Comparing outcomes in renal replacement therapy: how should we correct for case mix?

The need to evaluate the effectiveness of clinical practice to justify expensive therapy in the face of financial constraints in all areas of health care delivery makes it necessary to identify groups of patients who are likely to benefit most from treatment. Various risk stratification methods have been used for analyzing survival probabilities for patients receiving renal replacement therapy. Complicated risk stratification methods produce large numbers of risk groups of small sizes, which makes comparison between individual centers difficult. We compared three simple methods of risk stratification, that divided patients into low-, medium-, and high-risk groups, in a cohort of 1,407 patients who commenced renal replacement therapy in five European countries during a 7-year period. Method 1 considered age (>55 years) and diabetes alone; method 2 used a higher age limit (>70 years) and comorbid illnesses, including those other than diabetes; and method 3 used only the number of comorbidities (none, 1, or > or =2) for stratification. Kaplan-Meier survival curves were constructed for comparison between risk groups and Cox's regression model used to assess strength of relationship with mortality. Although patient survival was significantly different between the low-, medium-, and high-risk groups using all three methods, Cox's regression analysis showed that method 2 provided the greatest discrimination between risk groups. In predicting mortality, method 2 (based on comorbidities and age) showed the highest sensitivity and specificity (84% and 80%, respectively) compared with method 1 (80% and 74%) and method 3 (64% and 82%). Validation of this approach in other populations in a prospective study is required before this method, which takes into account the influences of both age and comorbidity for risk stratification, can be used for comparing survival data and for presenting results of renal replacement therapy.

Acute renal failure: factors influencing nephrology referral and outcome.

We investigated the incidence, factors affecting referral and outcome of acute renal failure (ARF), in an unselected (predominantly Caucasian) population in the Grampian region of Scotland served by a single renal unit. Case-notes were examined for all patients with a serum creatinine > or = 300 mumol/l. ARF (311 patients) was defined as a temporary rise in serum creatinine > or = 300 mumol/l, or, if the patient died during the acute illness, clinical features indicating acute deterioration of previously normal renal function. Advanced ARF at presentation (51 of the 311 with ARF) was defined as a first recorded serum creatinine > or = 500 mumol/l. Patients were classified into low-, medium-, and high-risk groups according to presence of comorbidity and age. The annual incidence of ARF was 620/million population (pmp), that of advanced ARF 102 pmp. The age-related incidence of ARF ranged from 30 pmp in the age group (0-19 years) to 4266 pmp in the age group > 80 years. Overall, 22% were referred to a nephrologist (34% after excluding those with advanced cancer and age > 80 years). Referral of patients decreased from 100% in the age group 0-19 to 5% in those > 80 years. Referrals in the low-, medium- and high-risk groups were 75%, 30% and 14%, respectively. Patient survival at 2 years was 80%, 42% and 19% for low-, medium-, and high-risk groups, respectively (86%, 44% and 32% for referred patients). Referral and outcome in patients with ARF were significantly influenced by age and presence of comorbidity at presentation.

Survival on renal replacement therapy in Europe: is there a 'centre effect'?

OBJECTIVE: Survival is the ultimate outcome measure in renal replacement therapy (RRT) and may be used to compare performance among centres. Such comparison, however, is meaningless if the influences of comorbidity, age and early deaths are not considered. We therefore studied survival rates on RRT in seven centres in Europe after taking into account the influence of age, early deaths, primary renal diagnoses, and comorbidity. DESIGN: A retrospective survival analysis was carried out on 1407 patients who commenced RRT in seven centres across five European countries during a 7-year period. Patients were stratified into low-, medium- and high-risk groups based mainly on comorbidity and to a lesser extent on age at commencement of RRT. Kaplan-Meier survival and Cox's proportional hazards model were used to compare survival. RESULTS: Before risk stratification overall 2-year survival across the seven centres ranged from 60.2 to 85.3% (69.3-89.9%) after excluding early deaths) masking a range of survivals of 27.4% for the high-risk group with the worst survival to 100% in the low-risk group with the best survival. After excluding early deaths 2-year survival in the low risk groups (n=622) was greater than 90% in all centres. Multivariate analysis showed that the mortality risk increased four fold from low- to medium- and a further 1.6-fold from medium- to high-risk group. However, despite this adjustment for comorbidity and age there still remained a significant difference in survival among some centres, i.e. a 'centre effect' which ranked the centres. CONCLUSION: Risk stratification diminishes the variance in survival between centres but a centre effect remains despite adjusting for age and comorbidity. Multicentre prospective studies are urgently required to identify the reasons for this apparent centre effect.

