By DR ADRIAN SAWYER
WORLD Kidney Day was celebrated globally on Thursday.
The Theme this year was “Kidneys & Women’s Health”. Since 2006, March has been designated as kidney month annually and World Kidney Day is fixed as the second Thursday in March. The campaign is designed to globally raise awareness of the importance of kidney disease and is supported by the International Federation of Kidney Foundation Members, The International Society of Nephrology, affiliated societies worldwide and other external endorsing organisations.
The stated mission objective is to raise awareness of the importance of kidneys to overall health and to reduce the frequency and impact of kidney disease and its associated health problems worldwide.
Approximately 10 per cent of the world’s population is affected by chronic kidney disease; in 2010 it was 18th in the list of causes of total number of deaths worldwide by the 2010 Global Burden of Disease Study. Only 2,000,000 people worldwide receive dialysis or kidney transplantation as treatment for kidney failure and most of these are treated in only affluent industrialised countries. In middle- income countries treatment of kidney failure with dialysis or transplantation is a huge financial burden for patients and in more than 112 less developed countries, people who cannot afford treatment die; approximately 1,000,000 persons annually. The 2,000,000 patients receiving treatment worldwide represent approximately 10 per cent of the world population that need treatment.
classification of chronic kidney disease
A patient is diagnosed with chronic kidney disease if they have abnormalities in kidney structure or function present for more than three months; markers of kidney damage include a measurement or calculated estimation of a level of kidney function called glomerular filtration rate. There are validated equations in use from which this measure can be calculated as the e-GFR (estimated GFR) by measurement of the blood level of a chemical breakdown product of lean body muscle mass called creatinine; patient age, gender and race/ethnicity are the other variables required for the measurement of e-GFR.
There are five stages of e-GFR used to classify chronic kidney disease usually denoted by the symbols G -1 through G-5, with G-5 representing a level at which patients require dialysis or transplantation; Stage G-3 is the critical level used to define chronic kidney disease (CKD)- e-GFR of less than 60.0 ml/min/1.73 m2.
The other established marker of kidney damage is the presence and level of protein, specifically albumin in the urine.
The major clinical consequences of having chronic kidney disease are those of multiplied risks of progression and death from cardiovascular diseases such as heart attacks, heart failure, sudden cardiac death, strokes, pre-mature death and infections, because CKD is associated with impairment of the immune system function. Impairment in quality of life and productivity are non-clinical sequelae. Most people with CKD die from the above noted complications before reaching stage G-5, requiring dialysis treatment or kidney transplantation. Of 100 stage three CKD patients, perhaps 10 will live to require kidney replacement treatment. The major causes of CKD/ end stage renal disease (ESRD) that require kidney replacement treatment are:
Diabetes which in the United States accounts for approximately 45 per cent of causes
Hypertension (high blood pressure)- accounts for some 30 per cent of causes
Inflammatory kidney diseases with glomerular and interstitial damage causing kidney failure account for approximately 10 per cent
Cystic and hereditary kidney diseases account for approximately 7-9 per cent
According to the United States Renal Data System 2017 report, which is most relevant to the Bahamian population, people of African ancestry/ethnicity have an almost fourfold greater prevalence (current total number of cases per million population) and incidence (number of new cases per year per million population) of kidney failure compare to Caucasians, with diabetes and more severe hypertension being the principal drivers.
Unadjusted comparable figures estimated for the current population of The Bahamas would be in absolute numbers which are most relevant for health planning efforts, would amount to approximately 2,000 prevalent patients on dialysis and approximately 150-250 new patients per year with end stage kidney failure.
With the direct cost of providing dialysis treatment to one patient ranging from $75,000 -$88,000 per year, the financial implications of undertaking care of these patients are staggering, especially within the projected context of proposed National Health Insurance projections. Like other jurisdictions, it will be clear that these patients utilise a disproportionate share of health care dollars, and worse still, with the anticipated increase in the incidence and prevalence of diabetes in an increasingly overweight/obese population, the figures are bound to increase.
Women and kidney disease
Clinical data indicates that women have a higher prevalence of pre-dialysis chronic kidney disease than men (16 per cent vs 13 per cent). Progression to dialysis occurs faster in men and the decline in function is more severe. Mortality is higher in men at all levels of pre-dialysis CKD.
There are several contributing factors related to unbalanced risks in women, some are gender/sex related and others not. Clinical conditions and diseases that pose special risks to the health of women’s kidneys are: obesity; high blood pressure; autoimmune diseases; and pregnancy.
Women with established CKD have reduced fertility rates, increased risk for pre-eclampsia, hypertensive crises in pregnancy, higher delivery rates of small for date babies and increased post delivery rates for hypertension and more advanced chronic kidney disease.
Pregnancy is a crucial factor affecting immunologic access to receiving a kidney from a deceased or living donor for women. Pregnancy is a state in which the mother is exposed to the fetus which has paternal proteins/antigens which are foreign to the mother’s immune system and consequently the maternal immune system mounts an antibody response, which is not destructive during the pregnancy; these antibodies can persist after the pregnancy, or re-emerge later on exposure to similar proteins/antigen and due to the presence of special “memory Cells” that can recall previous antigen exposure and mount an enhanced, vigorous antibody response; the presence of these antibodies lead to rejection of a transplanted kidney, therefore pre-transplantation tests that detect these antibodies, make it less likely that these women will be considered for kidney transplantation due to the high immunologic risk of rejection.
Other factors are: HIV infection and urinary infections in women.
All of the above noted areas are particular to kidneys and women’s health and represent a significant, expanding burden of population at risk of the consequences of chronic kidney disease: pre-mature death from heart-related disease such as heart attacks, sudden cardiac death, heart failure, strokes and all-cause death. It is imperative for medicine, patients and governments to undertake appropriate population screening, identification of risk groups and specific programmes for treatment to prevent or slow disease progression.
This can only be accomplished by education of patients, physicians and health policy officials to the extent of the risks and implement screening policies that identify persons at risk, namely persons with hypertension, diabetes, high cholesterol, increased body mass indices, family history of premature cardiac disease, kidney disease, pregnancy hypertensive diseases and recurrent kidney infections. Annual measurements of blood pressure, urine testing for the presence of protein or blood in the urine and screening for diabetes along with measurement of the renal function panel that includes the blood creatinine, from which the e-GFR can be calculated, are steps that are easily implemented with minimal disruption to the health care system. The awareness and identification of individuals with chronic kidney disease will significantly impact treatment to prevent progression to end stage kidney disease requiring dialysis or kidney transplantation.
• Dr Adrian Sawyer is director of The Dialysis Centre Bahamas