5 - Chronic renal disease - CCMTA Medical Standards
Chronic renal disease and medical fitness to drive.
5.1 About chronic renal disease
Chronic renal (kidney) disease is a progressive disease involving deterioration and destruction of renal nephrons, with a progressive and usually permanent loss of renal function. Diabetes, hypertension and glomeruonephritis are leading causes of chronic renal disease. It is divided into five stages of increasing severity, as shown in the table below. The stages are based on a measurement of kidney function called the glomerular filtration rate (GFR).
Stages of Chronic Renal Disease
|1||Slight kidney damage – normal or elevated GFR||More than 90|
|2||Kidney damage – mild decrease in GFR||60 to 89|
|3||Kidney damage – moderate decrease in GFR||30 to 59|
|4||Kidney damage – severe decrease in GFR||15 to 29|
|5||Kidney failure – dialysis or transplant required||Less than 15|
The prevalence of chronic renal disease in the adult population in the United States is estimated to be 11% and it is assumed that the prevalence in Canada would be approximately the same. It is more prevalent in the elderly population.
Stage 5 of chronic renal disease (kidney failure) is also referred to as end–stage renal disease (ESRD), and is characterized by a total or near–total loss of kidney function where an individual requires dialysis or transplantation to stay alive. The prevalence rates for ESRD have increased substantially since 1997, most likely because of improved survival rates among high-risk populations, e.g. people with diabetes and hypertension, as well as improvements in management of ESRD, and the aging of the population.
5.3 Chronic renal disease and adverse driving outcomes
The evidence linking chronic renal disease with adverse driving outcomes is weak because there has been limited research in this area and the research that is available is either dated or has methodological limitations.
5.4 Effect on functional ability to drive
|Condition||Type of driving impairment and assessment approach*||Primary functional ability affected||Assessment tools|
Chronic renal disease
(Stage 3 and 4)End-stage renal disease
|Persistent impairment: Functional assessment||
Variable - Cognitive and MotorMay also result in general debility
Medical assessmentsFunctional Assessment
|Renal transplant||Persistent impairment: Functional assessment||Variable - Cognitive and Motor||
Medical assessmentsFunctional Assessment
*See Part 1 for a discussion of the use of functional assessments for driver licensing decisions
Evidence suggests that cognitive impairment is associated with chronic renal disease and that with increasing disease severity there is also a corresponding decrease in cognitive functioning, which may impair functional ability to drive.
The highest risk of cognitive impairment is for those with ESRD (stage 5). There is a small body of literature indicating that ESRD is associated with diminished perceptual motor-coordination, impairments in intellectual functioning including decreased attention and concentration, and memory impairments. Some studies indicate that individuals with ESRD have a 2 to 7 times higher prevalence of cognitive impairment and dementia compared to the general population.
There is also evidence of a significant risk of cognitive impairment for those in Stage 3 and 4 of chronic renal disease. There is no evidence to suggest that risk of cognitive impairment in the early stages (stage 1 and 2) is significant enough to impair driving.
Research indicates that cognitive impairment ranging from mild to severe is common and often undiagnosed in dialysis patients. In particular, between 30% and 47% of older patients undergoing treatment by hemodialysis or peritoneal dialysis were classified as cognitively impaired. In the general population, 8% of Canadians 65 and over have dementia and another 17% have some form of cognitive impairment. One study also indicated that physicians had a tendency to underestimate cognitive impairment in patients undergoing dialysis.
Improvement in cognitive performance has been reported in individuals who have undergone a kidney transplant.
Drivers with chronic renal disease, particularly end-stage renal disease, may develop general debility resulting in a loss of stamina required to support the functions necessary for driving.
Drivers with chronic renal disease are not able to compensate for their functional impairment.
5.6 Guidelines for assessment
All drivers are eligible for a licence
|Conditions for maintaining licence||None|
|Information from health care providers||None|