Prenatal screening

This report discusses the role of prenatal screening in preventing congenital abnormalities or, when prevention is not possible, in avoiding the conception or the birth of those who would have untreatable abnormalities. Women who are found by screening not to be immune to rubella can be safely vaccinated prior to pregnancy; those found to be at risk of having children with genetic disorders such as Tay-Sachs disease or thalassemia have the option of avoiding the conception of affected offspring. Screening during pregnancy permits the primary prevention of Rb disease and its sequelae when it results in the prophylactic administration of Rh-immune globulin to unsensitized Rh-negative women. Maternal serum alpha-fetoprotein screening identifies pregnant women who are at increased risk of carrying fetuses with neural tube defects or Down’s syndrome, giving them the option of avoiding the birth of affected fetuses through abortion. Recombinant DNA technology will permit screening for many more genetic disorders as the disease-related genes and mutations are identified. For many of these disorders, the ability to predict the risk of disease will antedate preventive and therapeutic interventions by many years. During this lag phase, issues concerning the validity of the tests, the severity of the conditions for which screening is offered, the safety of the interventions, and the autonomy of the pregnant women in deciding to be screened are important.     

Glaucoma screening

Screening for glaucoma, usually by measuring intraocular pressure, has been popular, but repeated analysis indicates poor sensitivity and specificity. More extensive testing is required. Such testing should be focused on high-risk groups, including blacks and the elderly. Regular comprehensive eye examinations, on a schedule adjusted for these and other risk factors, are probably the most cost-efficient means of identifying patients with glaucoma. The primary care provider has a pivotal role: to encourage patients to undergo such examinations when warranted; and to encourage those on intraocular-pressure-lowering medications to comply with their medication use.     

Selective screening

Issues related to selective screening are discussed. The distinction between test accuracy and program accuracy is presented in the context of impact on cost/true case detection, which in turn reflects the gain in specificity and loss in sensitivity for the total target population. When two or more risk factors are combined to define high-risk subjects, a gain in program accuracy and a relative reduction in cost/true case found ensue if there is additive interaction between these risk factors. The author also discusses periodicity of screening and emphasizes the inappropriateness of using the notion of risk for disease occurrence as a criterion to define periodicity.     

Colorectal cancer screening

Colorectal cancer (CRC) is the third most common cause of cancer death worldwide and a major health problem. In this review, the different approaches for CRC screening will be outlined with emphasis on evidence-based medicine. Evidence from randomized trials on the effectiveness of CRC screening is summarized. Several screening tools for CRC are available. They can be categorized according to their mode of action: early detection tools such as the faecal occult blood test (FOBT) and cancer prevention tools such as flexible sigmoidoscopy and colonoscopy. Meta-analyses of randomized trials show that FOBT screening reduces CRC mortality by 16% (risk ratio 0.84; 95% confidence interval (CI) 0.78-0.9) compared with 30% (risk ratio 0.7; 95% CI 0.6-0.81) for flexible sigmoidoscopy screening. FOBT screening is cheap and noninvasive, but results in large numbers of false-positive tests and needs to be repeated frequently. Flexible sigmoidoscopy is more invasive, but is effective for once-only screening. Although colonoscopy screening is used in some countries, no randomized trials have been conducted to estimate its benefit, and therefore, it should not be recommended at the present time. Faecal occult blood test and flexible sigmoidoscopy are the two CRC screening tools that can be recommended as they have been proven to reduce CRC mortality. Colonoscopy has the potential to be superior to FOBT and flexible sigmoidoscopy, but needs to be evaluated in randomized trials before any recommendation can be provided.     

Colorectal cancer screening

INTRODUCTION Colorectal cancer is a major public health burden. It is the fourth most common form of cancer worldwide and the most frequent in North America, Australia, New Zealand, Argentina, and parts of Europe[1]. When colorectal can- cer is detected a…     

Colorectal cancer screening

It is clear that colorectal cancer (CRC) is a worldwide problem of sufficient magnitude that deserver screening. There is now a general consensus among national and international guidelines that CRC screening is effective in reducing incidence and mortality and is cost-effective. With more intensive chemotherapy it is even cost saving. The several options for screening can be confusing if all are available in a given community or country. However, a selection can be made regarding which option or options to offer people depending on available resources, finances, and the population cultures. Colonoscopy may be the choice in a high resource area whereas a quaiac based FOBT could be the choice in a low resource area. Similarly, the diagnostic workup most desirable in positively screened people is colonoscopy, but a barium enema may have to suffice where colonoscopy is not generally available. In each situation, however, the whole process must be high quality in performance and timely in diagnostic workup and treatment. If not, the whole screening process will fail. Organised screening is generally more effective then opportunistic screening, which requires greater individual motivation. There are many barriers to screening, personal, among providers and in the general medical system. Considerable research is ongoing in this area in order to find new directions to overcome these barriers and increase CRC screening rates to the level of mammography. Although we do not know which screening test is the best, we do know that any screening is better than none and the best test is the one that gets done. It is indeed tragic that so many people die each day from CRC when it is so highly curable and preventable. This is even more tragic when familial risk factors are so obvious in many families but remain unrecognised by relatives and by their physicians. Continued professional and public campaigns are necessary to modify dramatically the awareness of CRC and the availability of effective tools to control it.

