Epidemiology: Brain Tumors and Cellular and Cordless Phones - Essay Example

Running Header: epidemiology No: Question a) Tabular representation of the information. Smokers Non-smokers Total exposed 647 622 1269 Not exposed 2 27 29 Total 649 649 1298 b) Probability of smokers developing lung cancer as compared to non-smokers Relative Risk = population exposed Population non- exposed = 647/649 ÷ 622/649 = 1.04 c) The proportion of lung cancer associated with smoking: a. smokers = 647/649 = 0.99671*100 = 99.7% b. whole population = 647/1298 = 0.4984 * 100= 49.8% d) Name of these measures and interpretation These measures are called odds ratios and relative risk ratios. They are use to compare the likelihood of an event between two groups. For example, in our case study we are comparing the likelihood of lung cancer among smokers and non-smokers. The relative risk comes closer to what most people think of when they compare the relative likelihood of events. The odds compare the relative odds of cancer occurrence in both groups while the relative ratio compares the probability of developing lung cancer in each group rather than the odds. Both the odds ratio and the relative ratios are computed by division and are relative measures. In contrast, absolute measures, computed as a difference rather than a ratio, produce estimates with quite different interpretations. Name: Student No: a) The type of misclassification portrayed in this case study is non- differential and random. The same misclassification occurs in the same proportion in each group. The percentage unto which the cases were underestimated is the same percentage, which the controls were over estimated. These leads to an underestimation of the true association hence the true association cannot be established. b) Risk ratio for the misclassified data Cases Controls Totals Exposed 300 250 550 Non exposed 100 150 250 Total 400 400 800 Rates = 300/400=3/4 and 250/400= 5/8 Risk Ratio = 3/4÷5/8 = 1.2 Risk Ratio for the true results Cases Controls Totals Exposed 360 250 550 Non exposed 40 150 250 Total 400 400 800 Rates = 360/400 = 9/10 and 250/400= 5/8 Risk Ratio = 9/10 ÷ 5/8 = 1.44 A relative risk ratio of more than one indicates that the occurrence of the event at hand is more likely to the experimental group than the control group. This misclassification reduced the relative risk ratio hence reducing the likelihood of the event occurring to the experimental group. This means underestimating the true association. Name: Student No: 1. a. The null hypothesis, there is no connection between brain tumors and cellular and cordless phones. Alternative hypothesis: most brain tumors are caused by an exposure to radio frequencies (RF) between 400 - 2000MHz b. Outcome variables of a study are measurements of population’s current status which might include mean, mode and median of continuous counts of measurements for example radio frequency exposure in megahertz, age, duration of exposure of radiation in hours and type of phone used. Variables measurements Radio frequencies megahertz Age Years Duration of exposure years Ear exposed to RF and duration Right / left and hours c. Study factors (exposures): cellular phone calls radio frequency measure by the kind of phone used, the duration of use and the ear use to receive the call. The second factor is brain tumor measured by anatomical area of the tumor. 2. a. The participation rate in this study is the percentage of the total number targeted that participated in the study =2899/3234*100=89.64%. The high participation rate is one of the characteristic of a good epidemiologic study. This implies that the results of the study are highly representative of the actual population. b. Response rate in survey research refers to the ratio of number of people who answered the survey divided by the number of people in the sample. It is usually expressed in the form of a percentage. The response a rate in this study is 91%. Out of the sample population of 1617, 1470 respondents filled the questionnaires or responded to the research. The response rate is high and the higher the response rate; the more likely the results are representative of the population under study. Therefore, the results of this study are likely to be representative of the population under study. 3. Information bias is a logical error in the measurement of information on outcome or exposure, the study subject may also be categorized wrongly. In a clinical study, information bias arises from misclassification of the level of exposure. Information bias can arise from misunderstanding the interviewer. In this study, information bias is evident in that the recalling of information may differ between the cases and the controls. Cases may tend to recall the past exposures better than the controls. This is possible because individuals with diseases are more concerned about possible causes. Recall bias tends to overestimate the association of the outcome with exposure to a risk factor. In addition, the method of observation used gave skewed results in some nonrandom manner, leading to inaccurate results. The authors have not discussed the possibility adequately, they only show the possibility of the occurrence and the measures they used to prevent information bias that is through using blinded questionnaires but this is not enough to prohibit the recall bias. 4. Participation bias is another type of bias that is likely to affect the results. In that, not all subjects agreed to participate and some of the imaging studies or medical records available for review. Personal time constrain was another factor that possibly led to patients being inadvertently excluded from the study sample. Having only cases with pathological proof of the disease included, the cases of subjects with the disease and those who were image and unable to go through the biopsy or treated elsewhere were excluded from the search of a pathology database. This affected the results in some way, because even though they were to control other types of bias, unidentified differences between the intended sample and the actual sample participating still existed. 5. A confounding factor is an independent variable that distorts the association between another independent variable and the problem under study as it is related to both the variables. In this study microwave, exposure that is a different thing from the absorbed dose by the brain is the potential confounder. In the design stage, data collected on use inn a car with an external antennae or hands free device with an earpiece outside the car was taken as no exposure to microwaves. They also sought to get the frequent of phone use the duration and the ear used and if both were they used equally. In the analysis these aspects have been handled differently and carefully to bring out the significant variables out clearly and automatically. It is an important residual confounding that the people who are exposed to microwaves are at high risk of absorbing them into the brain hence increasing the risk of developing brain tumors. The study subjects were obtained form different geographical regions hence there was a possibility that they contained different genetic make up. These individuals are likely to respond differently to different doses of microwaves or radio frequencies. In this case, if some people are more sensitive to the radio frequencies than others are, the confounding factor is genetic composition and existence of carcinogenic components in the body prior the exposure to the radio frequency. Therefore, the tumor is not directly as a result of RF but presence of pro-carcinogen and genetic factors. 