Elevated red cell distribution width is an indicator for chronic mountain sickness in high altitude polycythemia patients: A retrospective study.

INTRODUCTION

Chronic mountain sickness (CMS) is featured by high altitude polycythemia (HAPC) with clinical symptoms and transition from HAPC to CMS represents dynamic continuum. Red cell distribution width (RDW), reflecting hypoxia, has been reported in altitude diseases. We explore a potential link between RDW and CMS in HAPC patients.

METHODS

Ten-year HAPC patients were enrolled in West China Hospital. CMS clinical symptoms were collected from medical records. Multivariable logistic regression and triple-knot restricted cubic splines analysis were employed to examine relationship between RDW and CMS clinical symptoms.

RESULTS

Among 200 HAPC patients, 71 had CMS symptoms. CMS patients showed elevated red cell distribution width standard deviation (RDW-SD) (56.38 ± 11.72 vs 50.77 ± 7.00; p = 0.002) and red cell distribution width coefficient of variation (RDW-CV) (17.37 ± 3.74 vs 15.87 ± 2.56; p = 0.010). In logistic analysis, higher RDW group (dichotomized by the median) predicted CMS (RDW-SD: OR = 2.17[1.15-4.08], p = 0.016), with stronger association at ≥ 4500m (RDW-CV: OR = 3.57[1.01-12.57], p = 0.047). RDW-SD exhibited linear association overall (p for overall = 0.002; p for nonlinear = 0.194) and very high altitude, but nonlinear at < 4500m.

CONCLUSION

Elevated RDW is an indicator for presence of CMS clinical symptoms in HAPC patients, especially in very high altitude subgroup.