Transient Azotaemia: High Risk of Death in Hospitalized Patients
Transient Azotaemia: High Risk of Death in Hospitalized Patients
Background. There are no suitably powered epidemiological studies of 'transient azotaemia' (TA). The objective of this study was to describe the epidemiology of TA and its independent association with hospital mortality. We hypothesized that TA would be associated with an independent increase in the risk of death.
Methods. We retrospectively studied all patients admitted to a university-affiliated hospital in Australia between January 2000 and December 2002. Patients were excluded if they were <15 years old, were on chronic dialysis, had kidney transplant or if their length of hospital stay was <24 hours. We defined TA as rapidly recovering acute kidney injury (AKI) (return to no-AKI risk, injury, failure, loss, end stage (RIFLE) class within 72 hours of onset). We performed descriptive and comparative statistical analysis of data. The primary outcome of the study was the association between TA and hospital mortality in multivariate logistic regression analysis.
Results. Among 20 126 study patients, 3641 (18.1%) had AKI according to the RIFLE criteria and 1600 had AKI, which recovered during their hospital stay. Recovery of AKI occurred most commonly within 1 day after diagnosis (37.7%, n = 603). Furthermore, 1172 patients (73.3%) who recovered from AKI did so within 3 days (TA). After correcting for confounding factors, compared with patients without AKI, patients with TA had a significantly higher odds ratio for hospital mortality (2.26; 95% confidence interval: 1.85–2.76).
Conclusions. Transient azotaemia is common in hospital patients, represents close to a third of all cases of AKI and is independently associated with a significantly higher risk of death.
Acute kidney injury (AKI) is common in hospitalized patients, and its associated mortality is high. The causes of AKI are commonly divided into three groups: pre-renal, intra-renal and post-renal. Within the group of patients with pre-renal failure, a typical further clinical subdivision is then applied depending on the speed of recovery from AKI. According to this paradigm, such transient azotaemia (TA) represents a separate entity characterized by a rapidly reversible increase in serum creatinine. This rapid reversibility is believed to reflect a functional reduction in glomerular filtration without established structural kidney injury (so-called acute tubular necrosis or ATN), which instead leads to sustained AKI. These two causes have been reported to account for 66% to 75% of all cases of AKI.
Early differentiation of TA from ATN is considered clinically important, and multiple studies have been conducted to deal with the issue of differential diagnosis, using urinalysis, serum and urinary biochemistries and ultrasound. These studies argue that TA is a benign condition, which, unlike ATN, does not carry a significant independent association with increased mortality. However, there are no suitably powered epidemiological studies of TA to establish its incidence and possible independent association with outcome.
We hypothesized that TA is common in hospital patients and that it carries an independent association with hospital outcome. We tested these hypotheses using a large database of hospitalized patients from an academic medical centre.
Abstract and Introduction
Abstract
Background. There are no suitably powered epidemiological studies of 'transient azotaemia' (TA). The objective of this study was to describe the epidemiology of TA and its independent association with hospital mortality. We hypothesized that TA would be associated with an independent increase in the risk of death.
Methods. We retrospectively studied all patients admitted to a university-affiliated hospital in Australia between January 2000 and December 2002. Patients were excluded if they were <15 years old, were on chronic dialysis, had kidney transplant or if their length of hospital stay was <24 hours. We defined TA as rapidly recovering acute kidney injury (AKI) (return to no-AKI risk, injury, failure, loss, end stage (RIFLE) class within 72 hours of onset). We performed descriptive and comparative statistical analysis of data. The primary outcome of the study was the association between TA and hospital mortality in multivariate logistic regression analysis.
Results. Among 20 126 study patients, 3641 (18.1%) had AKI according to the RIFLE criteria and 1600 had AKI, which recovered during their hospital stay. Recovery of AKI occurred most commonly within 1 day after diagnosis (37.7%, n = 603). Furthermore, 1172 patients (73.3%) who recovered from AKI did so within 3 days (TA). After correcting for confounding factors, compared with patients without AKI, patients with TA had a significantly higher odds ratio for hospital mortality (2.26; 95% confidence interval: 1.85–2.76).
Conclusions. Transient azotaemia is common in hospital patients, represents close to a third of all cases of AKI and is independently associated with a significantly higher risk of death.
Introduction
Acute kidney injury (AKI) is common in hospitalized patients, and its associated mortality is high. The causes of AKI are commonly divided into three groups: pre-renal, intra-renal and post-renal. Within the group of patients with pre-renal failure, a typical further clinical subdivision is then applied depending on the speed of recovery from AKI. According to this paradigm, such transient azotaemia (TA) represents a separate entity characterized by a rapidly reversible increase in serum creatinine. This rapid reversibility is believed to reflect a functional reduction in glomerular filtration without established structural kidney injury (so-called acute tubular necrosis or ATN), which instead leads to sustained AKI. These two causes have been reported to account for 66% to 75% of all cases of AKI.
Early differentiation of TA from ATN is considered clinically important, and multiple studies have been conducted to deal with the issue of differential diagnosis, using urinalysis, serum and urinary biochemistries and ultrasound. These studies argue that TA is a benign condition, which, unlike ATN, does not carry a significant independent association with increased mortality. However, there are no suitably powered epidemiological studies of TA to establish its incidence and possible independent association with outcome.
We hypothesized that TA is common in hospital patients and that it carries an independent association with hospital outcome. We tested these hypotheses using a large database of hospitalized patients from an academic medical centre.
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