1 Department of Nephrology and 2 Department of Internal Medicine, Erciyes University Medical Faculty Hospital, Kayseri, Turkey
Correspondence and offprint requests to:
Cengiz Uta MD, Erciyes Üniversitesi Tip Fakültesi, Nefroloji Klini
i, 38039 Kayseri, Turkey.
Abstract
Background. The aetiological spectrum of acute renal failure (ARF) has changed in developed countries. It was the purpose of the study to evaluate whether similar changes have occurred in this part of the world as well.
Methods. In a prospective study a total of 439 patients with ARF were evaluated. They had been admitted to one hospital during two successive periods, i.e. 19831990 and 19911997.
Results. Of 439 patients with ARF, 116 were admitted in 19831990 (first period) and 323 in 19911997 (second period). The age of presentation increased from 49.8±6.2 years in the first period to 58.8±16.4 years in the second. Medical causes were present in 259 cases (59%), surgical causes in 110 cases (25%), and obstetric causes in 70 cases (16%). The frequency of surgical cases decreased from 28.4% in the first period to 23.8% in the second period. The respective figures for obstetric cases were 18.9% and 14.8%. Mortality did not change with time (33.6% in the first and 31.0% in the second period); the overall mortality was 31.7%. The mortality was higher for surgical (45.5%) than for obstetric (27.8%) and medical ARF (24.3%).
Conclusion. In the mid-1970s, the most common causes of ARF in Turkey were obstetric complications and septic abortion. The aetiological spectrum of ARF has changed and today medical causes predominate. ARF resulting from septic abortion has become rare, possibly because of liberalization of abortion in 1983 in Turkey.
Keywords: acute renal failure; aetiology; mortality; septic abortion
Introduction
The aetiological spectrum of acute renal failure (ARF) is markedly different between developing and developed countries; it is closely linked to environmental and socioeconomic conditions. Surgery and trauma are the most common causes of ARF in developed countries [13]. Recently, the incidence of surgical and post-traumatic ARF has decreased, whereas that of medical ARF has increased. ARF due to septic abortion or obstetric complications has almost disappeared in developed countries, but remains significant in developing countries [17]. In Turkey, obstetric complications and septic abortion were the most common causes of ARF in the 1970s [8].
The aim of this study was to assess the aetiologies and outcomes, and their trends with time, of ARF in Central Anatolia (Turkey).
Subjects and methods
Four hundred and thirty-three patients with ARF were admitted to the Nephrology Department of Erciyes University Medical Faculty Hospital between 1983 and 1997 in Turkey. The patient population was from the city of Kayseri and other cities of Central Anatolia including urban and rural areas. The total population was approximately 2000000 in which 800000 of the people were living in the urban areas. Aetiologies and outcomes were compared in the two successive periods, i.e. 19831990 (first period) and 19911997 (second period). ARF was defined as an acute reduction of renal function, i.e. rise in serum creatinine levels to >2 mg/dl despite absence or correction of prerenal causes [9]. Patients were classified as oliguric (less than 400 ml urine/24 h) or non-oliguric (more than 400 ml urine/24 h). The diagnosis was based on history, physical examination, laboratory values, and clinical course. All patients were subjected to the following investigations: haemogram, urine analysis, urinary indices, blood chemistry tests, including concentrations of urea, creatinine, sodium, potassium, calcium, uric acid, phosphorus, and ultrasound examination of kidneys, ureter, and bladder. Patients with pre-existing renal disease were not included in the study. Indications for dialysis were volume overload, hyperkalaemia (above 7 mmol/l), severe uraemia (blood urea nitrogen above 100 mg/dl) and severe metabolic acidosis (bicarbonate under 15 mEq/l). Renal biopsy was performed in selected patients with unexplained renal failure, systemic disease, or signs suggesting glomerular, vascular, and interstitial lesions, and when duration of oligoanuria exceeded 4 weeks. Mortality was defined as death during the episode of ARF.
Statistics
Results were expressed as mean±SEM. Fisher's X2 test was used to compare data. The zero hypothesis was rejected at a P value <0.05.
