Mrs. Johnson is an 82-year-old widow living alone in her two-story home. She has a history of hypertension, osteoarthritis, and mild cognitive impairment. Mrs. Johnson prefers to age in place and maintain her independence. She receives weekly visits from a home health aide and occasional help from her daughter, who lives nearby. During a routine visit, the home health aide notes that Mrs. Johnson has had a few minor falls recently and has been forgetting to take her medications on time. She also appears to have lost some weight and seems more withdrawn than usual. Which of the following is the most important initial assessment to address Mrs. Johnson's recent falls?