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Determination of the fibrinolytic activity should be performed in patients with recurrent thromboembolic disease. As a screening procedure we suggest the euglobulin clot lysis time test after venous occlusion. This test is sufficiently reliable and easier to perform than the fibrin plate method, especially outside coagulation laboratories.
BACKGROUND: Delay to breast cancer diagnosis following an abnormal screening result is associated with anxiety and personal disruption. We assessed the patterns and timeliness of diagnostic follow-up after breast cancer screening for women with abnormal results who attended organized screening programs in 7 provinces. METHODS: Using data from the Canadian Breast Cancer Screening Database, we identified 203,141 women aged 50-69 years who underwent screening in 1996 through provincially organized breast cancer screening programs in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Nova Scotia and Newfoundland. We prospectively followed women with an abnormal screening result through to the completion of the assessment process. We evaluated the waiting times from screening examination to first assessment, from screening examination to first imaging, from screening examination to diagnosis and from first assessment to diagnosis for 13,958 women, stratified according to screening program, mode of detection, whether a biopsy was performed and whether cancer was diagnosed. RESULTS: We observed considerable variations between and within programs in the time to diagnosis. The median time from screening examination to first assessment was 2.6 weeks. The median time from screening examination to diagnosis was 3.7 weeks; this time increased to 6.9 weeks for women undergoing biopsy. Even when no biopsy was performed, 10% of the women waited 9.6 weeks or longer for a diagnosis, as compared with 15.0 weeks or longer for 10% of the women undergoing biopsy. Among the women who had a biopsy, the use of core biopsy was associated with a shorter median time to diagnosis than was open biopsy, and those found to have cancer had shorter waiting times than women with benign biopsy findings. INTERPRETATION: Women undergoing assessment of an abnormal breast cancer screening result waited many weeks for a diagnosis, especially when a biopsy was performed. To ensure that targets for timeliness, adopted nationally in 1999, are realized, improved models of care or dissemination of existing efficient techniques to reach a diagnosis will be needed.
Factor V(Leiden) is the most common abnormality detected in patients examined because of hereditary thrombophilia. The most widely used clot-based screening test is based on the activated partial thromboplastin (aPTT) time. This test has a low sensitivity. A comparison of the aPTT-based test with a Russell viper venom time test (RVVT) was performed in matched samples. All samples were analyzed by polymerase chain reaction (PCR) for the factor V(Leiden) defect. We studied 139 samples, of which 109 were PCR-negative; 30 were PCR-positive. Using the manufacturer's suggested threshold ratio of 2, the aPTT test showed a sensitivity of 0.43, a specificity of 0.86, and a positive predictive value (PPV) of 0.97. The RVVT test had a sensitivity of 1.0, a specificity of 0.95, and a PPV of 0.91. Segregation of a subpopulation of this study population into ABO group O vs non-group O showed an effect of ABO group on the aPTT test but not on the RVVT test, consistent with an influence of factor VIII clotting (factor VIII:C) on the aPTT test. The RVVT test seems superior to the unmodified aPTT test as a screening test for factor V(Leiden).
In some medical centers, the routine pre-operative evaluation of healthy children undergoing elective tonsillectomy and/or adenoidectomy (T and A) includes coagulation screening tests (PT, prothrombin Time; PTT, partial thromboplastin time; and INR, international normalized ratio). In this retrospective study, we determined whether there is a positive correlation between prolonged PT/PTT/INR tests in healthy children, with no prior medical history of coagulation problems, and bleeding during surgery and/or bleeding in the month following surgery. We reviewed the records of 416 elective T and A surgeries performed at the Soroka University Medical Center in Beer-Sheva, Israel, over the course of 1999. One hundred and twenty-one (29.1%) patients had preoperative prolonged PT values but only four (3.3%) of these patients experienced light bleeding during surgery. Seven (5.8%) of the 121 patients with prolonged PT tests experienced bleeding episodes during the 1st month subsequent to the surgery. Of the 65 (15.6%) patients who had prolonged pre-operative INR values, only three (4.6%) experienced light bleeding during surgery. Two (3.1%) patients with prolonged INR values experienced light bleeding during the 1st month subsequent to surgery. Sixty-one (14.7%) patients had prolonged first preoperative PTT values, only five of whom (8.2%) experienced light bleeding during surgery. Two (3.3%) of the 61 with prolonged PTT values experienced light bleeding during the 1st month subsequent to surgery. We therefore concluded that pre-operative coagulation screening tests provide low sensitivity and low bleeding predictive value. As such, routine coagulation tests before T &A are not indicated unless a medical history of bleeding tendency is suspected.
