuracy, employees participating in results based programs may have viable appeal if finger stick methods are used instead of venipuncture. From a clinical perspective, the McKenney et al. study recommends that physicians and others who rely on finger stick test results for diagnosis and treatment decisions should consider the degree of inaccuracy and imprecision in these values. In addition, Stein et al. reports significant variability in lipid determinations using finger stick measurements limited their clinical usefulness in individual patients, and they should not be used to make clinical decisions regarding the diagnosis and management of dyslipidemia in patients. What did we find when we performed an internal study? Shifting from a statistical significance argument to a practical application scenario, we examined the reported findings in a practical setting, with an internal study under normal screening conditions, examining the results from finger stick and venipuncture blood tests. For finger stick testing, we selected the analyzer that is widely accepted as the most accurate system for on-site cholesterol and blood glucose screenings that was used in the commissioned study referenced earlier. For venipuncture testing, we selected the national commercial laboratory, LabCorp.


LabCorp is the main laboratory that eHealthScreenings uses when processing venipuncture results; based on the commissioned study, LabCorp is the most accurate commercial laboratory. In the study, we tested 36 people who gave two finger capillary samples that were analyzed in duplicate on two of six different analyzers and one venous serum that was processed by LabCorp nationally. All of the analyzers were calibrated according to manufacturer protocols. Only 50 finger stick and blood test results were used in calculations based on the number of people who were fasting and completed both test methods.

Our findings:

The finger stick results in a practical setting not only failed to fall within the NCEP guidelines, they were alarmingly inaccurate. In addition, there was tremendous variability between samples on different devices taken from the same person, bringing into question the precision of finger stick testing. Our conclusion is that venipuncture blood testing is clearly the most accurate and logical choice for cholesterol screenings based on its proven accuracy and precision. With most of today’s wellness programs moving towards incentive based programming, we believe the added accuracy is needed to validate the program. Finger stick screenings may be better for health fair style screenings where it’s acceptable to have a ballpark number, but is NOT recommended for more advanced wellness programs.

We measured the accuracy of finger stick testing by comparing each person’s finger stick results to their venipuncture results. Based on the extremely low bias for LabCorp reported by the commissioned study, we used venipuncture as the gold standard and calculated the total error of finger stick testing compared with the NCEP analytical goals. It is important to mention the commissioned study did report a high bias for LabCorp’s HDL measurement. When we compared the finger stick results with NCEP total error guidelines, the findings revealed that none of the blood tests fell within the guidelines 95 percent of the time. Finger stick screening met NCEP guidelines for (Fig 2): % range Total Cholesterol HDL Cholesterol Triglyceride LDL Cholesterol

Confidence level

+8.9%

74%

+13%

34%

+15%

72%

+12%

74%

(37 out of 50 times) (17 out of 50 times) (36 out of 50 times) (37 out of 50 times)

Figure 2. Confidence levels



Now let’s take a look at the pros and cons of both venipuncture and finger stick methods: Category Accuracy

Venipuncture • •

Testing Panels

•

Pricing

•

Participation Levels

•

Delivery Of Results

• •

Coaching

•

Draw Risk

• • • • •

ROI

• •

Data

•

Testing time

•

Participant Experience

Finger Stick

Most accurate screening method Reliable measurement tool for validating results in an incentive based wellness program

• •

Abundant testing options including more comprehensive chemistry panels, lipid panels, glucose, nicotine/cotinine, PSA, HbA1c, Thyroid / TSH, CBC, hsCRP, Homocysteine, and many others Dependent on the company providing you with service. For eHealthScreenings, venipuncture is a much better value because of the volume of venipuncture screenings that we process and the technologies that we are able to use when facilitating venipuncture events

•

•

Good for general baseline data Can lead to misclassification of a participants risk categorization based on potential accuracy and total error issues Being “comparable” in accuracy when compared to venipuncture is not the same as being just as accurate Mostly limited to lipid panel and glucose

