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Biomedical subjects

Wendy Atkin

Publications and source records attributed to Wendy Atkin.

At least 19 recordsLinked to original sources
PubMed2006

The impact of illustrations on public understanding of the aim of cancer screening.

OBJECTIVE: To study the effectiveness of visual illustrations in improving people's understanding of the preventive aim of flexible sigmoidoscopy (FS) screening. METHODS: Three-hundred and eighteen people aged 60-64 were offered an appointment to attend FS screening and randomly allocated to receive either written information alone or written information plus illustrations. The illustrations showed the adenoma-carcinoma sequence and how it can be interrupted by removing polyps found during FS. Telephone interviews were conducted with a randomly selected sub-set of people prior to their screening appointment to assess their knowledge and understanding of the test (n=65). The interviews were tape-recorded, transcribed and content analysed by researchers blind to the condition people had been allocated to. RESULTS: In the written information only group, 57% understood that the test was looking for polyps rather than just cancer, whilst in the group who received written information and illustrations, 84% understood this. Logistic regression analyses confirmed that addition of illustrations resulted in significantly better understanding (OR=3.75; CI: 1.16-12.09; p=0.027), and this remained significant controlling for age, gender and Townsend scores (an area-based measure of deprivation) (OR=10.85; CI: 1.72-68.43; p=0.01). CONCLUSION: Illustrations improved understanding of the preventive aim of FS screening. PRACTICE IMPLICATIONS: Pictoral illustrations could be used to facilitate patient understanding of screening.

Audiovisual Aids↗
PubMed2006

Polyp measurement and size categorisation by CT colonography: effect of observer experience in a multi-centre setting.

The extent measurement error on CT colonography influences polyp categorisation according to established management guidelines is studied using twenty-eight observers of varying experience to classify polyps seen at CT colonography as either 'medium' (maximal diameter 6-9 mm) or 'large' (maximal diameter 10 mm or larger). Comparison was then made with the reference diameter obtained in each patient via colonoscopy. The Bland-Altman method was used to assess agreement between observer measurements and colonoscopy, and differences in measurement and categorisation was assessed using Kruskal-Wallis and Chi-squared test statistics respectively. Observer measurements on average underestimated the diameter of polyps when compared to the reference value, by approximately 2-3 mm, irrespective of observer experience. Ninety-five percent limits of agreement were relatively wide for all observer groups, and had sufficient span to encompass different size categories for polyps. There were 167 polyp observations and 135 (81%) were correctly categorised. Of the 32 observations that were miscategorised, 5 (16%) were overestimations and 27 (84%) were underestimations (i.e. large polyps misclassified as medium). Caution should be exercised for polyps whose colonographic diameter is below but close to the 1-cm boundary threshold in order to avoid potential miscategorisation of advanced adenomas.

Chi-Square Distribution↗
PubMed2006

CT colonography interpretation times: effect of reader experience, fatigue, and scan findings in a multi-centre setting.

Our purpose was to assess the effect of reader experience, fatigue, and scan findings on interpretation time for CT colonography. Nine radiologists (experienced in CT colonography); nine radiologists and ten technicians (both groups trained using 50 validated examinations) read 40 cases (50% abnormal) under controlled conditions. Individual interpretation times for each case were recorded, and differences between groups determined. Multi-level linear regression was used to investigate effect of scan category (normal or abnormal) and observer fatigue on interpretation times. Experienced radiologists (mean time 10.9 min, SD 5.2) reported significantly faster than less experienced radiologists and technicians; odds ratios of reporting times 1.4 (CI 1.1, 1.8) and 1.6 (1.3, 2.0), respectively (P<or=0.001). Experienced and less-experienced radiologists took longer to report abnormal cases; ratio 1.2 (CI 1.1,1.4, P<0.001) and 1.2 (1.0, 1.3, P=0.03), respectively. All groups took 70% as long to report the final five cases as they did with an initial five; ratio 0.7 (CI 0.6 to 0.8), P<0.001. For technicians only, accuracy increased with longer reporting times (P=0.04). Experienced radiologists report faster than do less-experienced observers and proportionally spend less time interpreting normal cases. Technicians who report more slowly are more accurate. All groups reported faster as the study period progressed.

