Costs and benefits of cervical screening. III. Cost/benefit analysis of a call of previously unscreened women

A population‐based cervical screening programme issued invitations to women with no record of a previous smear. This call was very good value, at £5780 per life saved or £159 per life‐year saved at 1991 prices. The first priority for the cervical screening service should be comprehensive coverage.     

Feasibility of cytology-based cervical cancer screening in rural Cameroon

OBJECTIVE: To determine the prevalence of cervical cancer and its precursors in a rural population in Cameroon and to evaluate the feasibility of a cytology-based screening program in such areas. STUDY DESIGN: A prospective study was conducted in the rural town of Bafang. Following an advocacy campaign, 750 women were recruited. After a clinical examination, all women had a Pap smear with the Cervex Brush. Each sample had two preparations, conventional and liquid based. The conventional smears were interpreted in Bafang. Cytologically abnormal cases, those with clinical inflammation and/or macroscopic cervical lesions, had a colposcopic examination and directed biopsy. HSIL and colposcopically abnormal cases were treated with large loop excision of the transformation zone (LLETZ). The liquid-based preparations and histopathology were performed in Geneva and the results sent to Cameroon for patient follow-up. RESULTS: Mean age and parity of the women screened were 43.7 years and 7.8, respectively. The conventional smears showed 3.6% cervical abnormalities: 2% (15/740) ASCUS/LSIL and 1.6% (12/740) HSIL. The liquid-based preparations showed 12.6% (91/722) cervical abnormalities: 10.1% (73/722) ASCUS/LSIL and 2.5% (18/722) HSIL. Fifty percent of samples in both preparations showed evidence of inflammation. Histology was performed on 64 colposcopically directed punch biopsies and LLETZ specimens. The histologic diagnoses agreed with the cytologic findings in 60% (14/23) of conventional smears and 85% (12/14) of liquid-based preparations. CONCLUSION: There is a high rate of cervical intraepithelial neoplasia in the unscreened rural population of Cameroon. The situation is complicated by a high rate of cervical infection. A population-based cytologic screening program for cervical cancer would not be feasible in rural Cameroon because of high cost, low quality and limited technical facilities. Rural Africa requires an algorithm using a simple, low-cost technique of mass screening and an improved cytology service only to triage selected patients.     

Adherence to recommendations for early repeat cervical smear tests.

OBJECTIVE--To assess adherence to recommendations for an early repeat cervical smear test in women with reports of cytological abnormalities, and to evaluate the impact of reminder letters to medical practitioners when such smear tests are overdue. DESIGN--Observational study. SETTING--Cytology (gynaecological) service for Victoria, Australia. SUBJECTS--Two groups of women who had abnormal cervical smears during 1985. Women in group A had some evidence of an important dysplasia and were advised to have a repeat smear in three months'' time whereas women in group B had a less serious abnormality and were advised to have a repeat smear test in six months'' time. In all, 971 of the 1036 women in group A and 1401 of the 1464 women in group B were eligible to have a repeat smear analysed by the service. INTERVENTION--If a repeat smear had not been received within three months of the recommended date a reminder letter generated by the service''s computer was sent to the medical practitioner who had taken the smear. END POINT--Thirty six months after the report on the abnormal smear was issued. MEASUREMENTS AND MAIN RESULTS--In all, 870 (90%) of the women in group A and 1154 (82%) of the women in group B had a repeat smear test. The mean time to a repeat test was 3.0 months (95% confidence interval 0.5 to 16.4) in group A and 6.0 months (1.2 to 30.3) in group B. The reminder letter to the practitioner potentially increased the rate of return for a repeat smear test by 18% in group A and 24% in group B. Adherence to the recommendation for a repeat test increased with increasing age. CONCLUSIONS--Achieving high rates of follow up smear tests and appropriate management in women with cytological abnormalities is critical to the impact of a screening programme for cervical cancer. The reminder system used in this study was not labour intensive or expensive and provided a fail safe mechanism for ensuring that reports of abnormal smears were not overlooked.     

Preliminary results of a district call scheme for cervical screening organised in general practice.

