Evaluation of Safety Benefits

3 Approach to Integrated Safety Evaluation Preventive Pedestrian Protection 

The second view is macroscopic. In case more than one event is evaluated, an aggregation of the single events is possible in order to assess the overall effects. If the sample under investigation happens to contain accident and non-accident events, an accident rate or prevention rate can be calculated as ratio of frequency of accidents (or one minus accidents) with a measure by frequency of accidents without the measure. Summary statistics can also be computed in non-accident events by statistically evaluating the indicators defined on the physical level. In comparison to a baseline without measure the change due to a specific safety measure can be evaluated at the desired level of detail. Within the accident group, rates for specific injury severities as well as a fatality rate can be estimated. 

As mentioned above, the appropriate metric depends on the research question as well as on the methodology used in the experiment. Considering, for example, a hardware test with dummies, the metric has to be based on the readings of the dummy. Commonly used physical measurements such as the Head Injury Criterion (HIC) can then be translated into an injury probability, which is a well-known procedure [29]. A comparable approach is feasible using simulation. In a finite-element simulation or a kinematic simulation of collisions, a human model, e.g., the Total Human Model for Safety (THUMS), can be used [30]. 

The two different ways of measurement, i.e., dummy and virtual human model, provide physical data and utilize injury probability models to derive information about injury severities. Another approach is based on the change in injury level, using in-depth accident data and information about the injuries. The so-called Injury Shift Method evaluates the change in single injuries due to a particular measure [31]. Given a statistically significant amount of injury data in the data set, this method allows for a fast calculation of benefits, but compared to other methods mentioned reties on rather crude assumptions as elaborated above (see p. 31). 

State of the art for evaluation on the physiological level are injury probability models (in case detailed collision simulations are not available or feasible). In many cases, e.g., if used in combination with a stochastic simulation, those models provide a translation of physical measurements at the moment of impact into physiological quantities. Considering pedestrians, models currently available are based on the person level (overall injury severity) and are mainly univariate using impact speed of 

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The design and implementation of a preventive system proves to be a challenge for the evaluation of safety benefits due to its internal complexity. The understanding of the basic functions and states of the system is thus necessary and must be included in the model, as they have a large influence on the overall effects. 

Safety auditors should collect the following safety facilities and non-fmancial information related to the project (1) the written request for the project construction units (2) safety preassessment report (3) safety specific report and relevant documentation about project preliminary design (4) written approval of preliminary design safety fadhties of construction projects (5) the project completion report and related construction drawings (6) the safety assessment report (7) safety faciUties construction project completion and acceptance approval letter (8) technicd indicator information apphes to the audited entity s safety faciUties three simultaneous . Safety facilities "three simultaneous" can be audited by audit, supervision, observation, inquiry, confirmation, calculation, analysis and review and other conventional methods of audit. Due to the comprehensive and technology of safety audit project, safety auditors should also use cost-benefit analysis and economic evaluation of safety and other methods. 

This book was written in response to many requests for more information regarding the details of probabilistic evaluation of safety instrumented functions. As the authors have had the great benefit of being asked to perform many such jobs, the problems apparent with previous methods have become clear to us. 

Determining the additional cost of safety measures is also difficult, but it is, however, a conceptually simpler task than the evaluation of the benefit of additional safety measures. 

Especially from the point of view of the last factor, improvement of safety and efficacy of the new products alone has not been enough to justify introducing new CDRF products. Evaluation of economic benefits, costs, and quality of life impact need to be assessed. 

Many types of program evaluation exist. For example, Rossi, Freeman, and Lipsey (1999) distinguish between the following types of program evaluations needs assessment, process evaluation, impact evaluation, cost-benefit or cost-effectiveness analysis, and targeting accuracy evaluation. We focus on the three most common types of evaluations of safety net programs process (or implementation) evaluation, assessment of targeting accuracy, and impact evaluation. Evaluations of cost-benefit and cost-effectiveness are also helpful, but are rare so not treated in depth here (see box 6.4). 

