Model of outcomes of screening mammography: information to support informed choices

Objective To provide easy to use estimates of the benefits and harms of biennial screening mammography for women aged 40, 50, 60, and 70 years.Design Markov process model, with data from BreastScreen Australia, the Australian Institute of Health and Welfare, and the Australian Bureau of Statistics.Main outcome measure Age specific outcomes expressed per 1000 women over 10 years.Results For every 1000 women screened over 10 years, 167-251 (depending on age) receive an abnormal result; 56-64 of these women undergo at least one biopsy, 9-26 have an invasive cancer detected by screening, and 3-6 have ductal carcinoma in situ (DCIS) detected by screening. More breast cancers (both invasive and DCIS) are diagnosed among screened than unscreened women. For example, among 1000 women aged 50 who have five biennial screens, 33 breast cancers are diagnosed: 28 invasive cancers (18 detected at screening and 10 interval cancers) and five DCIS (all detected at screening). By comparison, among 1000 women aged 50 who decline screening, 20 cancers are diagnosed over 10 years. There are about 0.5, 2, 3, and 2 fewer deaths from breast cancer over 10 years per 1000 women aged 40, 50, 60, and 70, respectively, who choose to be screened compared with women who decline screening at times determined by relevant policy.Conclusion Benefits and harms of screening mammography are relatively finely balanced. Quantitative estimates such as these can be used to support individual informed choices about screening.     

Aggressiveness of breast cancers found with and without screening.

OBJECTIVE--To examine how breast cancers found by mammographic screening differ from those found outside screening. DESIGN--Comparative cohort study. SETTING--Turku, southwestern Finland. PATIENTS--126 women aged 40-74 years with breast cancer detected during the first round of mammographic screening in 1987-90 and 125 women within the same age range with breast cancer detected outside screening during the same period. MAIN OUTCOME MEASURES--Primary tumour size, axillary nodal status, histological features, oestrogen and progesterone receptor concentrations, ploidy, and S phase fraction. RESULTS--Compared with the controls women with cancers detected by screening had a smaller primary tumour (57 (46%) screened v 11 (10%) controls had tumours less than or equal to 11 mm in diameter, p less than 0.0001), and less often had axillary nodal metastases (104 (83%) screened v 71 (57%) controls node negative, p less than 0.0001). After adjustment for the smaller size of the primary tumour compared with control cancers, those cancers detected by screening were less likely to have axillary nodal metastases (odds ratio 0.44, 95% confidence interval 0.23 to 0.84), poor histological differentiation (0.20, 0.08 to 0.49), high mitotic counts (0.38, 0.15 to 0.97), tumour necrosis (0.45, 0.22 to 0.93) or to be of the ductal histological type (0.46, 0.22 to 0.95). They had low oestrogen receptor (0.29, 0.12 to 0.70) and progesterone receptor (0.35, 0.17 to 0.92) concentrations less often and had smaller S phase fractions (0.72, 0.55 to 0.96) than control cancers. CONCLUSIONS--Even after adjustment for the smaller size of screen detected breast cancers, their histological and cytometric features suggest low malignant potential. They may also be less likely to metastasise to axillary lymph nodes than cancers found outside screening.     

Costs and cost effectiveness of cardiovascular screening and intervention: the British family heart study.

OBJECTIVE--To measure costs and cost effectiveness of the British family heart study cardiovascular screening and intervention programme. DESIGN--Cost effectiveness analysis of randomised controlled trial. Clinical and resource use data taken from trial and unit cost data from external estimates. SETTING--13 general practices across Britain. SUBJECTS--4185 men aged 40-59 and their 2827 partners. INTERVENTION--Nurse led programme using a family centered approach, with follow up according to degree of risk. MAIN OUTCOME MEASURES--Cost of the programme it self; overall short term cost to NHS; cost per 1% reduction in coronary risk at one year. RESULTS--Estimated cost of putting the programme into practice for one year was 63 pounds per person (95% confidence interval 60 pounds to 65 pounds). The overall short term cost to the health service was 77 pounds per man (29 pounds to 124 pounds) but only 13 pounds per woman (-48 pounds to 74 pounds), owing to differences in utilisation of other health service resources. The cost per 1% reduction in risk was 5.08 pounds per man (5.92 pounds including broader health service costs) and 5.78 pounds per woman (1.28 pounds taking into account wider health service savings). CONCLUSIONS--The direct cost of the programme to a four partner practice of 7500 patients would be approximately 58,000 pounds. Annually, 8300 pounds would currently be paid to a practice of this size working to the maximum target on the health promotion bands, plus any additional reimbursement of practice staff salaries for which the practice qualified. The broader short term costs to the NHS may augment these costs for men but offset them considerably for women.     

