Which condition increases a client's risk for complications following blood transfusions?

The condition that significantly increases a client's risk for complications following blood transfusions is a history of allergic reactions. Individuals with this history are more likely to experience transfusion-related allergic reactions, which can range from mild symptoms, such as urticaria and itching, to more severe anaphylactic responses.

Patients with a documented history of allergic reactions may have heightened sensitivity to foreign proteins present in the donor blood, which can lead to complications during or after the transfusion. This provides a clear rationale for closely monitoring these patients when they receive blood products and potentially premedicating them with antihistamines or corticosteroids to mitigate such risks.

While other factors like the presence of an infection, chronic kidney disease, and advanced age can contribute to the overall complexity of patient management during transfusions, they do not specifically increase the likelihood of transfusion reactions in the same direct manner. Thus, a history of allergic reactions stands out as a particularly critical risk factor in this context.