BACKGROUND: The effect of severity of screening result on delays to diagnosis has primarily been examined for mammographic abnormalities. This study will examine delays to assessment and diagnosis for women with an abnormal mammogram compared to women with an abnormal clinical breast examination (CBE) or abnormal CBE and mammogram. METHODS: Using data routinely collected by Ontario Breast Screening Program (OBSP), 12,675 women aged 50 to 69 with an abnormal screening result between January 1, 2000 and December 31, 2000 were followed prospectively to the completion of their assessment process. Median waiting times from abnormal screen to first assessment procedure and diagnosis were compared by modality of referral and among women with a breast cancer diagnosis by prognostic features. RESULTS: The median waiting time to first assessment and to diagnosis was significantly longer for women with only a clinical abnormality compared to women with a mammographic abnormality. In addition, women diagnosed with cancers of larger size had longer delays when the abnormality was detected only clinically. However, women referred by both modalities had significantly shorter waiting times to first assessment procedure and to diagnosis of poor prognosis cancers compared to women referred by mammography alone. INTERPRETATION: Women with an abnormal CBE and mammogram are assessed more promptly and have shorter diagnostic times. However, women with only a CBE abnormality had delays to diagnosis as a result of longer waiting times to first assessment procedure. Integration of the OBSP with assessment centres should improve times to diagnosis irrespective of modality of referral.
OBJECTIVE: The objective of our study was to compare acquisition times and interpretation times of screening examinations using screen-film mammography and soft-copy digital mammography. MATERIALS AND METHODS: Technologist study acquisition time from examination initiation to release of the screenee was measured for both screen-film and digital mammography (100 cases each) in routine clinical practice. The total interpretation time for screening mammography was also measured for 183 hard-copy screen-film cases and 181 soft-copy digital cases interpreted by a total of seven breast imaging radiologists, four experienced breast imagers, and three breast imaging fellows. RESULTS: Screening mammography acquisition time averaged 21.6 minutes for screen-film and 14.1 minutes for digital, a highly significant 35% shorter time for digital than screen-film (p < 10(-17)). The average number of images per case acquired with digital mammography was higher than that for screen-film mammography (4.23 for screen-film, 4.50 for digital; p = 0.047). The total interpretation time averaged 1.4 minutes for screen-film mammography and 2.3 minutes for digital mammography, a highly significant 57% longer interpretation time for digital (p < 10(-11)). In addition, technical problems delaying interpretation were encountered in none of the 183 screen-film cases but occurred in nine (5%) of the 181 digital cases. CONCLUSION: Compared with screen-film mammography, the use of digital mammography for screening examinations significantly shortened acquisition time but significantly increased interpretation time. In addition, more technical problems were encountered that delayed the interpretation of digital cases.
Regulation of cell volume was one of the earliest evolutionary demands for life and remains a universal measure of cell metabolism. Since conventional methods to measure cell volume, such as microscopy, are complex and time-consuming, cell volume has not been used as the basis for cell-based screening. We have developed a microfabricated chip that can measure the volume of small numbers of cells in real time with unprecedented resolution. The method is applicable to adherent or suspended populations of cells and membrane-bound organelles. Our prototype device can detect volume changes in a monolayer of tissue-cultured astrocytes responding to anisotonic stimuli of <1mOsm. We determined the sensitivity to antibiotics of different E. coli strains in <10 min at 24 degrees C. This time can be reduced at higher temperatures enabling on-site clinical testing of infectious agents. Using the chip to screen natural products, we found a peptide in spider venom that inhibits eukaryotic volume regulation at approximately 100pM. The prototype chip made in silicon is inexpensive, reusable, and runs on low-voltage electrical power. The technology can be readily transferred to large arrays in plastic.
This study investigates statistical approaches to quantitatively describing the age effect on screening sensitivity and sojourn time distribution in breast cancer screening studies. Such an investigation is directly motivated by the need to understand the inherent relationships between age and these important quantities. We incorporate the age effect through generalized linear models under a progressive disease modelling framework and obtain the corresponding parameter estimators using the maximum likelihood method. Among a set of potential models, we use Akeike's information criterion and likelihood ratio test in model selection and inferences. Extensive simulation studies show that the estimators have reasonable accuracy and the model selection criterion works well. The proposed methods are illustrated using data from two large breast cancer screening trials. The results show that the screening sensitivity increases with age at screening examinations based on these two trials.