Results
A total of 439 patients with ARF were treated from 1983 to 1997, i.e. 116 from 19831990 and 323 from 19911997. The rate of increase of the background population was 2.2%. As shown in Table 1, the age of patients increased with time; there were more men than women and the proportion of non-oliguric ARF increased with time, whilst the need for dialysis was similar in the two periods. The causes of ARF are listed in Table 2
. The pattern changed with time: ARF from medical causes increased (Figure 1
) with diarrhoeal disease and drug-induced ARF (including non-steroidal anti-inflammatory drugs, aminoglycosides, rifampicin, and penicillin) being the major causes. Other medical causes included sepsis, congestive heart failure, gastrointestinal haemorrhage, and acute myocardial infarction. In contrast, ARF from surgical causes decreased; the main categories were postoperative ARF, urinary tract obstruction, and crush injury.
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Of the 439 patients, 139 died; the rate did not change with time (Table 3). Mortality decreased, however, in the obstetric and the medical groups, but increased in the surgical groups. The major causes of death were sepsis and cardiorespiratory failure (Table 4
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Before the seventies, most studies in developed countries indicated that approximately 60% of cases of ARF were related to surgery or trauma, 30% occurred in a medical setting, and about 10% were related to the complications of pregnancy [1,2]. Over the past three decades, there have been changes in the relative frequency of conditions causing ARF in developed, but also in developing countries [3,1016]. While ARF resulting from trauma and surgery decreased, ARF due to medical diseases increased in developed countries [13]. The most obvious change was the decline in the incidence of obstetric ARF. Pregnancy-related ARF has become a rare cause in developed countries [13] because of safe and early delivery of complicated pregnancies, more effective treatment of pre-eclampsia, and disappearance of septic abortion [2,4]. In contrast, in developing countries, the decrease has been less pronounced [57].
In the mid-1970s, obstetric ARF was the main cause of ARF in Turkey, accounting for 78% of ARF [8]. The proportion of ARF related to septic abortion has decreased dramatically from 33.3% to 6.8% in Turkey over the past 20 years [1719]. This value is still high compared to developed countries, but it was minuscule in our series (1.8%). The decrease of obstetric causes of ARF is explained by improved socioeconomic conditions, early detection of pregnancy-related complications, and disappearance of septic abortion following the liberalization of abortion laws. The rate of obstetric ARF in Turkey is similar to that reported from developing countries [57], where a decline over the past two decades has occurred [57]. An impressive example is provided by Romania. After the 1989 revolution and liberalization of abortion, ARF due to septic abortion declined from 20.6% to 1.5% [20].
This study reflected the fact that in our region of Turkey, medical causes predominated as the cause of ARF, the commonest cause being diarrhoeal disease, which is rare in developed countries, but common in developing countries, e.g. in India [7]. The risk is related to low socioeconomic conditions, poor sanitation, and delay in correction of fluid and electrolyte loss. It is encouraging that the frequency of ARF from diarrhoeal disease tended to decrease with time. The use of oral rehydration therapy, better sanitation, and better socioeconomic conditions may have played a role. Conversely, there was a trend for the frequency of drug-induced ARF to increase, the main cause being antibiotics and analgesics.
The frequency of surgical ARF was approximately 25%, in sharp contrast to the situation in developed countries, where surgery and trauma were the major causes of ARF [1,2]. As a case in point, aortic aneurysm surgery is a major cause of ARF in developed countries [2,3,21,22], but no such operations had been performed in our centre in the study period.
Mortality rates in ARF range from approximately 7% among patients admitted with prerenal azotaemia to more than 80% among patients with postoperative ARF [23] and this changed little with time despite technical advances in renal replacement therapy and supportive care, possibly because of increasing age and increasing co-morbidity of patients [2,24,25]. Turney et al. reported that the mortality of ARF did not change with time, i.e. 51.2% in 1956 vs 48.2% in 1988, and that the mortality was higher in surgical than medical or obstetric ARF [2]. Others reported that survival in ARF due to cardiac and aortic surgery was poor compared with ARF from other causes [2,21,24]. Mortality did not change in our series, i.e. 33.6% in 19831990 and 31.0% in 19911997 respectively. The overall mortality rate of ARF was lower than in Western countries [13,26,28], possibly a reflection of different aetiologies of ARF with the notable absence of major surgical causes, such as aortic aneurysm or cardiac surgery.
In conclusion, causes of ARF in Turkey have changed with time and medical causes have become more prominent. There has been a dramatic decline in frequency of ARF due to obstetric complications, presumably due to improved prenatal care and change in abortion laws. Although ARF due to obstetric complications has decreased, it is still high compared to the rates in developed countries, and the overall mortality of ARF continues to be high.
References