]AGS 38:25-30, 1990

Incidence and Prognosis of Acute Renal Failure in Older Patients v

J. Pascual, MD, L. Orofino, MD, F. Lialio, MD, R. M a r c h , MD, M. T. Naya, MD, L. Orte, MD, and J. Ortulio, PhD

Few studies have assessed the prevalence and outcome of acute renal failure (ARF) in the elderly. Among 437 ARF cases prospectively studied during a nine-year period in a nephrology department, 152 (35%)occurred in patients over 70 years of age (Group 1). Patients over 70 account for only 10.5% of all hospital admissions in our county, and prevalence of ARF was 3.5 times higher in these patients than in younger people. Acute tubular necrosis (ATN) was diagnosed in 40% of Group 1 and 52% of the younger patients (Group 2) (P < .05),whereas prerenal ARF was found in 47% and 32%, respectively (P < .001). Dehydration was the most frequent cause of prerenal ARF in the elderly (51%). The etiological distribution of ATN was similar in both groups, being of multifactorial origin in most cases. Oliguria was present in 49% of

ATN in Group 1 and in 66% of Group 2 (P < .05).There were no significant differences in dialysis needs. Mortality was higher in the elderly in all types of ARF, although differences did not reach statistical significance. Need for dialysis, mechanical respiration, decreased level of consciousness, and hypotension were associated with poor prognosis in both groups. Total recovey from ARF in older persons was less frequent and slower than in younger patients. It may be concluded that patients over 70 years of age are at high risk for developing ARF; nevertheless, age should not be used as a discriminating factor in therapeutic decisions concerning ARF. J Am Geriatr SOC

cute renal failure (ARF) increases in incidence with age. Older kidneys are more sensitive to any hemodynamic change.'t2 The prognosis of ARF has not improved in recent de~ a d e s , despite ~ - ~ advances in dialysis techniques, antibiotherapy, parenteral nutrition, and other technologies that have improved prognosis in other conditions. To explain this paradox, it has been argued that the population of patients developing ARF has changed to include a larger proportion of elderly patients. Many authors agree that advanced age affects outcome adversely,'.6-10 but others have failed to show this relati~nship.~,"-'~ Only a few studies have reviewed prognosis and clin-

ical outcome of ARF in older patient^."^'^^'' This paper prospectively assesses incidence, causes, and prognosis of ARF in patients over 70 years of age and compares them to younger patients.

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38~25-30,1990

MATERIAL AND METHODS

General Data Between September 1977 and March 1986 we studied 437 consecutive patients with ARF who fulfilled the diagnostic criteria mentioned below. One hundred fifty-two of them (35%) were over 70 years of age (Group l), and 285 (65'Yo) were younger people (Group 2). The ages of the patients in both groups are depicted in Figure 1. The analysis is retrospective, but each patient's clinical course was prospectively observed by one of the authors (nephrologist). From the Department of Nephrology, Hospital Ram6n y Cajal, Ma- Forty-four percent of patients from Group 1 and 48% drid, Spain. from Group 2 were admitted with normal renal function Address correspondence and reprint requests to Dr Orofino, SeM- and developed ARF in the hospital. In the rest, ARF do de Nefrologia, Hospital Ram6n y Cajal, Carretera de Colmenar, occurred as a complication of their basic condition. Km 9,100,28034 Madrid, Spain. 0 1990 by the American Geriatrics Society

0002-8614/90/$3.50

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]AGS-]ANUARY 1990-VOL 38, NO. 1

PASCUAL ET AL

Definitions ARF was defined as the state that occurs when serum creatinine concentration (SCr) rises suddenly to more than 2 mg/dL in subjects with prior normal renal function. Prerenal ARF was defined as ARF due to renal hypoperfusion with recovery after correction of hemodynamic disturbances. Acute tubular necrosis (ATN) was diagnosed when renal function did not improve after correction of possible prerenal causes and when hepatorenal syndrome, vascular, interstitial, glomerular, and obstructive etiologies were excluded. A fractional excretion of sodium greater than 2% was considered to be additional evidence if diuretics had not was debeen used for the previous 48 h 0 ~ r s .Oliguria l~ fined as a urine output of less than 400 mL/24 h. Total recovery of renal function was defined as a decrease in SCr to stable values below 2 mg/dL. Partial recovery of renal function was defined as a decrease in SCr from its ARF peak but remaining at or above 2 mg/dL. Causes of ARF Surgery was assumed to be responsible whenever the SCr increased, as defined, within 72 hours of surgery. Nephrotoxics: Radiographic contrast media were considered to be the cause of ARF when SCr increased, as defined, within 24 hours following the use of such agents. Antibiotic nephrotoxicity was assumed to be the cause of the renal impairment if antibiotics were administered for a minimum of three days previously, and/or if high blood levels of the antibiotic were detected. Pigmenturia was considered to be the cause when hemoglobinuria or myoglobinuria were found in a compatible clinical context. Sepsis was diagnosed if at least one of three conditions was present -documented bacteremia, a known focus of infection, or immunosuppression with neutropenia -and at least two additional findings: rigors; unexplained hyperventilation; unexplained sudden fall in blood pressure; abrupt rise in temperature to more than 38°C not due to transfusion reaction; unexplained leukocytosis of more than 15,000mm3.

In each patient the following aspects were considered: demographic data (sex and age); cause (medical, surgical, nephrotoxics, and sepsis): clinical conditions at the first nephrological evaluation (see below); diuresis; need for dialysis; renal function at discharge or death; complications developed after the onset of ARF (infection, shock, cardiac, respiratory, bleeding, or neurological complications); and mortality in the hospital, whether or not renal function had been restored before death. Patients’ clinical conditions were defined as follows: (1) consciousness level as normal or deep neurological coma16(patients with less severe central nervous system depression, with metabolic coma, and with central nervous system depression caused by drugs were excluded from the analysis); (2) blood pressure as normal or persistent hypotension, arbitrarily defined as systolic blood pressure lower than 100 mm Hg over a period of eight hours or longer, whether or not inotropic drugs had been used; and (3)respiration as spontaneous breathing or mechanical respiratory support. Treatment Patients were treated with dialysis for ARF when the SCr was greater than 6 mg/dL and/or BUN concentration was higher than 100 mg/dL. Other indications for dialysis were severe metabolic acidosis (plasma bicarbonate < 10 mEq/L), extracellular volume overload, or serum potassium greater than 6.5mEq/L. We used hemodialysis preferentially on the basis of our hospital facilities. In each patient, supplements of water, proteins, calories, and minerals were individually administered as needed. Data analysis Every one of the aforementioned variables was individually studied in survivor and nonsurvivor patients included in both age groups, employing a 2 test with Yates’ correction. To compare duration of ARF between both groups we used the Student t-test. Values were considered to be significant at P < .05.

117

n

n 100

eo m 70 60

FIGURE 1. Distribution of ages of the patients with acute renal failure.

60 40 80 20

10 ~

14-20 21-SO 91-40 41-SO S1-

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ACUTE RENAL FAILURE IN THE ELDERLY

IAGS-IANUARY 1990-VOL 38, NO. 1

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TABLE 1. DISTRIBUTION OF ACUTE RENAL FAILURE Group 1 (>70 years)

Group 2 (

Incidence and prognosis of acute renal failure in older patients.

Few studies have assessed the prevalence and outcome of acute renal failure (ARF) in the elderly. Among 437 ARF cases prospectively studied during a n...
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