No association between excessive erythrocytosis and CMS score at 5100 m. (A-C) Individual intravascular volumes of participants categorized into no CMS (CMS⁻) and CMS (CMS⁺) with the CMS score including the [Hb] criterion. Erythrocytosis was determined by RBCV measurement. The effect of altitude was assessed with a Kruskal-Wallis test including all participants. Pairwise comparisons using a Mann-Whitney U test with Bonferroni correction were performed and visualized with brackets above the graphs. The effect of CMS at 3800 m or 5100 m was assessed with a Mann-Whitney U test with $P < .01 vs CMS⁻. Lines indicate median and interquartile range. (D-F) Individual intravascular volume data from all residents at 5100 m showing associations of intravascular volumes with the CMS score excluding the [Hb] criterion. Linear regression analysis was performed with β indicating the age-adjusted regression coefficient calculated from log-transformed data. β and P values for regression analysis with the CMS score including the [Hb] criterion were as follows: RBCV: β = 0.506, P = .130; PV: β = −0.762, P = .041; BV: β = 0.292, P = .499. For panel (E), the P value of the regression analysis was P = .111 when the individual with a score of 15 was removed from the analysis. (G) The distribution of CMS symptom severity between the 2 cities with different altitude with *P < .001 between 3800 m (Puno) and 5100 m (La Rinconada). The numbers on the right of the graph indicate the symptoms’ severity. BV, blood volume; PV, plasma volume.