Saudi Journal of Kidney Diseases and Transplantation

ORIGINAL ARTICLE
Year
: 2003  |  Volume : 14  |  Issue : 1  |  Page : 23--29

The Predictors of Early Mortality in Patients Starting Chronic Hemodialysis


S Gmar-Bouraoui1, H Skhiri1, A Achour1, A Frih1, N Ben Dhia1, S Hammami2, M El May1,  
1 Service de Néphrologie et Hémodialyse, Centre Hospitalo-universitaire Fattouma, Bourguiba, Monastir, Tunisia
2 Département de Statistique Médicale, Faculté de Médecine de Monastir, Tunisia

Correspondence Address:
S Gmar-Bouraoui
Service de Néphrologie et Hémodialyse, Centre Hospitalo-universitaire, Fattouma Bourguiba, Monastir
Tunisia

Abstract

To evaluate the predictors of early mortality in patients on chronic hemodialysis, we reviewed the records of 192 patients starting chronic hemodialysis at our centre between January 1996 and September 1999. The overall incident mortality within 90 days was 32 (16.7%) patients. The cardiovascular causes accounted for 50% of all the causes of mortality. By using multivariate stepwise logistic regression analysis, early mortality rate was not significantly increased in the comparison of age or gender groups but increased in patients with diabetes mellitus, as well as those with reduced dialysis frequency. The most powerful predictor of survival was serum albumin level of less than 30 g/l. Thus, the survival rates in patients with serum albumin less than 30 g/l and those with serum albumin equal to or greater than 30 g/l were 67.8% and 90.2%, respectively, (p<0.001). The odds ratio was 4.68. We conclude that these findings suggest that the important predictors of early mortality in the first 90 days of starting hemodialysis include the presence of diabetes mellitus, the decreased frequency of dialysis sessions and the presence of low serum albumin. The low serum albumin below 30 g/l was the strongest predictor of early mortality.



How to cite this article:
Gmar-Bouraoui S, Skhiri H, Achour A, Frih A, Dhia N B, Hammami S, El May M. The Predictors of Early Mortality in Patients Starting Chronic Hemodialysis.Saudi J Kidney Dis Transpl 2003;14:23-29


How to cite this URL:
Gmar-Bouraoui S, Skhiri H, Achour A, Frih A, Dhia N B, Hammami S, El May M. The Predictors of Early Mortality in Patients Starting Chronic Hemodialysis. Saudi J Kidney Dis Transpl [serial online] 2003 [cited 2020 Oct 31 ];14:23-29
Available from: https://www.sjkdt.org/text.asp?2003/14/1/23/33084


Full Text

 Introduction



Over the years selection criteria for acceptance on renal replacement therapy (RRT) became more liberal leading to an increase in the number of patients receiving this modality of treatment all over the world. [1] This expansion was associated with increased proportion of elderly patients and those with co-morbidity.

Previous studies showed that early mortality occurring in the first 90 days after starting RRT represented a high percentage of the first-year mortality rate, (ranged from 12.6% [2] to 32% [3],[4] ) . Short-term prognosis studies had variable results due to different methodo­logies. [5] The Canadian studies considered the early period as the first six months after starting RRT, [6],[7] while others excluded mortality that occurred in the first month. [8] The United States Renal Data System (USRDS) registry excluded all patients who did not survive beyond 90 days and only mortality that occurred in patients aged more than 65 years were taken into account in the statistical analysis. [9] The European Renal Association (ERA-EDTA) registry included mortality within 90-days but suffers from incomplete data particularly since 1992 [10] and early mortality was probably undere­stimated in this registry. [2]

Hypoalbuminemia has been demonstrated by most studies to be an adverse prognostic indicator in the long-term survival on RRT. [11],[12],[13]

However, an inverse correlation with early mortality was found by some studies [2],[6] but not by others. [7]

In this study we attempt to evaluate the predictive value of the serum albumin of early mortality in patients on chronic hemo­dialysis for less than 90 days.

 Patients and Methods



We reviewed the records of 345 new patients started on renal replacement therapy at the University Hospital Fattouma Bourguiba between January 1st, 1996 and September 30th, 1999.

We excluded patients with acute renal failure, rapidly progressive renal failure, acute on chronic renal failure, chronic renal failure with recovering residual renal function after a short period of RRT, patients with extrarenal diseases conferring poor prognosis independent of dialysis effect, such as neoplasia (primary or metastatic) and myeloma, and those with incomplete data especially serum albumin. There were 192 patients for the evaluation of mortality in the first 90 days of dialysis.

The reviewed clinical data included: age, gender, body mass index (BMI), cause of renal disease, comorbidity, first mode of hemo­dialysis (emergency or programmed dialysis), dialysis frequency (two times or three times a week), mortality within the first 90 days, and causes and duration to mortality.

