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PubMed1998

Estimating sensitivity and sojourn time in screening for colorectal cancer: a comparison of statistical approaches.

The effectiveness of cancer screening depends crucially on two elements: the sojourn time (that is, the duration of the preclinical screen-detectable period) and the sensitivity of the screening test. Previous literature on methods of estimating mean sojourn time and sensitivity has largely concentrated on breast cancer screening. Screening for colorectal cancer has been shown to be effective in randomized trials, but there is little literature on the estimation of sojourn time and sensitivity. It would be interesting to demonstrate whether methods commonly used in breast cancer screening could be used in colorectal cancer screening. In this paper, the authors consider various analytic strategies for fitting exponential models to data from a screening program for colorectal cancer conducted in Calvados, France, between 1991 and 1994. The models yielded estimates of mean sojourn time of approximately 2 years for 45- to 54-year-olds, 3 years for 55- to 64-year-olds, and 6 years for 65- to 74-year-olds. Estimates of sensitivity were approximately 75%, 50%, and 40% for persons aged 45-54, 55-64, and 65-74 years, respectively. There is room for improvement in all models in terms of goodness of fit, particularly for the first year after screening, but results from randomized trials indicate that the sensitivity estimates are roughly correct.

Aged↗
PubMed2004

Coronary angiography using a portable super-C-arm imaging system in a district general hospital.

BACKGROUND: New generation portable super-C-arm imaging systems may offer an alternative means of performing coronary angiography at a lower cost compared with a fixed laboratory. We evaluated the use of one such system (GE-OEC 9800) in a district hospital setting. METHODS: The demographics, procedure and screening times, emitted radiation dose and diagnoses of the first 200 consecutive patients were obtained from a prospective database. Comparison between the portable and fixed systems were made by analysing results from similar cohorts of patients who underwent angiography by the same operators. Image quality was assessed in 23 patients, by an independent cardiologist, comparing the GE-OEC 9800 angiograms with repeat images using a fixed laboratory Philips (HM 3000) system within 3 months of the first study. RESULTS: The procedure time (mean (S.D.)) was 18.9 (0.8) min for the 200 cases. The screening time was 255 (15) s with an emitted radiation of 22.8 (1.4) Gy/cm(2). Comparison between the C-arm and fixed systems revealed significantly longer screening time (230.6 (14.6) vs. 157 (12.9) s, p<0.001), whilst the total radiation doses were not significantly different (21.1 (1.5) vs. 18.6 (1.11) Gy/cm(2)). Independently assessed image quality was satisfactory. The main variance in 57 lesions seen in the 23 patients using the angiograms obtained from the fixed laboratory as reference included overestimated stenosis (two lesions), underestimated stenosis (or subsequent disease progression) (four lesions), lack of appreciation of side-branch ostial involvement (two lesions) and vessel calcification (one lesion). CONCLUSIONS: Portable imaging systems can offer a reliable and cost-effective diagnostic coronary angiography service in a district hospital.

Coronary Angiography↗
PubMedDate not supplied

Percutaneous transaortic occlusion of patent ductus arteriosus using a new versatile angiographic and delivery catheter.

We evaluated the usefulness of patent ductus arteriosus (PDA) occlusion using a new catheter that combines good angiographic properties, easy manipulation across the duct, documentation of aortic and pulmonary artery pressure, and coil delivery for percutaneous transaortic ductal occlusion. Thirty patients (13 females and 17 males) who met the clinical and echocardiographic criteria for the percutaneous closure of PDA were catheterized. The patients selected for this study had a small to moderate PDA with a conal or tubular shape, adequate aortic ampula, and normal or mildly elevated pulmonary artery pressure. The median age was 4.8 years (range, 10 months-20 years). Patients were catheterized by the transaortic approach using the new angiographic and coil delivery catheter specially designed for this procedure. A PDA was closed in every case. A single DuctOcclud pfm coil was delivered in 28 patients, and 2 patients had NitOcclud pfm coils for ductal occlusion. The screening time was measured and found to be 50% less than the measured screening time using other catheters in our laboratory. Only one catheter and one guidewire were used per procedure, with no need for exchange wires or the establishment of an arteriovenous loop. The procedure time was also reduced by 50%. A minimal residual shunt, demonstrated by color-flow Doppler mapping, was present in 2 patients. The new combined angiographic and coil delivery catheter is most suitable for transaortic PDA coil occlusion, significantly decreasing the procedure and screening time.

