This older patient's clinical findings are most likely the result of adverse medication effects related to polypharmacy, and her drug regimen requires adjustment. She has significant medical comorbidities and is taking numerous drugs. Administration of multiple medications increases the risk for inappropriate use, drug-drug interactions, adverse reactions, poor adherence, and medication errors. This patient is taking two anticholinergic agents (oxybutynin for urinary incontinence and the over-the-counter antihistamine loratadine). The American Geriatrics Society Beers Criteria recommend against the use of anticholinergic agents in older patients because they can cause confusion, urinary retention, constipation, and dry mouth. She is also on the proton pump inhibitor omeprazole without an apparent indication for treatment. In addition, the risk-to-benefit ratio of using a lipid-lowering agent to confer long-term benefits must be reassessed in very elderly adults. Prescriptions for statins are frequently carried over from previous years, but statin use results in additional cost, extra pills, and increased risk for drug-drug interactions. Lastly, parameters for blood pressure control are less stringent in older adults, and, in this patient, antihypertensive agents should be reassessed, as her hypertension is overtreated. Ongoing review of the indications, risks, benefits, and dosing of all drugs in older patients is recommended.

This patient has a history of mild chronic kidney disease; however, with normal volume status, normal electrolytes, and a minimal change in her serum creatinine level, she does not have evidence of significant worsening of her kidney function. This would make acute kidney injury an unlikely cause of her current clinical findings.

Infections are a frequent cause of systemic symptoms, including weakness, dizziness, anorexia, and altered mental status in older patients, with pneumonia and urinary tract infection being the most common types. However, this patient has no clinical findings consistent with pneumonia given her normal oxygenation, leukocyte count, and chest radiograph, or suggestion of urinary tract infection with a normal urinalysis. Therefore, the absence of evidence of infection makes this an unlikely cause of her current clinical findings.