R G Blanks

Colonoscopy quality measures: experience from the NHS Bowel Cancer Screening Programme

Objectives Colonoscopy is central to colorectal cancer (CRC) screening. Success of CRC screening is dependent on colonoscopy quality. The NHS Bowel Cancer Screening Programme (BCSP) offers biennial faecal occult blood (FOB) testing to 60–74 year olds and colonoscopy to those with positive FOB tests. All colonoscopists in the screening programme are required to meet predetermined standards before starting screening and are subject to ongoing quality assurance. In this study, the authors examine the quality of colonoscopy in the NHS BCSP and describe new and established measures to assess and maintain quality. Design The NHS BCSP database collects detailed data on all screening colonoscopies. Prospectively collected data from the first 3 years of the programme (August 2006 to August 2009) were analysed. Colonoscopy quality indicators (adenoma detection rate (ADR), polyp detection rate, colonoscopy withdrawal time, caecal intubation rate, rectal retroversion rate, polyp retrieval rate, mean sedation doses, patient comfort scores, bowel preparation quality and adverse event incidence) were calculated along with measures of total adenoma detection. Results 2 269 983 individuals returned FOB tests leading to 36 460 colonoscopies. Mean unadjusted caecal intubation rate was 95.2%, and mean withdrawal time for normal procedures was 9.2 min. The mean ADR per colonoscopist was 46.5%. The mean number of adenomas per procedure (MAP) was 0.91; the mean number of adenomas per positive procedure (MAP+) was 1.94. Perforation occurred after 0.09% of procedures. There were no procedure-related deaths. Conclusions The NHS BCSP provides high-quality colonoscopy, as demonstrated by high caecal intubation rate, ADR and comfort scores, and low adverse event rates. Quality is achieved by ensuring BCSP colonoscopists meet a high standard before starting screening and through ongoing quality assurance. Measuring total adenoma detection (MAP and MAP+) as adjuncts to ADR may further enhance quality assurance.

A comparison of cancer detection rates achieved by breast cancer screening programmes by number of readers, for one and two view mammography: results from the UK National Health Service breast screening programme:

Objective To determine the increased cancer detection rate, if any, of programmes in the UK National Health Service breast screening programme (NHSBSP) using more than single reading of mammograms. Design Information on the detection of cancers by individual screening programmes from annual (KC62) returns, supplemented by questionnaire information about the number of readers. Setting The 87 NHSBSP programmes from England and Wales for the screening year 1 April 1996 to 31 March 1997. The study includes all programmes for prevalent screens where two views are mandatory, but excludes the four programmes using two view mammography for incident screening. Main outcome measures Cancer detection, invasive cancer detection, and small (<15 mm) invasive cancer detection by mammographic reading protocol using single reading as the reference level. Results Programmes collectively using single reading detected the lowest rate of cancers at both prevalent (first) and incident (subsequent) screening. The highest rate of age standardised cancer detection was achieved by programmes using double reading with arbitration. At prevalent screens, where all programmes used two views, those programmes using double reading with arbitration detected 32% (95% confidence interval (CI) 3% to 69%) more small (<15 mm) invasive cancers than programmes using single reading. At incident screens, where all programmes analysed used one view this increased to 73% (95% CI 40% to 113%). Recall rates showed no obvious difference between single reading and the double reading protocols, being around 7% for prevalent screens and 3.5% for incident screens. Discussion The results suggest that the increase in cancer detection resulting from increasing the number of readers depends on the number of views, and is higher for one view than two views. Single reading of one view results in a low detection rate of small invasive cancers for most individual programmes. It is, however, recognised that a small number of individual readers may achieve high detection rates with such a protocol. All groups of programmes using different reader/view protocols are on average close to or above target cancer detection rates, except those using single reading of one view (mediolateral oblique) at incident screens.

Observer variability in cancer detection during routine repeat (incident) mammographic screening in a study of two versus one view mammography.

