More than 700 doctors nationwide wrote prescriptions for elderly and disabled patients in highly questionable and potentially harmful ways, according to a report of Medicare's drug program released Thursday. The review by the inspector general of the Department of Health and Human Services flags those doctors as "very extreme" in their prescribing and says Medicare should do more to investigate or stop them. The study mirrors a ProPublica investigation published in The Washington Post last month. That report found that Medicare had not protected patients from doctors and other health-care professionals prescribing large quantities of potentially harmful, disorienting or addictive drugs.