Recruitment methods for screening programmes: trial of a new method within a regional osteoporosis study.

OBJECTIVE--To estimate the response rates and operating costs of three recruitment methods within a regional osteoporosis screening programme. DESIGN--Randomised trial of three types of invitation letter: one offering fixed appointments with option to change time, one offering fixed appointments but requiring telephoned confirmation of intention to attend, and one inviting recipient to telephone to make an appointment. SETTING--Osteoporosis screening unit, Aberdeen. SUBJECTS--1200 women aged 45-49 years living within 32 km of Aberdeen and randomly selected from the community health index. 400 women were randomised to each appointment method. MAIN OUTCOME MEASURES--Numbers attending for screening; default rate among women who confirmed appointments; social class of attenders; cost per appointment slot and per completed scan. RESULTS--299 (75%), 277 (69%), and 217 (54%) women were scanned after fixed, confirmable, and open invitations respectively. Women who attended were given a questionnaire, and 694 (87.5%) returned it. No significant differences were found in the social class of attenders among the three methods. Of the 514 women who made or confirmed appointments, 494 attended for a scan. Total costs per scan were 25.00 pounds, 21.40 pounds, and 21.00 pounds for fixed, confirmable, and open invitations respectively. CONCLUSIONS--The offer of a fixed appointment requiring telephoned confirmation has the potential to reduce the costs of scanning without exaggerating any social bias or significantly reducing response rates provided that empty appointments can be rebooked at short notice.     

Cost effectiveness of antenatal screening for cystic fibrosis.

OBJECTIVE--To estimate the cost effectiveness of different antenatal screening programmes for cystic fibrosis. SETTING--Antenatal clinics and general practices in the United Kingdom. DESIGN--Four components of the screening process were identified: information giving, DNA testing, genetic counselling, and prenatal diagnosis. The component costs were derived from the literature and from a pilot screening study in Yorkshire. The cost of a given screening programme was then obtained by summing the components according to the specific screening strategy adopted (sequential and couple), the proportion of carriers detected by the DNA test, and the uptake of screening. Baseline assumptions were made about the proportion with missing information on carrier status from previous pregnancies (20%), the proportion changing partners between pregnancies (20%), and the uptake of prenatal diagnosis (100%). Sensitivity analysis was performed by varying these assumptions. MAIN OUTCOME MEASURE--Cost per affected pregnancy detected. RESULTS--Under the baseline assumptions sequential screening costs between pounds 40,000 and pounds 90,000 per affected pregnancy detected, depending on the carrier detection rate and uptake. Couple screening was more expensive, ranging from pounds 46,000 to pounds 104,000. From the sensitivity analysis a 10% change in the assumed proportion with missing information from a previous pregnancy alters the cost by pounds 4000; a 10% change in the proportion with new partners has a similar effect but only for couple screening; and cost will change directly in proportion to the uptake of prenatal diagnosis. CONCLUSIONS--While economic analysis cannot determine screening policy, the paper provides the NHS with the information on cost effectiveness needed to inform decisions on the introduction of a screening service for cystic fibrosis.     

An economic evaluation of thrombolysis in a remote rural community.

OBJECTIVES: To assess the cost effectiveness of community thrombolysis relative to hospital thrombolysis by investigating the extra costs and benefits of a policy of community thrombolysis, then establishing the extra cost per life saved by community thrombolysis. DESIGN: Economic evaluation based on the results of the Grampian region early anistreplase trial. SETTING: 29 rural general practices and one secondary care provider in Grampian, Scotland. SUBJECTS: 311 patients recruited to the Grampian region early anistreplase trial. INTERVENTIONS: Intravenous anistreplase given either by general practitioners or secondary care clinicians. MAIN OUTCOME MEASURES: Survival at 4 years and costs of administration of thrombolysis. RESULTS: Relative to hospital thrombolysis, community thrombolysis gives an additional probability of survival at 4 years of 11% (95% confidence interval 1% to 22%) at an additional cost of 425 pounds per patient. This gives a marginal cost of life saved at 4 years of 3,890 pounds (1,990 pounds to 42,820 pounds). CONCLUSIONS: The cost per life saved by community thrombolysis is modest compared with, for example, the cost of changing the thrombolytic drug used in hospital from streptokinase to alteplase.     