A recognised problem with the cervical screening programme in the United Kingdom is the failure to include women who have never had a cervical smear test, who are a high risk group. The implementation of a district based call scheme in East Berkshire in 1986 is described whereby women aged 20-64 with no record of a cervical smear test who were judged to be eligible for testing by their general practitioner were sent a personal invitation from their general practitioner to attend for a test. A list of high risk unscreened women was kept by each practice, and a duplicate sent to the cytology laboratory to update the central records. Six months after each batch of invitations had been sent the resulting number of women having a smear test was assessed. Forty three of 51 practices approached agreed to participate in the five year scheme. During the first year lists were sent to the 43 participating practices. The first list was returned to the cytology laboratory by 37 practices and the second by 33; practices varied in their responses, however, some needing considerable persuasion to return the lists. Of 972 identified unscreened women from the total 3757 women listed in the lists of the family practitioner committee, 247 (25%) had a cervical smear test in response to the invitation, representing an overall increase of 7% in the screened population. The preliminary findings of the five year study have shown that screening can be improved by a systematic call scheme. Coordinated support from the area health authority in health education, monitoring of screening, and feedback of data from the scheme to practices is required to reduce the proportion of unscreened women.     

Screening for squamous cervical cancer: duration of low risk after negative results of cervical cytology and its implication for screening policies. IARC Working Group on evaluation of cervical cancer screening programmes.

A collaborative study of screening programmes in eight countries was performed to estimate the risks of cervical cancer associated with different screening policies. Most of the data came from centrally organised screening programmes. Relative protection was higher in women who had had two or more negative results of screening tests than in those who had had only one negative smear, particularly in the first five years after the last test. There was little difference in the protection afforded by screening every year compared with every three years, but screening only once every five or 10 years offered appreciably less protection. The age of the women did not affect the sensitivity of the test or the sojourn time of the disease (the length of the detectable preclinical phase during which abnormal cytology could be picked up if a smear were taken); invasive cancer in women under 25 was rare. Centrally organised screening programmes were more effective than uncoordinated screening. Screening programmes should be aimed principally at women aged 35-60 but should start some years before the age of 35, and the intervals between screening should be three years or less.     

The use of screening episodes linked to CIN3 and invasive cancer registrations to study outcomes from the NHS Cervical Screening Programme

Objective: To examine how NHS cervical screening data can be collected and analysed in order to evaluate women’s screening histories as episodes rather than as individual smears. Design: Analysis of routine cervical screening data grouped into screening episodes for a cohort of women regarding episodes starting in a given year. Setting: NHS Cervical Screening Programme. Population: Data from four Health Authorities (now eight Primary Care Trusts) from the NHS Cervical Screening Programme with primary smears (first in an episode) taken between 1 April 1999 and 31 March 2000. Methods: Cytology information obtained from the call/recall (‘Exeter’) computer system was linked to cervical intraepithelial neoplasia (CIN) 3 and invasive cancer outcome information obtained from cancer registries. Screening histories were divided into episodes, each starting with a primary smear that was followed up to episode closure or, for episodes still open followed for an average 4.25 years, from the primary smear. The episode was divided into two parts (up to referral to colposcopy and following the referral). The outcomes of the episodes are described including referral rate to colposcopy and CIN3 and invasive cancer rates by factors such as age. Main outcome measures: Episode histories and rates of referral to colposcopy, CIN3 and invasive cancer. Results: There were 176 923 episodes from 176 319 women (1.003 episodes per woman) followed up to March 2004, the date at which the first phase of information accrual ceased. Of these episodes, 172 100 (97.3%) were closed either by a negative smear referring the woman back to routine recall or by default (defined as no smear recorded within 21 months following a smear requiring an action of repeat or refer to colposcopy). The remaining 4823 (2.7%) of episodes were still open, of which in 3121 (1.8%) the woman had been referred to colposcopy and in 1702 (1.0%) no referral decision had been made. Referral rates to colposcopy varied by age from 5.7% in women aged 20–24 years down to 0.9% in women aged 60–64 years. The overall efficiency of screening was highest for woman aged about 30 years, with a CIN3 detection rate of eight per 1000 women and a positive predictive value (for CIN3 or worse) of referral to colposcopy of 21%. Conclusion: The study has shown that routinely collected NHS cervical screening data can be combined to give information on complete episodes, allowing important performance measures to be studied. We suggest that in future information in the NHS screening system should be structured to facilitate such analysis and to allow cytology and histology information to be readily linked.     

Evaluation of the cervical cytology screening programme in an inner city health district.

District health authorities have been instructed to operate a cervical cytology call and recall screening programme using the age-sex registers held by family practitioner committees. A detailed evaluation of implementation in an inner London district showed that 477 out of 687 (69%) invitation letters sent to women by the family practitioner committee were either inaccurate or inappropriate: almost half of the recorded addresses were incorrect and a further fifth of the women were not eligible for a test. Overall, 90 women had a smear, which is only 13% of the total but 43% of those found to be eligible. The findings did not differ significantly with age. The findings have major implications not only for the effectiveness of call and recall for screening for cervical cancer but also for the future development of screening for breast cancer in such areas.     

