Screening - 8122MED PDF

SCREENING Dr. Emma Gale FAFPHM, MBBS, MPH, DCH Public Health Physician/Senior Lecturer   Define what screening is  Explain the biases associated with screening Learning  Describe the population wide screening programs available in Australia objectives...

SCREENING Dr. Emma Gale FAFPHM, MBBS, MPH, DCH Public Health Physician/Senior Lecturer   Define what screening is  Explain the biases associated with screening Learning  Describe the population wide screening programs available in Australia objectives  Discuss the requirements for a successful screening program. Levels of prevention  PRIMORDIAL improve the underlying social and environmental conditions to improve health (housing, education, poverty)  PRIMARY aim to stop an outcome from happening by reducing exposure to a risk factor in healthy individuals (immunisations)  SECONDARY aims to interrupt progression from early stage by early detection and treatment (screening)  TERTIARY aims to reduce complications and severity in those with established disease by offering treatments and interventions (optimise treatment)   "...identification of unrecognised disease or defects by means of tests, examinations or other procedures that can be applied rapidly...intended for all people, in an identified target population, who do not have symptoms of the disease or condition being screened for." - World Health Organisation Screening Definition  diagnosis and treatment Population screening explained - GOV.UK (www.gov.uk)  POPULATION all individuals in target group TYPES OF OPPORTUNISTIC (CASE-FINDING) SCREENING may be unrelated TARGETED (HIGH-RISK) BRCA, exposures NOT SCREENING  Patients showing symptoms in need of a diagnosis  A test performed to confirm or exclude diagnoses  This is a diagnostic test   Reduce mortality through early detection and treatment  Reduce incidence of a condition by identifying and treating AIMS OF precursors SCREENING  Reduce the severity of a condition  To increase choices available to patients by identifying conditions or risk factors at an early stage when more options are available Why do some diseases have a screening program and not others? Australian population-based screening framework warrant screening  Areas for consideration  1.The disease 2.The test 3.The treatment 4.The program The disease  An important health problem morbidity and mortality  Identifiable latent or early symptomatic phase  Natural history of disease needs to be understood  There is a treatment available that makes a different to outcomes The test  Acceptable to the population  Safe  Simple  Affordable if large numbers  Highly sensitive (low false negatives)  Highly specific (low false positives)  Validated  Agreed criteria for what constitutes a positive or negative result  Disease No disease Test + True + (TP) False + (FP) Test - False - (FN) True - (TN) How good is the test? SENSITIVITY = TP/(TP+FN) how many correctly identified all positives SPECIFICITY = TN/(TN+FP) THE DISEASE who actually have or not POSITIVE PREDICTIVE VALUE = TP/(TP+FP) THE TEST NEGATIVE PREDICTIVE VALUE = TN/(TN+FN)  Disease No disease Test + 80 (TP) 10 (FP) Test - 20 (FN) 90 (TN) Total 100 100 EXAMPLE SENSITIVITY? 80/(80+20) = 80% of people with the disease are correctly 80/80+20 identified as positive with the test down disease column SPECIFICITY? 90/(90+10) = 90% of people without the disease are correctly identified as negative with the test no disease column PPV? 80/(80+10) = 89% of positive tests are for people with the disease NPV? 90/(90+20) = 82% of negative tests are for people without the disease Diagnosis and treatment  Acceptable to population  Makes a difference to outcomes  Resources available (trained staff, infrastructure, equipment, diagnostics)  Equitable access The program  Identify a target population – those at risk  Database or systems able to issue invitations, follow up those with abnormalities, evaluate the program and impacts  Clearly defined processes, structure  Informed consent  Equitable  High coverage  Cost-effective (consider opportunity cost)  Not just a one-off, need long-term resources  Evidence-based  Benefits outweigh harms  Benefits  Reduce burden of disease  Reduce mortality  Reduce morbidity WEIGH UP  Improve disease outcomes BENEFITS Harms AND HARMS  False positives  False negatives  Over-diagnosis  Psychological and physical considerations  Opportunity cost BIASES IN Systematic error during the implementation of a screening program and/or the interpretation SCREENING of its results that can lead to false conclusions PROGRAMS about the program benefits. LEAD TIME BIAS DISEASE DETECTED FROM SCREENING HEALTHY ASYMPTOMATIC DISEASE SYMPTOMATIC DEATH DISEASE DETECTED FROM SYMPTOMS HEALTHY ASYMPTOMATIC DISEASE SYMPTOMATIC DEATH LEAD TIME Leads to an over-estimation of the benefits of a screening program. It looks like survival is better because the disease is diagnosed earlier through screening. LENGTH TIME BIAS SLOW DISEASE DEATH RAPID DISEASE SCRENING TEST TIME Less aggressive (slow growing) disease more likely to be picked up by screening making outcomes look better for those screened. HEALTHY VOLUNTEER BIAS  Type of selection