Adolescent↗
PubMed2002

Does cardiologist- or radiographer-operated fluoroscopy and image acquisition influence optimization of patient radiation exposure during routine coronary angiography?

The operator of radiation exposure during coronary angiography varies between different centres. The purpose of this study was to explore whether radiation dose was lower during cardiologist- or radiographer-controlled radiation exposure and to determine if the grade of cardiologist performing angiography influenced radiation dose. Patients were randomly allocated either to cardiologist- or radiographer-controlled radiation exposure during coronary angiography. Screening time and radiation dose during fluoroscopy and image acquisition, measured by dose-area product meter, were recorded. Mean radiation dose during cardiologist-controlled radiation exposure (n=176) of 15.6 Gy cm(2) (95% confidence interval (CI), 14.4-16.8) was significantly lower than that produced by the radiographer-controlled group (n=192) of 17.3 Gy cm(2) (95% CI, 16.2-18.6) (p<0.044). There was no significant difference in screening times produced by the two groups of radiation exposure operators. The difference in radiation dose produced by the two operator groups was principally owing to exposure produced at image acquisition. Irrespective of radiation exposure operator, consultant cardiologists produced significantly lower screening times and radiation doses compared with registrars. During routine coronary angiography, radiographer-controlled radiation exposure does not reduce screening time or radiation dose. Senior cardiologists produce the lowest radiation doses during coronary angiography when they are responsible for radiation exposure.

Body Height↗
PubMed2005

Compound image compression for real-time computer screen image transmission.

We present a compound image compression algorithm for real-time applications of computer screen image transmission. It is called shape primitive extraction and coding (SPEC). Real-time image transmission requires that the compression algorithm should not only achieve high compression ratio, but also have low complexity and provide excellent visual quality. SPEC first segments a compound image into text/graphics pixels and pictorial pixels, and then compresses the text/graphics pixels with a new lossless coding algorithm and the pictorial pixels with the standard lossy JPEG, respectively. The segmentation first classifies image blocks into picture and text/graphics blocks by thresholding the number of colors of each block, then extracts shape primitives of text/graphics from picture blocks. Dynamic color palette that tracks recent text/graphics colors is used to separate small shape primitives of text/graphics from pictorial pixels. Shape primitives are also extracted from text/graphics blocks. All shape primitives from both block types are losslessly compressed by using a combined shape-based and palette-based coding algorithm. Then, the losslessly coded bitstream is fed into a LZW coder. Experimental results show that the SPEC has very low complexity and provides visually lossless quality while keeping competitive compression ratios.

Algorithms↗
PubMed2005

Evolving a strategic approach to cervical cancer control in Africa.

Nigeria is a country in Western Africa where the incidence rate of cervical cancer is 25/100,000. There are 32 million women aged 15-64 years old. If we were to conduct a one-time screen over 1 year, 8000 new invasive cervical cancers would be detected. Currently, 80% of cases present in Stage III. While a one-time screen should detect some earlier stages, there could be as many as 6400 Stage III cancers to treat. Strategies to enable a one-time screen are being considered.

Adult↗
PubMed2003

Intention to be screened over time for colorectal cancer in male automotive workers.

