The economic impact of acute kidney injury in England. 
Acute kidney injury (AKI) is one of the most common complications affecting hospital inpatients around the world.  It is associated with high mortality and adverse long-term outcomes, but there is uncertainty regarding its prevalence and cost.  We estimate the prevalence of AKI in hospital inpatients in a universal health-care system, and the immediate and long-term impacts on survival, quality of life and health-care costs.  We examined prevalence of AKI in inpatients using both routine national data for the National Health Service (NHS) in England, and laboratory data from East Kent Hospitals.  We used regression analyses to estimate the impact of AKI on mortality and length of hospital stay, and a Markov model to estimate the impact on quality-adjusted life years and NHS costs.  AKI was recorded in 2.43% of hospital admissions in Hospital Episode Statistics (HES), but age- and gender-standardized estimates derived from laboratory data suggest the true prevalence may be more than five times as high (14.15%).  We estimate that the annual number of excess inpatient deaths associated with AKI in England may be above 40,000.  The annual cost of AKI-related inpatient care in England is estimated at £1.02 billion, just over 1% of the NHS budget.  The lifetime cost of post-discharge care for people who had AKI during hospital admission in 2010-11 is estimated at £179 million.  AKI prevalence in inpatients may be considerably higher than previously thought, and up to four fifths of cases may not be captured in routine hospital data.  AKI is associated with large numbers of in-hospital deaths and with high NHS costs.  Comparison of HES and East Kent data suggests that most of the cases recorded in HES may be relatively severe AKI (AKIN 2-3).