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Comment
The health service and personal costs of screening.
M Law. J Med Screen 1995 2: 61.

Clinical Trials
Private costs associated with abdominal aortic aneurysm screening: the importance of private travel and time costs.
S Bryan, M Buxton, M McKenna, H Ashton, and A Scott. J Med Screen 1995 2: 62-66.
OBJECTIVES--To assess the importance of the private costs incurred by patients when making a judgment on the economics of screening for abdominal aortic aneurysm (AAA), and to explore the variation in such costs depending on screening location.
SETTING--A district general hospital and general practitioner surgeries.
METHODS--Four hundred and ninety nine consecutive subjects attending for AAA screening completed a questionnaire asking about travel arrangements for the journey to and from the clinic, the distance travelled, the time taken, the mode of transport, and any out-of-pocket expenses incurred. In addition, at the clinic each subject was asked what activities they had forgone in attending the clinic. Time was valued differently depending on whether work or leisure activities were forgone. The total private cost for each attender was calculated and comparison was made between attenders at hospital and at general practice.
RESULTS--A significantly greater proportion of subjects were accompanied when attending hospital than when attending general practitioner (GP) surgeries. Most attenders travelled by car, but the journey time was significantly longer for those visiting hospital. The expected total private cost associated with attendance for AAA screening was 5.47 pounds. Attendance at GP surgeries had a lower private cost (4.21 pounds) than attendance at hospital (6.87 pounds). Only 7.3% of all men surveyed, and 6.5% of all companions, would have been taking part in some form of paid occupation if they had not attended for screening.
CONCLUSION--Despite the fact that most attenders for AAA screening will be retired, the associated private costs are appreciable and should be considered in assessing the economics of such screening programmes. The level of private costs varied depending on the location of screening; clinics held at GP practices had lower private costs than those held at hospital.

Screening for breast cancer in women aged under 50: mode of detection, incidence, fatality, and histology.
L Tabar, G Fagerberg, HH Chen, SW Duffy, and A Gad. J Med Screen 1995 2: 94-98.
OBJECTIVE--To assess the effect of screening for breast cancer in women aged 40-49 in the Swedish two county trial, in terms of mortality reduction, advanced cancer reduction, mode of detection, and the histology of tumours detected.
SETTING--The Swedish two county trial of screening for breast cancer, in which 77,080 women aged 40-74 (19,844 aged 40-49) were randomly allocated to receive regular invitation to mammographic screening for breast cancer, and 55,985 women aged 40-74 (15,604 aged 40-49) were allocated to an unscreened control group.
METHODS--The screening interval in the younger age group was two years and in the older age group about three years. Statistical analysis of mortality and incidence rates was performed by Poisson regression. Relative survival was estimated using proportional hazards regression.
RESULTS--The relative mortality for the group invited to screening compared with the control group was 0.87 (95% confidence interval 0.54 to 1.41) in the 40-49 age group, in close agreement with the relative incidence of advanced cancers. For Kopparberg county the relative mortality was 0.73 (95% CI 0.37 to 1.41) and for Ostergotland 1.02 (95% CI 0.52 to 1.99). The lesser effect in the 40-49 group as a whole was largely due to a higher rate of interval cancers in this age group, and the occurrence in Ostergotland of a higher number of cancers after randomisation, but before screening started, and in women who refused screening. The higher interval cancer rate was consistent with the higher proportion of ductal grade 3 and medullary cancers in women aged 40-49 at diagnosis.
CONCLUSIONS--A major difficulty in screening women aged 40-49 is the rapid progression of a subset of tumours arising in this age group. Shortening the screening interval from two years would be necessary to achieve a higher mortality reduction.

