Robustness of Evidence - Essay Example

Q a) In order to assess the robustness of any evidence, it is important that such evidence must be hierarchical in nature. (Gerrish & Lacy, 2006). Evidence can be considered as robust if it follows a "systematic review of multiple randomized controlled trials" (Gerrish & Lacy, 2006). Lyme disease vaccination is considered as the beneficial process for patients with the moderate risk of attracting infections. (Goldhagen & Rawlings, 2001). Shadick and Colleagues conducted the cost benefit analysis of same vaccination. However; the evidence which derived such calculations may not entirely be robust in its strict sense. The studies conducted by Shadick and colleagues focused on assessing the cost effectiveness of the vaccination against the Lyme disease by developing a decision analytic model. However, the evidence gathered for such an experiment may be not being considered as robust as it may seem because the probabilities and costs used by Shadick and Colleagues were taken from the literature which may not be considered as entirely satisfactory as it may seem. Further, best estimates were used on the base case analyses whereas the ranges used in sensitivity analysis were considered as clinically plausible only. Further, the evidence for compliance and risk effects were taken from relatively newer and recent trials which may not have considered as entirely satisfactory and untested due to lack of time tested empirical proofs. Further the evidence for cost effectiveness and management of Lyme disease were taken from one study only and the dollar values were updated up to 1998 only which may not entirely be considered as entirely accurate and relevant. Based on the above, it may be easily inferred that the evidence may not entirely be considered as robust as it lacks in many areas which were conceptually not corrected/designed according to the relevant economic variables. Q#1(b) At Eight years with 3% rate, the discount rate to be used is 0.789. Q#1(c) Any health state rated between zero and one can be rated as death or equivalent and perfect health whereas anything below zero on visual analogue scale may be termed as worse than death therefore based on three given states of A, B, C at 0.1, 0.45, 0.8, we can assign a utility of death or equivalent because all the utilities are greater than zero but less than one. Therefore, the utility assigned to all three states are effectively representing one state because all three are less than one and greater than zero. Q#1(d) An incremental cost effectiveness ratio (ICER) can be less than $40,000/- per quality adjusted year only if the persistence of vaccination efficacy is considered at three years. The traditional studies suggested that the cost effectiveness ratio, under two year time horizon of vaccination efficacy, the overall cost reach to $105,000/QALY. However, when this time horizon is stretched to three years, the incremental cost effectiveness ratio can reach up to $29,600/QALY. It is also important to note that Shadick & Colleagues took a radically larger efficacy period as in comparison to traditionally used. Q#1(e) With the increase in the vaccination cost by 100% i.e. from $150 to $300, the overall cost saving/QALY would decrease and the program would have moved up into the league table indicating smaller cost savings from the vaccination. The cost saving however is taken in terms of the costs averted while using the given vaccination. Q#2 Shadick and Colleagues considered a decision analytic model as one of the valid tools for making economic evaluation. Decision analytic tool is used when the intention of the researcher is to make justifiable and defendable decisions. Since, economics always involves a relative degree of abstraction therefore it sometimes becomes critical that such model for economic valuation is used which can provide researchers considerable degree of comfort while defending assessments made. (Arsham, 1994). Making comparison with earlier studies provide a peer reviewed evidence which can help researchers to take on the research further. Shadick and Colleagues also taken such an approach by citing previous research studies which attempted to address the same research questions. The study of Meltzer et.al also focused on assessing the cost effective analysis of the Lyme diseases in terms of the dollar cost averted on such a vaccination. Shadick and Colleagues are not only confirming the results of Meltzer et.al studies but also further extended the research findings. One of the main advantages of citing such an economic valuation therefore provides a better understanding of the conceptual evidence which has already been provided. Comparison also allows to fill the gaps left behind by previous studies. Therefore, by making a solid economic evaluation, not only a better understanding is developed but also already available evidence is counter checked for accuracy and further research opportunities. Further economic evaluation which has been undertaken by Shadick and Colleagues also include extending the focus and scope of different economic variables. For example, for assessing the efficacy of the vaccination trials, Shadick & Colleagues increased the number of efficacy years in order to further assess what future possibilities and probabilities can be driven by increasing the value of any economic variable. Shadick also considered the work done by Nichol and coworkers. However, Shadick's work contained slight variations in order to drive significantly different results from the studies conducted by Nichol and coworkers. Generally, Shadick's work has used the same economic variables however with differing rates so in order to achieve the desired research objectives of assessing the impact of vaccination of Lyme disease infection over non-vaccination of the same. Q#3 Studies conducted by Shadick and Colleagues as well as Nichol and coworkers basically attempted to under the cost effectiveness of the Lyme disease. However, the focus and direction of both the studies may be considered as different as both the studies employed different methods of economic evaluation to reach at relatively similar research objectives. Shadick referred to the studies of Nichol and Coworkers while assessing and assigning the utility weights to the different Lyme disease clinical states. Shadick used the power transformation as a method to convert the rating scores to utilities. However, Shadick and colleagues assigned relatively lower utilities to different variables undertaken. Further, Shadick considered Visual Analogue State or VAS as a rating scale to assess the different utilities to be assigned under different health states of the patients. VAS scales help to cover the entire spectrum of the values on the rating scales. Therefore, it provides a general tendency to cover almost all the health states through which a patient can pass through. It is because of this reason that VAS is considered as easy to use besides providing a high response rate. This provides a relatively more scientific credibility to the studies conducted by Shadick as they are based on a very defendable research methodology. It is however important to note that method used by Nichol provides an inbuilt assessment of opportunity cost which is certainly lacking in VAS method. Further, there are serious problems regarding the ordinal ranking in VAS as it fails to take into account proper ordinal ranking of utilities by the patients. The time trade off task method adopted by Nichol and coworkers however provide better results where higher durations are set as in comparison to the studies of Shadick which selected relatively smaller values. (Pinto et.al. 2003). Further, time trade off task is easier to understand as well as based on the choices made by the patients by addressing quantity versus quality trade off. However; it still lacks to account for the risk into its estimates whereas tradeoff is considered at constant proportion. References 1. Gerrish, Kate, Lacey, Anne (2006). The Research Process in Nursing. 5th ed. New York: Blackwell Publishing. 497 2. Goldhagen, Harry, Rawlings, MS Julie. (2001). Lyme disease Controversies. Available: http://www.medscape.com/viewarticle/418442. Last accessed 24 January 2009. 3. Arsham, Hossein. (1994). Tools for Decision Analysis:. Available: http://home.ubalt.edu/ntsbarsh/opre640a/partIX.htm#rwida. Last accessed 24 January 2009 4. Bleichrodtg, Han, Pinto, Jose Luis and Abellan-Perpianc, Jose Maria. (2003). A consistency test of the time trade-off. Journal of Health Economics. 22 (6), 1037-1052 Read More