“…Of these, seven studies enrolled ESA-naïve patients (n = 5817, 41%) [33-37, 40, 45], two trials only ESA-treated subjects (n = 498, 4%) [38,39] and those remaining evaluated a mixed population (n = 7863, 55%) [40,[42][43][44]. Efficacy of HIF-PHIs was compared with either placebo (4 trials) [33][34][35][36] or darbepoetin alfa (9 trials) [37][38][39][40][41][42][43][44][45]. Three studies had short duration (9 or 24 weeks, respectively) [36,42,45], 7 trials lasted 52 weeks [33-35, 38-40, 43] and the remaining three were carried out for ≥ 104 weeks [37,41,44].…”