Complex sentence: Compared with levodopa, dopamine agonists may delay the onset of complications of medication use, but are less effective at controlling PD symptoms, though, they are usually effective enough to manage symptoms in the initial years.
Split into simpler sentences: Compared with levodopa, dopamine agonists may delay the onset of complications of medication use, but are less effective at controlling PD symptoms. Nevertheless, they are usually effective enough to manage symptoms in the initial years.