Sensitivity Analysis

The probabilities and costs entered into the decision tree are based solely on the physician's estimates. The model is not intended to be published, convey absolute truths, or convince anyone but the physician involved in the management of this particular patient. As the example tries to demonstrate, such analysis relies primarily on the clinician's own assessment of the medical issues involved. In most cases the decision could be derived without digressing into an extensive study of the scientific literature or an elaborate cost analysis. The parameters built into a model are supposed to represent only crude estimates of the true values, reflecting the physician's medical understanding and using his or her current knowledge in the best and most efficient fashion. Potential uncertainties about relevant decision parameters can then be addressed by a subsequent sensitivity analysis.

In a sensitivity analysis, all questionable parameters are varied over a wide range to test their influence on the initial decision. The physician may not know, for example, how much the annual treatment with a COX-2 drug actually costs. The current value of $1,200 is only a crude estimate. In the subsequent sensitivity analysis, the drug cost entered into the first gray box on the right is, therefore, varied between $0 and $3,000. The outcome of the analysis is shown in the right panel of Figure 2-2. Negative values of the y-axis represent a cheaper COX-2 than PPI treatment strategy. An increase in COX-2 drug costs shifts the balance towards the PPI branch and changes the decision in its favor. When the COX-2 drug cost exceeds $1,902, the PPI strategy becomes the preferential treatment option.

Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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