This is important . It is important to go to appointments with elderly parents. Many times elderly parents do not communicate well with doctors. They may not tell the doctor everything that is going on. They are of the generation that does not ask questions. Many of their problems are complicated and elderly parents don't understand, or don't tell their families what is going on. If you can't go then call doctor.
Information. The complexity of the medical issues and the ability of the elder to absorb information should be the determinig factor whether the senior needs a person to accompany them. Other reasons may be if there is bad news, having another person there for support and information sharing is important.