title: Noninvasive Assessment of Excessive Erythrocytosis as a Screening Method for Chronic Mountain Sickness at High Altitude.
abstract: Vyas, Kaetan J., David Danz, Robert H. Gilman, Robert A. Wise, Fabiola León-Velarde, J. Jaime Miranda, and William Checkley. Noninvasive assessment of excessive erythrocytosis as a screening method for chronic mountain sickness at high altitude. High Alt Med Biol 16:162-168, 2015.--Globally, over 140 million people are at risk of developing chronic mountain sickness, a common maladaptation to life at high altitude (>2500 meters above sea level). The diagnosis is contingent upon the identification of excessive erythrocytosis (EE). Current best practices to identify EE require a venous blood draw, which is cumbersome for large-scale surveillance. We evaluated two point-of-care biomarkers to screen for EE: noninvasive spot-check tests of total hemoglobin and oxyhemoglobin saturation (Pronto-7, Masimo Corporation). We conducted paired evaluations of total serum hemoglobin from a venous blood draw and noninvasive, spot-check testing of total hemoglobin and oxyhemoglobin saturation with the Pronto-7 in 382 adults aged ≥35 years living in Puno, Peru (3825 meters above sea level). We used the Bland-Altman method to measure agreement between the noninvasive hemoglobin assessment and the gold standard lab hemoglobin analyzer. Mean age was 58.8 years and 47% were male. The Pronto-7 test was unsuccessful in 21 (5%) participants. Limits of agreement between total hemoglobin measured via venous blood draw and the noninvasive, spot-check test ranged from -2.8 g/dL (95% CI -3.0 to -2.5) to 2.5 g/dL (95% CI 2.2 to 2.7), with a bias of -0.2 g/dL (95% CI -0.3 to -0.02) for the difference between total hemoglobin and noninvasive hemoglobin concentrations. Overall, the noninvasive spot-check test of total hemoglobin had a better area under the receiver operating characteristic curve compared to oxyhemoglobin saturation for the identification of EE as measured by a gold standard laboratory hemoglobin analyzer (0.96 vs. 0.82; p<0.001). Best cut-off values to screen for EE with the Pronto 7 were ≥19.9 g/dL in males and ≥17.5 g/dL in females. At these cut-points, sensitivity and specificity were both 92% and 89% for males and females, respectively. A noninvasive, spot-check test of total hemoglobin had low bias and high discrimination for the detection of EE in high altitude Peru, and may be a useful point-of-care tool for large-scale surveillance in high-altitude settings.
authors.affiliation: 1 Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University , Baltimore, Maryland.
authors.forename: Kaetan J
authors.initials: KJ
authors.lastname: Vyas
authors.affiliation: 2 Biomedical Research Unit, A.B. PRISMA , Lima, Peru .
authors.forename: David
authors.initials: D
authors.lastname: Danz
authors.affiliation: 3 Program in Global Disease Epidemiology and Control, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University , Baltimore, Maryland.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Gilman
authors.affiliation: 1 Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University , Baltimore, Maryland.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wise
authors.affiliation: 4 Departamento de Ciencias Biológicas y Fisiológicas, Laboratorio de Adaptación a la Altura, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia , Lima, Peru .
authors.forename: Fabiola
authors.initials: F
authors.lastname: León-Velarde
authors.affiliation: 5 CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia , Lima, Peru .|6 Departamento de Medicina, Escuela de Medicina, Universidad Peruana Cayetano Heredia , Lima, Peru .
authors.forename: J Jaime
authors.initials: JJ
authors.lastname: Miranda
authors.affiliation: 1 Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University , Baltimore, Maryland.
authors.forename: William
authors.initials: W
authors.lastname: Checkley
mesh_terms: D000328:Adult; D000368:Aged; D000531:Altitude; D000532:Altitude Sickness / Q000097:blood / Q000175:diagnosis*; D002908:Chronic Disease; D005260:Female; D006403:Hematologic Tests / Q000295:instrumentation* / Q000706:statistics & numerical data; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010568:Peru; D019095:Point-of-Care Systems / Q000706:statistics & numerical data*; D011086:Polycythemia / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006454:Hemoglobins
keywords: chronic mountain sickness; excessive erythrocytosis; noninvasive methods; screening