Clinical Competence↗
PubMed2006

Polyp measurement using CT colonography: agreement with colonoscopy and effect of viewing conditions on interobserver and intraobserver agreement.

OBJECTIVE: This article presents inter- and intraobserver agreement for estimates of polyp diameter using CT colonography, including the effects of different visualization displays and prior experience. MATERIALS AND METHODS: Four observers, three of whom had prior experience with CT colonography, estimated the maximum diameter of 48 polyps using three different visualization displays: 2D colonography window, 2D abdominal window, and 3D surface rendering. Each re-measured a subset of 10 polyps. Polyps measured 2 to 12 mm according to a colonoscopic reference. Inter- and intraobserver agreement and agreement with the reference measurement were determined using the Bland-Altman method, paired Student's t testing, analysis of variance, and analysis of covariance (ANCOVA), and by calculating the components of variance. RESULTS: CT measurements overestimated polyp diameter, a phenomenon found least using the 2D abdominal display. Generally, 95% limits of agreement encompassed different size categories for individual polyps: the widest spanned 14.6 mm (-4.6 mm to 10.0 mm) for an experienced observer using the 3D display. When using the 2D abdominal display, no significant difference was found between estimates and the reference value for the other two experienced observers (p = 0.83 and 0.23). All the observers' measurements were significantly different from the reference when using the 3D display (p < 0.001). The novice was significantly different from the experienced observers in some analyses. Inter- and intraobserver agreement were poorest for the 3D display. CONCLUSION: Measurement of polyp diameter from CT colonography is subject to variation contingent on the observer's experience and the viewing display used. Although 3D visualization display is commonly used for polyp detection, it should not be used for measurement.

Colonic Polyps↗
PubMed2005

History of negative colorectal endoscopy and risk of rectosigmoid neoplasms at screening flexible sigmoidoscopy.

BACKGROUND AND AIMS: Screening sigmoidoscopy can reduce incidence of colorectal cancer and mortality. The optimal re-screening interval has not yet been defined. This study is aimed at estimating the risk of distal advanced adenomas (diameter >/=10 mm, villous component >20%, high-grade dysplasia) and cancer at screening flexible sigmoidoscopy in subjects aged 55-64 years who reported pre-screening negative colorectal endoscopy. PATIENTS: Eight thousands two hundred two subjects aged 55-64 years who underwent screening flexible sigmoidoscopy within the SCORE trial in Italy and who were able to report their previous history of colorectal endoscopy. RESULTS: Eight hundred eighty three of 8,202 subjects (10.8%) reported at least one prescreening negative endoscopy: among them, after 3-5 years, 6-10 years and >10 years intervals between last reported examination and screening endoscopy, the Absolute Risk of advanced adenomas was 1.5%, 0.9% and 0.9%; one cancer was detected (0.1%). Among the 7,319 subjects who did not report prescreening endoscopy the risks of advanced adenoma and cancer were 3.2% and 0.4%, respectively. Subjects with a previous colorectal examination had a 65% decreased risk of advanced adenomas (OR=0.35, 95%CI 0.18-0.66) and a 71% decreased risk of cancer (OR=0.29, 95%CI 0.04-1.12) as compared to those who did not. For subjects without family history of colorectal cancer the statistically significant decrease of the risk persisted up to ten years. The observed benefit seems not to apply to subjects with family history of colorectal cancer. CONCLUSIONS: Our results are consistent with the hypothesis that the interval between screening sigmoidoscopies could be safely expanded beyond 5 years for subjects without specific risk factors for colorectal cancer.

Adenoma, Villous↗
PubMed2005

CT colonography in the detection of colorectal polyps and cancer: systematic review, meta-analysis, and proposed minimum data set for study level reporting.

