In-hospital mortality in elderly patients with acute kidney injury requiring dialysis: a cohort analysis

Seasonal pattern in elderly hospitalized with acute kidney injury: a retrospective nationwide study in Italy

Purpose

Acute kidney injury (AKI) frequently complicates hospitalization and is associated with in-hospital mortality (IHM). It has been reported a seasonal trend in different clinical conditions. The aim of this study was to evaluate the possible relationship between seasons of the year and IHM in elderly hospitalized patients with AKI.

Methods

We selected all admissions complicated by AKI between 2000 and 2015 recorded in the Italian National Hospital Database. ICD-9-CM code 584.xx identified subjects with age ≥ 65 years and age, sex, comorbidity burden, need of dialysis treatment and IHM were compared in hospitalizations recorded during the four seasons. Moreover, we plotted the AKI observed/expected ratio and percentage of mortality during the study period.

Results

We evaluated 759,720 AKI hospitalizations (mean age 80.5 ± 7.8 years, 52.2% males). Patients hospitalized with AKI during winter months had higher age, prevalence of dialysis-dependent AKI, and number of deceased patients. In whole population IHM was higher in winter and lower in summer, while the AKI observed/expected ratio demonstrated two peaks, one in summer and one in winter. Logistic regression analysis demonstrated that parameters such as age, autumn, winter, comorbidity burden were positively associated with IHM.

Conclusion

We conclude that a seasonality exists in AKI, however, relationship between seasons and AKI could vary depending on the aspects considered. Both autumn and winter months are independent risk factors for IHM in patients with AKI regardless of age, sex and comorbidity burden. On the contrary, summer time reduces the risk of death during hospitalizations with AKI.

[Baseline characteristics of nonagenarians hospitalised due to acute kidney injury compared to other age groups]

BACKGROUND

The increase in life expectancy leads to higher hospitalisation rates in elderly patients. The aim of this work is to study the characteristics of the population over 90 years of age that are admitted due to acute kidney injury (AKI).

MATERIAL AND METHODS

A cross-sectional study was conducted that included all patients admitted to hospital with AKI in the years 2013 and 2014. Epidemiological characteristics, comorbidity, medication and baseline analytical data were collected, and a comparison was made between patients with age over 90 years-old and the others.

RESULTS

A total of 1733 patients were included, of whom 264 (15%) were over 90 years-old. A significantly higher proportion of these patients were women. The most frequent cause of AKI in patients older than 90 years was functional (81%) (p < 0.001 compared to other age groups). The main cause of hospital admission was infection. In the group of over 90 years of age, a higher prevalence was found for arterial hypertension (p = 0.005), chronic kidney disease (p = 0.014), congestive heart failure (p = 0.006), and cognitive impairment (p < 0.0001). The baseline glomerular filtration rate by CKD-EPI was lower in the group of patients older than 90 years (p < 0.0001). Patients under 90 years admitted to hospital due to AKI, had a higher prevalence of diabetes mellitus (p < 0.001), dyslipidaemia (p < 0.001), history of neoplasia (p < 0.001), and a higher Barthel index (p < 0.0001).

CONCLUSIONS

Nonagenarians admitted due to AKI have functional aetiology as the most common factor. These patients have a higher prevalence of hypertension, heart failure, chronic kidney disease, low functional status, and more cognitive impairment.