Faculty/Presenter Disclosure I WOULD NEVER ORDER THAT FOR THAT PERSON; LAB USE AND MISUSE IN ALBERTA 19/10/2016

Transcription

1 I WOULD NEVER ORDER THAT FOR THAT PERSON; LAB USE AND MISUSE IN ALBERTA Trefor Higgins DynaLIFEDx Edmonton, Alberta Faculty/Presenter Disclosure Presenter: Trefor Higgins Relationships that may introduce potential bias and/or conflict of interest: Grants/Research Support: Speakers Bureau/Honoraria: Trefor Higgins has received a speaker fee and expense support from the Alberta College of Family Physicians, Bio Rad Laboratories Consulting Fees: Other: Employee of DynaLIFEDx 1

2 Disclosure of Commercial Support This program is presented by the Alberta College of Family Physicians (ACFP) without any commercial or in kind support. The ACFP provides a speaker fee and expense support for presenting at the Practical Evidence for Informed Practice. Managing Sources of Potential Conflict and/or Bias Material/Learning Objectives and/or session descriptions were developed and reviewed by the Planning Committee composed of experts/family physicians/allied care professionals responsible for overseeing the program s needs assessment and subsequent content development to ensure accuracy and fair balance. Consideration was given by the Planning Committee to identify when speakers personal or professional interests may compete with or have actual, potential, or apparent influence over their presentations. Information and/or recommendations in the program are evidence and/or guidelines based, and the opinions of the independent speakers will be identified as such. 2

3 Purpose of laboratory testing Diagnosis Confirmation or rejection of clinical diagnosis. Prognosis Information regarding likely outcome of disease. Monitoring Follow natural history or response to treatment. Screening Detection of subclinical disease. The hype on laboratory tests 70% of all diagnosis are based on laboratory results 70% of objective data in a patient s file is laboratory data Some diagnosis have moved to a laboratory based diagnosis (thyroid, diabetes). Laboratory Medicine : A National Status Report Lewin Group 2008 IFCC Task Force; Current evidence and future perspectives on the effective practice of patient centered laboratory medicine 35% of Alberta s population visit a laboratory during the course of a year. 3

4 Laboratory related causes of diagnostic errors Ordering the wrong test Not ordering the right test Misapplying the test result due to misinterpretation or failure of synthesis Missing the test results not getting it to the right place at the right time Test results inaccurate Epner PL et al. When diagnostic testing leads to harm; a new outcome based approach for laboratory medicine. BMJ Qual Saf,22 (Suppl 2),ii6 10 (2013) Lipid testing To fast or not to fast? Is sending the patient to the laboratory with a request for non fasting lipid testing a waste of time and money and done solely for patient convenience? 10 to 25% of lipid testing is performed on patients who are not fasting Took 298 genuine fasting lipid panels and modified the results by the difference between fasting and non fasting states using a Monte Carlo simulation resulting in 5000 lipid panels and found that fasting and non fasting panels gave the same 10 year risk factor. For monitoring therapy fasting sample is mandatory as the true LDL cholesterol value can only be obtained on a fasting specimen For investigation for familial hypercholesterolemia fasting is mandatory Non HDL cholesterol will soon be included in the lipid battery 4

5 HbA1c. The best test to diagnose diabetes? The fastest growing test in Alberta ( 12% per year) despite restricting repeat frequency Recommended by diabetes societies as the test of choice for diagnosis of diabetes Convenient patient does not have to fast, laboratory does not have to worry about sample integrity Test is much more expensive than glucose When the HbA1c result does not correlate with clinical presentation consider Presence of hemoglobin variant Increased turn over of red blood cells Iron deficiency, renal failure, smoking, medications (Ribavirin) Plea: Please order a glucose when you order HbA1c Does this patient have diabetes? Patient is 27 y male Initial results fasting glucose 14.4 mmol/l (reference interval 3.3 to 6.0 mmol/l) and HbA1c 4.0% (reference interval 4.3 to 6.1%) Asked to make sense of these discrepant results Repeat HbA1c is 3.8%. Alternative HbA1c 4.0% Repeat fasting glucose 11.1 mmol/l (reference interval 3.3 to 6.0 mmol/l) Urine glucose 1+ (reference interval negative) Does the patient have diabetes? Fructosamine 497 umol/l (reference interval 180 to 330 mmol/l) 5

