They added that there had been no significant health hazard among the children during the first 18-month follow-up period.
During the follow-up period, which lasted an average of two years, 602 patients died.
The study says 160 people, or 55% of the participants, died during an average follow-up period of 14 years.
The follow-up period was between 24 and 62 months with a mean of 37 months.
Do not miss any scheduled visits to your doctor during this follow-up period.
During an average four-year follow-up period, about 8% of participants had developed memory problems.
During a follow-up period that ranged for two to 29 years, there were 8,478 strokes.
During the 15-year follow-up period, 27 people died of natural causes.
Improvement was maintained over a follow-up period of six months.
But 55 participants - about 18% of the entire group - died during the follow-up period.