Long Term Cohort Analysis HIV-NAT has one adult long-term cohort (HIV-NAT 006) and pediatric long-term cohort (HIV-NAT 015) studies. From the PREDICT study, one of its substudy is a long-term cohort study (HIV-NAT 035.3; additional information is in the Pediatric section). HIV-NAT also participates in the region’s long-term cohorts for both the adults (TAHOD) and paediatrics (TApHOD). HIV-NAT also participates in the collection, maintenance and analysis of Thailand’s database of HIV infected patients (PROGRESS studies). There is one HPV co-infection cohort study (TNT HIV 003) done with the Thai Red Cross – AIDS Research Centre. There are 2 hepatitis co-infection cohorts (additional information located in the Clinical Research Programs in Co-viral and Viral Infections section). In addition, hepatitis C co-infection cohort is being set up as we speak. There are two studies looking at the effects of syphilis and neurocognitive changes among patients from the 006 cohort. Other target population long-term cohorts are in the pipeline.Long-term cohorts are necessary in order to see the long-term effects of either the drugs and/or infection(s). Most of the studies do not look at long-term effects or over the span of 10 years and hence these cohorts will help elucidate some unanswered questions. Unfortunately the data may be difficult to analyse and compare between studied/analysed groups due to different initial regimens or missing data for some of our older patients. However, with time, additional information are collected as we find out which issues become important but the maintenance of such cohorts are also expensive. HIV-NAT’s hepatitis co-infection cohort is one of the largest in the world and other types of cohorts targeting different populations are in the pipeline.