Mass screening using the faecal occult blood test (FOBT) can reduce mortality from colorectal cancer. Reliable estimation of FOBT sensitivity is crucial in assessing the potential effectiveness of a mass-screening procedure. Available estimates could be inaccurate because they neglect the temporal aspect of screening. The aim of our study was to estimate the sensitivity of the FOBT in mass screening for colorectal cancer, taking into account the duration of the pre-clinical phase of the disease assessed by the mean sojourn time (MST), and to assess whether MST and FOBT sensitivity differ according to cancer subsite. We analysed data taken from the first round of the mass-screening programme of the department of Calvados (France), involving 164,364 subjects of whom 43.4% participated in FOB screening. MST and sensitivity were estimated using a simple empirical approach, a traditional maximum likelihood method and log-linear modelling using the Bayesian technique of Gibbs sampling. MST was estimated as between 4.5 and 5 years for all subsites combined. According to the Gibbs sampling method, MSTs were 3.5, 6.4 and 2.6 years for proximal colon, distal colon and rectal cancer, respectively. Our estimation methods give a low sensitivity for the FOBT (50%), results for different subsites being closer to each other, slightly higher for proximal cancer. Our results strongly suggest that tumour growth rates are very different according to subsite, slowest for distal cancer and speediest for rectal cancer. Consideration of FOBT sensitivity without MST appears unreliable. Our results by subsite suggest that combining FOBT and sigmoidoscopy could be a good strategy for colorectal cancer screening.
BACKGROUND: Although numerous studies have examined repeat mammography, they provide limited information about actual patterns of women's behavior over time. METHODS: In this study, 128 asymptomatic women ages 50 to 75 who had had their first mammograms 15 to 27 months previously were interviewed to determine rates of repeat mammography. Eighty-six of these women were HMO members; the remaining 42 were nonmembers. RESULTS: In both subpopulations, repeat mammography rates were low among women interviewed less than 21 months after their first mammogram, but much higher among those interviewed 21 months or more afterward. CONCLUSIONS: These data suggest that waiting up to 2 years to have a second mammogram may be at least as common a choice as having it after 1 year. It is of particular interest that this was found in a population of HMO members who receive reminders and vouchers for free mammograms annually.
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Analyses of chemical residues in animal tissue matrices require multistep sample preparation. To simplify this process, a methodology was developed that combines sorbent extraction and solid-matrix time-resolved luminescence (TRL); it was applied to tetracycline screening in milk. Reported here is an effort to extend its application to tissue matrices, illustrated by oxytetracycline (OTC) screening in catfish muscle. Extraction and enrichment are accomplished by immersing small C18 sorbent strips into tissue homogenates for 20 min, followed by a 3 min rinse in water and a 2 min dip in a reagent solution. After desiccation, TRL is measured directly on the sorbent surface. Tissue particulates no longer interfere via attenuation or scattering, rendering centrifugation and filtration unnecessary. The integrated TRL intensity shows a linear dependence on OTC concentration in the 0-8 microg/g range (R2 = 0.9992) with a 0.026 microg/g limit of detection. To screen OTC at 2 microg/g, the U.S. regulatory tolerance level, a threshold is established at x2-3sigma2, where x2 and sigma2 are the mean and standard deviation, respectively, of the TRL signals from 15 samples fortified at 2 microg/g. Among 45 blind samples randomly fortified at 0-4 microg/g, 41 were screened correctly and 4 negative samples were presumed positive. This method has the potential to improve throughput and save assay costs by eliminating acids, organic solvents, centrifugation, and filtration.