Cost effectiveness of day and inpatient psychiatric treatment: results of a randomised controlled trial.

OBJECTIVE: To compare direct and indirect costs of day and inpatient treatment of acute psychiatric illness. DESIGN: Randomised controlled trial with outcome and costs assessed over 12 months after the date of admission. SETTING: Teaching hospital in an inner city area. SUBJECTS: 179 patients with acute psychiatric illness referred for admission who were suitable for random allocation to day hospital or inpatient treatment. 77 (43%) patients had schizophrenia. INTERVENTIONS: Routine inpatient or day hospital treatment. MAIN OUTCOME MEASURES: Direct and indirect costs over 12 months, clinical symptoms, social functioning, and burden on relatives over the follow up period. RESULTS: Clinical and social outcomes were similar at 12 months, except that inpatients improved significantly faster than day patients and burden on relatives was significantly less in the day hospital group at one year. Median direct costs to the hospital were 1923 pounds (95% confidence interval 750 pounds to 3174 pounds) per patient less for day hospital treatment than inpatient treatment. Indirect costs were greater for day patients; when these were included, overall day hospital treatment was 2165 pounds cheaper than inpatient treatment (95% confidence interval of median difference 737 pounds to 3593 pounds). Including costs to informants when appropriate meant that day hospital treatment was 1994 pounds per patient cheaper (95% confidence interval 600 pounds to 3543 pounds). CONCLUSIONS: Day patient treatment is cheaper for the 30-40% of potential admissions that can be treated in this way. Carers of day hospital patients may bear additional costs. Carers of all patients with acute psychiatric illness are often themselves severely distressed at the time of admission, but day hospital treatment leads to less burden on carers in the long term.     

Screening for early familial ovarian cancer with transvaginal ultrasonography and colour blood flow imaging.

OBJECTIVE--To assess the value of transvaginal ultrasonography with colour blood flow imaging in detecting early ovarian cancer in women with a family history of the disease. DESIGN--Study of self referred symptomless women with a close relative who had developed the disease. Each woman was screened to detect persistent lesions and defined changes in ovarian volume. Morphological score and pulsatility index were recorded. SETTING--Ovarian screening clinic. SUBJECTS--1601 self referred women. INTERVENTIONS--Women with a positive screening result were recommended to have further investigations. MAIN OUTCOME MEASURES--Findings at surgery and histology of abnormal ovaries. Morphological score > or = 5 and pulsatility index < 1.0 at last scan. RESULTS--Women were aged 17 to 79 (mean 47) years; 959 (60%) were premenopausal, 469 (29%) were naturally postmenopausal, and 173 (11%) had had a hysterectomy. 157 women had a pedigree suggestive of the site specific ovarian cancer syndrome and 288 of multiple site cancers. 61 women had a positive screening result (3.8%, 95% confidence interval 2.9 to 4.9%), six of whom had primary ovarian cancer detected at surgery (five stage Ia, one stage III). Use of a high morphological score or a low pulsatility index increased the odds of finding ovarian cancer from 1:9 to about 2:5 (1:1 in the highest risk groups). Five interval cancers were reported (three ovarian and two peritoneal). Eight of the 11 cancers developed in women with pedigrees suggestive of inherited cancer. CONCLUSIONS--Transvaginal ultrasonography with colour flow imaging can effectively detect early ovarian cancer in women with a family history of the disease. The screening interval should be less than two years.     

Effectiveness of the public health policy for breast cancer screening in Finland: population based cohort study.