Intention is an important construct in health promotion research, yet very little is known about whether cross-sectional correlates of intention to be screened for colorectal cancer (CRC) also predict intention over time or intention change. We used survey data from The Next Step Trial, a worksite health promotion trial, to address the following questions: (1) What is the consistency over time of intention to be screened for CRC? (2) Are the patterns and magnitude of associations between intention to be screened and the Preventive Health Model variables consistent over time? (3) What are the predictors of improving weaker intention to be screened, i.e., changing to strong intention? (4) What are the predictors of no change in strong intention to be screened, i.e., maintaining strong intention? and (5) What is the predictive ability of the models to predict intention to be screened for CRC? The study population consisted of white male automotive employees who responded to baseline (1993) and follow-up (1994 and 1995) surveys and did not have CRC at baseline or develop it during the study period. Of 5042 eligible workers, 2903 (58%) returned a baseline survey, and 2556 (88% of survey responders) met eligibility criteria; 75% (1929 of 2556) returned the year 1 survey, and 74% (1892 of 2556) returned the year 2 survey. We fit logistic regression models separately for the Preventive Health Model variables measured at baseline and each outcome (intention at year 1, intention at year 2, improving weaker intention, and no change in strong intention). The prevalence of strong intention to be screened for CRC was approximately 60% on all three surveys. Overall, 66% maintained their baseline intention over time. The most consistent predictors of strong intention, improving weaker intention, and no change in strong intention were family support, belief in the salience and coherence of screening, prior screening, and lack of concern about screening-related discomfort. Intention measured at baseline predicted intention measured 1 and 2 years later. Perceived susceptibility and lack of fear and worry about a CRC diagnosis predicted improving weaker intention. Having a family history of CRC or polyps predicted maintaining strong intention. Plant factors, self-efficacy, and beliefs about polyp removal were not predictors beyond the baseline year. Basing intervention development on cross-sectional associations may miss important factors or may incorrectly assume that cross-sectional associations are stable over time. A more focused, tailored intervention may be developed using factors that consistently predict intention.

Attitude to Health↗
PubMed1996

Cost-effectiveness of screening for asymptomatic carotid atherosclerotic disease.

BACKGROUND AND PURPOSE: The value of screening for asymptomatic carotid stenosis has become an important issue with the recently reported beneficial effect of endarterectomy. The purpose of this study is to evaluate the cost-effectiveness of using Doppler ultrasound as a screening tool to select subjects for arteriography and subsequent surgery. METHODS: A computer model was developed to simulate the cost-effectiveness of screening a cohort of 1000 men during a 20-year period. The primary outcome measure was incremental present-value dollar expenditures for screening and treatment per incremental present-value quality-adjusted life-year (QALY) saved. Estimates of disease prevalence and arteriographic and surgical complication rates were obtained from the literature. Probabilities of stroke and death with surgical and medical treatment were obtained from published clinical trials. Doppler ultrasound sensitivity and specificity were obtained through review of local experience. Estimates of costs were obtained from local Medicare reimbursement data. RESULTS: A one-time screening program of a population with a high prevalence (20%) of > or = 60% stenosis cost $35130 per incremental QALY gained. Decreased surgical benefit or increased annual discount rate was detrimental, resulting in lost QALYs. Annual screening cost $457773 per incremental QALY gained. In a low-prevalence (4%) population, one-time screening cost $52588 per QALY gained, while annual screening was detrimental. CONCLUSIONS: The cost-effectiveness of a one-time screening program for an asymptomatic population with a high prevalence of carotid stenosis may be cost-effective. Annual screening is detrimental. The most sensitive variables in this simulation model were long-term stroke risk reduction after surgery and annual discount rate for accumulated costs and QALYs.

Angiography↗
PubMed1993

Cost-effectiveness of screening and cryotherapy for threshold retinopathy of prematurity.

BACKGROUND: Retinopathy of prematurity (ROP) is the leading cause of blindness among premature infants. A recent National Eye Institute-sponsored prospective, multicenter trial investigating the use of cryotherapy for treatment of ROP demonstrates a significant reduction in blindness and low vision for patients with sight-threatening (stage 3+) ROP. METHOD: A microsimulation model is presented to determine the cost-effectiveness of cryotherapy for ROP. Simulations are performed for three subpopulations of premature infants with birth weights 500 through 749 g, 750 through 999 g, and 1000 through 1249 g, and for three screening strategies--weekly, biweekly, and monthly. RESULTS: Appropriately timed screening for and treatment of ROP is predicted to result in a gain of 3899 to 4648 quality-adjusted-life-years and a net governmental budgetary savings of $38.3 to $64.9 million for each annual US birth cohort of 28,321 premature infants (500 through 1249 g). The cost per quality-adjusted-life-year gained is $2488 to $6045, depending on different screening strategies. CONCLUSIONS: Of greatest importance is the finding that properly timed screening and treatment for ROP is not only cost saving but may save approximately 320 infants per year from a lifetime of blindness.