CIN 2/3 and cervical cancer after an ASCUS pap smear. A 7-year, prospective study of the Norwegian population-based, coordinated screening program

OBJECTIVE: To estimate the risk of being diagnosed with cervical intraepithelial neoplasia (CIN) 2/3 or invasive cervical cancer (ICC) based on diagnostic and screening procedures performed after a diagnosis of atypical squamous cells of undetermined significance (ASCUS) and to compare this risk to that in women with a normal Pap smears. STUDY DESIGN: A 7-year, prospective, cohort study was performed in the Norwegian population-based, coordinated screening program. After excluding women in the midst of follow-up of an abnormal Pap smear or with a history of CIN 2/3 or ICC, the study population consisted of women 25-69 years of age with a normal (n = 526,661) or ASCUS Pap smear (n = 10,037) in 1995-1996. Risk estimates were calculated by logistic and parametric survival regression. RESULTS: Within 7 years of an ASCUS smear, 1,017 women (10.1%) were diagnosed with CIN 2/3 and 62 (0.62%) with ICC. Women with an ASCUS index Pap smear had a relative risk of 15-30 of being diagnosed with histologically verified CIN 2/3 or ICC within the first 2 years of follow-up as compared to women with a normal index smear. In long-term follow-up, women with an ASCUS index smear followed by a normal smear, which cancelled further clinical follow-up, were at > 3.5 times higher risk of both CIN 2/3 and invasive cancer as compared to women with a normal index smear. CONCLUSION: Pap smear follow-up of women with an ASCUS smear does not identify all women at higher risk of CIN 2/3 and ICC. Other diagnostic procedures should be implemented to improve the screening program.     

Long-term follow-up of patients following negative colposcopy: a new gold standard and its implications for cervical screening

From 1189 colposcopy referrals in 1997 at a single cervical screening centre, 88 women who had no biopsy taken at colposcopy (negative colposcopy) were identified. We followed up these women for a maximum of 4 years and calculated the positive predictive value (PPV) of a single smear before and after follow-up. Using slide review we attempted to correlate the grade of smear leading to colposcopy referral with final outcome. Our results showed that long-term follow-up alters the PPV of cervical cytology. Analysis showed a strong correlation between the review grade of the referring smear and the final outcome after follow-up. From these results we suggest an evidence-based protocol for cervical screening follow-up after negative colposcopy.     

Costs and benefits of cervical screening. I. The costs of the cervical screening programme

In 1991, the average total Health Service cost of a cervical smear, including follow up at the colposcopy clinic, was almost £22.70 in the Perth and Kinross district of Scotland. The average cost per colposcopy clinic visit was £30. The main cost elements were in general practice (55% of total) and the laboratory (33%), and most of the cost was for staff time.     

Cervical cytology screening and government policy.

OBJECTIVE--To assess the coverage of cervical cytology screening in one general practice surgery according to the criteria in the new Scottish general practitioner contract and to explore the difficulties of defining performance in such screening. DESIGN--Review of annual analysis of uptake of screening during 1984-8. SETTING--Suburban general practice surgery in Glasgow serving 3000 patients. PATIENTS--All women aged 35-64 registered in 1984 increasing in 1988 to all women aged 20-64. MAIN OUTCOME MEASURE--Assessment of uptake of smear tests and reasons for smear not being taken and of the effect of these outcomes on the new general practitioner contract. RESULTS--The numbers and percentages of women having a smear test in the previous five and three years were recorded, and the reasons why a smear was not taken were defined in the remainder (hysterectomy, test not offered, risk not known, test declined, patient moved away, and patient unaccounted for). In 1988, 85% (608/719) of the women aged 30-64 and 80% (693/870) of those aged 20-64 had had a smear test in the previous five years. An appropriate or irreducible reason for the lack of a smear test was defined in all the others. CONCLUSIONS--The population studied contained a substantial number of women in whom cervical smear was unnecessary, inappropriate, or refused. These factors and the likely demographic variation in the uptake of smear tests have important implications for the setting and achieving of the government''s targets for cervical cytology screening.     

Rationale for stopping cervical screening in women over 50.

