Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 43 9 2014 09 15 1248 58 Leila Jahangiry 1. Dept. of Health Education and Health Promotion, School of Public Health, Tabriz University of Medical Sciences , Tabriz, Iran. Davoud Shojaeizadeh 2. Dept. of Health Education and Health Promotion, School of Public Health, Tehran University of Medical Sciences , Tehran, Iran. Ali Montazeri 3. Mental Health Research Group, Health Metrics Research Center, Iranian Institutesfor Health Sciences Research, ACECR , Tehran, Iran. Mahdi Najafi 4. Tehran Heart Center, Tehran University of Medical Sciences , Tehran, Iran. Kazem Mohammad 5. Dept. of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences , Tehran, Iran. Mehdi Yaseri 5. Dept. of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences , Tehran, Iran. 2015 10 15 The aim of this study was to determine adherence and attrition rates in a lifestyle intervention for people with metabolic syndrome.Adherence and attrition data from a randomized controlled trial were collected. Participants were classified as adherence group if they completed assessments at 3 and 6 months follow-up and as attrition group if they did not. Physical activity and quality of life was measured using the International Physical Activity Questionnaire (IPAQ) and the Short Form Health Survey (SF-36). Generalized Estimating Equations (GEE) was used to explore predictors of attrition.The mean age of participants (n=160) was 44.1 years. Attrition rate in the intervention and control groups at first follow-up were the same (20%). However, the control group had significantly higher attrition rate (%33.7) compared to the intervention group (%20) at 6 months follow up. Results showed that low educated participants were more likely to not stay in the study than better educated participants (OR=2.95,CI:1.39-6.33,P=0.05). According with length of the study, attrition was decreased at six month (OR=0.66,CI:0.52-0.83,P<0.001). Also, some aspects of health-related quality of life contributed to the attrition rate. Those who had higher scores on general health (OR=0.66,CI:0.54-0.97,P=0.023), social functioning (OR=0.44,CI:0.40-0.76,P=0.032), role emotional (OR=0.74,CI:0.54-0.98,P=0.18), vitality (OR=0.55,CI:0.38-0.90,P=0.015) and mental health (OR=0.63,CI:0.45-0.85,P=0.033) were more likely to stay in the study.It remains a concern that Web-based lifestyle programs may fail to reach those who need it most. Participant in the study generally had better quality of life than those who were lost to follow up. https://ijph.tums.ac.ir/index.php/ijph/article/view/3928 https://ijph.tums.ac.ir/index.php/ijph/article/download/3928/3589