•

Finger stick screenings have a lot of hard costs associated with them that can often increase the price of service. The process takes longer to complete, the finger stick cassettes which are used in the devices are expensive and expire after a month making it harder to send additional supplies as any unused are a sunken cost • The equipment is time consuming to calibrate adding additional labor time Participation levels typically have to do with the incentives offered vs the type of screenings performed At eHealthScreenings, we typically see better participation with venipuncture Blood results ready in as little as 1-2 • Immediate results business days when using • Value added teachable moment eHealthScreenings proprietary e.b.i.t (awareness overview / coaching) System (encrypted biometric information transfer). Current industry standard is 7-10 business days Data accuracy enables coaches to create • Creates initial awareness suitable and reliable actionable plans • Difficult for coaches to determine true risk geared towards targeting each participants level because of result inaccuracies specific areas of concern Hematoma • Prolonged tenderness and soreness in testing finger for up to 3 days after Slight bleeding screening Light headed • Finger Hematoma Fainting • Temporary scaring Infection (slight risk any time the skin is • Blood borne infection broken) Data accuracy provides a precise target • Can create initial high-risk awareness reach which increases ROI through intervention effectiveness Advanced panel options allow for expanded awareness and coaching services Comprehensive individual lab and detailed • General awareness report handout health data reports containing bios and including bios and blood results blood results Approximately 10 minutes per participant • Approximately 12 minutes per participant with basic bios with basic bios

Venipuncture Finger Stick Impartial Method Invasiveness* 43% 50% 7% Accuracy Confidence* 93% 0% 7% Method Preference* 93% 7% 0% Procedure Discomfort* 7% 93% 0% Procedure Intimidation* 43% 43% 14% *based on survey results collected from subjects who participated in the conducted internal study.



So which method is the best choice for your company? Simply, the best testing method is predicated by a company’s wellness objectives. Venipuncture screenings are ideal when the wellness program objectives are centered around: • • • • • • • • •

Quantifiable results Targeting correct risk factors Participant incentive program tied to data Advanced testing panels Data Accuracy High return on investment Comprehensive participant and corporate aggregate reports The participants screening experience Per participant cost savings

Finger stick screenings are the best choice if the wellness program is focused on: • • •

Immediate results feedback Simple baseline data General awareness

Both testing methods have their respective places in the wellness industry. With today’s wellness programs evolving into incentivebased programming, improved accuracy in the venipuncture method is necessary to validate the program.

annual basis. Through our core values of Integrity, Efficiency, Quality, Service, Innovation and Excellence, we stand behind a steadfast commitment of delivering total customer satisfaction. eHealthScreenings advantages include: • • • • • • •

Superior service levels Technology Speed of data Pricing Integration Customization capabilities National scalability

For more information about the report or eHealthScreenings visit www.ehealthscreenings.com, call 888.708.8807 or email [email protected] About the author Charles Foltz Ph.D, M.P.H has over 14 years of experience in the health and wellness industry. He completed his doctorate degree in Interdisciplinary Molecular and Cellular Biology at Tulane University. In addition, he earned a Master’s in Public Health in Epidemiology during his time at Tulane University. Currently, he serves as the Vice President of Research and Development at eHealthScreenings.

References About eHealthScreenings eHealthScreenings is the nation’s leading onsite wellness screening company. We specialize in the facilitation of onsite biometric screening services, typically in partnership with large wellness companies, disease management companies, EAP’s, HR consultants, brokers and Third Party Administrators. We provided health screenings for businesses with as few as 25 employees to those where we screen more than 120,000 employees nationally on an


McKenney JM, Fary DF, Miller G, Proctor JD, Chinchili VM. 1993. An evaluation of two compact analyzers used for lipid analysis. J Fam Pract. 36(5):526-33. Volles DF, McKenney JM, Miller WG, Ruffen D, Zhang D. 1998. Analytic and clinical performance of two compact cholesterol-testing devices. Pharmacotherapy. 18(1):184-92. Stein JH, Carlsson CM, Papcke-Benson K, Einerson JA, McBride PE, Wiebe DA. 2002. Inaccuracy of lipid measurements with the portable Cholestech L.D.X analyzer in patients with hypercholesterolemia. Clin Chem. 48(2):284-90.


Venipuncture VS Finger Stick - eHealthScreenings

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