OBJECTIVE--To investigate whether the currently recommended age at which to stop cervical screening (64) can be lowered and what criteria should be used for safely doing so. DESIGN--Retrospective case analysis study. SETTING--Dundee and Angus districts of Scotland. SUBJECTS--Women diagnosed as having cervical intraepithelial neoplasia and microinvasive or invasive cancer of the cervix in 1989 and 1990 (798 cases). MAIN OUTCOME MEASURE--History of cervical cytology results according to age (age groups of five years) and screening interval (three years and five years). RESULTS--Cervical intraepithelial neoplasia was most common in women under 45 (711 cases in women of 45 and under v 38 cases in those of 46 and over). Cervical intraepithelial neoplasia occurring de novo was not seen in women over 50 who had been screened every three years. Microinvasive or invasive cancer of the cervix was diagnosed in 26 women over 50. None of these women had participated adequately in the cervical screening programme. CONCLUSION--Cervical intraepithelial neoplasia typically occurs in younger women. All women over 50 with an adequate history of negative results on smear testing every three years may be safely discharged from further screening if these findings are confirmed in other populations.     

A pilot study of cervical screening in an inner city area—lessons for a national programme

The objectives of this study were to examine aspects of organization of a proposed national screening programme based in general practice. The target population of women aged 25–59 years and their general practitioners (GPs), in a defined inner city area, was identified from a population register of persons eligible for free medical services; a computerized system was developed for invitations and record linkage of cytology results. Smears were examined in one laboratory and follow up of women with abnormal smears was undertaken by one gynaecologist. A random sample of non‐responders was surveyed by questionnaire. Response following two invitations was only 20%. Practices with male doctors only had significantly lower reponse rates ( P <0.001) than those with a female doctor/nurse. A survey of non‐responders showed that over 20% of addresses were incorrect and 16% of those interviewed were ineligible for smear tests. A preference for a female to undertake smears was expressed by 67%, and 77% believed that the purpose of the cervical smear was to detect cancer. An accurate population register, health promotion, support for GP practices, provision of alternative venues for smear tests, development of computer systems, accurate data entry and fail‐safe follow up are aspects of a cervical screening service which must be addressed prior to setting up a national service.     

Type 1 and type 2 cervical carcinomas: some cervical cancers are more difficult to prevent with screening

Although the Papanicolaou (Pap) smear is medical history's most successful cancer screening test, some cervical cancers are more difficult to prevent with screening than others. Cervical cancers that are difficult to prevent are seen disproportionately among interval cancers arising in previously screened women and in Pap test litigation. These include (i) rapidly progressing cervical cancers; (ii) cervical cancers in younger women; (iii) glandular cervical cancers; and (iv) cervical cancers in elderly women. Screening protocols have generally been designed to optimize prevention of slower-growing cervical squamous carcinomas in middle-aged women. To focus further attention on the heterogeneous screening challenges posed by different cervical cancers, we designate the more screening preventable majority as type 1 cervical cancers and the more difficult to prevent minority as type 2 cervical cancers. We review available data on why some cervical cancers are more difficult to prevent with screening and newer methods that may improve prevention.     

The preparation of additional smears from a cervical scrape: impact on the rate of detection of cervical neoplasia

The preparation of additional smears from a cervical scrape: impact on the rate of detection of cervical neoplasia It has been known for some time that only a proportion of the cells on the smear-taking device is transferred to the slide. This can give rise to errors in reporting although the smear may have been taken correctly. This study was undertaken to identify a quick and simple method of improving the accuracy of the Papanicolaou test. A conventional smear and five additional smears were obtained from 62 women attending a Genito-Urinary Medicine clinic. The cell content of the conventional smears and the additional smears was compared. Dyskaryotic cells were detected both in the conventional smear and in the first and second additional smears from 22 women. Dyskaryotic cells were detected in the first and second additional smears only in five women. Thus, the conventional smear failed to detect biopsy-confirmed cervical abnormality in these women. A cell count of the first additional smear in the five cases where the conventional smear was negative showed that they contained, on average, 310 dyskaryotic cells. The preparation of one additional cervical smear per cervical scrape could significantly increase the accuracy of the cervical smear test by 11% (P=0.025, McNemar's test).     

Prevalence of cervical pathogens in women with and without inflammatory changes on smear testing.

OBJECTIVE--To assess correlation between nonspecific cervicitis, inflammation, or exudate on cervical smears tests and confirmed presence of known cervical pathogens. DESIGN--Investigation of women attending a family practice clinic for smear test by microbiological screening for Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum, Trichomonas vaginalis, Candida species, group B streptococcus, Gardnerella vaginalis, and Neisseria gonorrhoeae. SETTING--Family practice teaching clinic in a university hospital. PATIENTS--411 women presenting for a smear test. MAIN OUTCOME MEASURES--Prevalence of genital infections associated with presence or absence of inflammatory changes on cervical smear. RESULTS--Of the 132 women with inflammatory changes on cervical smear, 64 (48%) had positive cultures. Of the 248 without inflammatory changes, 117 (47%) had positive cultures. Subgroup analysis on individual organisms also showed no significant difference between the two groups. CONCLUSION--Reports of inflammatory changes on cervical smear testing are a poor indicator of infection.     