Journal Articles
Impact of prenatal screening and diagnosis on the epidemiology of structural congenital anomalies.
LH Chi, DH Stone, and WH Gilmour. J Med Screen 1995 2: 67-70.
OBJECTIVE--To assess the impact of prenatal screening on the birth prevalence of three categories of structural congenital anomaly: abdominal wall defects (omphalocele and gastroschisis), renal agenesis/dysgenesis, and limb reduction defects.
SETTING--Glasgow, Scotland, United Kingdom.
METHODS--Data on the selected defects were obtained retrospectively from the population based Glasgow Register of Congenital Anomalies for the period 1980-91 inclusive. The register records all clinical or laboratory diagnoses of congenital anomaly in live births, stillbirths, and induced abortions occurring in women resident within the boundaries of the Greater Glasgow Health Board. The secular trends in the proportions of the defects diagnosed prenatally and terminated after screening, and in their prevalence at birth and during pregnancy, were examined. A total of 154,845 births were surveyed: 309 cases were identified in the selected anomaly categories.
RESULTS--83 cases of omphalocele/gastroschisis (5.4/10,000 births), 92 cases of renal agenesis/dysgenesis (5.9/10,000 births), and 134 cases of limb reduction defects (8.7/10,000 births) were found. Marked increases occurred over the study period in the proportions of cases diagnosed prenatally but not in the proportions terminated. The greatest difference between the prevalence at birth and during pregnancy was found for omphalocele. There were no significant secular trends in the prevalence of the selected defects.
CONCLUSIONS--Prenatal screening has made a limited epidemiological impact on the prevalence of these defects. It has been moderately (but inconsistently) effective in the avoidance of births of infants with omphalocele/gastroschisis and renal agenesis/dysgenesis but not of limb reduction defects. Future efforts should be directed towards improving the technical aspects of the ultrasonographic detection of fetal abnormalities and exploring in detail, locally, the reasons for the varying pattern of decision making about termination of pregnancy among prospective parents.

Prospects for the secondary prevention of colorectal cancer: screening by flexible sigmoidoscopy?
CB Woodman, P Prior, R Joseph, and A Watson. J Med Screen 1995 2: 71-78.
It may be useful to draw an analogy between the proposed screening programme for colorectal cancer and the cervical cancer screening programme. Both tumours show a spectrum of histological abnormalities consistent with a premalignant phase. The natural history of these premalignant lesions is poorly understood and although some will progress, if untreated, to invasive disease, most will not. Light microscopy cannot confidently distinguish which cases will progress and which will regress, and clinicians are therefore obliged to treat all. This will result in the destruction of many lesions of uncertain malignant potential. The secondary prevention of cervical cancer, although therapeutically efficacious, is inefficient. A lack of understanding of the natural history of intraepithelial neoplasia has frustrated attempts to develop rational referral criteria, and it is only now that the appropriate trials are being undertaken. The development of outpatient investigative and therapeutic procedures has resulted in many more women being referred for investigation and treatment, with predictable pressure on other services offered by gynaecologists, but no demonstrable saving of life. Similar uncertainties surround a screening programme for colorectal cancer. The principal concerns are not about the efficacy of polypectomy in interrupting the polyp cancer sequence, although uncertainties about the frequency with which cancer arises de novo do require that the effectiveness of this intervention is formally tested. Our major concerns are with compliance, and the management of the individual who tests positive--that is, who is found to have a distal polyp. Technological advances and operator enthusiasm may, as has happened with the cervical screening programme, lead to a relaxation in the indications for further investigation and treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Acceptance of screening for colorectal cancer by flexible sigmoidoscopy.
J Cockburn, RJ Thomas, SJ McLaughlin, and D Reading. J Med Screen 1995 2: 79-83.

OBJECTIVE--To determine the acceptance rate of screening by flexible sigmoidoscopy in a sample of general practice patients aged 50 to 60, and the acceptability of the procedure among those undergoing the test.
SETTING--Recruitment took place in selected general practices in Melbourne, Australia. Flexible sigmoidoscopies were performed at the local public hospital.
PATIENTS AND METHODS--187 patients aged between 50 and 60, and without bowel symptoms, were seen by one of 12 non-randomly selected general practitioners during the study period. At the conclusion of routine consultation general practitioners discussed colorectal screening with eligible patients and recommended that they attend a free screening clinic at the local hospital. The patients who attended the clinic underwent flexible sigmoidoscopy performed by experienced endoscopists. Clinic attenders completed a questionnaire which measured perceptions of the screening visit.
RESULTS--The attendance rate was 49%. All clinic attenders were satisfied with the care received at clinic. Sixty five per cent of people experienced either no discomfort or mild discomfort, while 15% of people experienced moderate or severe pain. A bloated feeling was common (80%), with around 36% of people experiencing moderate or extreme bloating. Most people said that they were not at all embarrassed (64%), though 9% reported moderate or extreme embarrassment. Seventeen people (19%) were found to have polyps.
CONCLUSIONS--Although the procedure was acceptable to those who underwent the screening test, further research on effective recruitment strategies is required if a full scale flexible sigmoidoscopy screening programme is to be considered feasible.