Objective To examine the reasons for observer variability of cancer detection using one and two view mammography at incident (subsequent) screening and determine whether false negative results (non-recall of a cancer) are due to failure to detect the associated features(s) of the cancer on the mammogram, or misinterpretation of the observed feature(s) as not indicative of malignancy. Setting A random selection of cancers (invasive and in situ) seen as incident cases during the second screening round (January 1994–January 1997) in the South West London Breast Screening Service were used. This service uses two view mammography and double reading with arbitration by a third or further readers for all screens. Methods Mammograms of cases were mixed with those of controls in a 1:2 ratio in two test sets. Eleven experienced film readers, each reading both test sets, took part in the study. Initially the oblique view only was read, then, additionally, the craniocaudal view. Previous films were available to the readers. Data on abnormalities noted on the films and probability of recall were recorded and analysed. Results 387 valid readings of 36 cancers (30 invasive and six ductal carcinoma in situ) were made by 11 readers. The overall sensitivity increased from 79% with one view to 85% with two views. For invasive cancers <10 mm the sensitivity was 71% with one view, but increased to 85% with two views. Recall of individual cancers by the readers varied substantially. With one view 15 (50%) of the 30 invasive cancers were recalled by all 11 readers, increasing to 18 (60%) with two views. Of the invasive cancers not recalled by all 11 readers, there was considerable disagreement, particularly for the smaller cancers.With one view 69% of invasive cancers <10 mm were correctly marked on the proforma compared with 87% with two views. Invasive cancers >10 mm were almost all marked on the proforma with one or two views. For invasive cancers, the misinterpreted feature that did not lead to recall was most commonly an asymmetry (42%), whereas for in situ cancers it was calcifications (67%). The finding of an irregular mass was the least misinterpreted feature. Conclusion The study showed that of those invasive cancers detected at routine repeat screening by a programme using two view mammography and double reading with arbitration, at least 50% could be described as “difficult” (for example, “minimal” signs) to recall using the single reading of one view, even under “favourable” study conditions with two normal subjects per case.The finding that at least 87% of invasive cancers <10 mm are detected (marked on the proforma) with two views, but only 69% with the one view, suggests that for single reading of mammograms with one view the detection of small invasive cancers is a major problem. This problem is helped by the second view. For invasive cancers ≥10 mm, interpretation (benign or malignant) rather than detection (under these study conditions) was the major cause of recall failure. The most common signs to be misinterpreted were calcifications and asymmetries; once visualised an irregular mass was least likely to be misinterpreted.This study provides evidence that detection and interpretation of most invasive cancers is improved by increasing the number of views, and by increasing the number of readers.

Automation-assisted versus manual reading of cervical cytology (MAVARIC): a randomised controlled trial

BACKGROUND The standard for reading cervical cytology is for a cytoscreener to manually search across an entire slide for abnormal cells using a conventional microscope. Automated technology can select fields of view to assess abnormal cells, which allows targeted reading by cytoscreeners. In the Manual Assessment Versus Automated Reading In Cytology (MAVARIC) trial, we compared the accuracy of these techniques for the detection of underlying disease. METHODS For this randomised controlled trial, women aged 25-64 years undergoing primary cervical screening in Manchester, UK, were randomly assigned (1:2) to receive either manual reading only or paired reading (automation-assisted reading and manual reading), between March 1, 2006, and Feb 28, 2009. In the paired arm, two automated systems were used-the ThinPrep Imaging System and the FocalPoint GS Imaging System. General practices and community clinics were randomised to either ThinPrep or to SurePath (for the FocalPoint system) liquid-based cytology with block randomisation stratified by deprivation index. Samples were then individually randomised to manual reading only or paired reading only. Laboratory staff were unaware of the allocation of each slide and concealment was maintained until the end of the reporting process. The primary outcome was sensitivity of automation-assisted reading relative to manual reading for the detection of underlying cervical intraepithelial neoplasia grade 2 or worse (CIN2+) in the paired arm. This trial is registered, number ISRCTN66377374. FINDINGS 73,266 liquid-based cytology samples were obtained from women undergoing primary cervical screening; 24,688 allocated to the manual-only arm and 48,578 to the paired-reading arm. Automation-assisted reading was 8% less sensitive than manual reading (relative sensitivity 0·92, 95% CI 0·89-0·95), which was equivalent to an absolute reduction in sensitivity of 6·3%, assuming the sensitivity of manual reading to be 79%. Specificity of automation-assisted reading relative to manual reading increased by 0·6% (1·006, 95% CI 1·005-1·007). INTERPRETATION The inferior sensitivity of automation-assisted reading for the detection of CIN2+, combined with an inconsequential increase in specificity, suggests that automation-assisted reading cannot be recommended for primary cervical screening.