PURPOSE: To assess the methodologic quality of available data in published reports of computed tomographic (CT) colonography by performing systematic review and meta-analysis. MATERIALS AND METHODS: The MEDLINE database was searched for colonography reports published between 1994 and 2003, without language restriction. The terms colonography, colography, CT colonoscopy, CT pneumocolon, virtual colonoscopy, and virtual endoscopy were used. Studies were selected if the focus was detection of colorectal polyps verified with within-subject reference colonoscopy by using key methodologic criteria based on information presented at the Fourth International Symposium on Virtual Colonoscopy (Boston, Mass). Two reviewers independently abstracted methodologic characteristics. Per-patient and per-polyp detection rates were extracted, and authors were contacted, when necessary. Per-patient sensitivity and specificity were calculated for different lesion size categories, and Forest plots were produced. Meta-analysis of paired sensitivity and specificity was conducted by using a hierarchical model that enabled estimation of summary receiver operating characteristic curves allowing for variation in diagnostic threshold, and the average operating point was calculated. Per-polyp sensitivity was also calculated. RESULTS: Of 1398 studies considered for inclusion, 24 met our criteria. There were 4181 patients with a study prevalence of abnormality of 15%-72%. Meta-analysis of 2610 patients, 206 of whom had large polyps, showed high per-patient average sensitivity (93%; 95% confidence interval [CI]: 73%, 98%) and specificity (97%; 95% CI: 95%, 99%) for colonography; sensitivity and specificity decreased to 86% (95% CI: 75%, 93%) and 86% (95% CI: 76%, 93%), respectively, when the threshold was lowered to include medium polyps. When polyps of all sizes were included, studies were too heterogeneous in sensitivity (range, 45%-97%) and specificity (range, 26%-97%) to allow meaningful meta-analysis. Of 150 cancers, 144 were detected (sensitivity, 95.9%; 95% CI: 91.4%, 98.5%). Data reporting was frequently incomplete, with no generally accepted format. CONCLUSION: CT colonography seems sufficiently sensitive and specific in the detection of large and medium polyps; it is especially sensitive in the detection of symptomatic cancer. Studies are poorly reported, however, and the authors propose a minimum data set for study reporting.

Colonic Polyps↗
PubMed2004

CT colonography: effect of experience and training on reader performance.

The purpose of this paper was to investigate the effect of radiologist experience and increasing exposure to CT colonography on reader performance. Three radiologists of differing general experience (consultant, research fellow, trainee) independently analysed 100 CT colonographic datasets. Readers had no prior experience of CT colonography and received feedback and training after the first 50 cases from an independent experienced radiologist. Diagnostic performance and reporting times were compared for the first and second 50 datasets and compared with the results of a radiologist experienced in CT colonography. Before training only the consultant reader achieved statistical equivalence with the reference standard for detection of larger polyps. After training, detection rates ranged between 25 and 58% for larger polyps. Only the trainee significantly improved after training ( P=0.007), with performance of other readers unchanged or even worse. Reporting times following training were reduced significantly for the consultant and fellow ( P<0.001 and P=0.03, respectively), but increased for the trainee ( P<0.001). In comparison to the consultant reader, the odds of detection of larger polyps was 0.36 (CI 0.16, 0.82) for the fellow and 0.36 (CI 0.14, 0.91) for the trainee. There is considerable variation in the ability to report CT colonography. Prior experience in gastrointestinal radiology is a distinct advantage. Competence cannot be assumed even after directed training via a database of 50 cases.

Clinical Competence↗
PubMed2004

Socioeconomic differences in cancer screening participation: comparing cognitive and psychosocial explanations.

This paper compares psychosocial and cognitive models of socioeconomic variation in participation in screening for colorectal cancer. The psychosocial model suggests that factors such as higher stress and lower social support explain, in part, why people from lower socioeconomic status (SES) environments are less likely to participate in screening. The cognitive model suggests that beliefs about cancer risk and screening will play an important part in differential participation. In practice both sets of factors may contribute to explaining socioeconomic differentials. The data for these analyses are drawn from a randomised controlled trial of colorectal cancer screening (the UK Flexible Sigmoidoscopy Trial). The participants are from the Scottish centre, where recruitment was stratified to generate a socioeconomically diverse sample. The dependent variable was interest in attending screening. A questionnaire covering demographic status, psychosocial and cognitive factors as well as interest in screening was sent to 10,650 adults. The results showed the predicted SES gradient in interest. There were also SES differences in both psychosocial and cognitive variables. A series of logistic regression models were used to test potential mediators of the association between SES and interest in attending screening by successively including psychosocial factors, cognitive factors, and then both, in the equation. Only the inclusion of the cognitive variables significantly reduced the variation associated with SES, providing better support for the cognitive than the psychosocial model.

