title: Higher platelet cytochrome oxidase specific activity in surviving than in non-surviving septic patients.
abstract: BACKGROUND
  In a previous study with 96 septic patients, we found that circulating platelets in 6-months surviving septic patients showed higher activity and quantity of cytochrome c oxidase (COX) normalized by citrate synthase (CS) activity at moment of severe sepsis diagnosis than non-surviving septic patients. The objective of this study was to estimate whether COX specific activity during the first week predicts 1-month sepsis survival in a larger cohort of patients.
  
  
  METHODS
  Using a prospective, multicenter, observational study carried out in six Spanish intensive care units with 198 severe septic patients, we determined COX activity per proteins (COXact/Prot) in circulating platelets at day 1, 4 and 8 of the severe sepsis diagnosis. Endpoints were 1-month and 6-months mortality.
  
  
  RESULTS
  Survivor patients (n = 130) showed higher COXact/Prot (P < 0.001) than non-survivors (n = 68) at day 1, 4 and 8 of severe sepsis diagnosis. More than a half of the 6-months survivor patients showed an increase in their COXact/Prot from day 1 to 8. However, most of the 1-month non-survivors exhibited a decrease in their COXact/Prot from day 1 to 8. Multiple logistic regression analyses showed that of platelet COXact/Prot > 0.30 mOD/min/mg at day 1 (P = 0.002), 4 (P = 0.006) and 8 (P = 0.02) was associated independently with 1-month mortality. Area under the curve of COXact/Prot at day 1, 4 and 8 to predict 30-day survival were 0.70 (95% CI = 0.63-0.76; P < 0.001), 0.71 (95% CI = 0.64-0.77; P < 0.001) and 0.71 (95% CI = 0.64-0.78; P < 0.001), respectively.
  
  
  CONCLUSIONS
  The new findings of our study, to our knowledge the largest series reporting data about mitochondrial function during follow-up in septic patients, were that septic patients that survive 1-month have a higher platelet cytochrome oxidase activity at moment of sepsis diagnosis and during the first week than non-survivors, and that platelet cytochrome oxidase activity at moment of sepsis diagnosis and during the first week could be used as biomarker to predict the clinical outcome in septic patients.
authors: Leonardo
authors: L
authors: Lorente
authors: María M
authors: MM
authors: Martín
authors: Esther
authors: E
authors: López-Gallardo
authors: Ruth
authors: R
authors: Iceta
authors: José
authors: J
authors: Blanquer
authors: Jordi
authors: J
authors: Solé-Violán
authors: Lorenzo
authors: L
authors: Labarta
authors: César
authors: C
authors: Díaz
authors: Alejandro
authors: A
authors: Jiménez
authors: Julio
authors: J
authors: Montoya
authors: Eduardo
authors: E
authors: Ruiz-Pesini
mesh_terms: D015415:Biomarkers / Q000097:blood; D001792:Blood Platelets / Q000201:enzymology*; D003576:Electron Transport Complex IV / Q000097:blood*; D006801:Humans; D007362:Intensive Care Units; D008928:Mitochondria / Q000201:enzymology; D010085:Oxidative Phosphorylation; D011379:Prognosis; D011446:Prospective Studies; D018805:Sepsis / Q000175:diagnosis / Q000201:enzymology* / Q000401:mortality; D017741:Survivors
chemical_list: D015415:Biomarkers; D003576:Electron Transport Complex IV