A case-control study to evaluate efficacy of screening for faecal occult blood.
D Lazovich, NS Weiss, NG Stevens, E White, B McKnight, and EH Wagner. J Med Screen 1995 2: 84-89.
OBJECTIVES--Faecal occult blood testing is routinely used for early detection of colorectal cancer, but evidence of its efficacy in preventing death from colorectal cancer is limited. A case-control study was carried out to evaluate whether screening for faecal occult blood is associated with a reduced risk of fatal colorectal cancer.
SETTING--A health maintenance organisation in western Washington State, which has offered its members faecal occult blood testing every two years since 1983.
METHODS--Cases (n = 248) were members of the health maintenance organisation who died from colorectal cancer between 1986 and 1991. For each case, two control subjects, who did not die from colorectal cancer and who were similar to each case in age, gender, and year of enrollment at the health maintenance organisation, were randomly selected from the membership list of the year in which the case was diagnosed (n = 496). Information about episodes of faecal occult blood testing (including the location and reason for the test, and the evaluation of positive tests) and potential confounders was obtained from medical records.
RESULTS--Cases were less likely than controls to have ever been screened (odds ratio (OR) = 0.7, 95% confidence interval (CI) 0.5 to 1.0), consistent with a beneficial impact of screening. There was little difference, however, for screening that had taken place within a three year period before diagnosis (OR = 0.9, 95% CI 0.6 to 1.2), the maximum interval during which most tumours ought to have been detectable by faecal occult blood testing. A reduction in risk was seen for home testing but not for office testing, and in individuals aged less than 75 but not in those aged 75 or older. Although most of the 21 controls with a positive faecal occult blood test underwent some additional testing, only five (24%) were evaluated with colonoscopy or air contrast barium enema.
CONCLUSIONS--While there can be uncertainty as to whether specific faecal occult blood tests were performed as screening or diagnostic tests, those performed at home and in younger persons may be relatively less likely to be diagnostic tests that were misclassified as screening. Thus the modest reduced risk associated with faecal occult blood testing in these settings/persons may reflect genuine benefit. However, the presence of a reduced risk associated with a screening faecal occult blood test received in the past, well before a tumour or polyp might bleed enough to allow detection, is compatible with uncontrolled confounding. Interpretation is further complicated by the fact that a number of individuals in the study group who had positive test results underwent limited or no diagnostic testing. Thus our results should be interpreted with considerable caution.

Sample size determination for a trial of breast cancer screening under age 50: population versus case mortality approach.
PG Peer, AL Verbeek, and H Straatman. J Med Screen 1995 2: 90-93.
OBJECTIVE--To determine the efficacy of screening for breast cancer in women aged 40 to 49.
METHODS--A large number of women will have to be enrolled to ensure adequate statistical power. Attention will be restricted to the deaths from breast cancer that occur among comparable groups of patients with breast cancer rather than to an analysis in which all women entering into the trial are considered at risk of dying from breast cancer (population mortality analysis). As the new trial is likely to be conducted in regions where screening has been established for all women from age 50 onward, comparability may be reached by including the breast cancers detected at the routine screening examination at age 50.
CONCLUSIONS--When comparability of cases can be reached, such a case mortality analysis requires 15-30% fewer women to be enrolled than a population approach.

