L. Berek. Westwood College of Technology.

Unlike quantitative research studies order zovirax 200 mg on-line, where the study objective is generally very specific and outcome-based generic zovirax 200mg without prescription, the objective or research question in qualitative studies frequently has a non- specific or general flavor order 400 mg zovirax with mastercard. In fact, it is one of the strengths of qualitative research that the specific details surrounding the study objective often emerge through the data collection and the analytic processes can actually change the direction Critical appraisal of qualitative research studies 211 of the research. Nevertheless, it is important for readers to be able to assess what the researchers originally set out to accomplish. Sampling While quantitative research studies generally recruit participants through ran- dom selection or other similar approaches to minimize the potential for selec- tion bias, qualitative research studies are not concerned with accruing a pool of individuals that resemble the larger population. Instead, qualitative studies use purposive sampling, the intentional recruitment of individuals with spe- cific characteristics to encompass the broadest possible range of perspectives on the issue being studied. Instead, researchers identify and recruit participants until it becomes apparent that all salient attitudes or perspectives have been identi- fied. This approach is known variously as theoretical saturation or sampling to redundancy. Readers should assess the researchers’ rationale for selecting and sampling the set of study participants, and that rationale should be consistent with the study objectives. Data Collection In assessing the validity of the results of quantitative studies, the reader can con- sider whether and how all relevant variables were measured, whether adequate numbers of study participants were included, and whether the data were mea- sured and collected in an unbiased fashion. Similarly, in qualitative research studies, the reader should expect to find a credible description of how the researchers obtained the data and be able to assess whether the data collec- tion approach likely yielded all relevant perspectives or behaviors being stud- ied. This criterion is tricky for both researchers and readers, since determining the spectrum of relevant concepts likely comprises part of the study’s objective. Researchers should describe the iterative process by which they collected infor- mation and used the data to inform continued data collection. Readers should ask, and authors should articulate, whether alternative approaches were considered and, if so, why they were not taken. Authors should also detail the efforts undertaken to ascertain information that may be sensitive for a variety of reasons. For example, there may be issues of privacy or social standing which could prevent individuals from revealing infor- mation relevant to the study questions. Researchers and readers must always be concerned about social desirability bias when considering the responses 212 Essential Evidence-Based Medicine or comments that participants may provide when they know they are being observed. The extent to which researchers attempt to collect richly detailed per- spectives from study subjects can help to reassure the reader that subjects at least had ample opportunity to express their knowledge, attitudes, or concerns. The approach that researchers take will reflect the study question, the nature of the available data, and the preferences of the researchers themselves. Nevertheless, several key principles should guide all qualitative analyses, and readers should be able to assess how well the study adhered to these principles. This point may seem obvious, but it is important that readers feel reasonably confident that the data collection not only captured all relevant perspectives but that the analysis did not disregard or overlook elements of data that should be considered. There is no sure-fire way to determine whether all data were included in the analysis, but readers can rea- sonably expect study authors to report that they used a systematic method for cataloguing all data elements. Consider whether multiple observers participated in the analysis and whether the data were reviewed multiple times. The agreement between observers, also known as the inter-rater reliability, should be measured and reported. The results of interviews or open-ended questions can be analyzed using an iterative technique of identification of common themes. First the answers to questions given by an initial group are reviewed and the important themes are selected by one observer. A sec- ond researcher goes over those same responses with the list of themes and cat- alogues the responses, blinded from the results of the first researcher. Following this process, inter-rater reliability is assessed and quantified using a test such as the Kappa statistic.

