Final answer:
The nurse should monitor for decreased bone density as an adverse reaction to long-term treatment of prednisone for rheumatoid arthritis.
Step-by-step explanation:
The nurse should monitor the client who has a new prescription for prednisone for the long-term treatment of rheumatoid arthritis for several possible adverse drug reactions. The most likely adverse effect from this list is decreased bone density. Long-term use of corticosteroids, like prednisone, can lead to a condition known as steroid-induced osteoporosis. Therefore, the correct answer is 4) Decreased bone density.
Prednisone can also lead to other adverse effects such as increased blood pressure, hyperglycemia (increased blood sugar levels), and susceptibility to infection due to its immunosuppressive effects, which can reduce the ability to fight off infections. Given prednisone's role in suppressing the immune response, this could also lead to an unexpected increase in white blood cell count as a reactive process, but this is not considered a common direct adverse effect of the drug like bone density reduction is.