bias  Higher socioeconomic status higher educational outcomes  Better underlying health  Health seeking behaviours  Adhere better to therapy  May live longer due to these reasons  National Bowel National National Cervical Cancer Screening BreastScreen Screening Program Australia Program Program also lung cancer screen Newborn Newborn Hearing Bloodspot Screening Screening Population-based screening programs in Australia BreastScreen Australia Program  Lifetime risk of 1 in 7 for women  Program started in 1991  The 5-year relative survival rate improved from 75% to 94%  Target group 50–74-year-olds with breast tissue suitable for screening  Mammogram every 2 years  Participation in women 50-74yo 2019-2020  36% First Nations women lower compared to non-Indigenous  49% non-indigenous women  36% very remote  40% language other than English BreastScreen Australia monitoring report 2022, Summary - Australian Institute of Health and Welfare (aihw.gov.au) About the BreastScreen Australia Program | Australian Government Department of Health and Aged Care Recall and diagnosis for further assessment BreastScreen Australia monitoring report 2022, Summary - Australian Institute of Health and Welfare (aihw.gov.au)  Why do you think breast cancer survival has increased in Australia since the screening program was implemented?  A – The screening program QUIZ  B – Improvements in treatments  C – Greater breast cancer awareness  D – All of the above D  National Bowel Screening Program  1/21 men and 1/31 women before age 75 affected by bowel cancer  Target group 50–74-year-olds  Faecal occult blood tests x 2  Test kits are posted to eligible people using Medicare details  40.9% participation in 2020-2021  6% needed further assessment return in envelope  1 in 27 of those with a positive screen diagnosed with colorectal cancer National Bowel Cancer Screening Program | Australian Government Department of Health and Aged Care National Bowel Cancer Screening Program monitoring report 2023, Summary - Australian Institute of Health and Welfare (aihw.gov.au) Bowel Cancer - Cancer Council QLD (cancerqld.org.au) National Cervical Screening Program  Nearly all cervical cancer caused by Human Papillomavirus (HPV) infection  Target group 25-74 year-olds with a cervix (even if vaccinated!)  Every 5 years  Self-collect vaginal sample or clinician collect cervical sample  Looking for high-risk HPV infections  Replaced the Pap test in 2017 which looked for abnormal cervical cells  62% eligible participation 2018-2021  In participants aged 25–74 in 2021  2% positive for oncogenic HPV types 16 or 18 (the two types of HPV that cause most cervical cancers)  9% positive for other oncogenic HPV types  Can we get rid of screening one day because of the HPV vaccine…? need national programme National Cervical Screening Program monitoring report 2022, Summary - Australian Institute of Health and Welfare (aihw.gov.au) National Cervical Screening Program | Australian Government Department of Health and Aged Care Newborn Bloodspot Screening  Heel prick blood test soon after birth  Placed on a special filter paper card  Tested for a range of serious conditions impaired metabolism  Cystic fibrosis, phenylketonuria, congenital adrenal hyperplasia  Varies between states  Around 99% participation Newborn bloodspot screening | Australian Government Department of Health and Aged Care Newborn Hearing Screening  All newborns  1-2 weeks of birth  Non-invasive pads and headphones  Series of clicking noises played and responses to noises recorded noises to trigger response  Immediate results – pass or refer  A pass indicates a baby can hear at the levels needed for normal speech and language development  A refer can often be due to babies being unsettled, background noise, fluid in ears from birth Newborn hearing screening | Service Detail | Children's Health Queensland   1/6 males diagnosed by 85  PSA protein produced by prostate gland cells  PSA blood test  Elevation not specific to prostate cancer (infection, benign enlargement)  Unclear cut off levels What about  Over-diagnosis of prostate cancer prostate cancer?  Many prostate cancers are slow growing (die with not from)  Harms from treatment (incontinence, erectile dysfunction)  No evidence to support a national screening program  Harms outweigh benefits at population level for PSA blood testing  Individual patients can discuss risk and testing with their doctor  New technologies and tests may emerge Prostate cancer screening in Australia – position statement (health.gov.au)  might save one persion from screen some have side effects harm over benefit Royal Australian College of General Practitioners prostate-cancer-screening-infosheet.pdf (racgp.org.au) QUIZ - screening or diagnostic? 1. 50-year-old male with rectal bleeding undertaking a faecal occult blood test Diagnostic 2. 25-year-old sexually active female with no symptoms presents for a pap smear Screening 3. 65-year-old female with a breast lump referred for a biopsy Diagnostic 4. Newborn having a newborn hearing test, their grandfather has age-related hearing loss Screening Please email Dr Gayatri Marwah with any questions on this topic at [email protected]