MO331: Acute Kidney Failure as a Risk Factor for Longer Hospital Stay, Renal Replacement Therapy and Mortality: A Public Health System Analysis Free

Acute kidney failure (AKI) is a well-known risk factor in coronary care unit (CCU) and postoperative patients. We aim to analyse their role in a multicentre database (DB) from a public regional health system (6 million inhabitants).

Observational, retrospective study, including all hospital admissions between January 2013 and December 2014 in all referral hospitals in Madrid. We grouped into three categories, admissions due to AKI (ON-AKI), AKI during stay (HOSP-AKI) secondary to other disease and admissions without AKI (no-AKI); ICD-9 code was 584. Admission from patients aged under 16, women to give birth or previous renal replacement therapy (RRT) were excluded. Study was approved by the ethics committee.

Of the 419 851 admissions registered in 2 years, 6.7% had an associated AKI (0.6% on arrival AKI and 6.1% during admission AKI). Patients admitted for AKI are older (ON-AKI: 74.8 years versus HOSP-AKI: 77.9 versus no-AKI: 63.6), with greater comorbidity (Charlson index 2.9 versus 3.1 versus 1.7); patients had more previous CV events (28.5% versus 46.8 versus 21.0), diabetes mellitus (34.1% versus 30.4 versus 17.1) and a higher prevalence of previous chronic kidney disease-CKD (41.3 versus 31.5 versus 4.9%). AKI kidney failure lengthens hospital stay by 3.2 days 95% confidence interval (95% CI) (2.8–3.5) after adjust by age, gender, Charlson index, surgery and major diagnostic categories.

Admissions with AKI are usually unscheduled and have a longer hospital stay (9.6 ON-AKI versus 12.6 HOSP-AKI versus 7.1 days in no-AKI admission). More patient died during hospital stay in AKI group (14.4% ON-AKI; 22.9 HOSP-AKI versus 3.5% No-AKI) and although 4.3% of admission needed dialysis, only 0.5% started a chronic RRT during admission.

Principal risk factor for developing secondary AKI (R² = 16%) is previous CKD [OR 3.6; (3.48–3.74)], after corrected by age, male, the Charlson index and non-surgical admission.

Mortality risk for patients with an admission for AKI (R² = 17%), corrected for age, sex, comorbidity, previous CKD, and type of admission is OR: 1.8 95% CI (1.57–2.08); secondary AKI is OR 3.73 (3.59–3.88) than no-AKI admission.

AKI is a huge burden for health system and patients, and associates significant longer stay, cost and a higher mortality. Main factor to develop secondary AKI is age and previous CKD.