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Ovid: Oxford Handbook of General Practice

Editors: Simon, Chantal; Everitt, Hazel; Kendrick, Tony Title: Oxford Handbook of General Practice, 2nd Edition Copyright ©2005 Oxford University Press > Table of Contents > Chapter 5 – Prevention Chapter 5 Prevention All patients aged 16–75y. are entitled to request a routine health check if they haven’t been seen, for health reasons, in the practice in the past 3y. All patients aged >75y. are entitled to a routine health check if they haven’t been seen, for health reasons, in the practice in the past year. P.158
Prevention and screening In all disease, the goal is prevention. Definitions

  • Primary prevention: Prevention of disease occurrence.
  • Secondary prevention: Controlling disease in early form (e.g. carcinoma in situ).
  • Tertiary prevention: Prevention of complications once the disease is present (e.g. DM).

Barriers to prevention

  • Patient: Blinkering (‘It’ll never happen to me’); rebellion (‘I know it’s bad—but it’s cool’); poor motivation (path of least resistance).
  • Doctor: Time; money—health promotion takes time and personnel; motivation—health promotion is repetitive and boring.
  • Society: Pressure from big business (e.g. cigarette advertising and Formula 1); other priorities; ethics (e.g. public uproar at threats not to offer cardiac surgery to smokers).

Screening The idea of screening is attractive—the ability to diagnose and treat a potentially serious condition at an early stage when it is still treatable. An ideal screening test should pick up all those who have the disease (have high sensitivity) and must exclude those who do not (high specificity). It must detect only those who have a disease (high positive predictive value—Table 5.1) and should exclude only those who do not have the disease (high negative predictive value). The Wilson-Jungner criteria* All screening tests should meet the following criteria before they are introduced to the target population:

  • The condition being screened for is an important health problem
  • Natural history of the condition is well understood
  • There is a detectable early stage
  • Treatment at early stage is of more benefit than at late stage
  • There is a suitable test to detect early stage disease
  • The test is acceptable to the target population
  • Intervals for repeating the test have been determined
  • Adequate health service provision has been made for the extra clinical workload resulting from screening
  • Risks, both physical and psychological, are < benefits
  • Costs are worthwhile in relation to benefits gained

UK screening programmes

  • Cervical cancer p.716
  • Diabetic retinopathy p.415
  • Breast cancer p.516
  • Genetic p.770
  • Antenatal p.770–3
  • Neonatal hearing p.827
  • Haemoglobinopathy p.773
  • Child health surveillance p.814
Table 5.1 Performance of screening tests
Present Absent
Test Positive True positive (a) False positive (b)
Negative False negative (c) True negative (d)
Sensitivity = a/(a+c) Negative predictive value = D/(c+d)
Specificity = d/(b+d) Positive predictive value = a+(a+b)

Screening in the future p.160 Performance of screening tests For a screening programme to be effective and ↓ morbidity and mortality, there must be:

  • Adequate participation of the target population.
  • Few false negative or false positive results (Table 5.1).
  • Screening intervals shorter than the time taken for the disease to develop to an untreatable stage.
  • Adequate follow-up of all abnormal results.
  • Effective treatment at the stage detected by screening.

There is no ideal screening test. Always explain:

  • Purpose of screening
  • Likelihood of positive/negative findings and possibility of false positive/negative results
  • Uncertainties and risks attached to the screening process
  • Significant medical, social, or financial implications of screening for the particular condition or predisposition
  • Follow-up plans, including availability of counselling and support services.
Table 5.2 Benefits and disadvantages of screening
Benefits Disadvantages
  • Improved prognosis for some cases detected by screening.
  • Less radical treatment for some early cases.
  • Reassurance for those with negative test results.
  • Increased information on natural history of diesease and benefits of treatment at early stage.
  • Longer morbidity in cases where prognosis is unaltered.
  • Overtreatment of questionable abnormalities.
  • False reassurance for those with false negative results.
  • Anxiety and sometimes morbidity for those with false positive results.
  • Unnecessary intervention for those with false positive results.
  • Hazard of screening test.
  • Diversion of resources to the screening programme.

