Complex sentence: Compliance rates during closely monitored studies are usually far higher than in later real-world situations: for example, there may be up to 97% compliance in some studies on statins, but only about 50% of patients continue at six months.
Split into simpler sentences: Compliance rates during closely monitored studies are usually far higher than in later real-world situations. For example, there may be up to 97% compliance in some studies on statins, but only about 50% of patients continue at six months.