Colorectal Neoplasms↗
PubMed2004

Wide variation in adenoma detection rates at screening flexible sigmoidoscopy.

BACKGROUND & AIMS: Wide between-center variation in adenoma detection rates (ADRs) was observed in the U.K. Flexible Sigmoidoscopy Screening Trial (overall, 12.1%; range, 8.6%-15.9%; P < 0.0001). The aim of this study was to determine whether the observed differences could be attributed to varying performance by endoscopists, to examine the effect of experience on performance, and to identify an attainable, standard ADR to which endoscopists could aspire. METHODS: Thirteen medical endoscopists, one per trial center, each performed about 3000 examinations (200 per month) using the same equipment and protocol. Overall and monthly ADRs were compared using multivariable logistic regression. RESULTS: Differences in ADRs were not explained by patient characteristics, incidence of colorectal cancer in the local population, or the endoscopists' medical specialty or previous experience. Average ADRs increased significantly with screening experience (up to 400 examinations). Endoscopists were classified as higher, intermediate, or lower adenoma detectors, and performance levels were maintained over time. Higher detectors had ADRs of 15% overall (men, 20%; women, 10%) and also detected more adenomas per case (higher/lower detectors, 21.7/10.4 adenomas per 100 examinations). CONCLUSIONS: The differences in ADRs were due to variation in performance of the endoscopists. Long-term follow-up will determine whether this variation is clinically important. We suggest that the standards in higher detecting centers should be achievable by all endoscopists screening unscreened populations aged older than 55 years. Endoscopists should aim to stay above the lower 95% confidence interval band for 200 examinations (10% overall; 5% in women, 15% in men).

Adenoma↗
PubMed2004

NCF1 (p47phox) and ncf1 pseudogenes are not associated with inflammatory bowel disease.

Crohn's disease (CD) and ulcerative colitis (UC) have a strong genetic component, contributing to a patient's susceptibility for inflammatory bowl disease (IBD). Linkage analysis has detected an IBD susceptibility locus in a region on chromosome 7q that encompasses the p47 (NCF1) gene and p47 (PsiNCF1) pseudogenes. Involvement of the NCF1 locus in IBD was supported by the observation that chronic inflammation of the bowel is a feature of chronic granulomatous disease caused by NCF1 mutation in 25% of cases. The pseudogenes have a dinucleotide deletion (PsiGT) at the beginning of exon 2, resulting in a frameshift and premature stop codon. APsiNCF1 (DeltaGT) to NCF1 (GTGT) ratio of 2:1 has been proposed as the predominant ratio in humans; but variability may occur after DNA exchange by recombination between PsiNCF1 and NCF1 to produce a potentially functional gene hybrid (type IIPsiNCF1). A preliminary study suggested an association between individuals with a 1:1 ratio and susceptibility to IBD. The possible presence of type IIPsiNCF1 was proposed as a susceptibility factor. We have now established the PsiNCF1 to NCF1 ratio for a significant number of IBD patients (n = 488) and control subjects (n = 181) and show that there is no statistically significant difference between the frequency of the 1:1 ratio in CD (11.2%) or UC (12.2%) patients and controls (13.4%). The 2:1 ratio was identified as the most common ratio (83.3%). Our data show there is no association of the 1:1 ratio with IBD and that susceptibility is unlikely to be a consequence of an inherited 1:1, rather than a 2:1 (PsiNCF1:NCF1) ratio.

Case-Control Studies↗
PubMed2003

Optimizing colonic distention for multi-detector row CT colonography: effect of hyoscine butylbromide and rectal balloon catheter.