Independent double reading of screening mammograms.
S Ciatto, MR Del Turco, D Morrone, S Catarzi, D Ambrogetti, A Cariddi, and M Zappa. J Med Screen 1995 2: 99-101.
OBJECTIVE--To evaluate the cost effectiveness of independent double reading of screening mammograms.
SETTING--Prospective study of 18,817 women undergoing first or repeat screening in a population based programme in the Florence district.
METHODS--Mammograms were independently double read by experienced radiologists. Subjects with mammographic abnormalities reported by at least one reader were recalled for diagnostic assessment. The mean increase in recall rate, cancer detection rate, and screening costs attributable to double reading was calculated.
RESULTS--Eleven of 125 cancers were detected by only one reader. The mean increase in cancer detection rate attributable to double reading compared with single reading was 4.6% (95% confidence interval (CI) 1.1 to 8.9). From a total of 748 cases referred for diagnostic assessment, 196 subjects were referred by one reader only. The mean increase in referral rate attributable to double reading compared with single reading was 15.1% (CI 12.3 to 17.8). Double reading caused a marked increase in the cost for each woman screened -8.5% at the first screening and 6.2% at repeat screening and a more limited increase in the cost for each cancer detected -3.5% at the first screening and 2.7% at repeat screening. Cancers detected by only one screener were at an earlier stage than those detected by both screeners (P = 0.6, not significant).
CONCLUSIONS--Independent double reading results in only a modest increase in the detection of cancers and therefore may not be cost effective.

Setting standards for cervical screening fail-safe mechanisms: a target based on an audit of cytopathology laboratory records.
E Roberts, GA Cook, JP Walsworth-Bell, and S Barrow. J Med Screen 1995 2: 102-104.
OBJECTIVE--To examine the efficacy of cytopathology laboratories in monitoring action following an abnormal cervical smear.
SETTING--11 screening laboratories serving 19 districts in the former North Western region of the United Kingdom.
METHOD--944 validated cases were identified at 11 laboratories. The screening history for each abnormal smear was obtained from the screening laboratory and compared with the records from the relevant family health services authority (FHSA) database.
RESULTS--Laboratories held complete follow up records in 740 (78.4%) cases; the FHSA records extended this to 910 (96.4%) cases. Poor communication was the main problem; computerisation was not necessary to improve fail-safe procedures.
CONCLUSIONS--Audit of fail-safe procedures is a valuable purchasing tool, identifying weaknesses and strengths, setting and maintaining standards.

What are women told about Pap smears that lack endocervical cells?
MJ Schofield, JE Byles, and R Sanson-Fisher. J Med Screen 1995 2: 105-108.
BACKGROUND--Debate exists about the definition of what constitutes an adequate Pap smear and about the recommended rescreening interval for Pap smears lacking an endocervical component. This study aimed at determining whether women are currently informed about the endocervical status of their Pap smears and what rescreening recommendations are made to women whose smears lack endocervical cells.
METHOD--Consecutive Pap smears lacking an endocervical component were identified from pathology records. After obtaining consent from the referring doctor, 165 women were interviewed by telephone.
RESULTS--Only 110 (67%) of 165 women received active notification of their Pap test result and only six (4%) were aware that their smear lacked endocervical cells. Thirteen (8%) had been advised to have a repeat smear within three months. Nearly half the women reported that they would like more information about their result.
CONCLUSIONS--It seems that current Pap smear notification patterns for women in New South Wales could be improved. One third are not actively informed at all about their results, and few are given detailed information about their Pap test results. Methods of enhancing the level of information women are given about their medical and screening tests need to be improved.

Glaucoma screening.
RP Wormald and A Rauf. J Med Screen 1995 2: 109-114.
National screening programmes probably cannot be justified at present given difficulties with test validity, manpower, and some doubts about the natural history of the disease. The opportunity cost could be prohibitive, especially when resources are badly needed in other areas of ophthalmology, such as cataract programmes, diabetic retinopathy, and low vision services. The situation could change with an improved test with greater validity for primary screening and such tests are currently under investigation. The results of these investigations will not be available for at least three years. Screening for eye disease at the primary care level begs questions about manpower which need to be answered not just for glaucoma screening but also for detection of diabetic retinopathy and visual impairment in the elderly. A new cadre of ophthalmic paramedics as is already in wide use in some developing countries, who amalgamate the skills of optometrist, orthoptist, and eye trained nurse, is an interesting possibility. Meanwhile, much has to be done to improve current case finding with agreed standards of examination and referral criteria and special facilities available for those at increased risk.

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