• Colorectal Cancer deaths and cases are increasing worldwide because of the expansion and aging of the population.

• Screening is effective in reducing deaths by detecting earlier curable cases.

• Screening is also effective in reducing incidence by finding and removing adematous polyps.

• Screening is cost-effective, and cost saving where intensive chemotherapy is used for advanced cases.

• The most effective test among the offered option is not known.

• The magnitude of the incidence and mortality reduction by screening colonoscopy needs to be studied in a randomised trial.

• More effective methods need to be developed to overcome patient, provider and systems barriers in order to increase screening rates.

Colorectal cancer screening

Colorectal cancer is one of the most common malignancies in Australia, and screening to detect it an earlier stage is cost‐effective. Furthermore, detection and removal of precursor polyps can reduce incidence. Currently, there are limited data to determine the screening rate in Australia, but it is certainly lower than the 80% screening rate considered desirable. Whether colonoscopy is used as the screening test or to follow up positive results of an initial non‐invasive test, it plays a fundamental role. Despite high sensitivity and specificity, it is expensive and invasive with measurable risk and is not acceptable as an initial test to many participants. It does not provide complete protection, and interval cancers between planned colonoscopies are associated with proximal location, origin in sessile serrated adenomas and operator‐dependent factors. An essential component of colorectal screening is the measurement of colonoscopy quality indicators, such as caecal intubation and adenoma detection rates, which are known to be associated with the rate of interval cancer. The non‐invasive screening test currently recommended in Australia is biennial testing for faecal occult blood between the ages of 50 and 75 using a faecal immunochemical test, with positives evaluated by colonoscopy. This is provided through the National Bowel Cancer Screening Programme, currently for those at the ages of 50, 55, 60 and 65 years, with full implementation of biennial screening by 2020. To improve screening in Australia, the most fruitful approach may be to acknowledge that there is a choice of screening tests and to focus on the goal of improving overall participation rate and being able to measure this.     

Blood cholesterol screening

OBJECTIVE: To compare fasting and nonfasting total and high-density lipoprotein (HDL) cholesterol values in adults and to determine how closely classification into risk groups for coronary heart disease based on nonfasting blood tests compares with classification based on fasting studies. DESIGN: Cross-sectional study. SETTING: A community hospital general internal medicine clinic. PATIENTS: One hundred eighty-one patients at least 20 years of age receiving medical care at a community hospital general internal medicine clinic. INTERVENTIONS: Total and HDL cholesterol levels were measured twice in each patient within 7 days, once while not fasting and once after a minimum 12-hour fast. MEASUREMENTS AND MAIN RESULTS: Fasting and nonfasting total and HDL cholesterol values were compared, patients were classified into desirable, borderline-high, and high cholesterol groups on the basis of fasting and nonfasting blood studies. There were small, statistically significant but clinically insignificant differences in fasting and nonfasting results for total cholesterol. Nonfasting HDL cholesterol levels were similar to fasting HDL levels. The agreement in classification of patients into desirable and high-cholesterol groups between fasting and non-fasting blood testing was 86.7% and 89.5%, respectively. In the borderline-high group, for whom levels of HDL cholesterol are important in determining subsequent management, there was 95% agreement between fasting and nonfasting HDL cholesterol results. Only a small fraction of the patients were classified into lower-risk groups by the nonfasting assessment, creating the potential for less-rigorous monitoring and treatment of their cholesterol status than if fasting results were utilized. These findings were confirmed in this study also for the subgroups of men aged 35 years and older and women aged 45 years and older. CONCLUSIONS: Screening nonfasting adults for total and HDL cholesterol is appropriate for making decisions about primary prevention of coronary heart disease.     

Colon cancer screening. The dilemma of positive screening tests

Despite doubts about the benefits of colon cancer screening, sigmoidoscopy and fecal occult blood tests are now often performed by clinicians who must then deal with positive test results. The purpose of this literature review is to examine potential strategies for dealing with positive screening test results. If positive results are obtained, current data support the use of colonoscopy as the single most effective diagnostic strategy. Exceptions include situations that reduce the predictive value of the screening test. Several important areas of controversy are highlighted that need to be assessed in subsequent studies.