Point-of-Care Testing: What does is really mean today and is it relevant to the local

situation ?

Patrick St.LouisDépartement de biochimie

Hôpital Ste-Justine et Université de Montréal

Montréal, Canada

SCPC, Havane, 2004

Point-of-Care Testing (POCT) the analysis of

(biochemical) parameters at or near the patient’s bedside.

A new name for satellite lab testing ? ER, OR, ICU

Clinical benefit of POCT reduces the time intervalbetween the decision to order the test and the clinicalaction based on the test result (total turn-around time;

TAT)test needed/request specimen lab test/result report

One classification of POCT

• in vitro (traditional)

manual: urinalysis, occult blood

instrumented: glucose meters, ACT, gases

• in vivo

invasive e.g. pulmonary artery catheter

non-invasive e.g. transcutaneous bilirubin, pulse oximetry (transcutaneous)

• ex vivo

in-line sensors; through an extracorporeal circuit

some examples

The present scope of POCT: Tests possible in the ER

• Blood gases, electrolytes, creatinine, lactate

• hemglobin/hematocrit • cardiac markers: myoglobin, troponin, BNP - NPV for

Dx of CHF = 98%; precludes the need for echocardiography

• Coagulation: PT/INR, ACT, D-dimer

• glucose

• urinalysis, urine pregnancy test

• hemoccult/gastroccult/pH

• drugs screens

• rapid HIV

How is POCT used and what are its advantages?

1. POCT for glucose:

• improves response time for

high risk neonates with hypoglycemia,

diabetics in hyperglycemia

patients in Tight Glycemic Control protocols

• decreases iatrogenic blood loss - l of capillary blood

2.

Clinical applications of anticoagulation therapy

• OR - cardiac surgery, interventional cardiology and radiology (heparin)

• critical care

• satellite sites: dialysis, ECMO, anticoagulation clinic

• Patients on coumadin/warfarin therapy

Monitoring anticoagulation therapy

treament monitor with

• heparin (intrinsic pathway) ACT, aPTT

• coumadin/warfarin PT/INR

(extrinsic pathway)

• direct thrombin inhibitors ???

(common pathway)

• Thrombolytics (clot) TT, fibrinogen

• POC coagulation testing for monitoring patient status post-thoracic/cardiovascular surgery; studies have shown that this permits the evaluation and management of microvascular bleeding:

complications

- blood loss

- need for blood and blood products

- re-operations (repeat surgery)

overall cost of care

satisfaction

Patients on coumadin/warfarin therapy:

• Monitor using PT/INR testing

• Patient self-testing a major direction with clear advantages

There are Advantages and Problems related to the use of instrumented POCT:

POSITIVES

for the most part these POCT devices are robust and easy to use; require minimal maintenance

testing process is generally simple

results are usually reliable

• Data management in instrumented POCT systems– calibration curves, AMR– QC: lot information, automated QC– material information: strip lot numbers, parameters– identifiers: operator, patient– results: tests, QC, unique event time stamp– lock-out: operator and patient ID, QC demanded,

prohibits use of expired reagents– have comment codes, response protocols– notices and messages

Issues with POCT devices

• method characteristics : AMR (measuring range), linearity, precision usually not as good as central lab

• sample type in relation to normal (reference) intervals- blood glucose: capillary/venous blood

plasma/whole blood

• QC; operator attitude to QC

• results and charting; ensuring that the information gets to the Laboratory Information System and into the patient chart - Connectivity

POSSIBLE CAUSES OF POOR PERFORMANCE

• novel technologies– transcutaneous bilirubin: interferences, calibration

– hematocrit determination by conductivity

• interferences– gel separator tubes

– drugs in patient samples

– Extraneal (icodextrin; a dialysis solution)- GDH-PQQ-based glucose meters

• patient-related – high hematocrit in neonatal samples for glucose

THE COST FACTOR

No standardised manner of calculating costs for POCT

Generally the cost/patient result is higher than the corresponding central laboratory cost

Some factors:• reagent costs: the single-use disposable strip or cassette or

multi-test packs versus standard laboratory reagent packaging in hundreds of tests; the incremental effects of utilisation on costs more costs less

• equipment costs: additional to central lab system• labour costs: operators, coordinators, • other: QC, training, re-certification, regulatory requirements

Cost can also be affected by the total number of tests; demand for confirmation, correlations.

