5 - Chronic Renal Disease

5.1About chronic renal disease

Overview

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

Stage Description

GFR

mL/min/1.73m2

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

5.2Prevalence

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.

5.3Chronic 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.

5.4Effect 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 Motor

May also result in general debility

Medical assessments

Functional Assessment
Renal transplant Persistent impairment: Functional assessment Variable - Cognitive and Motor

Medical assessments

Functional Assessment

*See Part 1 for a discussion of the use of functional assessments for driver licensing decisions.

Cognitive impairment

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.

General debility

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.

5.5Compensation

Drivers with chronic renal disease are not able to compensate for their functional impairment.

5.6Guidelines for Assessment

5.6.1 Stage 1 to 4 renal disease (Commercial and Non-commercial)

National Standard

All drivers are eligible for a licence if

  • medical assessment shows no residual effects
  • the functional abilities necessary for driving are not impaired
BC Guidelines

If further information regarding an individual’s medical condition is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report; or
  • additional information from the treating physician
Conditions for maintaining licence None
Reassessment RoadSafetyBC will not re-assess, other than routine commercial or age-related re-assessment
Information from health care providers RoadSafetyBC will not re-assess, other than routine commercial or age-related re-assessment
Rationale
  • Stage 1 or 2 renal disease is unlikely to cause impairment of the functions needed for driving.
  • Drivers with stage 3 or 4 chronic renal disease are at significant risk for cognitive impairment that could impair their functional ability to drive

5.6.2 Stage 5 - End-stage renal disease - (Commercial and Non-commercial)

National Standard

All eligible for a licence if

  • Complete medical assessment by treating physician shows no residual effects
  • The functional abilities necessary for driving are not impaired, and
  • the conditions for maintaining a licence are met
BC Guidelines

If further information regarding an individual’s medical condition is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report, or
  • additional information from the treating physician
If the treating physician indicates possible impairment of one or more of the functions necessary for driving, RoadSafetyBC may request functional assessment(s) as appropriate for the type(s) of impairment and class of licence held, unless there has been no significant change in the individual’s condition or functional ability since a previous functional assessment
Conditions for maintaining licence
  • Routinely follow prescribed dialysis regimen
  • Do not drive if dialysis treatment is delayed or circumstances do not allow for maintaining dialysis schedule
  • Remain under regular medical supervision by a treating physician to ensure that any progression of the disease or development of co-morbid conditions is monitored
Reassessment RoadSafetyBC will re-assess annually
Information from health care providers
  • Stage of renal disease
  • Functional Limitations, if any
  • History of compliance with prescribed dialysis regimen
  • Opinion of treating physician on compatibility of work schedule with dialysis regimen
  • Whether the driver has insight into the impact their medical condition may have on driving
  • If known or applicable, whether the driver is compliant with any current conditions of licence
Rationale Drivers with end-stage renal disease are at significant risk for cognitive impairment and general debility that could impair functional ability to drive.  Regular dialysis is required to maintain overall functional ability

5.6.3 Renal transplant

National Standard

All drivers eligible for a licence if

  • Complete medical assessment by treating physician shows no residual effects
BC Guidelines

If further information regarding an individual’s medical condition is required, RoadSafetyBC may request

  • a Driver’s Medical Examination Report, or
  • additional information from the treating physician.
If the treating physician indicates possible impairment of one or more of the functions necessary for driving, RoadSafetyBC may request functional assessment(s) as appropriate for the type(s) of impairment and class of licence held, unless there has been no significant change in the individual’s condition or functional ability since a previous functional assessment
Conditions for maintaining licence None
Reassessment If transplant has occurred within 1 year of assessment, RoadSafetyBC will re-assess in one year. At that time, if the treating physician indicates that there has been no decline in functions post-renal transplant, no further re-assessment, other than routine commercial or age-related re-assessment, is required
Information from health care providers Functional limitations, if any
Rationale Even after a successful renal transplant, there may be persistent cognitive impairment that could impair functional ability to drive