Prospective randomised controlled trial of methods of call and recall for cervical cytology screening.

OBJECTIVE--To discover whether systematic methods of call and recall are more effective than a non-systematic method and to see which of the two systematic methods was more effective. DESIGN--Prospective randomised controlled trial over a year. SETTING--One group general practice. PATIENTS--416 Women over 35 eligible for a smear test who had never had a cervical smear test or in whom a smear test was overdue (previous test more than five years before). INTERVENTIONS--One group received written invitations to have a smear taken. The second group had their notes tagged so that the doctor would remind them (when they attended for another reason) to have a smear test. No special intervention was made in the third group. MAIN OUTCOME MEASURE--Performance of a cervical smear test during the year of the study. RESULTS--32% (45/140) of the screened group, 27% (39/142) of the tagged group, and 15% (20/134) of the control group had a smear test during the year. The percentage of women having a smear test in the screened group was not significantly different from that in the tagged group, but the percentages in the two groups were significantly different from that in the control group. Whether a woman had had a previous smear test significantly affected the uptake of the invitation to have a smear test independently of the method of invitation. CONCLUSIONS--The systematic methods of call and recall were more effective than a non-systematic method. There was no significant difference between the two systematic methods (sending letters or tagging the notes) at one year.     

Effectiveness of a call/recall system in improving compliance with cervical cancer screening: a randomized controlled trial

OBJECTIVE: To determine the effectiveness of a simple call/recall system in improving compliance with cervical cancer screening among women not screened in the previous 3 years. DESIGN: Prospective randomized controlled study. SETTING: Two family medicine clinics (1 urban, 1 rural) affiliated with Memorial University of Newfoundland, St. John''s. PARTICIPANTS: A sample of women aged 18-69 years who were listed as patients of the clinics but who had not had a Papanicolaou test (Pap test) within the 3 years before the start of the study. Of 9071 women listed as patients 1360 (15.0%) had not undergone screening in the previous 3 years. A random sample of 650 were selected, 209 of whom were excluded because they had had a hysterectomy, had had a recent Pap test, had moved or had records containing clerical errors. This left 441 women for the study. INTERVENTION: The 221 women in the intervention group were sent a letter asking them to seek a Pap test and a reminder letter 4 weeks later. The 220 in the control group were sent no letters. MAIN OUTCOME MEASURES: Number of women who had a Pap test within 2 months and 6 months after the first letter was sent. RESULTS: Within 2 months, more women in the intervention group than in the control group had been screened (2.8% [5/178] and 1.9% (4/208] respectively). There was also a difference between the overall proportions at 6 months (10.7% [19/178] and 6.3% [13/208] respectively). None of the differences was statistically significant. CONCLUSION: A letter of invitation is not sufficient to encourage women who have never or have infrequently undergone a Pap test to come in for cervical cancer screening. The effectiveness of added recruitment methods such as opportunistic screening by physicians, follow-up by telephone and the offer of a specific appointment should be evaluated.     

Are women sufficiently well informed to provide valid consent for the cervical smear test?

Three hundred women attending colposcopy for the first time, following an abnormal cervical smear, were invited to fill in a questionnaire. This covered aspects of their understanding of the cervical smear test and the NHS Cervical Screening Programme (NHSCSP). In addition, it covered aspects of consent to the test. The response rate was 83%. Seventy percent thought that the NHSCSP is working well and 72% were aware that probably over 3000 cases of cervical cancer per year are being saved by the NHSCSP. However, 55% did not know that the death rate from cervical cancer is decreasing. 96% were aware that the main reason for a cervical smear is to prevent the development of cervical cancer, by finding early treatable abnormalities. Similarly, 94% were aware that the presence of abnormal cells on a cervical smear indicated a possible but not definitive indication of cervical precancer or cancer. Disappointingly, only 5 had seen the new NHSCSP information poster on the cervical smear test and only 44% had been given written information about the test. Consent for the test in 59% of women had been implied rather than expressed and 30% of women providing expressed consent had signed to that effect. In 42% of women, the smear taker or a doctor had failed to discuss the reason for having a cervical smear and had not explained about its advantages and limitations. In 72%, the smear taker or doctor had not explained that the cervical smear test can never be 100% accurate and that some laboratory errors are unavoidable. It is likely that women attending for colposcopy are a highly motivated cohort in relation to their understanding of the cervical smear test and the NHSCSP. Accordingly, understanding in the more general female population is likely to be considerably less. It would appear that women are often suboptimally informed to provide valid consent for the cervical smear test.