PURPOSE: To investigate the effects of hyoscine butylbromide and an inflatable rectal balloon catheter on luminal distention during computed tomographic (CT) colonography. MATERIALS AND METHODS: One hundred thirty-six subjects undergoing CT colonography were randomized to receive either 20 mg or 40 mg of hyoscine butylbromide or no spasmolytic. Subjects were also independently randomized to undergo CT colonography with an inflatable rectal balloon catheter or a standard thin rectal tube. Multi-detector row CT colonography was performed with patients in prone and supine positions, with colonic segmental distention assessed by a single observer with a four-point scale. A simple assessment of whether distention was adequate for clinical interpretation was also made, and the effect of hyoscine butylbromide and catheter use was examined by using multivariate ordered logistic regression. RESULTS: Administration of hyoscine butylbromide was associated with significantly improved cecal (P =.05), ascending (P =.001), and transverse (P <.001) colonic distention when patients were supine and improved ascending (P <.001) and descending (P <.001) colonic distention when patients were prone. Compared with control subjects, patients given a spasmolytic had odds of 6.49 for clinically adequate distention throughout all colonic segments (P =.001). There was no incremental advantage with use of a 40-mg dose. In contrast, rectal balloon catheter use was not significantly associated with improved distention. CONCLUSION: Hyoscine butylbromide improves colonic distention during CT colonography and should be routinely administered where it is available. Use of a thin rectal tube for insufflation is adequate.

Adult↗
PubMed2003

Receiving a screen-detected diagnosis of cancer: the experience of participants in the UK flexible sigmoidoscopy trial.

The experience of receiving a screen-detected diagnosis of colorectal cancer was explored using open-ended interviews. Twenty four people who had been diagnosed with cancer at flexible sigmoidoscopy screening were interviewed at their homes over the telephone. Thematic analysis of the transcripts showed that the experience of gaining a diagnosis of cancer through screening was characterised by a lack of prior expectation that cancer would be detected and feelings of shock. This was largely because of the absence of symptoms and current feelings of well-being. Some interviewees expressed feelings of relief and gratitude at having cancer diagnosed at an early enough stage that 'something could be done about it'. The experience of receiving a screen-detected diagnosis could be summarised as one of 'moderated shock' whereby the shock of the unexpected diagnosis was often moderated by the news that the cancer had been caught early. Whilst these screen-detected cancers were diagnosed relatively rapidly, a significant number of interviewees had a period in which they were effectively 'symptomatic' (e.g. knew they had an adenoma but did not know whether it was malignant or benign). However, they did not use this period to prepare themselves for a possible cancer diagnosis. Raising awareness of the adenoma-carcinoma sequence may help reduce the shock of a screen-detected diagnosis. However, any interventions aimed at reducing the distress of a screen-detected cancer would need to consider the overall benefit to screening attenders, most of whom will have benign polyps detected.

Adenoma↗
PubMed2003

Psychological impact of colorectal cancer screening.

This article examines the psychological impact of participating in sigmoidoscopy screening for colorectal cancer prevention. The 1st study examined psychological well-being at 3 months, in relation to screening outcome, in 4,153 individuals. The 2nd study used longitudinal data to examine changes in psychological functioning from before to after screening in relation both to screening outcome and baseline indicators of vulnerability. There were few psychological differences between those who had received negative results or had polyps detected. These findings were confirmed in the longitudinal study, which also found no evidence for vulnerability to adverse effects among those who were initially most anxious or who perceived their risk of cancer to be higher. The longitudinal data suggested that screening might produce transient positive effects.

Anxiety↗
PubMed2003

Increasing attendance at colorectal cancer screening: testing the efficacy of a mailed, psychoeducational intervention in a community sample of older adults.

This article describes a trial of a psychoeducational intervention designed to modify negative attitudes toward flexible sigmoidoscopy screening and thereby increase screening attendance. The intervention materials addressed the multiple barriers shown to be associated with participation in earlier studies. Adults ages 55-64 (N = 2,966), in a "harder-to-reach" group were randomized either to receive an intervention brochure or to a standard invitation group. Attitudes and expectations were assessed by questionnaire, and attendance at the clinic was recorded. Compared with controls, the intervention group had less negative attitudes, anticipated a more positive experience, and had a 3.6% higher level of attendance. These results indicate that psychoeducational interventions can provide an effective means of modifying attitudes and increasing rates of screening attendance.

Attitude to Health↗
PubMed2003

Multi-detector row CT colonography: effect of collimation, pitch, and orientation on polyp detection in a human colectomy specimen.