Colonoscopic factors associated with adenoma detection in a national colorectal cancer screening program

BACKGROUND AND STUDY AIMS Adenoma detection is a key objective of colonoscopy, particularly in the context of colorectal cancer screening. The aim of this observational study was to identify the technical colonoscopy factors associated with adenoma detection. PATIENTS AND METHODS The study analyzed data from the English Bowel Cancer Screening Programme. The indication for all colonoscopies was a positive fecal occult blood test. The relationships between the following colonoscopy factors and adenoma detection (one or more adenomas, advanced adenomas, right-sided adenomas, and total number of adenomas) were examined in multivariable analyses: bowel preparation quality, cecal intubation, withdrawal time, rectal retroversion, colonoscopist experience, antispasmodic use, sedation use, and start time of procedure. The following patient factors were controlled for: age, sex, body mass index, smoking, alcohol, deprivation, and geographical location. RESULTS A total of 31088 colonoscopies were analyzed. The following technical factors increased the relative risk of adenoma detection (P < 0.001 in multivariable analysis unless otherwise stated): cecal intubation, increased withdrawal time, higher quality bowel preparation, intravenous antispasmodic use, earlier procedure start time within a session (P = 0.018), and greater colonoscopist experience. Detection of advanced and right-sided adenomas also increased with these factors. Adenoma detection did not differ between sedated and unsedated colonoscopy (P = 0.143). CONCLUSION This study demonstrated important associations between colonoscopy practice and adenoma detection. Use of intravenous antispasmodic was associated with increased adenoma detection. The effect of the start time of colonoscopy suggests that endoscopist fatigue may have a deleterious impact on adenoma detection.

Monitoring and evaluating the UK National Health Service Breast Screening Programme: evaluating the variation in radiological performance between individual programmes using PPV-referral diagrams

A high quality breast cancer screening programme can be defined as one offering both a high cancer detection rate and a low referral rate of women for further investigation. Such a programme will have as few women as possible undergoing further investigations who do not have a final diagnosis of breast cancer—that is, a high positive predictive value of referral for further investigation. This paper introduces a graphical technique to illustrate individual programme performance. The graph plots positive predictive value of referral against referral rate, with the cancer detection rate expressed as “isobars” on the graph. Confidence limits can be expressed as “boxes” on the diagram. The graph not only illustrates programme performance but also enables suggestions to be made to improve performance. The definition of high quality screening is seen to have a subjective element as well as an objective element, as radiologists have to balance screening sensitivity with specificity. The technique is illustrated using data from the individual screening programmes in the UK National Health Service Breast Screening Programme for the screening year 1 April 1998 to 31 March 1999. The methodology could also be applied to other national screening programmes.

Calculating appropriate target cancer detection rates and expected interval cancer rates for the UK NHS Breast Screening Programme. Interval Cancer Working Group.

OBJECTIVES: To enable better monitoring of interim outcome measures in the NHS Breast Screening Programme by providing revised targets for cancer detection rates, and revised expected interval cancer rates. DESIGN AND SETTING: Expected detection rates of invasive cancers at prevalent screen are calculated, using estimates of the underlying England and Wales incidence rates and age specific prevalence incidence ratios from the Swedish Two County Study. Expected interval cancer rates are also derived from this study, and are used to calculate expected detection rates at rescreening. RESULTS: The expected invasive cancer detection rates at first screen for women aged 50-52 is 3.6 per 1000. The expected rate at rescreening for women aged 53-64 is 4.0 per 1000. Expected interval cancer rates for women screened from 1995/6 onwards are 0.45 per 1000, 0.65 per 1000, and 1.2-1.3 per 1000 for the periods within 0-<12, 12-<24, and 24-<36 months of screening. CONCLUSIONS: The target cancer detection rates and expected interval cancer rates for the NHS Breast Screening Programme have been revised in the light of more recent data. Monitoring of the extent to which the programme is meeting these revised targets will give a more accurate indication of the potential to meet the Health of the Nation target of a 25% reduction in breast cancer mortality by the year 2000.

