{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T11:47:14Z","timestamp":1782820034544,"version":"3.54.5"},"reference-count":47,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T00:00:00Z","timestamp":1782777600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medical Sciences"],"abstract":"<jats:p>Background: Evidence on the prognostic utility of biological markers in critically ill patients with COVID-19 across different geographic altitudes remains limited. Objectives: The aim of this study was to determine the prognostic value of inflammatory and hematological markers, particularly the neutrophil-to-lymphocyte ratio (NLR) and mean platelet volume (MPV), for mortality risk in critically ill patients with COVID-19 receiving invasive mechanical ventilation and living at different geographic altitudes. Methods: A multicenter retrospective cohort study was conducted using secondary data from a clinical database. A total of 362 critically ill patients with COVID-19 admitted to intensive care units (ICUs) between April 2020 and March 2022 were included. Patients were treated at three hospitals in Ecuador located at different altitudes: sea level (4 m above sea level [masl]), moderate altitude (2200 masl), and high altitude (2850 masl). Clinical, laboratory, and outcome data were obtained from electronic medical records. Results: The mean age was 54.44 years, and 71.27% of patients were male. Post hoc, altitude-stratified NLR and MPV thresholds were associated with increased odds of ICU mortality: at sea level, NLR \u2265 12.50 and MPV \u2265 8.80 fL; at moderate altitude, NLR \u2265 11.50 and MPV \u2265 9.80 fL; and at high altitude, NLR \u2265 16.30 and MPV \u2265 9.00 fL. Conclusions: In mechanically ventilated patients with critical COVID-19, NLR and MPV values above post hoc, altitude-stratified cutoff points were associated with higher ICU mortality. However, because each altitude stratum corresponded to a different hospital and these thresholds were not ROC-derived or internally\/externally validated, these findings should be interpreted as exploratory and hypothesis-generating.<\/jats:p>","DOI":"10.3390\/medsci14030363","type":"journal-article","created":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T10:01:17Z","timestamp":1782813677000},"page":"363","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Variation of the Neutrophil-to-Lymphocyte Ratio and Mean Platelet Volume in a Multicenter Study of Critically Ill Patients with COVID-19 Living at Different Altitudes"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6392-3895","authenticated-orcid":false,"given":"Pablo Andr\u00e9s","family":"V\u00e9lez-P\u00e1ez","sequence":"first","affiliation":[{"name":"Facultad de Ciencias M\u00e9dicas, Universidad Central del Ecuador, Quito 170403, Ecuador"},{"name":"Unidad de Terapia Intensiva, Hospital de Especialidades Quito N\u00b0 1 de la Polic\u00eda Nacional, Quito 170525, Ecuador"},{"name":"Unidad de Terapia Intensiva, Centro de Investigaci\u00f3n Cl\u00ednica, Hospital Pablo Arturo Su\u00e1rez, Quito 170315, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6956-4475","authenticated-orcid":false,"given":"Jorge Luis","family":"V\u00e9lez-P\u00e1ez","sequence":"additional","affiliation":[{"name":"Facultad de Ciencias M\u00e9dicas, Universidad Central del Ecuador, Quito 170403, Ecuador"},{"name":"Unidad de Terapia Intensiva, Centro de Investigaci\u00f3n Cl\u00ednica, Hospital Pablo Arturo Su\u00e1rez, Quito 170315, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Iv\u00e1n","family":"Best","sequence":"additional","affiliation":[{"name":"Carrera de Medicina, Facultad de Ciencias de la Salud, Universidad San Ignacio de Loyola, Lima 15024, Peru"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luis Arturo","family":"Herrera-Le\u00f3n","sequence":"additional","affiliation":[{"name":"Hospital General Ibarra, Ibarra 100104, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pedro","family":"Ren\u00e9-Torres","sequence":"additional","affiliation":[{"name":"Facultad de Medicina, Universidad T\u00e9cnica del Norte, Ibarra 100150, Ecuador"},{"name":"Empresa P\u00fablica de Salud Universitaria del Norte, Hospital Universitario, Ibarra 100101, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jorge","family":"Vasconez-Gonzalez","sequence":"additional","affiliation":[{"name":"One Health Research Group, Universidad de las Americas, Quito 170124, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1178-0546","authenticated-orcid":false,"given":"Juan S.","family":"Izquierdo-Condoy","sequence":"additional","affiliation":[{"name":"One Health Research Group, Universidad de las Americas, Quito 170124, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1895-7498","authenticated-orcid":false,"given":"Esteban","family":"Ortiz-Prado","sequence":"additional","affiliation":[{"name":"One Health Research Group, Universidad de las Americas, Quito 170124, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"191","DOI":"10.5498\/wjp.v13.i4.191","article-title":"COVID-19 Pandemic in the Intensive Care Unit: Psychological Implications and Interventions, a Systematic Review","volume":"13","author":"Monti","year":"2023","journal-title":"World J. 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