PURPOSE: To investigate the effects of orientation, collimation, pitch, and tube current setting on polyp detection at multi-detector row computed tomographic (CT) colonography and to determine the optimal combination of scanning parameters for screening. MATERIALS AND METHODS: A colectomy specimen containing 117 polyps of different sizes was insufflated and imaged with a multi-detector row CT scanner at various collimation (1.25 and 2.5 mm), pitch (3 and 6), and tube current (50, 100, and 150 mA) settings. Two-dimensional multiplanar reformatted images and three-dimensional endoluminal surface renderings from the 12 resultant data sets were examined by one observer for the presence and conspicuity of polyps. The results were analyzed with Poisson regression and logistic regression to determine the effects of scanning parameters and of specimen orientation on polyp detection. RESULTS: The percentage of polyps that were detected significantly increased when collimation (P =.008) and table feed (P =.03) were decreased. Increased tube current resulted in improved detection only of polyps with a diameter of less than 5 mm. Polyps of less than 5 mm were optimally depicted with a collimation of 1.25 mm, a pitch of 3, and a tube current setting of 150 mA; polyps with a diameter greater than 5 mm were adequately depicted with 1.25-mm collimation and with either pitch setting and any of the three tube current settings. Small polyps in the transverse segment (positioned at a 90 degrees angle to the z axis of scanning) were significantly less visible than those in parallel or oblique orientations (P <.001). The effective radiation dose, calculated with a Monte Carlo simulation, was 1.4-10.0 mSv. CONCLUSION: Detection of small polyps (<5 mm) with multi-detector row CT is highly dependent on collimation, pitch, and, to a lesser extent, tube current. Collimation of 1.25 mm, combined with pitch of 6 and tube current of 50 mA, provides for reliable detection of polyps 5 mm or larger while limiting the effective radiation dose. Polyps smaller than 5 mm, however, may be poorly depicted with use of these settings in the transverse colon.

Colon↗
PubMed2003

Cardiovascular effects at multi-detector row CT colonography compared with those at conventional endoscopy of the colon.

PURPOSE: To compare the cardiovascular effects of computed tomographic (CT) colonography and conventional endoscopy in a group of patients undergoing both procedures. MATERIALS AND METHODS: A total of 144 patients underwent CT colonography followed by flexible sigmoidoscopy (40 patients) or colonoscopy (104 patients). Pulse, blood pressure, and oxygen saturation were measured before, during, and after the procedures. Forty patients also underwent continuous Holter electrocardiographic (ECG) monitoring. Periprocedural pain was assessed by using a handheld counting device. Outcome variables were assessed by using a combination of paired t testing and multilevel linear regression. RESULTS: When a spasmolytic was not used, CT colonography was associated with only a small increase in oxygen saturation (P =.03), while use of a spasmolytic caused an increase in pulse (mean increase, 19.9 beats per minute; P <.001) and diastolic blood pressure (mean increase, 5 mm Hg; P <.001). Compared with that at CT, oxygen saturation decreased significantly during and after colonoscopy and sigmoidoscopy (mean decrease after colonoscopy with sedation, 1.0%; P <.001). Systolic and diastolic blood pressure also decreased during and after colonoscopy (mean systolic decrease after colonoscopy with sedation, 16.6 mm Hg, P <.001; mean diastolic decrease after colonoscopy with sedation, 7.5 mm Hg, P <.001). Patients were 30.3 times more likely to develop bradycardia after endoscopy (95% CI: 2.65, 346; P =.006). Ventricular couplets were significantly higher at endoscopy than at CT in patients with a history of cardiac disease (odds ratio: 72.5 and 95% CI: 4.56, 1,153 at CT vs odds ratio: 14.6 and 95% CI: 0.96, 222 at endoscopy; P =.002). Patients were 1.89 times more likely to register pain during colonoscopy than during CT (95% CI: 1.06, 3.38; P =.03). CONCLUSION: CT colonography had no significant cardiovascular effect other than spasmolytic-induced tachycardia. Endoscopy-and colonoscopy in particular-causes cardiovascular effects that are largely related to sedation. CT colonography is less painful than colonoscopy and is comparable to flexible sigmoidoscopy.

Adult↗