2.1.1 Introduction
This chapter introduces the user to the user interface and basic functionality of the ITC application.
2.1.2 In this chapter
2.2.1 Introduction
The ITC application is launched either from the disk or from your desktop.
2.3.1 Introduction
The ITC application has been developed in Visual Basic to assist with various calculations associated with indirect comparisons.
When entering data, you can tab from one cell to the nex |
2.3.2 Screen 1: Main Window
The ITC application consists of two windows. On the first window, the effect measure of interest is identified. Information for each consecutive pair of treatments is entered in terms of the point estimate and 95% confidence interval (CI) of the effect measure for each direct comparison involved in the indirect comparison. The resulting indirect comparison estimates for the effect measure and the 95% CI as well as the P value for the test of association corresponding to this effect measure are provided.
Figure 1: Main Window
2.3.3 Effect Measure
2.3.4 Number of Treatments
The order of entry of the treatment pairs must follow the exact sequence indicated with the bridging comparison groups linking the treatment pairs.
For example, if 1 = Treatment A, 2 = Treatment B, and 3 = Treatment C, then (1,2) is (A,B), and for (2,3) we can enter (C,B) and use the reverse option to switch it to (B,C). This option can be useful when B is a placebo and the results are given as the active treatment versus placebo (i.e., A versus Placebo[B] and C versus Placebo[B]).
2.3.5 Toolbars
The toolbars on the main window allow you to calculate, clear, import, and save your data as well as exit the application.
Table 1: Main Window Toolbars
Button | Description |
Calculate |
When all data has been entered, returns the desired calculations. |
Clear |
Clears all data from the main window. |
Save |
Allows the user to save the data (*.txt file). |
Open |
Allows the user to import previously saved data. |
Exit |
Closes the application without saving the data. |
2.3.6 Screen 2: Requested Weights Window
If the test of association is needed, the weights used for the calculation of each weighted average estimate from the main window are required for its calculation. The requested weights window is accessed by clicking the arrow to the right of the corresponding information for each consecutive pair of treatments.
The requested weights window calculates the weighted effect measure for the direct comparison on the main window. These weights are needed to calculate the test statistic for the test of association. There are various formats in which the information to calculate these weights can be provided, and these formats are identified through the weight selections (direct versus derived; fixed versus random), and the specific information for each study involved in the direct comparison is then identified and requested.
The desired Weight is chosen by selecting the corresponding option button.
The option is available to enter the weights directly. In particular, if the effect estimate is based on one study, then a single weight of 1 can be entered.
The weights can also be computed from first principles, based on the frequencies (for RR, odds ratio, and risk difference) or the standard errors (for mean difference), using either the fixed or random effects model, or the general inverse method.
Figure 2: Requested Weights Window
2.3.7 Toolbar
The toolbar on the requested weights window allows you to save your data and close the window, or clear your data.
Button | Description |
Close | Saves data and closes the window. |
Clear | Clears all data from the window. |