basic of diagnostic

8/10/2019 Basic of Diagnostic

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Basic principles of Diagnostic test (1)

Ideal diagnostic testsright answers:

(+) results in everyone with the disease and

( - ) results in everyone else

Clinical prediction rules, algorithm

Usual clinical practice:

The test be studied in the same way it would beused in the clinical setting

Observational study, and consists of:

Predictor variable (test result)

Outcome variable (presence / absence of the

disease)


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Sensitivity, specificity

Prevalence, prior probability, predictive values

Likelihood ratios

Dichotomous scale, cutoff points (continuousscale)

Positive (true and false), negative (true and

false) ROC (receiver operator characteristic) curve

Basic principles of Diagnostic test (2)


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Diagnostic testgeneral structure : 2 X 2 tables

Target disorder

Positive

(disease)

Klp sakit

Target disorder

Negative

(normal)

Klp sehatPredictor

Test

positive

True positive

TP

a

False positive

FP

b

Predictor

Test

negative

False negative

FN

c

True negative

TN

d

Sensitivity, specificity, predictive values, likelihood ratios, ROC


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EBM Issues on diagnostic tests:

Is this evidence about the accuracy of adiagnostic test valid?

Does this valid evidence demonstrate animportantability to accurately distinguishpatients who do and dont have a specificdisorder?

Can I applythis validandimportantdiagnostic test to a specific patient?


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Validity


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Does this (valid) evidencedemonstrate an importantability ofthis test to accurately distinguish

patients who do and dont have aspecific disorder?

Sensitivity Specificity

Likelihood ratios

Importance (1)


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Specifity

If a test is 100 % specific, it reactspositively only when the client actually hasthe condition being tested. The importantfactors that can effect a false positivereaction such as drugs.


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Sencitivity

The sencitivity of a test is the degree towhich a test detects disease withoutyielding a false negative diagnosis.


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Normal Reference Values

Normal reference values or referencevalues is not as normal values because itslaboratory must determine what is normalfor a test performed in specific laboratory


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Metric Measurments Used in Laboratory Reports

WeightKilogram (kg) 2,2 lbGram (g) 453 g = 1 lbMilligram (mg) = 1/1000 of a gMicrogram (g) = 1/1000 of a mgNanogram (ng) = 1/1000 of a g

Picogram (pg) = 1/1000 of a ngFemtogram (fg) = 1/1000 of a pg

VolumeLiter (L) = 1000 ml (or 1000 cc) 1.05 qtDeciliter (dL) = 100 ml or 1/10 of a L

Milliliter (mL) = 1 ml or 1/1000 0f a L


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Usual Test Done Automatically by Cell Counters

Hct Hematocrit Hb Hemoglobin WBC White blood cells/ leukocyte RBC Red blood cells/ eritrocyte MCV Mean corpuscular volume MCH Mean corpuscular hemoglobin MCHC Mean corpuscular hemoglobin concentration RDW Red blood cell distribution width

PLT (Plateled counts may also be performed with somecounters


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Importance (2)


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Importance (3)

Odds = ratio of two probabilities

Odds = p/1-p

Probability = odds/1+odds

Likelihood ratio(+) :

Prop (+) result in people with the disease

Prop (+) result in people w/out the disease

Pretest Odds X LR = Posttest Odds
http://c/CATmaker/CATMAKER.EXE


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Pretestprobability

Likelihood ratio

Posttestprobability
http://c/CATmaker/CATMAKER.EXE


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The usefulness of 5 levels ofdiagnostic test result


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Accuracy of the test The accuracy of the test

depends on how well thetest separates the groupbeing tested into those withand without the disease inquestion

Accuracy is measured by the

area under the ROC curve.An area of 1 represents aperfect test; an area of 0.5represents a worthless test(AUC)

0.90-1.00 = excellent (A) 0.80-0.90 = good (B) 0.70-0.80 = fair (C) 0.60-0.70 = poor (D) 0.50-0.60 = fail (F)


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Applicability


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Diagnostic tests

Is not about finding bsolute truth, but about limiting uncert inty

establishes both the necessity and the logical base for introducing

probabilities, pragmatic test-treatment thresholds ..