Computer Simulation↗
PubMed1996

Bile duct stenting: a comparison of the One-Action Stent introduction system with the conventional delivery system.

BACKGROUND AND STUDY AIMS: A "One-Action Stent Insertion System" (OASIS) for use with biliary stents has been produced, which is said to be easier to use than conventional insertion systems. The aim of this study was to assess whether there was any measurable difference in the technique in a comparison between the two methods. PATIENTS AND METHODS: A prospective study was carried out. Twenty consecutive patients requiring stents for biliary obstructing lesions were randomly allocated to have the stent inserted either using the OASIS system or the conventional system. All the sent insertions were performed by two experienced endoscopists. The actual time of the insertion procedure and the screening time were recorded. RESULTS: Patients' tolerance for the procedure was similar in the two groups. In nine out of ten OASIS stent insertions, the endoscopist considered the procedure to be easy, compared with five out of ten conventional stent placements. Both techniques resulted in satisfactory positioning of the stent in nine out of ten patients. Although there was no statistically significant difference in the screening times for the two methods (p = 0.16), the actual time taken using the conventional method was significantly longer than with the OASIS method (p < 0.001). CONCLUSION: The One-Action Stent Insertion Set (OASIS) allows easier insertion of biliary stents. The system decreases the number of exchanges that need to be undertaken, precluding inadvertent wire displacement and the need to reinitiate cannulation and guide wire insertion. The actual time required for insertion is significantly less using this method, and this may also reduce the radiation exposure.

Adult↗
PubMed2003

Warm or cold contrast medium in the micturating cystourethrogram (MCUG): which is best?

AIM: The purpose of this study was to determine what difference using room temperature ("cold") or body temperature ("warm") contrast medium had on the outcome of MCUG examinations in infants under 1 year of age. MATERIALS AND METHODS: One hundred infants (50 males and 50 females) referred for an MCUG were identified. Individuals with known bladder neuropathy were excluded. Each was randomized to receive either warm or cold contrast medium. The screening time, volume of contrast instilled, number of attempts at voiding, patient distress, completeness of bladder emptying and incidence of reflux were measured and the results between the two groups compared. RESULTS: No difference was found between the two groups with regards to screening time, volume of contrast instilled or number of attempts at voiding. There was a statistically significant (p<0.05, chi square) difference in distress levels, with more children crying during instillation of cold contrast medium than warm. Bladder emptying was more often to completion when using cold contrast medium (32 compared with 16%), and vesicoureteric reflux (VUR) was more commonly demonstrated when using warm contrast medium (16 compared with 6%), although these values did not reach statistical significance. CONCLUSION: Warm contrast medium causes significantly less distress than cold contrast medium, but does not prolong screening time or increase the volume of contrast required.

Body Temperature↗
PubMedDate not supplied

Comparison of ThinPrep preparations with conventional cervicovaginal smears. Practical considerations.

This study compared cytologic quality, diagnostic accuracy, detection of endocervical and endometrial cells and yeast, screening times and costs for 128 ThinPrep preparations (TP) to the corresponding conventional cervicovaginal cytologic smears (CCVS). Final diagnoses agreed in 114 (89%) cases. There were four discrepancies between atypical squamous cells of undetermined significance and low grade squamous intraepithelial lesion. The number of abnormal cells was lower in TP than in CCVS. Endocervical and endometrial cells were detected less frequently in TP than in CCVS. Yeast forms were seen rarely but were identified in both CCVS and TP. Inflammation and blood were less prominent on TP. While some CCVS showed artifacts related to fixation, cell preservation was optimal in all TP. Screening times were significantly shorter for TP than for CCVS. The combined cost of reagents, preparation and screening for an average TP was $1.78 higher than for a CCVS. We conclude that the use of TP for cervicovaginal smears reduces screening time and produces better cytologic preparations. However, cost-benefit analyses, readjustments in criteria for diagnosis of dysplasia and improvements in the recovery of glandular cells may be necessary before this method is used instead of CCVS.

