Injuries in the Elderly

Injuries in the Elderly

Introduction

The incidence rate of acute kidney injury (AKI) is highest in elderly patients, who make up an ever-growing segment of the population at large. AKI in these patients is associated with an increased risk of short- and long-term death and chronic kidney disease, including end-stage renal disease. Whether AKI in older individuals carries a larger relative risk for these outcomes compared with younger individuals is unclear at this time. Other domains, such as health-related quality of life, may be mildly impacted on after an episode of AKI. No effective therapies for AKI currently are available for widespread use. However, because the incidence of AKI is highest in the elderly and the phenotype is not discernibly different from AKI in all populations, future randomized controlled trials of interventions for AKI should be performed in the elderly population.

Acute kidney injury (AKI; formally referred to as acute renal failure) is increasingly common in the population at large and is associated with significant morbidity, mortality, and health care costs. In hospitalized patients, the risk of death associated with AKI is increased 3- to 6-fold compared with those without AKI.1 Despite significant advances in health care technology during the past several years, the incidence of AKI appears to be increasing over time. This may be related to more aggressive medical and surgical therapies that result in stress to the kidney, the increasing number of comorbid conditions in the population that accumulate during an increasing life span, and the older age of the population at large. In the developed world, the increase in life expectancy has resulted in a continuous growth of the population older than 70 years.2 The segment of the population in which the incidence of AKI has been increasing the most rapidly is those with advanced age. Thus, it is likely that the aged population will yield the greatest potential for successful studies of possible interventions for AKI.

Risk Factors for AKI in Elderly Individuals

The higher incidence of AKI in elderly persons potentially can be attributed to the following factors: (1) comorbid conditions that accumulate with age may facilitate AKI (eg, renovascular disease and congestive heart failure); (2) comorbid conditions may necessitate procedures, drugs, or surgery that function as kidney stressors and nephrotoxins; and (3) the kidney undergoes age-dependent structural and functional alterations over time. The result of the latter is decreased glomerular filtration rate (GFR) at baseline and diminished kidney reserve in the setting of pathophysiologic challenges, making elderly patients very vulnerable to acute stress and more likely to develop clinically relevant AKI.

• Decrease in total renal mass

• Glomerulosclerosis

• Decrease in active cortical parenchyma

• Thickening of glomerular basement membrane

• Mesangial expansion

• Decrease in amount and length of tubules

• Thickening of large-vessel walls

• Decrease in renal blood flow (10%decade at age >40 y)

• Decrease in GFR (1 mLminy at age >45 y)

• Blunted nitric oxide production

• Decreased maximum osmolality

• Increased susceptibility to apoptosis

• Decrease in renal growth factors (EGF, IGF-1, VEGF)

Abbreviations: EGF, epidermal growth factor; GFR, glomerular ...