Serum creatinine trajectories in real-world hospitalized patients: clinical context and short-term mortality.

Fluctuations in serum creatinine (SCr) during hospitalization may provide additional prognostic value beyond baseline renal function. This study aimed to identify groups of patients with distinct creatinine trajectories over hospital stay and assess them in terms of clinical characteristics and short-term mortality. This retrospective study included 35 853 unique adult admissions to a tertiary referral center between January 2012 and January 2016 with at least three SCr measurements within the first 9 days of stay. Individual SCr courses were determined using linear regression or linear-splines model and grouped into clusters. SCr trajectories were described as median SCr courses within clusters. Almost half of the patients presented with changing, mainly declining SCr concentration during hospitalization. In comparison to patients with an increase in SCr, those with a significant decline were younger, more often admitted via the emergency department, more often required a higher level of care, had fewer comorbidities and the more pronounced the fall in SCr, the greater the observed difference. Regardless of baseline renal function, an increase in SCr was related to the highest in-hospital mortality risk among compared clusters. Also, patients with normal renal function at admission followed by decreasing SCr were at higher risk of inpatient death, but lower 90-day postdischarge mortality than patients with a stable SCr. Acute changes in inpatient SCr convey important prognostic information and can only be interpreted by looking at their evolution over time. Recognizing underlying causes and providing adequate care is crucial for improving adverse prognosis.