OBJECTIVE: To evaluate the effectiveness of screening for breast cancer as a public health policy. DESIGN: Follow up in 1987-92 of Finnish women invited to join the screening programme in 1987-9 and of the control women (balanced by age and matched by municipality of residence), who were not invited to the service screening. SETTING: Finland. SUBJECTS: Of the Finnish women born in 1927-39, 89893 women invited for screening and 68862 controls were followed; 1584 breast cancers were diagnosed. MAIN OUTCOME MEASURES: Rate ratio of deaths from breast cancer among the women invited for screening to deaths among those not invited. RESULTS: There were 385 deaths from breast cancer, of which 127 were among the 1584 incident cases in 1987-92. The rate ratio of death was 0.76 (95% confidence interval 0.53 to 1.09). The effect was larger and significant (0.56; 0.33 to 0.95) among women aged under 56 years at entry. 20 cancers were prevented (one death prevented per 10000 screens). CONCLUSIONS: A breast screening programme can achieve a similar effect on mortality as achieved by the trials for breast cancer screening. However, it may be difficult to justify a screening programme as a public health policy on the basis of the mortality reduction only. Whether to run a screening programme as a public health policy also depends on its effects on the quality of life of the target population and what the resources would be used for if screening was not done. Given all the different dimensions in the effect, mammography based breast screening is probably justifiable as a public health policy.     

National Health Service breast screening programme results for 1991-2.

OBJECTIVES--To report the results of the NHS breast screening programme for the year March 1991 to April 1992. DESIGN--A report of statistics was derived from Körner (K62) returns and from the radiology quality assurance programme. MAIN OUTCOME MEASURES--Detection rates for breast cancer and small (< or = 10 mm diameter) invasive cancer, benign biopsy rates, and recall and acceptance rates. RESULTS--The acceptance rate for screening across the United Kingdom was 71.3%. The referral rate for further investigation was 6.2% (regional 4.3-9.0%). The breast cancer detection rate was 6.2 cancers per 1000 women screened (5.1-9.0) and the detection rate of invasive cancers < or = 10 mm was 1.4/1000 (1.0-2.3). 72% of screening programmes reached the target 70% acceptance rate, and 95% of programmes achieved a recall rate of less than 10%. 75% of programmes had a cancer detection rate of more than 5/1000, but only 32% had a detection rate for invasive cancers < or = 10 mm of more than 1.5/1000. CONCLUSIONS--Overall, the results of the screening programme for the year 1991-2 can be regarded as extremely satisfactory, given the size and complexity of the operation.     

Is the three year breast screening interval too long? Occurrence of interval cancers in NHS breast screening programme's north western region.

OBJECTIVE--To report the detection rate of interval cancers in women screened by the NHS breast screening programme. DESIGN--Detection of interval cancers by computer linkage of records held by the screening centres in the North Western Regional Health Authority with breast cancer registrations at the regional cancer registry. SETTING--North Western Regional Health Authority. SUBJECTS--137,421 women screened between 1 March 1988 and 31 March 1992 who had a negative screening result. RESULTS--297 invasive interval cancers were detected. The rate of detection of interval cancers expressed as a proportion of the underlying incidence was 31% in the first 12 months after screening, 52% between 12 and 24 months, and 82% between 24 and 36 months. CONCLUSION--The incidence of interval cancers in the third year after breast screening approaches that which would have been expected in the absence of screening and suggests that the three year interval between screens is too long.     

Cost effectiveness analysis of different approaches of screening for familial hypercholesterolaemia

ObjectivesTo assess the cost effectiveness of strategies to screen for and treat familial hypercholesterolaemia.DesignCost effectiveness analysis. A care pathway for each patient was delineated and the associated probabilities, benefits, and costs were calculated.ParticipantsSimulated population aged 16-54 years in England and Wales.InterventionsIdentification and treatment of patients with familial hypercholesterolaemia by universal screening, opportunistic screening in primary care, screening of people admitted to hospital with premature myocardial infarction, or tracing family members of affected patients.ResultsTracing of family members was the most cost effective strategy (£3097 (€5066, $4479) per life year gained) as 2.6 individuals need to be screened to identify one case at a cost of £133 per case detected. If the genetic mutation was known within the family then the cost per life year gained (£4914) was only slightly increased by genetic confirmation of the diagnosis. Universal population screening was least cost effective (£13 029 per life year gained) as 1365 individuals need to be screened at a cost of £9754 per case detected. For each strategy it was more cost effective to screen younger people and women. Targeted strategies were more expensive per person screened, but the cost per case detected was lower. Population screening of 16 year olds only was as cost effective as family tracing (£2777 with a clinical confirmation).ConclusionsScreening family members of people with familial hypercholesterolaemia is the most cost effective option for detecting cases across the whole population.

