Prognostic importance of low baseline serum creatinine levels in patients admitted to medical intensive care unit

Serum creatinine level, which has been universally used to estimate glomerular filtration rate, has also been proposed as a surrogate marker for muscle mass becausecreatinine generation can be altered in persons with variable skeletal muscle mass. Therefore, it has been suggested that there is a relationship between low creatinine level and mortality among patients admitted to intensive care units (ICU). The objective of this study was to evaluate theassociation between low serum creatinine level at admission and mortality in medical ICU. This was a retrospective single-center cohort study conducted at Adıyaman University Medical Faculty Training and Research Hospital, Medical ICU. We searched our hospital database to identify all adult patients (18 years) admitted to medical ICU. Patients who had stayed longer than 24 hoursin medical intensive care unit were included in the study. Age, sex, albumin, creatinine levels, length of stay were included in the analyzes. Admission serum creatinine level was categorized into 7 groups: 0.4 (group 1), 0.5-0.6 (group 2), 0.7-0.8 (group 3), 0.9-1.0 (group 4), 1.1-1.2 (group 5), 1.3-1.4 (group 6), and 1.5 mg/dL (group 7). Cox regression analysis was performed to obtain the hazard ratio of in-ICU mortality for the various admission creatinine levels, using creatinine value of 0.7-0.8 mg/dL as the reference group. Of 2.359 included patients, 699 (29.6%) died in the medical ICU. The association between different categories of admission creatinine value and in-ICU mortality assumed a "U-shaped" distribution, with both low and high creatinine values associated with higher in-ICU mortality. At low creatinine level (creatinine 0.4 mg/dl), the mortality rate was 71.4% in males and 10.7% in females (p<0.001). In cox regression analysis, group 1 and group 2 were significantly associated with increased mortality (HR:0.721, 95% CI; 0.555-0.936, HR: 0.509, %95 CI; 0.285-0.909, respectively). Low admission serum creatinine level is associated with increased in-ICU mortality and lower survival in patients, admitted in medical ICU. Key words: Serum Creatinine Level, Mortality, Medical Intensive Care Unit