In medical studies, treatments are tested within a group of study participants. You will be given a sentence of a study report in which your task is to list the phrases that give information about the participants of the study. You should list the phrases in the same order that they appear in the text, separated by commas. If no information about the participants is mentioned, just output "not found". Relevant information about participants include: gender, medical conditions, location, number of people participating. Do not contain participant mentions without relevant information.

Approximately two thirds were smokers and were randomized to be tested after either a 12-hr nicotine deprivation or administration of nicotine gum .
two thirds were smokers

Outcome results applied to life expectancy tables were used to estimate QALYs .
not found

The mean hematocrit of the subjects ( 26.23±2.03 % ) at the end of the study was also higher , p < 0.001 .

not found