What is already known on this topic

In the United Kingdom there are an estimated 110 000 men and women with familial hypercholesterolaemia, only a small percentage of whom have been identified to dateWithout identification and treatment, over half of these people will have a fatal or non-fatal coronary heart disease event by the age of 50 (men) or 60 (women)Effective treatment of high cholesterol concentrations reduces total and coronary heart disease mortalityNo recommended screening strategy currently exists in the United Kingdom for familial hypercholesterolaemia

What this study adds

Computer modelling has shown that the earlier familial hypercholesterolaemia is diagnosed the more cost effective the screening strategy becomesIdentifying relatives of people with familial hypercholesterolaemia is the most cost effective screening option for all age groupsAs technology improves and the cost of statins falls all strategies will become more cost effective     

Costs and benefits of cervical screening. II. Is it worthwhile reducing the screening interval from 5 to 3 years?

A reduction in screening interval from 5 years to 3 years would greatly increase the cost of the programme, but would save few extra lives. The cost per life saved would be around £250 000 at 1995 prices, or around £8000 per life per year saved. There would in addition be human costs for the women screened. The opportunity cost of reducing the interval may be too great, since it is likely that the Health Service would achieve greater health benefits by investing the funds in other health care activities.     

Use of mobile screening unit for diabetic retinopathy in rural and urban areas.

OBJECTIVES--To compare the effectiveness of a mobile screening unit with a non-mydriatic polaroid camera in detecting diabetic retinopathy in rural and urban areas. To estimate the cost of the service. DESIGN--Prospective data collection over two years of screening for diabetic retinopathy throughout Tayside. SETTING--Tayside region, population 390,000, area 7770 km2. SUBJECTS--961 patients in rural areas and 1225 in urban areas who presented for screening. MAIN OUTCOME MEASURES--Presence of diabetic retinopathy, need for laser photocoagulation, age, duration of diabetes, and diabetic treatment. RESULTS--Compared with diabetic patients in urban areas, those in rural areas were less likely to attend a hospital based diabetic clinic (46% (442) v 86% (1054), p < 0.001); less likely to be receiving insulin (260 (27%) v 416 (34%), p < 0.001 and also after correction for differences in age distribution); more likely to have advanced (maculopathy or proliferative retinopathy) diabetic retinopathy (13% (122) v 7% (89), p < 0.001); and more likely to require urgent laser photocoagulation for previously unrecognised retinopathy (1.4% (13) v 0.5% (6), p < 0.02). The screening programme cost 10 pounds per patient screened and 1000 pounds per patient requiring laser treatment. CONCLUSION--The mobile diabetic eye screening programme detected a greater prevalence of advanced retinopathy in diabetic patients living in rural areas. Patients in rural areas were also more likely to need urgent laser photocoagulation. Present screening procedures seem to be less effective in rural areas and rural patients may benefit more from mobile screening units than urban patients.     

Endpiece: A newspaper

ObjectiveTo assess the cost effectiveness of ultrasound screening for abdominal aortic aneurysms.DesignPrimary analysis: four year cost effectiveness analysis based directly on results from a randomised controlled trial in which patients were individually allocated to invitation to ultrasound screening (intervention) or to a control group not offered screening. Secondary analysis: projection of the data, based on conservative assumptions, to indicate likely cost effectiveness at 10 years.SettingFour centres in the United Kingdom. Screening delivered in primary care settings with follow up and surgery offered in the main hospitalsParticipantsPopulation based sample of 67 800 men aged 65-74 years.ResultsOver four years there were 47 fewer deaths related to abdominal aortic aneurysms in the screening group than in the control group, but the additional costs incurred were £2.2m. After adjustment for censoring and discounted at 6% the mean additional cost of the screening programme was £63.39 ($97.77, €100.48) (95% confidence interval £53.31 to £73.48) per patient. The hazard ratio for abdominal aortic aneurysm was 0.58 (0.42 to 0.78). Over four years the mean incremental cost effectiveness ratio for screening was £28 400 (£15 000 to £146 000) per life year gained, equivalent to about £36 000 per quality adjusted life year. After 10 years this figure is estimated to fall to around £8000 per life year gained.ConclusionsEven at four years the cost effectiveness of screening for abdominal aortic aneurysms is at the margin of acceptability according to current NHS thresholds. Over a longer period the cost effectiveness will improve substantially, the predicted ratio at 10 years falling to around a quarter of the four year figure.