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Ranavirus infection might be implicated in declines elsewhere cheap zovirax 800 mg visa, but data are lacking cheap zovirax 800 mg with mastercard. There are potential economic losses due to potential risk of disease spread to fish generic zovirax 200mg with amex. An insect-borne viral disease that primarily affects animals but can also affect humans. The virus is mostly transmitted by the bite of infected mosquitoes, mainly of the Aedes species, which acquire the virus when feeding on infected animals. The disease can cause abortions and high mortality in young animals throughout its geographic range. In humans it causes a severe influenza-like illness, with occasionally more serious haemorrhagic complications and death. Species affected Many species of terrestrial mammal, particularly sheep, cattle and wild ruminants, although most indigenous livestock species in Africa are highly resistant to the disease. Geographic distribution Endemic in tropical regions of eastern and southern Africa, with occasional outbreaks in other parts of Africa. Major epidemics occur at irregular intervals of 5-35 years: in Africa, outbreaks typically occur in savannah grasslands every 5-15 years, and in semi-arid regions every 25-35 years. Epidemics are associated with the hatching of mosquitoes during years of heavy rainfall and flooding. Aedes, Anopheles, Culex, Eretmapodites and Mansonia species) and other biting insects. In mammalian species the virus can also be transmitted to the foetus of an infected female. How does the disease The main amplifying hosts are sheep and cattle and once livestock are spread between groups of infected, many species of mosquitoes (e. Eretmapodites and Mansonia species) and biting insects can then spread the disease to other animals and humans. Transmission can also occur through direct contact, which may become relatively more important as an outbreak progresses. The disease may be spread by ingesting the unpasteurised or uncooked milk of infected animals. There is a higher risk of an outbreak in irrigated areas or if there is surface flooding in savannah or semi-arid areas followed by prolonged rains, if the mosquito populations are high, and if there is concurrent illness. Humans may suffer from influenza-like symptoms which can include fever, headache, muscular pain, weakness, nausea, sensitivity to light, loss of appetite and vomiting. Complications can lead to ocular disease (with loss of vision), meningoencephalitis, hepatitis, haemorrhagic fever and occasionally death. Recommended action if Contact and seek assistance from animal and human health professionals suspected immediately if there is any illness in livestock and/or people. For dead animals, whole blood, liver, lymph nodes and spleen are preferable tissues for detecting the virus. Construct artificial homes or manage for mosquito predators such as bird, bat and fish species. Reduce mosquito breeding habitat: Reduce the number of isolated, stagnant, shallow (2-3 inches deep) areas. Install fences to keep livestock from entering the wetland to reduce nutrient loading and sedimentation problems. In ornamental/more managed ponds: Add a waterfall, or install an aerating pump, to keep water moving and reduce mosquito larvae. Keep the surface of the water clear of free-floating vegetation and debris during times of peak mosquito activity. Vector control (chemical) It may be necessary to use alternative mosquito control measures if the above measures are not possible or ineffective: Use larvicides in standing water sources to target mosquitoes during their aquatic stage. This method is deemed least damaging to non- target wildlife and should be used before adulticides. However, during periods of flooding, the number and extent of breeding sites is usually too high for larvicidal measures to be feasible.

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Cholesteryl esters cheap zovirax 400 mg with amex, comprising 10 to 15 percent of total dietary cholesterol buy zovirax 400 mg otc, are hydro- lyzed by a specific pancreatic esterase order 200 mg zovirax fast delivery. Cholesterol absorption by enterocytes is believed to occur primarily by passive diffusion across a concentration gradient established by the solubilization of cholesterol in bile acid micelles. However, recent evidence has shown that scavenger receptor class B type I is present in the small intestine brush-border membrane where it facili- tates the uptake of micellar cholesterol (Hauser et al. As discussed below, such variability, which is likely due in part to genetic factors, may contribute to interindividual differ- ences in plasma cholesterol response to dietary cholesterol. In addition, cholesterol absorption may be reduced by the cholesterol content of a meal and by decreased intestinal transit time (Ros, 2000). Although fatty acids are required for intestinal micelle formation, there is no strong evidence that fat content (or other dietary constituents such as fiber) has a significant effect on cholesterol absorption. They are not known to have important biological effects in humans at the levels consumed in the diet. An exception is sitosterolemia, a rare genetic disorder that is charac- terized by markedly increased absorption and tissue accumulation of plant sterols and elevated plasma cholesterol levels (Lütjohann et al. Moreover, increased expression of these genes induced by cholesterol feeding may be of importance in limiting cholesterol absorption (Berge et al. The ability of very high intakes of plant sterols to lower plasma cholesterol concentrations by reducing cholesterol absorption may also involve regulation of this trans- port process (Miettinen and Gylling, 1999). The hydrolysis of chylomicron triacylglycerols in peripheral tissues by lipoprotein lipase and subsequent remodeling by lipid transfer proteins yields a “remnant” particle that is internalized by receptors, primarily in the liver, that recognize apoprotein E and perhaps other con- stituents. These genes play a role in cholesterol regulatory pathways, including those involved in cholesterol synthesis that are suppressed by cholesterol (e. Thus, increased hepatic cholesterol delivery from diet and other sources results in a complex admixture of metabolic effects that are generally directed at maintaining tissue and plasma cholesterol homeostasis. All cells are capable of synthesizing cholesterol in sufficient amounts for their structural and metabolic needs. Cholesterol synthesis via a series of intermediates from acetyl CoA is highly regulated. Endogenous cholesterol synthesis in humans is approximately 12 to 13 mg/kg/d (840 to 910 mg/d for a 70-kg individual) (Di Buono et al. Another group of diet-derived sterols with potential biological effects are oxysterols (Vine et al. These cholesterol oxidation products can have major effects on cholesterol metabolism and have been shown to be highly atherogenic in animal models (Staprans et al. Overall, body cholesterol homeostasis is highly regulated by balancing intestinal absorption and endogenous synthesis with hepatic excretion of cholesterol and bile acids derived from hepatic cholesterol oxidation. As an example, many Tarahumara Indians of Mexico consume very low amounts of dietary cholesterol and have no reported developmental or health problems that could be attrib- uted to this aspect of their diet (McMurry et al. The question of whether cholesterol in the infant diet plays some essential role on lipid and lipoprotein metabolism that is relevant to growth and development or to the atherosclerotic process in adults has been diffi- cult to resolve. The idea that the early diet might have relevance to later lipid metabolism was first raised by Hahn and Koldovsky´ (1966) in pre- maturely weaned rat pups and later supported by observations that normal weaning to a high intake of cholesterol resulted in greater resistance to dietary cholesterol in later adulthood (Reiser and Sidelman, 1972; Reiser et al. This led to the hypothesis that cholesterol in human milk may play some important role in establishing regulation of cholesterol homeostasis. Since human milk typically provides about 100 to 200 mg/L (Table 9-1), whereas infant formulas contain very little cholesterol (10 to 30 mg/L) (Huisman et al. Formula-fed infants also have a higher rate of cholesterol synthesis (Bayley et al. Differences in cholesterol synthesis and plasma cholesterol concen- tration are not sustained once complementary feeding is introduced (Darmady et al. Also, no clinically significant effects on growth and development due to these differences in plasma cholesterol concentration have been noted between breast-fed and formula-fed infants under 1 year of age. The effects of early cholesterol intake and weaning on cholesterol metabolism later in life have been studied in a number of different animal species (Hamosh, 1988; Kris-Etherton et al.