Adenocarcinoma↗
PubMedDate not supplied

Thin-layer preparations of dithiothreitol-treated bronchial washing specimens.

OBJECTIVE: To evaluate the combined effect of dithiothreitol (DTT) treatment and ThinPrep (TP) (Cytyc Corp, Boxborough, Massachusetts, U.S.A.) processing on bronchial washing specimens. STUDY DESIGN: A total of 431 bronchial washing specimens were initially treated with 0.05% DTT in a 30% methanol solution. After centrifugation, 1 TP slide and 2-4 conventional cytospin or smear preparations (CPs) were prepared. The reports of both preparations were compared in all cases. All 48 abnormal cases and 52 consecutive negative cases were also compared for cellular composition, distribution of the cells, ease of interpretation and overall preparation quality. Screening time was recorded for 20 of the cases. RESULTS: The diagnostic accuracy of one TP slide appeared comparable to that of 2-4 CPs. The TP slide was assessed to be equal or superior in overall quality to CP in 85% of 100 cases of paired specimens. The cleaner background and smaller cellular area of TP slides significantly reduced the screening time. Mucolysis and specimen homogenization were not always optimal, occasionally resulting in uneven subsampling and poorly cellular TPs. However, in general, TP slides were considered superior to CPs in overall quality. CONCLUSION: Improvement in specimen quality and reduced screening time have to be balanced against the high cost of consumables with the TP technique.

Artifacts↗
PubMed1994

Radiofrequency ablation of accessory pathways: implications of accumulated experience and time dedicated to procedures.

Previous reports on radiofrequency ablation of accessory pathways have shown that the experience of the operator is of crucial importance in reducing fluoroscopy time and achieving higher success rates. However, a detailed analysis of this important issue has not been previously attempted. We analysed 71 consecutive ablation procedures undertaken at St George's Hospital by the same electrophysiology group and always with the same first operator. Of all procedures, 66 (91.6%) were successful, as judged by abolition of accessory pathway conduction without recurrence within the next 24 h. Failures included two out of 38 left-sided pathway procedures (5.3%), one out of 11 intermediate septal (9.1%) and four out of 22 right-sided pathway procedures (18.2%). These differences were not statistically significant. Average procedure and screening times for all procedures were 162.9 +/- 86.0 min and 56.8 +/- 48.2 min respectively, whereas the median of the number of discharges was 12, ranging from one to 51. There was no significant difference between pathway groups or between concealed and non-concealed pathways in respect to procedure and screening time or number of discharges. There was a significant tendency towards decreased procedure and screening times with accumulating experience and this was similar for all pathway groups. There was also a tendency towards improved cumulative success rates with time dedicated to procedures. We conclude that a certain amount of ablation experience is required, even by experienced electrophysiologists, before a relatively high success rate without long radiation exposure can be achieved, regardless of the location or the mode of conduction of the pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2006

Interval breast cancers: prognostic features and survival by subtype and time since screening.

OBJECTIVES: To investigate the hypothesis that interval cancers arising soon after the previous screen and true interval cancers are biologically aggressive and have a relatively poor prognosis compared with other interval cancers, and to assess which prognostic features are relevant to interval cancers. METHODS: Analysis of prognostic pathological features (grade, lymph node stage, size, vascular invasion, oestrogen receptor [ER] status and histological type), radiological features (comedo/non-comedo calcification and spiculation) and survival for 538 invasive interval breast cancer cases by type and time since previous screen. RESULTS: Late interval cancers were less likely to be lymph node positive (13 versus 43%, P = 0.003). Type 1 interval cancers were more likely to be histological grade 3 than type 2 (minimal signs) and type 3 (false-negative) intervals (52 versus 35%, P = 0.05). Type 3 interval cancers were more likely to have lobular features than other intervals (47 versus 20%, P < 0.0001). There was no significant survival difference by interval cancer type (P = 0.64) or interval year (P = 0.83). At univariate analysis of all interval cancers, tumour size, grade, nodal stage, ER status, vascular invasion and comedo calcification were associated with survival. On multivariate analysis of prognostic features significant at univariate analysis, nodal stage (P value = 0.009), tumour size (P = 0.001), ER status (P < 0.0001) and vascular invasion (P < 0.0001) maintained independent significance. CONCLUSIONS: Our study shows that true intervals and interval cancers arising quickly after screening do not have a worse prognosis than other interval cancers, and that interval cancers have a unique set of prognostic features.