What is already known on this topic

Small trials have suggested that an ultrasound screening programme to detect abdominal aortic aneurysms in older men may be effectiveThere is uncertainty about the cost effectiveness of routine screening, with widely varying estimates

What this study adds

A cost effectiveness analysis of data from a large randomised trial with follow up over four years showed 47 fewer deaths and additional costs of £2.2m in the group invited to screeningThe adjusted net cost per patient was £63.39 and per life year gained was £28 400The projected cost per life year gained after 10 years was £8000, which is substantially lower than the perceived NHS threshold value     

Evaluating resistance to Bt toxin Cry1Ab by F2 screen in European populations of Ostrinia nubilalis (Lepidoptera: Crambidae)

The large-scale cultivation of transgenic crops producing Bacillus thuringiensis (Bt) toxins have already lead to the evolution of Bt resistance in some pest populations targeted by these crops. We used the F2 screening method for further estimating the frequency of resistance alleles of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), to Bt maize, Zea mays L., producing the Cry1Ab toxin. In France, Germany, and Italy, 784, 455, and 80 lines of European corn borer were screened for resistance to Mon810 maize, respectively. In Slovakia, 26 lines were screened for resistance to the Cry1Ab toxin. The cost of F2 screen performed in the four countries varied from U.S. dollars 300 to dollars 1300 per line screened. The major difference in cost was mostly due to a severe loss of univoltine lines during the screen in Germany and Slovakia. In none of the screened lines did we detect alleles conferring resistance to Mon810 maize or to the Cry1Ab toxin. The frequency of resistance alleles were < 1.0 x 10(-3), < 1.6 x 10(-3), < 9.2 x 10(-3), and < 2.6 x 10(-2) in France, Germany, Italy, and Slovakia, with 95% probability, respectively. The average detection probability over all lines was approximately 90%. Making the assumption that European corn borer populations in these countries belong to the same genetic entity, the frequency of alleles conferring resistance to the Cry1Ab produced by the Mon810 maize in western and central Europe was 1.0 x 10(-4), with a 95% confidence interval of 0-3.0 x 10(-4).     

Prevalence of HIV infection among pregnant women in Newfoundland.

OBJECTIVE: To determine the prevalence of HIV infection among pregnant women in Newfoundland. DESIGN: Anonymous unlinked seroprevalence study. SETTING: Newfoundland. PATIENTS: A total of 14911 women receiving prenatal care or undergoing an abortion, representing nearly all pregnancies in Newfoundland from Nov. 1, 1991, to Oct. 31, 1993. OUTCOME MEASURES: HIV antibody status, as determined by enzyme immunoassay of leftover serum samples (initially obtained for routine screening) and confirmation of reactive samples by the Western blot technique, health region of residence, and age group. RESULTS: Of the 14911 serum samples 13 were positive for HIV, for an overall crude prevalence rate of 1 per 1147 or 8.7 per 10000 pregnant women (95% confidence interval [CI] 4.7 to 14.9). Seven of the positive samples were from women residing in the Eastern Health Region of the province, for a crude prevalence rate of 1 per 376 or 26.6 per 10000 pregnant women (95% CI 10.7 to 54.8) for that region. All women found to be HIV positive were 15 to 29 years of age, the peak prevalence (20.8 per 10000 pregnant women [95% CI 9.5 to 39.4]) was observed among those 20 to 24 years. CONCLUSIONS: The overall prevalence rate of 8.7 per 10 000 pregnant women in Newfoundland is the highest provincial rate recorded among those from similar studies in Canada. Although it may be concluded that there are an estimated 125 HIV-positive women of childbearing age in Newfoundland (95% CI 67 to 213), the age-adjusted estimate is 84 (95% CI 36 to 131). This study provides an independent confirmation of an outbreak of HIV infection among women in the Eastern Health Region of the province.     

Cervical cancers diagnosed after negative results on cervical cytology: perspective in the 1980s.