This irrationality is not due to lack of knowledge since physicians respond no differently than non- physician patients buy discount zovirax 400mg. This is related to how individuals relate to numbers and how well people understand probabilities order zovirax 200 mg mastercard. In general generic zovirax 200 mg otc, people (including physicians and other health-care providers) do not understand probabilities very well. Physicians tend to give qualitative rather than quantitative expressions of risk in many different and ambiguous ways. From the patient perspective, a rare event happens 100% of the time if it happens to them. Finally, patient values change when they have the disease in question as opposed to when they do not. Patients who are having a stroke are much more willing to accept moderate disability than well persons who are asked about the abstract notion of disability if they were to get a stroke. This means that stroke patients assign a higher value to the utility (U) of residual deficit than well peo- ple asked in the abstract. Most clinical studies of these issues that are now being done have quality-of-life and patient-preference measures attached to possible outcomes. They should help clarify the effects of variations in patient values on the outcomes of decision trees. The health-care provider of the future will seek to use the most cost-efficient methods to care for her or his patients. Cost-effectiveness analysis can be used to help choose between treat- ment options for an individual patient or for large populations. Governments and managed care organizations use cost-effectiveness techniques to justify their coverage for various health-care “products. Health-care providers, policy makers, and insurance- plan administrators must be able to evaluate the validity of these claims through the critical analysis of cost-effectiveness studies. If one treatment costs less and is clearly more effective than the alternative option, there is no question about which treatment to use. Similarly, if the 350 Cost-effectiveness analysis 351 treatment costs more and is clearly less effective, there will also be no question about which to use. Treatment with the most effective treatment modality would proceed for the patient and that would also save money in the process. More often than not, however, the situation arises for which one therapy costs much more and is marginally more effective than a much less expensive therapy or the converse, where one therapy is clearly less effective but is also less expensive. Cost-effectiveness analysis gives us the data to answer the question “how much more will this extra effectiveness cost or how much more will use of the less effec- tive therapy ultimately cost? If one very expensive treatment is beneficial for a few people and we decide to pay for that treatment, we may be unable to afford other equally or more effective treatments that may help many more people. There is only so much money to go around and you can’t spend the same dollar twice! If we fund bone marrow transplants for questionably beneficial indications, we may not be able to pay for hypertension screening leading to treatment that could prevent the need for certain other high cost therapies like kidney or heart organ transplants in the future. A bone marrow transplant may prolong one life by 6 years, yet result in loss of funds for hypertension screening and treatment pro- grams which could prevent six new deaths from uncontrolled hypertension in that same period. Cost-effectiveness analysis should be able to tell if the cost of a new therapy is “worth it” or if we should be paying for some other, cheaper, and possibly more effective therapy. The wealthy can get any medical procedure done regardless of efficacy or cost while the poor must wait for available services. This is known as de-facto rationing and is man- ifested by long waiting times in a municipal hospital emergency department or for an appointment to be examined by a specialist or get diagnostic studies done. In the United States, there may be reduced availability of certain drugs to patients in some managed care organizations, on Medicaid and certainly to uninsured working people who cannot afford to pay for that drug out of their own pockets. The State of Oregon used a type of cost-effectiveness analysis to decide what ser- vices the State Medicaid program should cover. We are constantly making value judgments over how we as a society will spend our money. This chapter will present the tools needed to evaluate studies of cost-effectiveness. However, the manner in which the analysis is set up will have an enormous impact on what kind of result will be obtained.

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