Screening. James L. Coyle, Ph.D., CCC-SLP, BRS-S University of Pittsburgh. J. Coyle 1

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1 Screening James L. Coyle, Ph.D., CCC-SLP, BRS-S University of Pittsburgh J. Coyle 1

2 Disclosure University of Pittsburgh (salary) Continuing education Northern Speech Services State Conferences and Conventions Braintree Neurorehabilitation Conference University of Toronto/Baycrest Rehabilitation NIH RO-1 (25% effort) 2

3 The Diagnostic Process Example: patient with pneumonia Patient fails 2 oz water swallow screen Clinical exam reveals neurological signs consistent with pharyngeal disorders Clinician recognizes inability to identify physiology of pharyngeal disorder Instrumental examination evaluates physiology And assesses effects of interventions Patient correctly diagnosed and treated Success (dx & tx correct) or failure (something wrong) J. Coyle 3

4 The Diagnostic Process Less invasive tests and screens are performed to obviate the need for invasive testing. Their results are compared a gold standard SO WHAT IS THE MOST ACCURATE, DEFINITIVE GOLD STANDARD TEST? The autopsy. But it is not very practical. Medical tests try to predict the autopsy result While patient is still alive. J. Coyle 4

5 Screening Screening tests sort out apparently well persons who probably have a disease from those who probably do not. A screening test is not intended to be diagnostic World Health Organization

6 Screening Screening: high sensitivity Meaning: more important to identify those who MAY HAVE the target disorder Inherent risk of OVERIDENTFYING Best screens: predict most at-risk patients while identifying fewest healthy people J. Coyle 6

7 Screening Seeks to rule out signs of a disorder Determines whether more testing is needed Uses ONE sign (positive, negative) Generates a PASS-FAIL result Does NOT identify source/cause of the FAILED screen Does NOT generate justifications for treatment J. Coyle 7

8 The diagnostic process Screen Normals Screening: Healthy people are screened for possible disease PASS Not at risk Does not have Disorder FAIL At risk Has Disorder J. Coyle 8

9 Properties of good screens Disease/disorder Must be well defined Prevalence and natural history Policy Cost effective and feasible for my facilities Patient must agree with intervention if FAILS The test itself Safe, cheap, noninvasive, with a reasonable cut-off Valid and reliable Grimes & Schulz, 2002 J. Coyle 9

10 Common screening tests Take blood pressure for hypertension Fasting blood sugar for diabetes PAP smear for cervical cancer Mammogram for breast cancer PSA for prostate cancer 3 oz. water swallow for dysphagia None diagnose the disease/disorder J. Coyle 10

11 Case finding Case finding is a strategy for targeting resources at individuals or groups who are suspected to be at risk for a particular disease. It involves actively searching systematically for at risk people, rather than waiting for them to present with symptoms or signs of active disease. J. Coyle 11

12 Case finding This is what we really do when we screen Patients with suspicion of disorder are tested Typical serial screening They exhibit signs of disorder They are already sick J. Coyle 12

13 Common case-finding tests Bedside examination of swallowing function Patient admitted with a stroke, etc. Assess for dysphagia: prevent pneumonia/death Chest CT with perfusion study Sudden onset dyspnea: Assess for pulmonary embolism prevent death Neither of these tests is a proper Screening J. Coyle 13

14 The diagnostic process Timing of screening or case finding Testing too early: fails to detect disease Good timing: disease treated early Testing too late: disease took its course Disease begins Early Detection Possible Disease fully manifests Outcome Grimes & Schulz, 2002 Patient gets better or doesn t get worse Adverse outcome but not fatal Death J. Coyle 14

15 Types of Screening Parallel screening We have 2 (or more) tests If patient fails either, we do not do the second test Patient is referred for diagnostic test or is treated Series screening We have 2 (or more) tests Patient must fail both tests to be referred for diagnostic test or be treated. J. Coyle 15

16 Combining Screens Patients who FAIL two screens: Much higher probability of having disorder Patients who PASS two screens: Much higher probability patient does not have disorder This is what we do in bedside examinations! J. Coyle 16

17 One Screening Example MGH swallow screen 1. readiness for oral intake Tolerance of HOB elevated; wakefulness; stable respiratory function; mouth clean 2. Swallowing/aerodigestive tract features Tongue movement, volitional cough, pharynx sensation, voice 89-93% sensitivity; 61-64% specificity

18 When is screening enough? When it is NOT necessary to know what is actually wrong and how to fix it Screening may be enough When the actual diagnosis is necessary, SCREENING IS NOT ENOUGH J. Coyle 18

19 Screening and testing Is the true diagnosis necessary? If we care only about the immediate term: no Is patient likely to choke in the short-term? If we care about anything else, yes Will patient develop pneumonia later on? Is there dysphagia? How can the cause of aspiration be fixed? J. Coyle 19