Telematics in undergraduate teaching.

The use of telematics in the practice of medicine has received much recent attention but little has been written about the use of these techniques in medical education. This is a report of a pilot study in which an interactive video-conference took place between medical students at the UAE University and their opposite numbers at Aberdeen University. In Aberdeen, the Dean of the Medical Faculty simultaneously taught Aberdeen and UAE students on a clinical case. He was able to confine his activities largely to the correction of misconceptions, the emphasis of important points and the addition of missing information, while the students themselves conducted most of the presentation. The UAE students presented their Community Health projects and had a spirited discussion on them with the Aberdeen students. Recent technological advances have so improved the quality of transmission of both visual and auditory images and at reasonable cost, using the ISDN telephone system, that the feasibility of using this medium as an aid to teaching has suddenly materialized. The experiment showed that the technology was adequate for easy, fully interactive teaching among students from different continents and with different cultural backgrounds. It is particularly suitable for the Arab world where it is the custom to teach males and females separately. The pilot study has pointed out the existence of a medium of communication and teaching which, if proved to be effective, could have far-reaching consequences in the undergraduate and postgraduate teaching of medicine.

Death during the first 90 days of dialysis: a case control study.

Comparison of survival data among centers may be used to assess performance, but may be influenced by the number of patients who die during the first 90 days of renal replacement therapy (RRT). Data published by registries in Europe do not detail these deaths, and US data generally exclude them from analysis for financial reasons. To study factors influencing such deaths we compared 42 patients who died within 90 days of first commencing RRT in one Scottish renal unit (group A) between 1971 and 1992 with 42 age- and sex-matched controls who started RRT over the same period and survived longer (group B). Patients who died within 90 days of RRT ranged in age from 25.3 to 83.7 years and had a mean age of 65.2 (SEM, 1.6; 95% confidence interval, 61.9 to 68.4). The proportion of patients who died during the first 90 days of RRT increased from 2% of all patients treated before 1981 to 12% in subsequent years. Thirty-three patients in group A received emergency dialysis via temporary venous access compared with only nine in group B (P < 0.055). There were more patients in group A with a diagnosis of arteriosclerotic renal artery stenosis (14 v 1) and with a history of smoking (15 v 2) than in group B (P < 0.0005). Median renal or nonrenal follow-up before RRT was 1.1 month in group A and 10.6 months in group B (P < 0.0001). Fewer patients in group A had no coexisting disease (1 v 17; P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Patients' perception of health on renal replacement therapy: evaluation using a new instrument.

Patients' perception of their health is an important outcome measure in the management of chronic disease. Comparing that perception from patients receiving different forms of renal replacement therapy (RRT) with data from the general population could be used to monitor the effectiveness of treatment. The short form 36 (SF-36) questionnaire is a general measure of health status which has been validated in the UK and uses eight health scales comprising physical function, social function, role limitation (physical and emotional), mental health, energy, pain and overall health. Using the SF-36 questionnaire, the perception of health of patients receiving RRT was compared with data from healthy control subjects. One hundred and seventy-two of 185 (93%) patients receiving RRT--transplant (n = 102), haemodialysis (n = 43), and peritoneal dialysis (n = 27) completed the questionnaire; scores were compared with those from 542 healthy control subjects. The perception of health of haemodialysis and peritoneal dialysis patients was significantly worse than transplanted patients and controls in six of the eight scales (P < 0.05 dialysis versus transplant and controls). That of transplanted patients was worse in only two and better in one of the eight scales compared with the general population (P < 0.05). Patients were also stratified into low, medium, and high-risk groups based on age and comorbidity and were analysed irrespective of treatment modality. Scores were significantly different across the risk groups in five of the eight scales. We conclude that the SF-36 questionnaire is acceptable to patients on RRT and enables the perception of health of patients receiving RRT to be compared with that of the general population.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic renal failure: factors influencing nephrology referral.

