Sander is 67 years old with a long history of knee osteoarthritis for which he self medicates regularly with over-the-counter (otc naproxen. he is in the clinic today complaining of a swallowing difficulty that has progressively worsened over the past several months. he has otherwise been healthy and has not seen a doctor in many years. he denies significant past medical history. a review of systems is negative except for arthritic symptoms and swallowing difficulty. he denies noticing blood in his stool or vomiting blood. he denies history