Chronic kidney disease in adults: assessment and management

Excerpt

Chronic kidney disease (CKD) describes abnormal kidney function and/or structure. It is common, frequently unrecognised and often exists together with other conditions (such as cardiovascular disease and diabetes). Moderate to severe CKD is also associated with an increased risk of other significant adverse outcomes such as acute kidney injury, falls, frailty and mortality. The risk of developing CKD increases with age. As kidney dysfunction progresses, some coexisting conditions become more common and increase in severity. CKD can progress to end-stage kidney disease in a small but significant percentage of people.

CKD is usually asymptomatic, but it is detectable, and tests for CKD are simple and freely available. There is evidence that treatment can prevent or delay the progression of CKD, reduce or prevent the development of complications, and reduce the risk of cardiovascular disease. However, CKD is often unrecognised because there are no specific symptoms, and it is often not diagnosed or diagnosed at an advanced stage.

The classification of CKD has evolved over time. In 2004, the Department of Health’s National service framework for renal services adopted the 2002 US National Kidney Foundation Kidney Disease Outcomes Quality Initiative classification of CKD. This classification divides CKD into 5 stages and uses the combination of an index of kidney function, the glomerular filtration rate (GFR), and markers of kidney damage to define the stages. Stages 3–5 were defined by a GFR less than 60 ml/min/1.73 m² with or without markers of kidney damage, on at least 2 separate occasions separated by a period of at least 90 days. Stages 1 and 2 were defined by the presence of markers of kidney damage including albuminuria, urine sediment abnormalities, electrolyte and other abnormalities caused by tubular disorders, abnormalities detected by histology, structural abnormalities detected by imaging and a history of kidney transplantation.

To delineate an increased risk of adverse outcomes, the 2008 NICE guideline on chronic kidney disease suggested 2 key changes to this classification: the subdivision of stage 3 into 3a (GFR 45–59 ml/min/1.73 m²) and 3b (30–44 ml/min/1.73 m²), and the addition of the suffix ‘P’ to denote significant proteinuria at any stage. The 2008 NICE guideline defined significant proteinuria as a urinary albumin:creatinine ratio (ACR) of 30 mg/mmol or higher (roughly equivalent to a protein:creatinine ratio of 50 mg/mmol or higher). In 2013, the Kidney Disease: Improving Global Outcomes (KDIGO) guidance on the evaluation and management of chronic kidney disease adopted the subdivision of GFR categories suggested by the NICE guideline, but also included 3 ACR categories (ACR under 3 mg/mmol, 3–30 mg/mmol, and over 30 mg/mmol) for each GFR category in an updated classification (as shown in the following tables).

This update of the NICE guideline reviews the classification of CKD.

Kidney Disease Improving Global Outcomes GFR categories: [Table: see text]

Kidney Disease Improving Global Outcomes ACR categories: [Table: see text]

Late presentation of people with kidney failure increases morbidity, mortality and associated healthcare costs. Diagnosis of people with kidney disease has improved since the introduction of national estimated GFR reporting and CKD indicators in the primary care Quality and Outcomes Framework, and also because there is increased public and health professional awareness of CKD. However, late presentation was still reported as 19% overall in the Renal Association’s 2013 UK Renal Registry report.

The total cost of CKD in England in 2009–10 was estimated at between £1.44 and £1.45 billion, which was approximately 1.3% of all NHS spending in that year. More than half of this amount was spent on renal replacement therapy for the 2% of people with CKD that progresses to kidney failure. It was estimated in the economic model that approximately 7000 excess strokes and 12,000 excess myocardial infarctions occurred in people with CKD in 2009–10 (relative to an age- and gender-matched population without CKD), with an estimated cost of between £174 and £178 million. Strategies aimed at earlier identification and prevention of progression to end-stage kidney disease are clearly needed.

This guideline seeks to address these issues by updating the 2008 NICE guidance in areas where new data have become available, and providing new guidance in areas where previously no evidence existed.

The new and updated areas include:

1. identification and investigation of people who have or are at risk of developing CKD

2. classification of CKD and identification of people at risk of CKD complications and progression

3. the definition of CKD progression

4. the relationship between acute kidney injury and CKD

5. self-management of CKD

6. pharmacotherapy for CKD.

Drug recommendations: The guideline will assume that prescribers will use a drug’s summary of product characteristics to inform decisions made with individual patients.