6. Role of chance in epidemiology is the likelihood of what was found being a true finding. The authors have discussed the role of chance in this study; they have made inferences of exact facts and variables. In other words, they have shown zero generalization in this study. This makes the internal validity of the study stronger. They show the evidence of what they did in the study; what they did in the study caused what they observed happen. They have created a clear connection between the two variables. They have shown the association of the variables under study. The outcome is a function of the variables that are measured, controlled or manipulated in the study. 7. Systematic error caused by factors that systematically affect the measurement of the variables across the sample. There is a possibility of temporal sequence of the data. The disease my cure the exposure. The disease can disappear in the latent period of the study, which makes it difficult to calculate the incidence of the disease, the population’s relative risk of attribute risk. High chances of bias are associated with this error hence hard to determine the true association. The causative factors for brain tumors might be because of other factors other than microwaves. 8. In place of case-control type of study used in this particular case, a longitudinal study can be used where subjects are followed over a time with continuous repeated monitoring of the risk factors or the health outcomes or both. This enables the best assessment of exposure and dealing with changes in exposures instead of only handling the changes when formulating the results. It is good for establishing temporal sequence and the natural history f the disease. In addition it helps examine multiple outcomes that are linked to the exposure and find other effects that the hypothetical one. 9. The internal validity of this study is medium. In this study, we cannot accurately state that the independent variable produced the observed effects. In deed, it is prone to a lot of bias both by the respondent and by the interviewer. The exposure and the absorbed dose of microwaves are quite technical to determine that hence the validity of this study is medium. For this reason, the researchers have defined the different kinds of phones that are being used by the study population. The exposure on the other hand may not the only thing that led to development of a brain tumor; the respondents may have had an underlying problem that leads to development of the tumor. 10. The results can only be generalized among the population that uses the analogue and digital cellular phones only. The other population that is exposed to the microwave but not through the cellular phones was not represented in the study population. This is to mean the study was specifically representative to the population defined in the study. Therefore, it cannot be generalized to the population beyond those confines. 11. The data collected in this study shows that radio frequency exposure may have biological effects in target tissues or cells. When cells are expose to Radio frequencies, DNA breakage leads to development of a tumor. These RF are produced by cellular phones that use frequencies between 400 to 2000MegaHertz. Other studies have revealed an increased rat DNA breakage at 2450MHz RF radiation. In general, the study revealed that cellular phone users are at risk of developing brain tumors due to DNA breakage in the exposed tissues especially Ipsilateral analogue cellular phone users. In this study, cases were compared with a reference group hence we had a case control study. In this kind of a study, researchers have the outcome at hand what they are looking for is an exposure. As an epidemiologist, I would recommend a cross- sectional study when dealing with matters of health; this is because cross- sectional study design looks for both outcome and the exposure. This makes a health study more representative of the population and creates opportunities to prevent and control bias. If the population of such a study is, at baseline, divided into two groups, the investigators enforce health interference upon one of the groups. Just as many of the epidemiology researches fails to distinguish a confounder from a mediator is the commonest error. These two variables are hard to differentiate on statistical grounds, they can only be separated from each other on the based on fully understanding of the total disease. In the same way are the results subject to misinterpretation if not well explained or presented to the population. This I recommend education to the public and the population at large of the risks associated with the use of cellular phones in relation to brain tumors. The population should be advised to consider switching between right and left the ears when conversing over the phone for a longer duration, and minimize the number of calls they make from their analogue cellular phones. The ministry of health can use media to inform the public about these potential hazards. The minister being part of the government should push for the banning of ipsilateral analogue cellular phones from the market. This step will help to reduce exposure to lethal Radio frequencies produced by ipsilateral cellular phones. This would come hand in hand with an improvement in technology. To start with, a technology that does not damage the brain cells for example enhanced hands free technology or Bluetooth this may work to reduce the dose of radio frequencies reaching the brains to a point of damaging the cells. Adoption of screening technology to help early detection of the brain tumors for prevention and help the population avoid things that would lead to activation of pro-carcinogen and expose them to the danger of developing brain tumors. The government should also explore the possibilities of developing Radio Frequency free phones. The minister can also push for the development of phones that uses earphones or hands free place of earpiece to minimize the microwaves reaching the ear. Reference: Hardell L, Mild KH and Carlberg M., (2003) Further aspects on cellular and cordless telephones and brain tumours. International Journal of Oncology 22: 399-407. Read More