Role of EQA/Inter laboratory testing Dr. R.Selvakumar CMC; Vellore Quality is.... • invisible when GOOD • impossible to ignore when BAD Changes over a Century 2012 1912 • • • • • • • • • 485 million Poor Healthcare Infrastructure Poor socioeconomic status Time plenty, Money scarce Communicable diseases Clinical science Caregiver driven Conservative mindset Minimal regulatory control • • • • • • • • • 1.25 billion Robust Healthcare Burgeoning middle class Money plenty , Time scarce Non communicable diseases Technology driven Patient driven Informed mindset Stringent regulatory control Consequences of poor quality • Inappropriate action – Over‐investigation – Over‐treatment – Mistreatment • Inappropriate inaction – Lack of investigation – No treatment • Delayed action • Loss of credibility of laboratory • Legal action Factors influencing internal quality Sample Transport Sample handling Sample Collection Sample receiving Analysis Patient preparation Outside laboratory Within laboratory Requisition Results Patient Doctor Reports Factors influencing quality PROFICIENCY OF PERSONNEL: Education, Training, Aptitude, Competence, Commitment, Adequate number, CME, , Motivation USE OF APPROPRIATE CONTROLS: • Internal: Labs, Calibrated against national • External: Supplied by manufacturer, National, International Assessment REAGENTS STABILITY, INTEGRITY AND EFFICIENCY: Stable, Efficient, Desired quality, Continuously available, Validated EQUIPMENT RELIABILITY: Meet technical needs, Compatible, User & maintenance friendly, Cost effective, Validated ANALYTICAL PERFORMANCE DOCUMENTATION: All the written policies, plans, procedures, instructions and records, quality control procedures and recorded test results involved in providing a service SPECIFICITY & SENSITIVITY OF SELECTED TEST: Adequate ST, cost effective, compatible with, available infrastructure and expertise, interpretable, meets the needs/ objectives, validated Procedural reliability using Standard Operating Procedures Laboratory Mistakes in Stat Testing Types of Mistakes Department Preanalytical Analytical Postanalytical No. % No. % No. % Intensive care 39 67 6 10 12 23 Surgery 26 81 5 16 1 3 Medicine 33 61 9 17 12 22 Nephrology 31 69 5 11 9 20 Total 129 68.2 25 13.3 35 18.5 Phlebani and Carraro Clin Chem 43:1348, 1997 History of EQAS 1946 1953 1966 1970 1971 1975 - Belk & Sunderman (USA) Clinical Chemistry (UK) Finland Lab quality, Clinical Chemistry Regional Clinical survey, Uppsala Med. Microbiology –NEQAS (UK) EQALIS – national survey in most areas of lab medicine 1978 - ACBI / CMC EQAS 1980 - Survey in medical microbiology 1982 - Project SEQLA Pilot QC survey – Christian Medical College and Hospital, Vellore, April 1977. Constituent No. of Labs reporting Range of values reported mg% Acceptable results Sugar Urea Cholesterol Calcium 36 40 42 20 57 – 173 15 – 80 120 – 288 5.7 – 15.2 61% 53% 38% 55% First QC survey done by CMC Lab. No. 1 2 3 4 5 Glucose mg/dl 114, 107, 109, 114 108, 112, 114, 110 82, 84, 83, 84 172, 169, 170, 174 66, 130, 83, 127 Acceptable Range 102 - 118 Mean 110 Proficiency Testing (PT) External peer - comparison program Approved PT required if available Alternative PT if external not available - Split samples testing - Testing of known specimens - Clinical validation by chart review Integrated with routine workload Evaluation and corrective action What is EQA ? EQA is a part of the quality menu of the laboratory. It aims to analyse the accuracy of the entire testing procedure from the receipt of the sample and testing to reporting of the results. 10 commandments for Sample Quality Thou shall not overly clench fist at collection Thou shall not leave tourniquet on for too long Thou shall draw tubes in proper sequence Thou shall draw correct volume of blood Thou shall mix specimen adequately Thou shall wait till serum tube fully clots Thou shall centrifuge at proper speed & time Thou shall not re-spin primary tubes Thou shall not pour but aspirate to 2nd container Thou shall store sample under proper conditions QUALITY CONTROL QC is the most important and often least appreciated activity in the laboratory Every laboratory must know that QC is an obligation to the patient Every laboratory should strive to give an accurate test result for an analyte which is as close as possible to the “true” value for that analyte. QC helps to improve precision and accuracy. QC helps to reduce errors and to give both the laboratory personnel and the clinician confidence in the results. May be required for accreditation. Internal QC [Precision] QC External QC [Accuracy] [Proficiency Testing] INTERPRETATION OF QC DATA According to WHO an analytical system is out of control if one of the four criteria is met. A QC value lies entirely outside the control limit Seven consecutive values show a rising tendency Seven consecutive values show a falling tendency Seven consecutive values lie on the same side of the mean WESTGARD’S WARNING RULE Use of QC at one or two different levels will provide valuable information on the type of error. 12S –One control observation exceeding mean ± 2s ‐ warning 1 3S ‐ one observation is ±3 SD of the mean – rejection – Random error 2 2S ‐ two observations of the same level QC are more than mean ± 2 SD ‐ rejection ‐ systematic error R 4S ‐ difference between two observations within the run is more than 4 SD – rejection – random error 4 1S ‐ four consecutive observations are > 1SD ‐ rejection – systematic error 10 X ‐ ten consecutive observations are on the same side of the mean ‐ rejection – systematic error Plasma Glucose concentration Levey Jennings Chart for Glucose 95% confidence limits 150 + 6 mg% 156 154 152 150 148 146 144 142 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Days Good practices in testing PT samples PT samples must be tested with the laboratory’s regular samples. PT samples must be tested the same number of times that patients samples are tested. Laboratories should not send PT samples to another laboratory for analysis Laboratories must not engage in inter laboratory comparison of PT sample results before these results are submitted to the sponsor of the PT programme by the required report date. Laboratories must document all steps like handling, processing, testing and reporting of PT sample. Characteristics of a good QC material The analyte concentration should be at medically significant levels. The material should be available in large quantities. The material matrix should be as much like the human sample as possible. Constituents should be stable for a long period of time. The material should have low vial to vial variability After the vial has been opened and the material prepared, it should be stable during the period of use. The material should be ready to use or require minimum preparation. Control material should be reasonably priced ALTERNATIVE APPROACHES Whenever EQAS samples are not available the labs may use other appropriate materials as • • • • • Certified reference materials Samples previously examined Material from cell or tissue repositories Exchange of samples from other labs Control materials that are tested daily in interlaboratory comparison programmes. VELLORE Quality Assurance is a journey and not a Destination In other words: Organisations should be striving for continual improvements to their Quality Management System CONCLUSION The pathology can be found in a patient but not in the laboratory
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