Diagnosis and Screening: The evidence basis needed for developing screening policies and implementing screening programmes, including established programmes such as breast and cervix and those currently in development, being piloted or subject to major research activity, current examples (amongst others) being colon cancer, chlamydia screening and certain antenatal/ neonatal screening tests
Health Technology Assessment
Health technology assessment (HTA) uses evidence to promote health and prevent and treat disease. HTA includes the implication of heath technology to improve health outcomes. It asks whether technology provides benefits for the population and if it presents value for money.
The evidence basis for screening is whether early detection is beneficial, and if persons identified with early-state disease detected through screening have better health outcomes than those who come to clinical attention without screening. It is not enough to know that a screening test actually identifies early diseases or conditions at a specific point of disease development. There must also be an effective intervention, which itself must be scientifically assessed.
The evidence to support or refute particular screening programmes is often limited. This may be because of the complexity of the screening issue, or the rarity of the conditions being screened for. The best evidence for screening comes from randomised controlled trials (or meta-analysis of RCTs).
Table 3.8.1 SCREENING TESTS THAT CAN BE HARMFUL
|
Screening test |
Proposed benefits |
Potential harms |
|
Whole-body computerised tomography (CT) |
To rule-out undiagnosed diseases |
High radiation dose Unlikely to prevent disease |
|
Whole-body magnetic resonance imaging (MRI) |
To rule-out undiagnosed diseases |
No radiation dose, but raised chance of false alarms of nodules in lung, cysts in liver, etc. |
|
Exercise electrocardiogram (ECG) |
Screening for heart problems |
Benefit is limited to only some people with heart disease, but not for healthy people |
|
Prostate Specific Antigen (PSA) |
Early detection of prostate cancer |
Many false alarms due to benign tumours, leading to unnecessary and potentially harmful medical procedures. No evidence that mortality is reduced. |
|
Mammography under 50 years old |
Early detection of breast cancer |
False alarms in low prevalence population |
Source: Adapted from Types of Screening that can do more harm than good, Angel Raffle (2006)
Table 3.8.2 Screening programmes under development in the UK (as of June 2008)
|
Condition |
Description of programme |
Status |
|
Antenatal |
|
|
|
Familial Dysautonomia* |
Not currently offered |
Ongoing review by NSC |
|
Predictors of preterm labour |
Not currently offered |
HTA review ongoing |
|
Streptococcus B |
Not currently offered |
Being considered by NSC |
|
Thrombophilia** |
Not currently offered |
Being considered by NSC |
|
Newborn Babies |
|
|
|
Amino acid metabolism disorder screening |
Not currently offered |
Being considered by NSC |
|
Medium chain acyl CoA dehygrogenase deficiency (MCADD) |
Should be offered to all babies |
Offered to all babies in England by March 2009 (not Scotland, Wales, NI) |
|
Cannavan's disease † |
Not currently offered |
Being considered by NSC |
|
Congenital heart disease |
Not currently offered |
HTA review ongoing |
|
Cystic fibrosis |
Should be offered to all babies |
Phased implementation across the UK by 2008 |
|
Adults |
|
|
|
Abdominal aortic aneurysm |
Should be offered to all men aged 65+, but with clear information of risk of elective surgery, and need to develop vascular surgical services |
Implementation of a screening programme is being planned for roll-out over the next 5 years |
|
Anal cancer |
Not currently offered |
HTA review ongoing |
|
Bowel cancer |
Currently offered to men and women aged 50+ |
Began in Jul. 2006 and phased in by Dec. 2009 |
|
Deafness |
Not currently offered |
Being considered by NSC |
|
Domestic violence |
Not currently offered |
Ongoing review by NSC and Home Office |
|
Prostate cancer |
Can be offered if the man fully understands the lack of good quality evidence about the benefits and risk of testing |
HTA is conducting a trial of prostate cancers detected at an early stage |
|
Vascular risk |
Should be offered to whole population |
A Vascular Risk Management Programme is being introduced |
HTA: Health Technology Assessment
* Disease or malfunction of the autonomic nervous system
** Propensity to develop thrombosis
† Progressive degenerative disease of nerve cells in the brain
Reference Materials
-
Oortwijn W, David Banta H and Cranovsky R. Introduction: mass screening, health technology assessment, and health policy in some European countries
-
International Journal of Technology Assessment in Health Care. 2001:17;269-274
-
UK National Screening Committee's Policy Positions, June 2008 http://www.nsc.nhs.uk/pdfs/
© Dr Murad Ruf and Dr Oliver Morgan 2008
