Learning Task Uji Diagnostik.docx

MODULE Screening and Diagnostic Testing Dr. Putu Cintya Denny Yuliyatni, MPH (Reference Greenberg, p. 127-136)

AIMS: To be able to describe validity and reliability of certain test to apply in the individual and or community context

LEARNING OUTCOMES: 1. 2. 3. 4.

To describe definition of accuracy, validity and reliability To explain parameters used to indicate validity and reliability To describe concept of test validity of the continues or multilevel outcome result To choose ideal diagnostic test in certain situations related to individual and community context

CURRICULUM CONTENTS: 1. Definition of diagnostic test and screening program 2. Accuracy, validity (sensitivity, specificity, predictive value, and likely hood ratio) and reliability 3. Screening program

ABSTRACTS All clinical information is subject to error. Accounting for the various errors that can arise in diagnostic testing allows the physician to select tests and interpret the result of those tests appropriately. The errors are false- negative, false-positive. Sensitivity and specificity are characteristics of a diagnostic test. It is useful to consider two other measures, positive predictive value (PV+) and negative predictive value (PV-), which are use to interpret the results of a diagnostic test. For multilevel or continuous outcome test results, a dividing line or cut off point can be chosen to separate findings considered to be positive or negative. The performance of diagnostic tests also can be assessed by use of likelihood ratios.

SELF DIRECTING LEARNING Basic knowledge and its application that students must know include: 1. Accuracy 2. Sensitivity, specificity, predictive value, likelihood ratio 3. Cut off point 4. Screening program

SCENARIO & LEARNING TASK Case 1 The result of screening test was as bellow; Diabetic retinopathy S

Sakit

K

Positif

R

Negatif

I

Total

Tidak Sakit

Total

3.200

1.400

4.600

150

29.000

29.150

3.350

30.400

33.750

N

Learning Tasks 1 I 1. Calculate the sensitivity, specificity, and predictive value of diabetic retinopathy and Interpret each N of your calculation



G

Sensitivitas  3200/3350 = 9,6%



Specificity  29000/30400 = 9,5%



PPV  3200/4600 = 6,95%



NPV  29000/29150 = 9,9%



Interpret SN  hasil screening untuk mendapatkan hasil positif diabetic retinopathy sebesar 9,6% atau diantara 100 orang yang mengalami diabetic retinopahthy, 97 orang dinyatakan positif



Interpret SP  hasil screening untuk mendapatkan hasil negatif diabetic retinopathy sebesar 9,5% atau diantara 100 orang sehat, 95 orang akan dinyatakan negatif oleh tes screening

2. What is the prevalence of diabetic retinopathy among the population? 3. What is the relation between prevalence and predictive value? What is the relation with the target group for screening program? 4. When you conduct screening test among elderly population, which prevention you have done: primary, secondary, or tertiary?

Case 2 A detailer has come to dr. Arjuna for offering cheap rapid test for anemia. Dr. Arjuna asked 3 tests for trial. Fortunately, Mrs. Drupadi came for consultation of malaise and continuing dizziness. Dr. Arjuna asked permission from mrs. Drupadi to take the blood sample for checking anemia. At the same time, he also told her that he wanted to check the rapid test for anemia. Using cyan-met HB, the result of hemoglobin was 12.5mg%, while the result of rapid test respectively was 10.5 mg%; 10.2mg%; and 12.0mg%.

Learning Task 2 If the criteria of anemia was <11 mg%, how you conclude the result of the rapid test for anemia that just being tried by dr. Arjuna?

Self Assessments: 1. What is the definition of sensitivity? 2. What is the definition of specificity? 3. If the prevalence increases, what other value will also increase? 4. If the prevalence of a certain disease is high, while the sensitivity and specificity are stable, than ................... will be low.