Morbidity, mortality and economic burden of renal impairment in cardiac intensive care

• Published in: Internal medicine journal Vol. 36; no. 3; pp. 185 - 192
• Main Authors: Chew, D. P., Astley, C., Molloy, D., Vaile, J., De Pasquale, C. G., Aylward, P.
• Format: Journal Article
• Language: English
• Published: Melbourne, Australia Blackwell Publishing Asia 01-03-2006; Blackwell Science
• Subjects: Adult; Aged; Aged, 80 and over; Analysis of Variance; Australia; Biological and medical sciences; cardiology; Cardiovascular Diseases - diagnosis; Cardiovascular Diseases - economics; Cardiovascular Diseases - mortality; Cardiovascular Diseases - therapy; Cause of Death; chronic renal disease; Coronary Care Units - economics; Coronary Care Units - statistics & numerical data; Coronary Disease - diagnosis; Coronary Disease - mortality; Coronary Disease - therapy; Cost of Illness; Cost-Benefit Analysis; Creatinine - urine; Female; General aspects; Glomerular Filtration Rate; Health Care Costs; Heart Failure - diagnosis; Heart Failure - mortality; Heart Failure - therapy; Humans; Kidney Failure, Chronic - diagnosis; Kidney Failure, Chronic - economics; Kidney Failure, Chronic - mortality; Kidney Failure, Chronic - therapy; Kidney Function Tests; Linear Models; Male; Medical sciences; Middle Aged; mortality; Multivariate Analysis; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; Probability; Proportional Hazards Models; Renal failure; Retrospective Studies; Risk Assessment; Severity of Illness Index; Survival Analysis; Australia; Kidney disease; Costs; Intensive care; Urinary system disease; Mortality; Cardiovascular disease; Chronic kidney disease; Epidemiology; Morbidity; Medicine; Heart disease; Health economy; Renal failure; Economic aspect; Cardiology; chronic renal disease
• ISSN: 1444-0903; 1445-5994
• DOI: 10.1111/j.1445-5994.2006.01012.x

Background: Moderate to severe impairment of renal function has emerged as a potent risk factor for adverse short‐ and long‐term outcomes among patients presenting with cardiac disease.
Aims: We sought to define the clinical, late mortality and economic burden of this risk factor among patients presenting to cardiac intensive care.
Methods: A clinical audit of patients presenting to cardiac intensive care was undertaken between July 2002 and June 2003. All patients presenting with cardiac diagnoses were included in the study. Baseline creatinine levels were assessed in all patients. Late mortality was assessed by the interrogation of the National Death Register. Renal impairment was defined as estimated glomerular filtration rate <60 mL/min per 1.73 m2, as calculated by the Modified Diet in Renal Disease formula. In‐hospital and late outcomes were compared by Cox proportional hazards modelling, adjusting for known confounders. A matched analysis and attributable risk calculation were undertaken to assess the proportion of late mortality accounted for by impairment of renal function and other known negative prognostic factors. The in‐hospital total cost associated with renal impairment was assessed by linear regression.
Results: Glomerular filtration rate <60 mL/min per 1.73 m2 was evident in 33.0% of this population. Among these patients, in‐hospital and late mortality were substantially increased: risk ratio 13.2; 95% CI 3.0–58.1; P < 0.001 and hazard ratio 6.2; 95% CI 3.6–10.7; P < 0.001, respectively. In matched analysis, renal impairment to this level was associated with 42.1% of all the late deaths observed. Paradoxically, patients with renal impairment were more conservatively managed, but their hospitalizations were associated with an excess adjusted in‐hospital cost of $A1676.
Conclusion: Impaired renal function is associated with a striking clinical and economic burden among patients presenting to cardiac intensive care. As a marker for future risk, renal function accounts for a substantial proportion of the burden of late mortality. The burden of risk suggests a greater potential opportunity for improvement of outcomes through optimisation of therapeutic strategies.