Accuracy of screening for gastric cancer using serum pepsinogen concentrations.
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BACKGROUND/AIMS: The characteristics of pepsinogen screening for gastric cancer were investigated to establish a suitable cut off point for identifying gastric cancer, using endoscopic diagnosis as the yardstick. SUBJECTS/METHODS: Serum pepsinogen concentrations were measured in 5113 subjects who were also screened for gastric cancer by endoscopy. The cut off point for pepsinogen was determined using receiver operator characteristics curves. RESULTS: The most suitable cut off point was a pepsinogen I concentration of less than 70 ng/ml and a ratio of pepsinogen I to pepsinogen II of less than 3. 0. Using this cut off point, the sensitivity and specificity of pepsinogen screening for gastric cancer were 84.6% and 73.5% respectively. All cases of gastric cancer in patients with severe atrophic gastritis were detected. However, two of four cases of gastric cancer in patients with mild atrophic gastritis were overlooked. In subjects with mild atrophic gastritis, when gastric cancer arises within the fundic gland region, the size of the lesion determines whether it is possible to detect cancer by serum pepsinogen screening. CONCLUSION: Pepsinogen screening has many advantages, including its suitability for combination with other screening methods because it is simple and inexpensive. (+info)
Cost comparison of predictive genetic testing versus conventional clinical screening for familial adenomatous polyposis.
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BACKGROUND: Mutations of the APC gene cause familial adenomatous polyposis (FAP), a hereditary colorectal cancer predisposition syndrome. AIMS: To conduct a cost comparison analysis of predictive genetic testing versus conventional clinical screening for individuals at risk of inheriting FAP, using the perspective of a third party payer. METHODS: All direct health care costs for both screening strategies were measured according to time and motion, and the expected costs evaluated using a decision analysis model. RESULTS: The baseline analysis predicted that screening a prototype FAP family would cost $4975/ pound3109 by molecular testing and $8031/ pound5019 by clinical screening strategy, when family members were monitored with the same frequency of clinical surveillance (every two to three years). Sensitivity analyses revealed that the genetic testing approach is cost saving for key variables including the kindred size, the age of screening onset, and the cost of mutation identification in a proband. However, if the APC mutation carriers were monitored at an increased (annual) frequency, the cost of the genetic screening strategy increased to $7483/ pound4677 and was especially sensitive to variability in age of onset of screening, family size, and cost of genetic testing of at risk relatives. CONCLUSIONS: In FAP kindreds, a predictive genetic testing strategy costs less than conventional clinical screening, provided that the frequency of surveillance is identical using either strategy. An additional significant benefit is the elimination of unnecessary colonic examinations for those family members found to be non-carriers. (+info)
Evaluation of screening for nasopharyngeal carcinoma: trial design using Markov chain models.
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In this paper, we develop a Markov chain model to estimate parameters pertaining to the natural history of nasopharyngeal carcinoma (NPC). The model is of progression from no disease to Epstein-Barr virus (EBV) infection, preclinical screen-detectable tumour and clinical tumour. We derive tentative estimates of the parameters of the model, based on limited published data, to assess the efficacy of serum screening in conjunction with clinical assessment (indirect mirror examination for NPC), for example the average duration of the preclinical screen-detectable phase is estimated as 3.1 years. We further apply these parameters to a hypothetical screening trial in the Hong Kong population to assess the efficacy of serum screening with clinical assessment by different combinations of screening regime. Results suggest: (1) there is no substantial difference between 3-yearly and 6-yearly serum screening; and (2) within the same serum screening regime annual and 3-yearly clinical assessment can prevent 33% and 28% of deaths from NPC respectively. Prediction of deaths and surrogate end points can be used to estimate the required sample size and duration for designing a randomized trial of screening for NPC. Based on these findings and power projections, we suggest a design for a randomized trial in a high incidence area such as Hong Kong. (+info)
Comparison of the entropy technique with two other techniques for detecting disease clustering using data from children with high blood lead levels.
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The entropy technique was compared with two other case-control techniques for detecting disease clustering using data on blood lead levels of children who were patients at the King/Drew Medical Center in South-Central Los Angeles in 1991 to 1994. The other two methods are the nearest neighbor technique (NNT) and Moran's IPOP technique, a variation of Moran's I test, in which rates are adjusted for population size. Four different blood lead levels (15 microg/dl, 20 microg/dl, 30 microg/dl, 35 microg/dl) were used as cutoff levels to designate cases. Persons with blood lead levels greater than or equal to the cutoff level were designated as cases. The authors found significant clustering for all four cutoff levels using the entropy method, and for the first three cutoff levels using the NNT. They found significant clustering with Moran's IPOP for some scales for two of the cutoff levels. While performance of the entropy technique and the NNT were independent of scale, that of Moran's IPOP was highly scale-dependent. (+info)
Health screening in older women.
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Health screening is an important aspect of health promotion and disease prevention in women over 65 years of age. Screening efforts should address conditions that cause significant morbidity and mortality in this age group. In addition to screening for cardiovascular disease, cerebrovascular disease and cancer, primary care physicians should identify risk factors unique to an aging population. These factors include hearing and vision loss, dysmobility or functional impairment, osteoporosis, cognitive and affective disorders, urinary incontinence and domestic violence. Although screening for many conditions cannot be proved to merit an "A" recommendation (indicating conclusive proof of benefit), special attention to these factors can decrease morbidity and improve quality of life in aging women. (+info)
The need for cataract surgery: projections based on lens opacity, visual acuity, and personal concern.
