BackgroundAs many longitudinal studies, follow-up in the ANRS-PEDIACAM study is disrupted by repeated absences of participants to scheduled visits. This lead to missing data which influence the quality of results. We describe reasons for participants absence or non-compliance (NC) and assess the influence of phone call reminders (CR) on retention in care.MethodsFrom November 2007 to 2011, 611 infants divided in three groups were included and followed in three referral hospital in Cameroon: HIV-infected children followed from the first week of life or not but diagnosed before seven month of life (n=210), HIV-uninfected children born to HIV-infected (HEU) (n=205) mothers or not (HUU) (n=196). From 2014 to 2017, CR were reinforced to record reasons of missing visits. we used frequency, chi-square or Fisher test for categorical variables; means, median (IQR) and non-parametric Kruskal Wallis test for continuous variables. A multistate transition modelling approach was used to analyse the retention care cascade. The R software was used to perform all statistical analysis.ResultsDuring the study period, 45.1% (246/546) of children were NC at least once of which 16.3% (25/153), 58% (116/200), 54.4% (105/193) respectively among HIV-infected, HEU and HUU-children. Among NC, 69.5% (171/246) has been reachable at least once and 22.2% (38/171) of them returned to follow-up after a median delay of 32 days (IQR: [2.0 – 110]); 44.4% (109/246) were not seen throughout the study period (HIV-infected: 12/153, HEU-children: 57/200, HUU-children: 40/193). A total of 276 reasons have been reported among 54%(115/213) of the NC, mainly related to delocalisation (30.4%), lack of time (23.6%), wish to stop follow-up (11.6%), travelling (9.8%), schooling (9.4%), forgetting (7.2%). Comparing before and after period, CR allowed to divided by three adjusted relative risk ratio to miss one clinical visit (RRR [CI]: 0.35[0.24 – 0.52]), However CR effect was not significant among children who are non-compliant.ConclusionOur finding suggest that maternal HIV and socio-economic status are related to attendance of children in HIV care. Also, the CR are an effective strategy to improve attendance. However, to make this strategy effective for children who are non-compliant, it needs to be strengthened by community monitoring.