Start thinking about

what youre going to do with the results of the

diagnostic test, and

whether doing the test will help your patients
http://c/CATmaker/Diag.pdfhttp://c/CATmaker/Diag.pdf


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onclusion

EBM is nothing more than aframework of systematic use of

current valid study results

relevant to our patients


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End result

Self directed, life-longlearning attitude

for high quality patient care


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The Principle of diagnostic

determine :1. Anamnestic

2. Physical Diagnostic

Auscultation, Palpation Percution, Inspection etc

3. Diagnostic Tests :

LABORATORY

X-RAY

E.K.G

ENDOSCOPY


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Clinical Laboratory Test

1. HEMATOLOGY

2. CLINICAL CHEMISTRY3. IMUNO SEROLOGY

4. MIKROBIOLOGY/PARASITOLOGY


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The useful of Laboratory test

1. Determine of disease

2. To Help established diagnostic3. To evaluation of disease prolong.

4. Monitoring of therapy.

5. To predict of prognostic


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Hemathology tests

1. FULL BLOOD COUNT

RBC/ERYTHROCYTE, WBC/LEUKOCYTE,HB, HCT, MCH, MCHC, MCV, PLT, DIFF

WBC COUNT (PMN, LYMFOCYTE,MONOCYTE), ESR.

2. BLOOD FILM

3. HEMOSTATIC TESTS :PT.APTT,TT,FIBRINOGEN

4. RETICULOCYTE COUNT

5. BONE MARROW ASPIRATION


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Clinical Chemystri Tests :

1. Liver Function Tests : GGT, ALT/SGPT, AST/SGOT,BILIRUBIN TOTAL, BIL. DIRECT/INDIRECT, ALKALIPHOSPHATASE, TOTAL PROTEIN, ALBUMIN, GLOBULIN

2. Diabetic Mellitus Tests:GLUKOSE (PUASA,PP2

JAM,OGTT), HbA1c3. Renal Function Test: UREUM,KREATININ CLEARANCEUREUM,CREATININ

4. Cardiac Enzyme Tests: CK, CKMB, MYOGLOBIN, LDH).5. Blood Lipid tests: TG, TOTAL CHOLESTEROL, HDL/LDL

CHOLESTEROL, LIPOPROTEIN, APO A,B,C .6. Uric Acid7. ELEKTROLYTE (K,Na,CL) MINERAL(Ca.Mg,P) DLL


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IMUNOSEROLOGI TESTS

1. Virus Infection Tests: VIRAL HEPATITIS A (Ig M,igG HAV) VIRAL HEPATITIS B (HbsAg .Anti HBS, HBeAg Anti

HBe,HBV DNA) VIRAL HEPATITIS C(Anti HCV)

Tes HIV, DHF, TORCH, DLL.

2. Bacterical Infection Tests (WIDAL,VDRL,TPHA, MYCODOT, ETC)

3. Paracyte Infection Tests(ICT PLASMODIUM

VIVAX, FALCIPARUM ETC)4. Hormonal Tests(TSH, FT 4, ETC)5. Tumor Markers Tests :(CEA, AFP, PSA, CA

125, ETC)


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MIKROBIOLOGY/PARASITOLOGY TESTS :

1. IDENTIFICATION DAN ISOLATIONTEST (CULTUR, BIOKIMIA)

2. MICROSCOPYC TESTS (GRAM, ZIEHL

NILSEN, NEISSER ETC)3. P.C.R TEST

4. BLOOD FILM THIN/THICK

(MORFOLOGY PLASMODIUM, AMOEBA,HELMINTHES, YEAST ETC

5. IMUNOLOGY/SEROLOGY


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Routine Urinalysis and Other UrineTests :

pH

Specific Gravity

Protein

Sugar

Ketones

Sediment (crystals, casts, WBCs, RBCs )

Leukocyte Esterase

Urinary Porphyrins

Bilirubin

Urobilinogen

Nitrites


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