The reported proportions, however, could not be meaningfully compared to each other, because the definition of retention, the length of time during which participants were enrolled in a study (enrolment period), and the length of time between the end of the enrolment period and the time when retention results were observed (lag time) varied widely across studies.
Ninety-two parefusednto refused to participate and 14 participants died before enrolment, resulting in a study population of 599 participants at the age of 85 years (response rate 87%).
Alternatively, participation in a study may increase health care utilization due to improved rapport with physicians as suggested in a report of persons enrolled in a study of traumatic events where higher rates of health care utilization was found following 12-month enrolment in a research study [ 21].
From July 12, 2017 to September 2, 2017, women either in pregnancy or who have delivered in the previous 7 days were prospectively screened at the Maternal and Child Department, Careggi University Hospital for enrolment in a retrospective cohort study, still ongoing.
Actively approaching counseling means that, after enrolment in the study, a trained counselor contacted the informal caregiver by telephone.
These results are in accordance with findings from a study of the effect of selective enrolment in a large population-based study of pregnant women [ 8].
4 6 16 17 Indeed, we have shown that including prevalent patients, that is, patients with PAH already diagnosed at the time of enrolment in the study, was a bias as it led to an improved survival of the cohort.
We also expect a better enrolment in the study if the patients have a twofold chance of being allocated to the laparoscopic group as the reduced morbidity seems to be substantial.
Patients who completed the 12-week treatment period were offered enrolment in a long-term extension study, NCT01118728.
Women were intentionally over sampled in the control group at all ages to accommodate their simultaneous enrolment in a parallel case-control study of ovarian cancer [ 24].