Screening serum levels of prostate-specific antigen (PSA) is now a major strategy for early detection of prostate cancer (PC). Quantification of the lead time thus obtained is important both for understanding the development of PC and for evaluating the advantages and disadvantages of widespread screening. In our study, 1,233 randomly selected men living in Stockholm in 1988 were invited to participate in an early detection (ED) program, in which suspicious findings provided by digital rectal examination (DRE), transrectal ultrasonography (TRUS) and/or a PSA value >/=10.0 ng/mL were followed up by biopsy. The cumulative incidence (Kaplan-Meier) of PC in the 946 participants (ED) during 12 years of follow-up was compared to that of an age-matched, randomly selected reference population (RP) of 657 men for whom PSA values (from frozen serum samples) could also be obtained. The PC incidence in men in the RP with PSA values >/=3.0 ng/mL reached the corresponding level for the ED group after 10.6 years (the "catch-up" point). After 12 years of follow-up, the estimated median lead time for men with PSA values in this interval was 4.5 years in the ED population, compared to 7.8 years in the RP. With 20 years of follow-up, the estimated median lead time of the RP was enhanced to 10.7 years. The lead time in connection with PC was influenced by the initial PSA level (although with large variations), length of follow-up and sensitivity of the ED procedure employed. The ED program described here was not associated with major overdetection.
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OBJECTIVE: To test a screening protocol for retinopathy of prematurity (ROP) that uses the dual criteria of postconceptional age and chronological age, rather than a single parameter, to determine precisely when to begin eye examinations. METHODS: We retrospectively reviewed medical records of 179 infants (326 eyes) who had undergone laser treatment for threshold ROP. We entered their chronological and postconceptional ages at treatment into a database and evaluated various screening parameters to determine the combination of criteria that would allow us to safely postpone the initial eye examinations. RESULTS: Screening infants at 7 weeks of chronological age or 34 weeks of postconceptional age (whichever comes first), but not before 5 weeks of chronological age, seems to reliably detect the onset of threshold ROP while reducing the number of unnecessary early examinations. CONCLUSION: Simultaneously applied dual criteria of chronological age and postconceptional age may be a superior method of determining when to initiate ROP examinations and is preferable to using either chronological age or postconceptional age alone.
To determine the sensitivity for detection of coagulation factor deficiencies by commercial reagents for canine plasma, 5 commercial activated partial thromboplastin time (APTT) reagents with different types of contact activator and phospholipid of various origin were examined. Thirty canine plasma samples with minor or moderate deficiencies of coagualition factors that influence the APTT were examined. Significant differences were found for the sensitivity of various reagents, but no correlation was found with the type of contact activator. Following the test instructions provided by the manufacturers, the number of APTT results that were prolonged beyond the reference range varied between 20 and 30 (sensitivity = 0.67-1.00); the number of corresponding results using a standardized test protocol varied between 19 and 28 (sensitivity: 0.63-0.93). The most sensitive reagent contained kaolin as a contact activator and a human placental thromboplastin. The results of this study indicate that the APTT test optimized for human plasma is also a sensitive screening test of the intrinsic system of canine plasma, provided that a suitable reagent is used.
Functional significance of renal artery stenosis (RAS) was assessed by 99Tcm-DTPA radionuclide scintigraphy, using the mean parenchymal transit time (MPTT) of the tracer as an index of renovascular disorder. Two groups of subjects were investigated retrospectively: eight normal live kidney donors; and 11 patients with hypertension, six with and five without significant RAS. MPTT was 171 +/- 11 s in the kidney donors, and there was a significantly prolonged MPTT in patients with RAS, 313 +/- 27 s (p less than 0.05). MPTT was also prolonged in three hypertensive patients with intrinsic renal disorders. The advantages and limitations of this technique are discussed. It is concluded that prolongation of MPTT can detect functionally significant renovascular disorder without pharmacological challenge.
Preoperative tests of coagulation function have been suggested to detect patients who are likely to have abnormal bleeding during and after surgery. A study was designed to determine the yield of prothrombin time (PT) and partial thromboplastin time (PTT), both in discovering patients who are at risk for abnormal bleeding and in inducing changes in patient care or outcome. Of 750 patients on three surgical services, 611 (81%) patients had no indication of a bleeding disorder on history or physical examination. Of the 139 patients who had clinical indications, 25 (18.0%) patients had an abnormal PT or PTT. Of the 611 patients without clinical indications, 480 patients had the PT or PTT determined, and 13 (2.7%) patients had abnormal results. One (0.2%) of the 480 patients might have benefited from the test result (this patient required a second operation to control arterial bleeding). The prolonged PT or PTT was of no apparent clinical importance in the remaining 12 patients without indications of bleeding disorders preoperatively. The low yield of the PT and PTT in detecting unsuspected bleeding disorders preoperatively was further obscured by the larger number of apparently false-positive results.