OBJECTIVES--To assess the magnitude of the problem of interval cancers of the cervix (those that are diagnosed within a short time after negative screening test results) in the 1980s, to compare the nature of interval cancers in younger women with that in older women, and, by reviewing negative cervical smears, to determine the proportion of interval cancers that might represent the development of malignancy anew compared with the proportion that might be associated with difficulties in sampling or errors in reporting. DESIGN--An audit of the interval cases of cervical cancer that had been diagnosed within 36 months of a smear having been reported as negative by the Victorian Cytology Gynaecological Service among women registered with cervical cancer during 1982-6. SETTING--The Victorian Cytology Gynaecological Service, a free public sector cytology laboratory in Victoria, Australia. SUBJECTS--138 Women, all of whom had had cervical cancer diagnosed during the 36 months after having had a negative cervical smear. Subjects were divided into two age groups: younger women, aged less than 35; older women, aged 35-69. INTERVENTIONS--Negative slides were reviewed for evidence of optimal sampling and for the presence of cellular abnormalities that had been missed at the time of the original reporting. MAIN OUTCOME MEASURES--The number of interval cases of cancer of the cervix registered during 1982-6. The proportion of interval cases occurring in younger women and the proportion occurring in older women. Division of women into three risk categories based on clinical history and screening history that broadly corresponded to the probability that a diagnosis of cervical cancer might be expected during the 36 months after the issuing of a negative smear report. RESULTS--138 Of 1044 (13.2%) women who had been registered with cervical cancer during 1982-6 had had one or more negative smears during the 36 months preceding the diagnosis of cancer. Interval cancers comprised a larger proportion of registrations of cervical cancer in women aged less than 35 years than in women aged 35-69 (21.1% v 11.0%, p less than 0.01). Women with interval cancer who had had at least three negative smears during the 10 years before the diagnosis of cancer were commoner in the younger age group than in the older age group (7.0% v 2.5%, p less than 0.01). When, however, the number of observed cases of squamous cell carcinoma was related to the number of expected cases in the absence of screening, no significant difference was found between the two age groups (6.8% v 4.8%, p greater than 0.10). The rate of diagnosis of interval cancer per 100,000 negative tests was lower among younger women than among older women (10/100,000 v 16/100,000). Review of the negative slides showed that 11.9% were again considered to be negative with an optimal sample having been obtained as evidenced by the presence of endocervical cells or metaplastic cells, or both. CONCLUSIONS--Interval cancers might comprise a larger proportion of all registered cases of cervical cancer among younger women owing to the larger proportion of such cancers being prevented in this age group. Among women with interval cancer review of the negative slides showed that most were accounted for by suboptimal sampling or by errors of reporting.     

Cervical Abnormalities Are More Common among Indigenous than Other Australian Women: A Retrospective Record-Linkage Study, 2000–2011

Indigenous Australian women have much higher incidence of cervical cancer compared to non-Indigenous women. Despite an organised cervical screening program introduced 25 years ago, a paucity of Indigenous-identified data in Pap Smear Registers remains. Prevalence of cervical abnormalities detected among the screened Indigenous population has not previously been reported. We conducted a retrospective cohort study of population-based linked health records for 1,334,795 female Queensland residents aged 20–69 years who had one or more Pap smears during 2000–2011; from linked hospital records 23,483 were identified as Indigenous. Prevalence was calculated separately for Indigenous and non-Indigenous women, for cytology-detected low-grade (cLGA) and high-grade abnormalities (cHGA), and histologically confirmed high-grade abnormalities (hHGA). Odds ratios (OR) were estimated from logistic regression analysis. In 2010–2011 the prevalence of hHGA among Indigenous women (16.6 per 1000 women screened, 95% confidence interval [CI] 14.6–18.9) was twice that of non-Indigenous women (7.5 per 1000 women screened, CI 7.3–7.7). Adjusted for age, area-level disadvantage and place of residence, Indigenous women had higher prevalence of cLGA (OR 1.4, CI 1.3–1.4), cHGA (OR 2.2, CI 2.1–2.3) and hHGA (OR 2.0, CI 1.9–2.1). Our findings show that Indigenous women recorded on the Pap Smear Register have much higher prevalence for cLGA, cHGA and hHGA compared to non-Indigenous women. The renewed cervical screening program, to be implemented in 2017, offers opportunities to reduce the burden of abnormalities and invasive cancer among Indigenous women and address long-standing data deficiencies.