Treatment change episodes (TCEs) of (A) PI-naïve and NRTI/NNRTI-experienced patients receiving a new regimen containing a ritonavir-boosted PI and (B) NNRTI-naïve and NRTI/PI-experienced patients receiving a new regimen containing an NNRTI. The flow diagrams illustrate the process by which the patients meeting the selection criteria where extracted from the TCE Repository. To reflect the clinical reality in resource limited settings, patients receiving an integrase inhibitor, fusion inhibitor, or maraviroc were excluded. The tables beneath the flow diagrams contain the numbers of patients (n) according to the specific PI/r (A) or NNRTI (B) and the proportions with virological suppression to <50 copies/ml within 48 weeks (virological response; VR). The NRTI GSS was derived using the Stanford HIVdb algorithm (http://hivdb.stanford.edu; accessed January 25, 2012). Abbreviations: PI - protease inhibitor; PI/r - ritonavir-boosted PI; NRTI - nucleoside RT inhibitor; NNRTI - non-nucleoside RT inhibitor; LPV - lopinavir; FPV - fosamprenavir; SQV - saquinavir; IDV - indinavir; ATV - atazanavir; DRV - darunavir; EFV - efavirenz; NVP – nevirapine.