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AIM: To assess the projected needs for cataract surgery by lens opacity, visual acuity, and patient concern. METHODS: Data were collected as part of the Melbourne Visual Impairment Project, a population based study of age related eye disease in a representative sample of Melbourne residents aged 40 and over. Participants were recruited by a household census and invited to attend a local screening centre. At the study sites, the following data were collected: presenting and best corrected visual acuity, visual fields, intraocular pressure, satisfaction with current vision, personal health history and habits, and a standardised eye examination and photography of the lens and fundus. Lens photographs were graded twice and adjudicated to document lens opacities. Cataract was defined as nuclear greater than or equal to standard 2, 4/16 or greater cortical opacity, or any posterior subcapsular opacities. RESULTS: 3271 (83% response) people living in their own homes were examined. The participants ranged in age from 40 to 98 years and 1511 (46.2%) were men. Previous cataract surgery had been performed in 107 (3.4%) of the participants. The overall prevalence of any type of cataract that had not been surgically corrected was 18%. If the presence of cataract as defined was considered the sole criterion for cataract surgery with no reference to visual acuity, there would be 309 cataract operations per 1000 people aged 40 and over (96 eyes of people who were not satisfied with their vision, 210 eyes of people who were satisfied with their vision, and three previous cataract operations). At a visual acuity criterion of less than 6/12 (the vision required to legally drive a car), 48 cataract operations per 1000 would occur and people would be twice as likely to report dissatisfaction with their vision. CONCLUSIONS: Estimates of the need for cataract surgery vary dramatically by level of lens opacity, visual acuity, and patient concern. These data should be useful for the planning of health services. (+info)
Screening methods for thyroid hormone disruptors.
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The U.S. Congress has passed legislation requiring the EPA to implement screening tests for identifying endocrine-disrupting chemicals. A series of workshops was sponsored by the EPA, the Chemical Manufacturers Association, and the World Wildlife Fund; one workshop focused on screens for chemicals that alter thyroid hormone function and homeostasis. Participants at this meeting identified and examined methods to detect alterations in thyroid hormone synthesis, transport, and catabolism. In addition, some methods to detect chemicals that bind to the thyroid hormone receptors acting as either agonists or antagonists were also identified. Screening methods used in mammals as well as other vertebrate classes were examined. There was a general consensus that all known chemicals which interfere with thyroid hormone function and homeostasis act by either inhibiting synthesis, altering serum transport proteins, or by increasing catabolism of thyroid hormones. There are no direct data to support the assertion that certain environmental chemicals bind and activate the thyroid hormone receptors; further research is indicated. In light of this, screening methods should reflect known mechanisms of action. Most methods examined, albeit useful for mechanistic studies, were thought to be too specific and therefore would not be applicable for broad-based screening. Determination of serum thyroid hormone concentrations following chemical exposure in rodents was thought to be a reasonable initial screen. Concurrent histologic evaluation of the thyroid would strengthen this screen. Similar methods in teleosts may be useful as screens, but would require indicators of tissue production of thyroid hormones. The use of tadpole metamorphosis as a screen may also be useful; however, this method requires validation and standardization prior to use as a broad-based screen. (+info)
Clinical outcomes after hepatitis C infection from contaminated anti-D immune globulin. Irish Hepatology Research Group.
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BACKGROUND AND METHODS: In February 1994, batches of anti-D immune globulin used in Ireland during 1977 and 1978 to prevent Rh isoimmunization were found to be contaminated with hepatitis C virus (HCV) from a single infected donor. In March 1994, a national screening program was initiated for all women who had received anti-D immune globulin between 1970 and 1994. Of the 62,667 women who had been screened when this study began, 704 (1.1 percent) had evidence of past or current HCV infection, and 390 of those 704 (55 percent) had positive tests for serum HCV RNA on reverse-transcription-polymerase-chain-reaction analysis. All 390 were offered a referral for clinical assessment and therapy. We evaluated 376 of these 390 women (96 percent); the other 14 were not seen at one of the designated treatment centers. RESULTS: The mean (+/-SD) age of the 376 women was 45+/-6 years at the time of screening. They had been infected with hepatitis C for about 17 years. A total of 304 women (81 percent) reported symptoms, most commonly fatigue (248 [66 percent]). Serum alanine aminotransferase concentrations were slightly elevated (40 to 99 U per liter) in 176 of 371 women (47 percent), and the concentrations were 100 U per liter or higher in 31 (8 percent). Liver biopsies showed inflammation in 356 of 363 women (98 percent); in most cases the inflammation was slight (41 percent) or moderate (52 percent). Although the biopsy samples from 186 of the 363 women (51 percent) showed evidence of fibrosis, only 7 women (2 percent) had probable or definite cirrhosis. Two of the seven reported excessive alcohol consumption. CONCLUSIONS: Most of the women with HCV infection 17 years after receiving HCV-contaminated anti-D immune globulin had evidence of slight or moderate hepatic inflammation on liver biopsy, about half had fibrosis, and 2 percent had probable or definite cirrhosis. (+info)