1. POCT for glucose; central laboratory volume (6 months):

pre-POCT = 20406; post-POCT = 24028; figures were not related to bed occupancy or to patient mix; do not include glucose meter (POC) testing (Lum, 1997)

Similar results from a recent study at HSC, Toronto2. HSJ Glucometer program

projected annual workload: 40,000

actual year 2000: patients = 35,459

controls = 22,931

actual total 58,390

QC and QA in POCT

Quality Control

POCT, like all laboratory testing, demands regular QC testing to assure acceptable performance (CAP Q-probes)

For single-use reagent test strips or cassettes - lot validation

Instrumented, multitest systems - traditional QC procedures Electronic QC: these are simulators designed to monitor the

performance of the hardware/reader part of the system; they do not evaluate the chemistry/reagent part of the system.

iQM: used in the IL GEM 3000; FDA approved; a complex algorithm using the same liquid material for QC and calibration

• Just as in traditional central laboratory testing, QA is important in POCT; there are however some different issues

With POCT variable number of individual devices; multiple sites; many operators; training? need clear protocols ensure appropriate QC practices; resistance to QC assure proper storage of reagents, supplies eliminate use of expired reagents, cassettes, slides, etc verify error-free operator and patient ID results: documentation and reporting

meters September October November

no. of ID # (%)patients

no. of ID # (%)patients

no. of ID # (%)patients

2 95 71 (75%) 206 151 (73%) 163 142 (87%)

4 204 127 (62%) 208 119 (57%) 154 94 (61%)

1 68 45 (66%) 142 112 (79%) 157 129 (82%)

4 165 132 (80%) 488 384 (79%) 453 359 (79%)

1 12 3 (25%) 8 3 (38%) 10 9 (90%)

patient tests control ratio p/c

405 281 1,41466 873 1,71375 493 2,8841 351 2,456 17 3,3

898 858 1,0930 832 1,11090 258 4,21652 525 3,1213 479 0,4563 787 0,7657 854 0,8

10146 6608 1.54

HOW CAN YOU OPTIMALLY USE POCT?

• manual tests are already used

• Common instrumented POCT types glucose meters

blood gas analysers (electrolytes, creatinine, lactate)

coagulation analysers

cardiac marker systems

urinalysis instruments

glucose meters

• personal or hospital type; relative complexity and costs of instruments

• lack of QC and data handling capacity in P types

• reliability of results for close clinical management; American Diabetic Association and NCCLS guidelines neither should be used for diagnosis.

• cost of strips; cost of QC material;

• Validation of instrument performance; NCCLS guidelines for POCT performed outside lab support

• Blood gases; single use i-STAT and IRMA

• multi cassette ABL700 series

• GEM Premier series; more tests; reliable, less costly on a per/test basis; wastage; how portable?

• co-oximetry: O2 sats, Hb and Hct assays, technology

Trends in POCT

MUCH OF POCT IS NO LONGER ACUTEThe introduction of new clinical standards is motivating physicians to demand testing be done closer to the patient. (Dr. R.

Christenson, U. of Maryland)

Out-patient and specialty clinics

EVIDENCE BASED LABORATORY MEDICINE NACB/AACC project for POCT impact on patient outcomes; looking at all areas -gases, electrolytes, glucose, creatinine, coagulation, fertility, peri-natal testing (fetal scalp pH, fern testing, pH testing for ruptured membranes), transcutaneous bilirubin, cardiac markers, etc

CONCLUSIONS

Like the “Core Lab” concept, POCT is here to stay? Is it more cost-effective?

? Better patient care

? more satisfaction: patient and caregiver

Newer paradigms

? is POCT now physician driven; is this any different from the past?

Trends in evidence-based POCT