A 72-Year-Old Woman with Moderate Dementia Is Brought to the Physician

A 72-year-old woman with moderate dementia is brought to the physician by her son for weight loss and poor appetite over the last 4-5 months.  She eats small amounts and often refuses to eat due to abdominal cramping and back pain after meals.  She has no vomiting but does have constipation.  The patient has lost 7 kg (15 lb) during this period.  Computed tomography scan of the abdomen 1 month ago showed no masses.  Her past medical history is also significant for coronary artery disease requiring bypass graft 10 years ago, congestive heart failure, lacunar stroke, and hypertension.  Her medications include metoprolol, lisinopril, aspirin, simvastatin, and donepezil.  She is an ex-smoker with a 40-pack-year history.  She needs assistance with most activities of daily living.
The patient's blood pressure is 114/62 mm Hg, pulse is 68/min, and respirations are 14/min.  She appears well groomed and answers questions appropriately.  Cardiac examination shows a right carotid bruit.  Lungs are clear to auscultation bilaterally.  The abdomen is soft with mild diffuse tenderness to palpation.  Rectal examination shows guaiac-negative brown stool.  There is trace bilateral pedal edema.  The remainder of the examination is within normal limits.
Laboratory results are as follows:

Upper gastrointestinal endoscopy and colonoscopy show mild esophagitis and sigmoid diverticulosis.
Which of the following is the most appropriate next step in management of this patient?

A) Aggressive diuresis to reduce bowel wall edema
B) Capsule endoscopy for small-bowel evaluation
C) Magnetic resonance angiography of the abdomen
D) Megestrol and nutritional supplements
E) Mirtazapine and nutritional supplements