The laboratory parameters were recorded at starting hemodialysis and included: blood urea nitrogen (BUN), creatinine clearance (Clcr) using Cockroft-Gault formula, total serum cholesterol, triglycerides, serum CO2, potassium, calcium, phosphorus, alkaline phosphatase, as well as hemoglobin level, leucocytes count and urinalysis.

 Statistical Analysis



In order to determine which parameters were associated with early mortality, patients who died within the first 90 days were compared to those who survived. We used BMDP computer software for the statistical analysis. Univariate statistical tests using chi-square for binary variables and t-test for con­tinuous variables were performed. Variables statistically associated with early mortality were introduced into a multivariate stepwise logistic regression with p [10] The estimated early mortality rate varied in the medical literature from 11% to 26%. [2],[3],[5],[7],[10],[14] This variation between centers is due to different methodologies used in the collection and analysis of data.

There was no influence of advanced age on early mortality in our study compared to other studies. [2],[7],[10] This may be due to our inclusion criteria that excluded patients with neoplasia and myeloma, which are potentially of poor prognosis at short term and occur mostly in the older patients.

Our study showed that early mortality was not statistically different between males and females. Some studies reported lower risk of mortality in females in a one-year survival analysis. [12]

The cardiovascular causes and withdrawal from dialysis were the most common causes of early mortality particularly in diabetic and elderly patients. [12],[15],[16] Though the cardiovascular comorbidity was the most common cause of death in our study but there were no withdrawals from dialysis.

Early nephrological referral seemed to be beneficial in the short-term prognosis in patients starting RRT. [15] Early mortality was more frequent in the group of late referral. [17] There was no correlation between early mortality and regular nephrological follow­up in our study. Nevertheless we did not calculate the follow-up period in order to evaluate the effect of early nephrological follow-up on the outcome.

In our study, dysrhythmia was associated with poor prognosis, while ischemic heart disease and cardiac failure were not, mostly because patients with severe cardiac failure were admitted on peritoneal dialysis in our centre, and patients treated by this kind of RRT were excluded from the study. Further­more, we did not find coma and ventilatory dependence associated with early mortality as in previous studies. [7]

One of the major prognostic indicators in our study was the primary renal disease. Diabetes mellitus and amyloidosis were associated with the highest mortality rates. Diabetes mellitus is well known in long­term survival studies to carry poor progno­sis. [3],[16],[18] It has also been suggested as a risk factor associated with adverse prognosis in a large scale study [10] but was not in another. [7]

Mortality in amyloidosis, may be due to Addisonian crisis secondary to adrenocortical insufficiency related to amyloid deposits in the adrenal glands. [19] Detecting this disorder systematically at starting chronic hemodialysis may be indicated. In this study, glomerulo­nephritis and polycystic kidney disease seemed to be associated with low risk of mortality, a finding that was noted in many other series. [9],[10],[12]

Chronic hemodialysis is associated with a typical atherogenic profile consisting mainly of hypertriglyceridemia with increased very low-density lipoprotein (VLDL) and low­ density lipoprotein (LDL). [20],[21] This explains why cardiovascular etiolgies remained the most frequent cause of mortality in patients on RRT over the years. [22] In our study, the univariate analysis showed that hyper­triglyceridemia was associated with excess of mortality.

Low systolic blood pressure as a marker of severe cardiac failure has been reported as an adverse prognostic indicator in acute renal failure. [23] This was also demonstrated in a prospective study in the chronic dialysis population. [24]

Up to 29.7% of our patients were treated twice a week. This group was at higher risk of early mortality. The adverse effect of shorter treatment time on mortality was also demonstrated in long-term survival analysis. [12] Low delivered dialysis dose is well known to increase mortality. [25]

One of the powerful independent predictors of mortality in patients on RRT is hypo­albuminemia; an indicator of malnut­ration [11],[12],[26],[27] serum albumin was found to be a predictive factor of hospitalization and mortality. [28],[29] In our study, patients with low serum albumin had a high mortality rate. However, the low serum albumin did not correlate with the adequacy of dialysis estimated by the urea reduction rate. [27],[30]

Furthermore, C-reactive protein and serum amyloid A were suggested as determinants of serum albumin concentration in hemo­dialysis patients. [30] Hypoalbuminemia was suggested as a component of the acute­ phase response. [31]

We conclude that our study findings suggest that the important predictors of early mortality in the first 90 days of start on hemodialysis include the presence of diabetes mellitus, the decreased frequency of dialysis sessions and the presence of hypoalbuminemia. The low serum albumin below 30 g/l was the strongest predictor of early mortality.

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