Contrast Results

The results for Length of stay are identical to the results from the previous model. However, the results for Log-cost are different from those for Treatment costs. The significance values for both contrasts are less than 0.05, suggesting that the differences in costs between the newer drugs and streptokinase are not due to chance. The contrast estimate for the difference between reteplase and streptokinase is 0.0217. Since you are looking at differences in log-transformed cost, this means that the ratio of costs is exp(0.0217) = 1.0219. That is, the ratio of the costs incurred by patients given reteplase is approximately 2.19 percent higher than the costs incurred by patients given streptokinase. If the typical MI patient incurs 25,000 to 35,000 dollars in treatment costs, that means reteplase patients incur, roughly, an extra 550 to 770 dollars in costs. The contrast estimate for the difference between alteplase and streptokinase is 0.0243. Since you are looking at differences in log-transformed cost, this means that the ratio of costs is exp(0.0243) = 1.0246. That is, the ratio of the costs incurred by patients given alteplase is approximately 2.43 percent higher than the costs incurred by patients given streptokinase. If the typical MI patient incurs 25,000 to 35,000 dollars in treatment costs, that means alteplase patients incur, roughly, an extra 600 to 860 dollars in costs.

These contrast results show that while alteplase and reteplase do seem to reduce patient length of stay, the reduction is not enough to equalize the treatment costs. Thus, determining whether alteplase and reteplase should be used in place of streptokinase will require further study of the cost of these drugs versus their effectiveness at increasing the success of surgery.

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