Factors influencing referral of all 304 patients who developed persistent renal failure during one year were studied in the stable Grampian population. The annual incidence of chronic renal failure (CRF) (creatinine > or = 300 mumol/l) was 450/million of the population and of persistent advanced CRF (creatinine > or = 500 mumol/l), 132/million. After excluding those aged > 80 years and those with advanced malignancy, the corresponding incidence figures were 240/million/year and 81/million/year. Only 109 patients (35.8%) were referred to a nephrologist. Patients were divided according to age and coexisting disease into low, medium and high risk groups; 69% of CRF patients in the low, 58% in the medium, and 21% in the high risk group were referred (100%, 88% and 37%, respectively, of the patients with advanced CRF). Two-year patient survival in the low, medium and high risk groups was 100%, 63% and 27%, respectively, in referred patients, and 100%, 48% and 14%, respectively, in non-referred patients. This method of risk stratification identifies patients (particularly those with advanced CRF) likely to have a poor outcome irrespective of referral to a nephrologist. Earlier referral for interventions to delay the progress of the patients' renal and comorbid illnesses has considerable implications for future planning and funding of renal services.

Systemic hypertension--an unusual presentation of T-cell lymphoma.

Systemic hypertension is not commonly associated with lymphoid malignancy. We present two patients who had renal involvement with non-Hodgkins lymphoma (NHL) in which systemic hypertension was a major problem on presentation and resolved soon after appropriate chemotherapy.

Membranous nephropathy and granulomatous interstitial nephritis in sarcoidosis.

A 56-year-old woman developed nephrotic syndrome in association with pulmonary sarcoidosis. Renal biopsy revealed both granulomatous interstitial nephritis and membranous nephropathy. Treatment with steroids resulted in a decrease in proteinuria and there was no deterioration in renal function over a subsequent period of 10 months. This case provides further evidence that secondary membranous nephropathy associated with sarcoidosis should be treated with steroids.

Social deprivation indices of patients on renal replacement therapy (RRT) in Grampian.

The social deprivation scores of 169 patients who resided in Grampian region and commenced renal replacement therapy (RRT) in Aberdeen during the period 1 January 1985-30 June 1991 were measured when their serum creatinine concentrations were first > = 300 mumol/l, using the Jarman Underprivileged Area (UPA) and Carstairs indices. The numbers in the population of Grampian for each score were obtained from the Information Services team of Grampian Health Board based on the 1981 census. Comparison of the numbers of patients in each category of both Jarman and Carstairs indices showed no differences between the observed numbers of patients and the numbers in the general population. Thus in this study social deprivation occurred no more frequently in those commencing RRT than in the general population.

Long-term complications of dialysis: infection.

It is widely accepted that patients with renal failure have an increased risk of infection. Laboratory studies have established defects in cellular immunity, neutrophil function and complement activation. Clinical studies undertaken almost a quarter of a century ago indicated that infection caused or contributed to 30% of deaths in patients on long-term hemodialysis. Apart from infection related to access, however, current evidence indicates that serious infections are not common in patients who are on either maintenance hemodialysis or continuous ambulatory peritoneal dialysis and are associated with a mortality rate of less than 3%. Despite the depressed immune response associated with uremia, it would thus appear that patients on maintenance dialysis therapy do not have significantly increased morbidity or mortality from infectious diseases with the exception of those related to dialysis access.

Influence of coexisting disease on survival on renal-replacement therapy.

Survival of patients on renal-replacement therapy (RRT) is no longer improving. Increasingly, such patients are older and have co-morbid conditions affecting organs other than the kidney. In a retrospective study, we calculated actuarial survival of 375 patients starting RRT during a 6 1/2 year period at renal units in Aberdeen and Dundee, UK, after stratification of patients into three risk groups (low, medium, and high) based predominantly on co-morbidity and to a lesser extent on age. 2-year survival differed significantly between low, medium, and high risk groups both before (86%, 60%, and 35%, respectively; p < 0.002 for all comparisons) and after (90%, 70%, 46%; p < 0.004 for all comparisons) excluding early deaths (within 90 days of starting RRT). Overall survival was 61% in Aberdeen and 68% in Dundee (p = 0.04), but 73% and 74%, respectively, when deaths in the first 90 days were excluded (p = 0.73). We conclude that RRT is a highly successful treatment (86% 2-year survival) for patients aged under 70 with no co-morbid conditions (low-risk group); that coexisting non-renal disease has an important influence on survival of patients on RRT; and that risk stratification and analysis of data including and excluding early deaths should allow more valid comparison of data from different centres.

Secondary polycythaemia associated with idiopathic membranous nephropathy.

A 44-year-old man developed idiopathic membranous nephropathy and true secondary polycythaemia. With advancing azotemia, polycythaemia gradually resolved and venesection was no longer required. Only 2 cases of polycythaemia associated with membranous nephropathy have been reported previously. Secondary polycythaemia is a rarely reported association of membranous nephropathy and may increase the risk of thromboembolism, which might be prevented with venesection.