An eGFR blood test is used whenever there is suspicion of a kidney disease. This is usually the case in patients who are suffering from diabetes or from hypertension for a prolonged period of time.
In the case that your APP file doesn't open, it is highly likely that you do not have the correct software application installed on your PC to view or edit APP file extensions. If your PC opens the APP file, but it's the wrong application, you'll need to change your Windows registry file association settings. In other words, Windows is associating APP file extensions with the wrong software program.
This also means that programs like MS Word and Outlook can open the .APPLICATION file only if Internet Explorer is set as the default browser. Other files formats may use a similar file extension, but they really have nothing to do with ClickOnce Deployment Manifest files. For example, APP files may be macOS or FoxPro application files, and APPLET files are used by Eclipse as Java Applet Policy files.