Planning clinical-endpoint trials in patients with HIV remain difficult as long-term follow-up of many patients is required. Cohort studies of patients with HIV can provide key estimates of the likely disease progression, required sample size and follow-up.
Royal Free Centre for HIV Medicine, Dept Primary Care and Population Sciences, Royal Free and University College Medical School, Royal Free Campus, Rowland Hill St, London NW3 2PF, UK. a.mocroft@pcps.ucl.ac.uk