| Associated    factors | 
        Definition | 
        All patients 
          (n° 409) | 
        HC 
          (n° 63) | 
        Controls  
          (n° 346) | 
        p | 
      
      
        | Age (median ± SD) | 
          | 
          | 
        72.9 ± 13.17 | 
        68.9 ± 14.8 | 
        0.02 | 
      
      
        Gender  
          Male  
          Female  | 
          | 
        
            60.9% 
          39.1% | 
        
            60.3% 
          39.7% | 
        
            61% 
          39% | 
        0.70 | 
      
      
        Admission diagnosis 
           | 
        
            Elective surgery-planned ICU admission  
              Elective surgery-unplanned ICU admission  
              Surgical emergency  
          Medical | 
        
            47.4% 
              4.1% 
              18.6% 
          29.8% | 
        
            33.3% 
              7.9% 
              22.2% 
          36.5% | 
        
            53.8% 
              3.7% 
              17.9% 
          24.6% | 
        
            0.001 | 
      
      
        | SAPS II score (median ±    SD) | 
          | 
          | 
        32 ± 16.4 | 
        36.4 
          ± 14.9 | 
        0.05 | 
      
      
        | Cigarette smoking | 
        > 40 packs year | 
        0.03% | 
        17.5% | 
        0.3% | 
        0.001 | 
      
      
        | Cancer | 
        Neoplastic lesion, with or without    metastasis,  
          treated or untreated | 
        39.4% | 
        52.4% | 
        37% | 
        0.021 | 
      
      
        | Vasculopathy | 
        Claudicatio intermittens, arterial bypass,     
          vascular gangrene, arterial insufficiency,  
          untreated chest or abdominal    aortic aneurysm | 
        29.1% | 
        39.7% | 
        27.7% | 
        0.044 | 
      
      
        | Coronary artery disease | 
        Stress test or pharmacological inducible     
          chest pain, history  
          of Acute Myocardial Infarction/angina | 
        8% | 
        15.9% | 
        6.6% | 
        0.049 | 
      
      
        | Chronic atrial fibrillation | 
        Chronic Atrial Fibrillation | 
        11.7% | 
        19% | 
        10.4% | 
        0.050 | 
      
      
        | Hypertension | 
        SBP>140 and/or DBP>90 | 
        51.3% | 
        66.7% | 
        48.5% | 
        0.068 | 
      
      
        | PTCA/CABG | 
          | 
        5.3% | 
        6.3% | 
        2.3% | 
        0.081 | 
      
      
        | Chronic Renal Failure  | 
        Creatinine clearance less than 90 ml/min/m2 | 
        8.8% | 
        11.1% | 
        8.4% | 
        0.095 | 
      
      
        | Chronic liver failure | 
        Hepatitis for more than three months,    with or without  
          presence of cirrhosis    or its complications | 
        6.6% | 
        7.9% | 
        6.4% | 
        0.23 | 
      
      
        | OSAS (Obstructive Sleep Apnea Syndrome) | 
          | 
        0.7% | 
        1.6% | 
        0.6% | 
        0.38 | 
      
      
        | DM (Diabetes Mellitus) | 
        ADO or insulin therapy or diabetes-related    complications | 
        23.2% | 
        30.2% | 
        22% | 
        0.48 | 
      
      
        | Myocardial infarction | 
          | 
        14.1% | 
        9.5% | 
        15% | 
        0.44 | 
      
      
        | Stroke/TIA | 
          | 
        3% | 
        8% | 
        2% | 
        0.49 | 
      
      
        | Heart Failure | 
        Progressive dyspnea, according to NYHA classes | 
        13.4% | 
        7.9% | 
        14.4% | 
        0.83 | 
      
      
        | COPD | 
        Progressive dyspnea, with or without specific     
          therapy, with or 
          without home oxygen therapy, with hypoxemia 
          and/or 
          chronic    hypercapnia | 
        40% | 
        38.1% | 
        40.5% | 
        0.94 |