Breast Neoplasms↗
PubMed2025

Genome-wide analysis of screen behaviors among adolescents identifies novel loci and overlap with educational attainment and mental disorders.

Technological devices play a central role in adolescents' life. Despite concerns about negative effects of excessive screen time, there is little knowledge of screen behaviors' genetic architecture. Using self-reports from adolescents in the Norwegian Mother, Father, and Child Cohort Study (n&#x2009;=&#x2009;18,490), we performed genome-wide association analysis for four screen behaviors: time spent (1) watching television; (2) gaming; (3) sitting/lying down with a screen device; and (4) using social media. The resulting summary statistics were analysed using the conditional false discovery rate (condFDR) approach to increase genetic discovery. We also estimated SNP-heritabilities of the screen behaviors and genetic correlations with eight psychiatric disorders (schizophrenia, bipolar disorder, major depressive disorder, autism spectrum disorder, attention-deficit hyperactivity disorder,&#xa0;anorexia nervosa, cannabis use disorder and alcohol use disorder), and educational attainment. Screen behaviors displayed significant SNP-heritabilities (0.048-0.12). We observed significant genetic correlations between screen behaviors and psychiatric disorders (rg range: 0.21-0.42). Educational attainment demonstrated negative genetic correlation with screen behaviors, most strongly with social media use (rg&#x2009;=&#x2009;-&#x2009;0.69). CondFDR analysis identified three novel loci associated with social media use. Thus, we show that screen behaviors are heritable, polygenic traits that partly share genetic signal with mental disorders and educational attainment.

Humans↗
PubMed2004

Flexible ureterorenoscopy: prospective analysis of the Guy's experience.

OBJECTIVE: To report our outcomes with small diameter, actively deflectable flexible ureterorenoscopy from a prospective database. PATIENTS AND METHODS: 114 flexible ureterorenoscopies were performed in 105 patients (mean age, 49.5 years; range, 19-85 years; 71 males, 34 females) over a 9-month period. Of these, 101 were for refractory stones following failed ESWL and 13 for diagnostic reasons. An Olympus URF P3 flexible ureteroscope with pressure irrigation was used. Electrohydraulic lithotripsy was used to fragment stones and the fragments were retrieved with Graspit, triradiate graspers or tipless baskets. RESULTS: Stents had previously been placed in 53% and dilatation of the ureteric orifice was necessary in 15%. In the stone group, the median operating time was 55 min (range, 15-210 min) and the median screening time 2.2 min (range, 0.3-9.1 min). Success was defined as complete stone clearance or good fragmentation to 2 mm or less. Overall success in this group was 72.3%. There was no statistically significant difference between lower and other calyces (P=0.83 Chi-square test). Successful outcome was achieved in 72% for stone size 10 mm or less, 80% for 11-20 mm and 50% for greater than 20 mm. Two or more procedures were needed in 8 patients. In the diagnostic group, the median operating time was 45 min (range, 20-60 min) and the median screening time 2 min (range, 0.3-8.3 min). The majority were for upper tract filling defects. Access and successful diagnosis was achieved in all cases. The major complication rate was 2.6%. The ureteroscope needed repair once during this series. CONCLUSIONS: Flexible ureterorenoscopy is an effective diagnostic and therapeutic tool in a select group of patients. It should be considered for ESWL-resistant upper tract stones but the results are poor in stones larger than 20 mm and percutaneous nephrolithotomy may be a better option in these patients.

Adult↗