Use of two view mammography compared with one view in the detection of small invasive cancers: further results from the National Health Service breast screening programme.

Objective— To examine further the effect of using two view mammography in comparison with one view mammography in the detection of small (<15 mm) invasive cancers for programmes in the National Health Service breast screening programme (NHSBSP). The study is in two parts: First the effect on the small invasive cancer detection rate for programmes that changed from using one view to two views for first (prevalent) screens, and secondly the effect on the small invasive cancer detection rate for programmes that used two views for subsequent (incident) screens compared with programmes that used one view. Setting— Screening programme data from the NHSBSP. Methods— Data were collated from all screening programmes in the United Kingdom on standard “Korner” returns (KC62 forms) for the screening years 1 April 1994 to 31 March 1995 and 1 April 199S to 31 March 1996. The comparison between one and two view mammography was made using indirectly age standardised invasive cancer detection rates. Results— For prevalent (first) screens, programmes changing from one view mammography in 1994/95 to two views in 1995/96 reported a 45% (95% confidence interval (CI) 25% to 68%) increase in the detection of invasive cancers of <15 mm. In comparison, programmes that were already using two views in 1994/95 showed no change in 1995/96. For incident (subsequent) screens the small number of programmes that have opted to use two views reported 25% (95% CI 1% to 55%) more invasive cancers of <15 mm than programmes using one view in 1995/96, and 42% (95% CI 11% to 81%) more in 1994/95. Conclusions— These results confirm the benefit of using two view mammography in the detection of small invasive cancers, and provide evidence that this effect is seen in subsequent screens as well as the first screen.

Monitoring the performance of breast screening programmes: use of indirect standardisation in evaluating the invasive cancer detection rate.

Close monitoring of data from individual programmes is required to evaluate the potential of the breast screening programme to reach the Health of the Nation target of 25% reduction in breast cancer mortality in the invited age group by the year 2000. This paper outlines the use of indirect age standardisation techniques to compare the performance of individual programmes in terms of their invasive cancer detection rates. Expected invasive cancer detection rates are calculated by applying data from the Swedish two county study to estimated England and Wales background incidence rates for different age strata. If the national programme overall meets these targets then the required mortality reduction should be achieved. The same method can be used by other (national) screening programmes by applying the relevant background incidence figures to produce internationally comparable data.

Efficiency of cancer detection during routine repeat (incident) mammographic screening: two versus one view mammography

Objective To examine the influence of one view versus two view mammography on cancer detection and recall for further investigation of women attending incident (subsequent) screening. Setting All cancers (invasive and in situ) detected as incident cases during the second screening round (January 1994 to January 1997) at the South West London Breast Screening Service were used. This service uses two view mammography and double reading, with arbitration by a third or further readers for all screens. Methods Mammograms of cases were mixed with those of controls in a 1:2 ratio in nine test sets; each set was read independently by three film readers. Fourteen readers, each reading from one to four test sets, took part in the study. Initially, the oblique view only was read, then the craniocaudal view was read in addition. Previous films were available to the readers. Data on abnormalities noted on the films and probability of recall were recorded and analysed. Results 10 of the 14 readers obtained increased sensitivity using two views (p=0.04), for two readers there was no difference, and for two readers sensitivity decreased. The mean sensitivity increase was 6.1% (p=0.01). The overall increase in sensitivity from all readings of invasive cancers was 8.9%, with no increase seen for in situ cancers. 11 of the 14 readers obtained an increase in specificity (p=0.006), two readers showed no increase, and the specificity for one reader was decreased. The mean increase in specificity using two views was 5.7% (p=0.006). Conclusion This study showed an increase of 8.9% in sensitivity for the detection of invasive cancers when two views are used at incident screening, with a ratio of two control mammograms for every case. This is equivalent to a sample from population screening with a cancer detection rate of 333 per 1000. Such a study is considered to be likely to underestimate the benefit of two views in screening under non-test conditions where the cancer detection rate is of the order of five per 1000. The use of two view mammography for the detection of in situ cancers showed no increased benefit. A randomised controlled trial is needed to obtain a reliable estimate of the increase in cancer detection rate for incident screening in normal populations.