Complex sentence: In the United Kingdom use of Allergen Immunotherapy has reduced significantly since the late 80's due to studies that showed the risk of death was much higher than previously thought, therapy in asthmatic patients is considered particularly dangerous and is rarely used in the UK.
Split into simpler sentences: In the United Kingdom use of Allergen Immunotherapy has reduced significantly since the late 80's due to studies that showed the risk of death was much higher than previously thought. Therapy in asthmatic patients is considered particularly dangerous and is rarely used in the UK.