There are four primary stages in the progression of pain.  The first stage or acute stage generally lasts up to three months during which time there are no apparent psychological changes.  The second phase of pain is referred to as a subacute phase and typically lasts from three to six months. During this stage, the patients may become apprehensive if the pain does not diminish.  After six months, the patient in the third or chronic stage of pain usually begins to experience symptoms of anxiety.  The fourth phase, the subchronic stage, is characterized by preoccupation with depression and physical complaints.  As the pain becomes more chronic, the focus on treatment becomes less important and the approach to the psychosocial factors becomes more important.