The antiviral properties of anionic polymers have recently received a lot of attention as agents to protect against infection with sexually transmitted diseases. Due to the cationic nature of most viruses, several anionic polymers are known to bind viruses. As early as the 1960s, researchers had studied the anti-viral properties of a variety of synthetic polymers [118]. However, not all anionic polymers inactivate viruses. Several classes of anionic polymers have been studied for their ability to inactivate the HIV virus. These polymers include poly(styrene-4-sulfonate), 2-naphthalenesulfonate-formaldehyde polymer, and acrylic acid-based polymers. Certain chemically modified natural polymers (i.e., semisynthetic) such as dextrin/dextran sulfates, cellulose sulfate, carrageenan sulfate, and cellulose acetate phthalate have also been investigated for this purpose. Of a number of such anionic polymers that have shown in-vitro and in vivo anti-HIV activity, a couple of polymeric drug candidates have proceeded to early stage human clinical trials for the evaluation of safety/tolerability [119]. While most of these have shown the desired tolerability and safety, further clinical trials are necessary to discern the therapeutic benefit and see if anionic polymers will be applicable as anti-HIV therapies. 

Auditing enables management to ensure that their policy is being carried out and that it is having the desired effect. Auditing complements the monitoring prr ramme. Economic auditing of a company is well established as a tool to ensure economic stability and it has been shown that similar systematic evaluation of safety performance has equal benefits. 

Process Hazards Analysis. Analysis of processes for unrecogni2ed or inadequately controUed ha2ards (see Hazard analysis and risk assessment) is required by OSHA (36). The principal methods of analysis, in an approximate ascending order of intensity, are what-if checklist failure modes and effects ha2ard and operabiHty (HAZOP) and fault-tree analysis. Other complementary methods include human error prediction and cost/benefit analysis. The HAZOP method is the most popular as of 1995 because it can be used to identify ha2ards, pinpoint their causes and consequences, and disclose the need for protective systems. Fault-tree analysis is the method to be used if a quantitative evaluation of operational safety is needed to justify the implementation of process improvements. 

As a general rule, clinical data are required as evidence to support conformity with the requirements of the Active Implantable Medical Devices (AIMD) and the Medical Device (MD) directives with regards to safety and effectiveness under the normal conditions of use, evaluation of undesirable side effects, and the acceptability of the benefit/risk ratio. Risk analysis should be used to establish key objectives that need to be addressed by clinical data, or alternatively to justify why clinical data are not required (mainly for Class I devices). The risk analysis process should help the manufacturer to identify known (or reasonably foreseeable) hazards associated with the use of the device, and decide how best to investigate and estimate the risks associated with each hazard. The clinical data should then be used to establish the safety and effectiveness of the device under the intended use conditions, and to demonstrate that any of the residual risks are acceptable, when weighed against the benefits derived from use of the device. 

For any intervention intended to impact favorably upon human health, it is important to evaluate its safety and efficacy in order to demonstrate that it does not cause harm and it does provide the expected benefit. The gold standard method for evaluating any intervention, whether it be a botanical product, dietary supplement, drug, medical device or medical procedure, is the randomized, clinical trial (RCT). A clinical trial is a type of experiment conducted in human subjects where the effects of at least two interventions are compared. Often, the clinical trial takes the form of an active treatment compared to an inactive control or placebo. 

Where possible, it is preferable to demonstrate safety without the application of advanced risk assessment techniques such as QRA, which can be resource intensive, time consuming, and costly. The decision to proceed with QRA should be based on an estimate of the benefits to be derived from such a study. Management should evaluate the expected cost of improving safety against the cost of conducting a detailed QRA to determine if there is potential benefit to performing QRA. If the expected benefits of perform-... 

In order to associate a number to represent the utility of these four outcomes we have to choose between several types of economic evaluations, basically between cost-effectiveness analysis, cost-utility analysis and cost-benefit analysis. The first of these is ruled out because it measures the health outcome in natural units. Given that the side effects of drags are of a varied nature, we need to be able to aggregate the different seriousness of these side effects in order to obtain a single utility, at least for the NSEA event. Furthermore, this utility must be comparable with that of, for example, the SER event. This is not possible with cost-effectivity. If we chose cost-utility, the utility associated with each event would be measured in QALYs gained or lost in each option. As QALYs are a universal measure of health benefit, cost-utility analysis could be appropriate for this type of decision. Lastly, cost-benefit analysis would also be appropriate, as it measures the utilities associated with each outcome in monetary terms, which reflect the willingness to pay for one of the outcomes in terms of safety and effectiveness. 

There is no doubt that the continuing evaluation of the safety of medicines into the post-marketing period is an expanding and stiU developing area of research. Matters relating to safety spread over into efficacy, which together imply risks and benefits which, in the present international climate of healthcare provision, have consequences for outcomes and costs. A whole new field of research - pharmacoeconomics - is in the process of development and it is to be anticipated that many of the methods used for safety evaluation will be modified and applied in this area. 

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