Footnote * Wilson and jungner (1968) Principles and practice of screening for disease (Public Health Paper Number 34). Geneva: World Health Organization. P.160
Screening in the future Prostate cancer 2nd most common cause of death from cancer in UK men. Prevalence is rising. Problems with screening:

  • Incidental post-mortem evidence of prostate cancer is high (>75% men >75y.), very few become clinically evident → many more men would be found by screening with prostate cancer than would die or have symptoms from it;
  • Natural history of prostate cancer is not understood—there is no means to detect which ‘early’ cancers become more widespread;
  • Inadequate screening tests (see below);
  • It is not clear if early treatment enhances life expectancy;
  • Peak incidence of morbidity and mortality is in old age (75–79y.), so potential years of life saved by screening are small.

Screening tests

  • Prostate specific antigen (PSA): Routinely measured in men with urological symptoms. Abnormal PSA is a common reason for referral to a urologist. Its sensitivity and specificity are poor. Other reasons for ↑ PSA:
    • Acute and chronic prostatitis
    • BPH
    • Physical exercise
    • Instrumentation
    • Ductal obstruction

PSA may be normal when early prostate cancer is present. There is considerable demand for PSA testing amongst men worried about the disease. The Government has introduced a PSA Informed Choice Programme. A key element is information provision for men requesting the test to enable them to decide whether or not to take it.

  • Digital rectal examination (DRE): Operator-dependant; fails to detect early prostate cancers; and lacks specificity. Annual screening in the USA and Germany has not ↓ mortality.
  • Transrectal ultrasound (TRUS): Too expensive for widespread use.

The most effective screening regime involves DRE and PSA testing followed by TRUS for suspicious lesions5. Optimal screening interval is unknown but serial screening ↑ detection. Ovarian cancer 4th most common cause of cancer death in women. Confined to 1 ovary [approximate, equals]90% 5y. survival but 80% are picked up at later stages when 5y. survival is [approximate, equals]10%. No reliable screening test. Options are USS, measurement of CA125, and genetic screening. USS and CA125 have low sensitivity/specificity. Genetic screening can only detect a few familial cases. If an abnormality is found on screening, laparotomy is required to exclude cancer, and there is a lack of evidence that treatment at an early stage ↓ mortality. Further information is expected when a large trial of screening for ovarian cancer reports in 2010. P.161
Colorectal cancer Common cause of death with well-defined premalignant phase (adenomatous polyp). Prognosis depends on stage at diagnosis. Patients with strong FH of large bowel cancer, or ulcerative colitis are screened already with colonoscopy with proven benefit, but colonoscopy is too expensive for use in a universal screening programme. Possible alternatives:

  • Faecal occult bloods (FOBs): +ve in 56–78% patients with asymptomatic colorectal cancer. Malignancies detected are less advanced. Problems: 40% cancers are missed and high false +ves—but does ↓ mortality. Very short lead time, so frequent screening is needed. Completed pilot study recommended introduction of a national screening programme1.
  • DRE: <40% within reach.
  • Sigmoidoscopy: Could detect 60% cancers. May be protective for up to 10y. Problems: overtreatment (some polyps may never become malignant), acceptability of test, cannot detect proximal tumours.
Table 5.3 Screening programmes currently under evaluation in the UK
Screening under evaluation Page Notes
Abdominal aortic aneurysm p.358 Initial pilot +ve; larger pilot underway
Ovarian cancer p.160 Pilot will report in 2010
Lung cancer p.388 US pilot results awaited
Bladder cancer p.700 For high-risk groups only
Genital chlamydia p.743 National programme planned
Glaucoma p.948
Oral cancer p.910
HPV infection p.744 Pilot findings awaited
Cystic fibrosis (neonatal) p.394 New programme agreed
Cystic fibrosis (antenatal) p.394 HTA report recommended screening2
Colorectal cancer p.161 +ve findings from large-scale pilot
Type 2 diabetes p.405
Thyroid disease p.422 Pilot project underway
Prostate cancer p.160 Prostate cancer risk management programme started

Further information National Electronic Library for Screening http://www.nelh.nhs.uk/screening NHS Cancer Screening Programmes http://www.cancerscreening.nhs.uk DoH http://www.dh.gov.uk UK Newborn Screening Programme Centre http://www.newbornscreening-bloodspot.org.uk Footnotes 1 Available on http://www.cancerscreening.nhs.uk/colorectal/finalreport.pdf 2 HTA (1999), vol. 3, no. 8 P.162
Accident prevention ‘A safe, secure and sustainable environment is a prerequisite for a healthy nation’ Department of Health, ‘Our Healthier Nation’, 1998 Accidents are the most common cause of death in children >1y. They also cause death and permanent disability for thousands of adults and elderly people every year. High-risk groups are children ≤4y.; elderly people; alcoholics; and teenage males. Drowning 3rd most common cause of accidental death among the under 16s. >½ those who drown can swim. 44% of drownings occur in rivers or streams; 3% in garden ponds; 2% in swimming pools; and 5% in home baths. Alcohol is a contributory factor in 14% cases. The best way to ↓ drowning is prevention—spot the dangers; take safety advice; don’t go near water alone; learn how to help others. Road safety Responsible for 30–40% of all fatal accidents. Prevention:

