Urgent questions concerning screening in Switzerland General aspects Marcel Zwahlen Institut für Sozial- und Präventivmedizin, Universität Bern http://www.ispm.unibe.ch
Swiss Urologists April 2009 Aufgrund der vorliegenden Datenlage kann ein systematisches Testen der männlichen Bevölkerung mit dem PSA-Test nicht befürwortet werden. Given the currently available evidence, systematic PSA testing of men (older over 50 years) can not be endorsed. PSA-testing could be performed for men in the age 50 to 70 years with a life expectancy of at least 10 years after the man has been well informed with regard to PSA-testing. http://www.urologie.ch/upload/prostatafrueherkennung09.pdf
The ACS recommends that asymptomatic men who have at least a 10-year life expectancy have an opportunity to make an informed decision with their health care provider about screening for prostate cancer after they receive information about the uncertainties, risks, and potential benefits associated with prostate cancer screening. Prostate cancer screening should not occur without an informed decision-making process. published online March 3, 2010 http://caonline.amcancersoc.org/cgi/content/full/60/2/70
Is this an official recommendation? Where can a man of age 50 get an official recommendation on screening for prostate cancer? Swiss Urologists Hompage March 2010 Early detection of diseases The Swiss Society of Urologists recommends that beginning at age 50 years all men get their prostate checked by means of a digital rectal examination and blood measurement of the PSAantigen. http://www.urologie.ch/de/index.php?m=5&c=5&e=1 checked March 14, 2010
What is screening? Screening is a process of identifying apparently healthy people who may be at increased risk of a disease or condition. They can then be offered information, further tests and appropriate treatment to reduce their risk and/or any complications arising from the disease or condition. (The UK National Screening Committee webpage) Screening encompasses the whole system or programme of events necessary to achieve risk reduction. Screening is a programme not a test. (A. Raffle, M. Gray)
Wilson-Jungner Criteria (WHO 1968) I Disease / Risk factor Important health problem Recognizable latent or early symptomatic stage Natural history is understood Consensus about treatment
Wilson-Jungner Criteria (WHO 1968) II Screening-Test Accurate Simple Not expensive Acceptable to the population
Wilson-Jungner Criteria (WHO 1968) III Programme Resources for follow-up diagnostics and therapy are available Good coverage The cost of case-finding (including diagnosis and treatment of patients diagnosed) should be economically balanced in relation to possible expenditure on medical care as a whole Case-finding should be a continuing process and not a once and for all project.
Sensitivity and Specificity of Screening Mammography Sensitivity Specificity 70% to 95% 90% to 97% Screening round first subsequent Age younger (40-49) older (50-69) somewhat higher somewhat lower lower higher lower higher lower higher
In a population in which 3 out of 1000 women have breast cancer : Probability of breast cancer in case of a positive mammogramm Result = 26 / 325 = 8% 10'000 women Positive predictive value 299 positive no BCa 9970 negative 30 with BCa 26 4 positive negative
Positive predictive value app 5 % (age 40-49) app 10 % (age 50-59) 15-20 % (age 60-69)
Difficulties in Assessing the Impact of Cancer (and other) Screening Lead-time bias Length-time bias Overdiagnosis
Lead time bias Start of the disease process Detectable via Screening Symptoms Diagnosis Cure Complications Death With Screening Preclinical Phase Lead time Clinical Phase Without Screening Overestimation of survival time due to the backward shift in the starting point for measuring survival
Length-time Bias A Screening examination A B A Screening examination B B A systematic error due to selection of disproportionat e numbers of long duration cases in the screen detected cases. A A B B A A B B A B A B A B A B Time A: detectable by screening test B: occurrence of clinical symptoms
Screening examination Overdiagnosis A death A B A B A B The possibility that a cancer detected by screening would never have led to a diagnosis in the life time of a person. A: detectable by screening test B: occurrence of clinical symptoms
