Therapeutic Erythrocytapheresis Is Effective in Treating High Altitude Polycythemia on the Qinghai-Tibet Plateau

Introduction-High altitude polycythemia (HAPC) is a common chronic disease at high altitudes. It is characterized by excessive erythrocytosis (2190 g.L-1 in females or 2210 g.L-1 in males). HAPC severely jeopardizes the health status of plateau dwellers. The Qinghai-Tibet plateau, with an elevation above 4000 m, is the highest plateau in the world. Both Han and Tibetan populations residing there face the threat of HAPC. Therapeutic erythrocytapheresis (TE) was introduced to Tibet as an alternative to phlebotomy in 2015. Methods-In this study, we retrospectively analyzed 155 patients with HAPC treated with TE in Tibet. Routine blood testing values before and after TE were compared to evaluate treatment efficacy. The efficiency rate, defined as the rate of increase in red blood cell depletion attained by TE compared with 450 mL whole blood phlebotomy, was calculated using whole blood volume and hematocrit before and after treatment and used to identify patients who maintained a normal hemoglobin level in the year after the TE procedure. Results-On average, TE reduced red blood cell levels by 1.5x10(12).L-1, hemoglobin concentration by 52 g.L-1, and hematocrit by 14% (P<0.001 for each). Patients who underwent TE with an efficiency rate 21.9 were more likely to maintain a normal hemoglobin level in the following year than those who underwent TE with an efficiency rate <1.9 (90 vs 28%, P<0.01). Conclusions-TE is a feasible therapeutic method to treat HAPC on the Qinghai-Tibet plateau. The efficiency rate is a useful tool to predict the expected interval between TE procedures.