  • Avoid alcohol or any other drugs that hamper driving performance when driving
  • Keep speed down
  • Do not drive if tired or ill
  • Wear seatbelts and appropriate protective clothing (e.g. helmet if riding a pedal or motor cycle)
  • Ensure children are properly strapped in
  • Keep vehicles well maintained
  • When cycling, use cycle tracks if available
  • Supervise children close to roads; teach them the Green Cross code

Home safety Every year >4000 people die due to accidents in the home and nearly 3 million seek treatment in A&E departments. Inside the home, most accidents occur in the living/dining room, followed by the kitchen. Accidents inside the home include fires, choking/suffocation, drowning, falls, poisoning, injury by hot substances, and electrical injuries. Prevention: Spot the dangers; take safety advice (e.g. from HV if young children in the house); fit smoke alarms and safety devices (e.g. stair gates for toddlers); ensure adequate supervision of children or elderly confused people; maintain equipment correctly. Prevention of falls Falls are one of the biggest risk factors for fracture. Tendency to fall ↑ with age. All elderly people should have their risk of falls assessed regularly—whether or not they have osteoporosis. Is a falls assessment needed? Ask if patients fall—they may not volunteer the information spontaneously.

  • The ‘Get up and go’ test—people who can get up from a chair without using their arms, walk several paces, and return with no difficulty or unsteadiness are at low risk of falling.
  • People who have difficulty with the ‘Get up and go’ test, have to stop walking while talking, present following a fall, or who have recurrent falls, need a falls assessment.

Falls assessment If available, refer to a specialist falls service. Record:

  • Frequency and history of circumstances around any previous falls
  • Drug therapy: polypharmacy, hypnotics, sedatives, diuretics, antihypertensives may all cause falls
  • Assessment of vision
  • Examination of gait and balance, including abnormalities due to foot problems or arthritis, and motor disorders e.g. stroke, PD
  • Examination of basic neurological function, including mental status (impaired cognition and depression), muscle strength, lower extremity peripheral nerves, proprioception, and reflexes
  • Assessment of basic cardiovascular status including BP (exdude postural hypotension), heart rate, and rhythm
  • Assessment of environmental risk factors e.g. poor lighting (particularly on the stairs), loose carpets or rugs, badly fitting footwear or clothing, lack of safety equipment such as grab rails, steep stairs, slippery floors, or inaccessible lights or windows

Measures to ↓ risk of falls and damage from falling

  • Modify identified hazards or risk factors
  • Assess and correct vision, if possible
  • Correct postural hypotension—alter medication; consider compression stockings (but many elderly people cannot themselves apply stockings tight enough to be of any use)
  • Treat other medical conditions e.g. refer to cardiology if arrythmia
  • Review medication and discontinue/alter inappropriate medication
  • Remove environmental hazards—arrange bath at a day centre, refer to OT to identify and correct hazards in the home e.g. remove loose carpets, wheeled trolley for use indoors, commode or urine bottle for night time use, moving the bed downstairs
  • Refer to OT to identify and correct hazards in the home
  • Liaise with other members of the primary healthcare team and social services to provide additional support if needed; refer to local council for ‘carephone’ or alarm system to call for help if any further falls
  • Refer to rehabilitation/physiotherapy to improve confidence after falls and for weight-bearing exercise (focusing on strength and flexibility) and balance training (↓ risk of falls)
  • Use of hip protectors ↓ fracture risk in patients at high risk, but compliance is a problemc

Falls amongst the elderly p.996 Osteoporosis and prevention of fracture p.568 Medicines Warn patients to keep all medicines out of the reach of children. Advise patients to dispose of unwanted medicines by returning them to a supplier/GP surgery for destruction. Further information The Royal Society for the Prevention of Accidents Email: help@rospa.co.uk http://www.rospa.com SIGN (2002) Prevention and management of hip fracture in older people http://www.sign.ac.uk

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