6 Potassium. Why is it sometimes elevated for no clinical reason? 62 y male has potassium test performed at a community laboratory with a result of 6.1 mmol/l. Physician called and patient is asked to go to the hospital for repeat test which is 4.2 mmol/l. The community laboratory cannot perform potassium testing correctly The patient clenches their fist during collection The patient has increased red cell fragility The patient has increased platelet count Patient is on ACE inhibitors A wing set ( butterfly) was used for collection Chloride and CO2 In a community setting the CO2 is of dubious value because of the prolonged time between collection and analysis Chloride is reflective of Na and adds little additional information 6

7 Allergy testing The RAST test is like the dodo bird extinct please do not order IgE no longer needed with allergy testing Requests for 20+ allergens quite common ( maximum is 5 for family physicians). Record is 64 allergens requested. In Ontario patients pay per allergen ($15) Wall of shame vodka, air, alcohol, saw dust, everything, water Plea; Take a good history asking when and where the response happens and what are the symptoms Anemia Common ordering pattern is CBC (1), Ferritin (0.61) and Vitamin B12(0.54) On average we analyze 1500 B12 tests per day of which 1 to 3 are below the reference interval (0.3%). After the elderly the second most common group with of low B12 values is females aged 21 to 34 y 1700 Ferritin test daily of which 7.6% are below the reference interval Since folate fortification folate testing is no longer useful in most cases. Saw 2 low folate with macrocytosis cases in 6 months both due to liquid diets folate tests performed in Alberta yearly with possibly 8 low folates values and macrocytosis at a cost per low folate $ to 50% of folate results are too high to measure 7

8 ANA What does a positive result mean? On average we perform 100 ANA tests per day of which 15 to 20% are positive. Incidence of SLE is 0.2 % of population. Thyroid testing What really is ordered Optimal practice guidelines (TOP) recommend a reflex TSH test for initial assessment. Further testing is automatically performed if the TSH is outside certain values. For monitoring use TSH. Wait 4 to 6 weeks after medication change before testing. Analysis of 1 year of thyroid testing ( test orders) at DynaLIFEDx 10.4 % of all thyroid testing did not follow practice guidelines and all thyroid tests were ordered in 59% of these. Analysis of cases where all thyroid tests ordered showed using reflex testing gave identical results in all but 1 case Thyroid testing performed more than 9 times a year on 860 pa ents accoun ng for 9400 tests Thyroid antibody testing performed as frequently as once a month TSH can change by 62% due to biological and analytical variation between successive measurements 8

9 ESR or CRP? Both are non specific as markers for inflammation/infection CRP rises faster and rises to higher multiples of the reference interval CRP reference intervals are independent of gender/age ESR needs a special collection device which causes discomfort to some patients and sample cannot be used for more tests CRP uses a regular collection tube and sample can be used for other tests. CRP is better analytically, clinically and is superior from a patient safety perspective ESR is preferred test for temporal arteritis Liver panels ALT, AST, Alkaline phosphatase, GGT (bilirubin, total protein) ordered as a battery liver panel AST a stupid test ALT a lovely test Multiple papers documenting that ALT and GGT (or Alk Phos) sufficient for liver investigation 9

10 ATTG the test of the year Perform between 100 to 350 per day In 83 and 95% of the samples the ATTG level is too low to quantitate 2 to 3% are positive In Summary: TEST Test volume Action ANA to 20% positive Follow check list before ordering ATTG to 90% too low to measure 2 to 3% are positive. Is patient really celiac? Allergy 500 Good history, 5 maximum B B12 0.2% deficient Order B12 if macrocytosis Ferritin 7.6% deficient suspected C Limited value due to delay Chloride Values mimic sodium ESR/CRP 500 CRP bad ESR worse Folate 50 4 per year macrocytosis Limited utility after fortification HbA1c Not great for diagnosis Lipid panel Fasting not needed for initial assessment Liver panels 500 ALT and GGT are sufficient Thyroid Algorithm is very efficient 10