Overdiagnosis is a reality for several cancer screenings Prostate cancer Skin cancer Breast cancer
Smith DP et al. Prostate cancer and prostate-specific antigen testing in New South Wales. MJA 2008; 189: 315 318
Cancer Incidence : USA Age-standardised rates Jemal, C A Cancer J Clin 2009;59:225
Consequences of overdiagnosis Unnecessary treatments and the resulting consequences Paradoxical treatment success Difficulties with overdiagnosis Almost impossible to document in an individual Can only be inferred from population-based information The true extent is difficult to estimate
Benefits and Harms of Screening Benefit Improved treatment outcome Less aggressive treatment Reassurance if screening detects no problem Harm Consequences of follow-up diagnostics if screening indicates abnormality (false positive results) Unnecessary treatments in case of over diagnosis Missing disease due to false negative results
Science 2010; 327: 936
The balance of benefits, harm and quality Amount of benefit or harm Low High Amount of harm Amount of benefit A B C A: Minimal acceptable quality B: Good quality C: Excellent quality Low High Quality A: Screening programs that fall below this standard require improvement or should be closed. B: The majority of screening programs should achieve this level. C: This level is achievable in research settings or by the top 5% of screening programs. Adapted from Gray JA. New concepts in screening. Br.J Gen.Pract. 2004;54:292-8
Issues in implementing screening Quality assurance Attaining good coverage Information of the population Achieving "informed decision
Implementation of screening Type Not selective Selective Systematic by invitation of the population Opportunistic case-finding (contacts with health system) Mass screening Testing of all patients Targeted screening Testing of patients full filling criteria
Implementation of screening in Switzerland Rare metabolic disorders in newborns A centralised system with close to 100% coverage Screening for cardiovascular risk factors Opportunistic screening in private practice Cervical cancer screening Opportunistic screening in private practice
Cardiovascular Mortality in Switzerland 1971-2004 100 200 300 400 500 1970 1975 1980 1985 1990 1995 2000 2005 Men Women age standardised rates (pro 100 000 inhabitants), European standard popula tion
Cancer Mortality in Women in Switzerland 1971-2004 0 10 20 30 40 1970 1975 1980 1985 1990 1995 2000 2005 Lung Breast Colon Liver Cervix Skin Age standardised rates per 100 000 inhabitants
Early detection for cervix cancer Swiss Heath Interview Survey - 2002 TOTAL in the last 12 months ever Age 25-34 35-44 45-54 55-59 Nationaliity Swiss Foreigner 8 REGIONEN GE,VD,VS FR,JU,NE AG,BE,S0 BS,BL Zürich Ostschweiz Zentralschweiz Tessin Educational level Ohne Ausbildung Obligat. Schule Sekundarstufe II Tertiärstufe Insurance type allgemein halbprivat privat 10% 25% 50% 75% 90%
Breast cancer screening in Switzerland Organised screening programmes introduced in French speaking part of Switzerland / opportunistic screening in in private practice Health insurance coverage if screening is done in a screening programme
Early detection for breast cancer Swiss Heath Interview Survey - 2002 TOTAL in the last 12 months ever Age 50-69 60-69 Nationality Swissn Foreigner 8 REGIONEN GE,VD,VS FR,JU,NE AG,BE,SO BS,BL Zürich Ostschweiz Zentralschweiz Tessin Educational level Ohne Ausbildung Obligat. Schule Sekundarstufe II Tertiärstufe Insurance type allgemein halbprivat privat 10% 25% 50% 75% 90%
Information on screening Stern, März 4, 2010 Comite de l'herault de la ligue contre le cancer, Sept 2009
Where can one obtain robust information on screening in Switzerland? What do medical societies recommend? What is covered by basic health insurance? What do patients associations recommend? There is no single place to get answers about recommended screenings in Switzerland.
Preliminary conclusions Screening is a multi phased process. Screening can be beneficial on the population level but will also have side effects and harms. Increasing technological developments and scientific knowledge will expand the list of possible screenings. Switzerland lacks one place where one can get screening recommendations?
Thank you for your attention