4.1 Pre-Dialysis - Retarding Progression and Reducing the Comorbid Burden in Renal Disease

4.1.1 Causes of End Stage Renal Failure (ESRF)

Although the management of patients receiving RRT dominates the workload in renal centres, the care of patients with progressive renal impairment is equally important not least because it may be possible in certain situations to retard disease progression. Although RRT is the domain of the nephrologist, management of early renal disease may be managed jointly with Primary Care Teams.

The causes of ESRF in patients starting RRT in England and Wales were recently reviewed (ref.3). A similar breakdown in 193 patients referred to a single DGH is also collated below (ref.30) as is information from the UK Renal Registry (ref.1).

Diabetic Nephropathy
Diabetes is the leading cause of ESRF in the western world. Approximately 20-30% of patients with type 1 or type 2 diabetes mellitus will develop overt nephropathy (ref.31,32). Although a greater proportion of type 1 diabetics subsequently progress to ESRF, 50-60% of diabetic patients receiving RRT have type 2 diabetes because of the greater prevalence of this type of diabetes in the general population (ref.33). The well-known susceptibility of Asians living in the UK (ref.34) contributes to their increased incidence of ESRF(ref.16). A higher proportion of Asian diabetics than white diabetics develop nephropathy (ref.35).

The impact is amplified by the associated co-morbidity. Up to 30% of diabetic ESRF patients are blind due to retinopathy (ref.36) and almost all diabetics will require laser photocoagulation prior to or during RRT. Peripheral vascular disease is common so that 50-70% of all non traumatic amputations are performed in diabetics (ref.37,39). Coronary heart disease is accelerated in diabetics and the protective effect of female gender is lost.

Glomerulonephritis or 'nephritis' is a group of conditions in which there is long term (chronic) inflammation mainly involving the part of the kidney which filters the blood - the glomerulus. The kidneys may be involved in isolation or as a part of a generalised disorder of the immune system. Systemic lupus erythematosus (SLE) is a known example. When this occurs early in the disease, renal failure may be postponed or even prevented but success is unusual once progressive renal failure is established. The low figure quoted by the UK Renal Registry (ref.1) is due to counting only biopsy-confirmed cases of glomerulonephritis.

Polycystic kidneys. This is the most common inherited disorder, the chance of transmission being one in two for each child. Throughout life normal kidney tissue is replaced by large cysts which grow at the expense of functioning renal tissue. Families of polycystic patients are often well known to renal units.

Chronic interstitial nephritis. This is a unifying term to include conditions which damage the main body of the kidney by a process of scarring. They include reflux nephropathy, a congenital disease in which reflux of infected urine from the bladder back into the kidney early in life can initiate scarring. Prompt treatment and investigation of recurrent urinary infection in small children is the key to successful intervention. The group also includes damage following obstruction to the urinary tract. Obstruction due to prostatic disease can occur in men usually above the age of 50 and has important implications for potential future screening programmes in primary care. The group also includes damage due to long term ingestion of analgesics (pain killers).

Hypertension. While hypertension superimposed on renal disease can undoubtedly accelerate decline in renal function and accelerated ('malignant') hypertension can cause renal failure, it is less clear whether uncomplicated hypertension causes ESRF. The general view is that it does not (ref.40). However, the lack of consensus partly explains why the reported prevalence of hypertensive renal failure between countries varies markedly, being as high as 29% in the USA (ref.12). Patients of African decent can experience severe and damaging hypertension which may partly explain the high incidence of renal failure in this group (ref.41). On the other hand it is possible that many patients identified as having hypertensive renal disease actually have indolent nephritis.

Myeloma. This is a cancer of the plasma cells of the bone marrow which impacts on RRT because of its ability to produce ESRF 'acutely'. Since patients may feel well in the early stages of the disease they are often accepted for RRT despite the relatively poor prognosis.

Small kidneys. This is the finding in significant numbers of patients when they first present with signs and symptoms of renal disease or in whom renal impairment is found incidentally. The implication is that indolent disease has been present for a long time. Some will have had or continue to have glomerulonephritis. Biopsy is seldom performed since the implications for treatment are usually minimal.

Vasculitis. This describes a complex group of diseases in which there is inflammation of blood vessels. The kidney is densely endowed with small arteries, the inflammation of which can produce devastating renal disease. Fortunately there is often scope for intervention with immunosuppressive drugs. On the other hand, the symptomatology of these diseases is vague and diagnosis is sometimes missed or delayed.

Renovascular Disease. The arteries leading to the kidney are susceptible to atheroma just as are carotid, coronary and peripheral arteries. The prevalence rises with age. Renal arteries are amenable to angioplasty and stenting. However, the value of these procedures in preventing renal failure is uncertain and is the subject of current controlled trials which will also assess their cost effectiveness.