The Tribune

By DR ADRIAN SAWYER

Today has been designated as World Kidney Day. This initiative undertaken and sponsored, now for the 11th successive year, by The International Society of Nephrology (ISN) and The International Federation of Kidney Foundations (IFKF), aims to bring global awareness to the importance of kidneys to overall health.

Since the inception of this initiative in 2006, March of each year has been designated as Kidney Month and the second Thursday in March is observed as World Kidney Day, with specific targeted themes related to the effects of kidney diseases on populations. The aim is to inform, educate and raise awareness of the emerging epidemic of kidney disease worldwide with a view to engaging local and national health authorities in efforts to plan for and undertake measures to treat and prevent the devastating sequelae - End Stage Kidney Disease (ESRD) - which requires dialysis and/or kidney transplantation for the maintenance of life at substantial costs for the individual, health care providers and governments.

Diabetes and high blood pressure are the major risk factors for Chronic Kidney Disease (CKD).

In the Bahamas, diabetes and high blood pressure are major non-communicable diseases that are highly prevalent; the current government initiatives to implement a National Health Insurance (NHI) scheme have significant implications for funding allocations considering that the cost for treating ESRD by dialysis or transplantation will consume disproportionately high levels of health care expenditures. The current direct cost of one year of haemodialysis treatment per patient is more than $86,000.

Data on the prevalence of diabetes in the adult population of the Bahamas from the International Diabetes Federation (IDF) for 2014 was 13.3 per cent, one of the highest among its members.

Data by Moser et al on the prevalence of high blood pressure in adults in the Bahamas has been reported to be 27 per cent for males and 36 per cent for females.

Figures for adolescent hypertension suggest that 10 per cent of this age group may be hypertensive. The prevalence of obesity nationally is 36.6 per cent, placing the Bahamas tenth highest in the world for this emerging medical disorder. Corresponding figures for regional countries are Barbados 33.2 per cent; Trinidad & Tobago 32.3; Jamaica 26.8; Antigua 31; Canada 30.1; and the United States 35.

The relevance of this years’ World Kidney Day theme - Kidney Disease and Obesity - to the national health planning agencies, government, health care providers, the public and economic burden attendant to the consequences of diabetes, hypertension and obesity on the ever-increasing numbers of patients with kidney diseases, cannot be ignored.

In defining and clinically assessing obesity doctors use the combination of measured waist circumference, recorded in centimetres or inches and a Body Mass Index (BMI), which is derived from your weight measured in kilograms, and your height, measured in metres.

Values between 18.5 to 24.9kg/M2 are regarded as normal or ideal; between 25.0 to 29.9kg/M2 are considered as overweight; in excess of 30.0kg/M2 are the definition of obesity, which have three levels of classification: mild, moderate and morbid.

Waist circumference measurements currently vary related to ethnicity. A further refinement of assessment of obesity clinically is the ratio of the circumferences of the waist at its maximal point to the hip circumference at its widest point.

The combination of these measurements, which are easy to document in the ordinary clinical setting, have been proven to correlate with the proportion of body fat distribution in multiple clinical studies that show evidence of increasing morbidity and mortality associations, disease specific associations and co-morbidities, with increasing values of these parameters.

Disease risks

Multiple clinical and observational studies have shown that increasing obesity is associated with reduced life expectancy, cardiovascular diseases, such as coronary vessel atherosclerotic disease leading to heart attacks, high blood pressure (hypertension), diabetes, dyslipidaemia (abnormal circulating fat components, cholesterol and triglycerides), sleep-apnoea (disordered breathing during sleep), certain cancers and progressive CKD and ESKF.

Diabetes is a progressive disease with time and requires increasing doses of anti-diabetic medications due to continuing loss of beta cell function in the pancreas. The risk of progressing to ESRD over 20 years of diabetes is 30 to 40 per cent.

For almost all national registries that track the kidney failure/dialysis populations, diabetes is the single leading cause, accounting for approximately 40 to 45 per cent. Hypertension accounts for 25 to 35 per cent of kidney failure leading to dialysis or transplantation. The combination of diabetes and hypertension account for more than 70 per cent of all cases of ESRD.

Obesity affects kidney disease directly and indirectly. Directly, increasing levels of obesity have been found to increase the risk of chronic kidney disease by causing increasing amounts of protein loss from the kidneys which leads to progressive structural kidney damage; obesity also accelerates the rate of deterioration of kidney function in people with non-obesity related kidney disease. Over the last 30 years, a specific form of kidney disease related to obesity has been recognised that causes a specific form of damage to the glomeruli which are the essential functional units of the kidney (approximately 1,000,000 in each kidney), for which the only effective treatment is weight loss alone which can reverse the disease.

Indirect effects of obesity include the genesis of high blood pressure and diabetes, leading to avenues for progressive kidney damage by promoting atherosclerosis, blood vessel damage, blood perfusion abnormalities to vital organs such as the brain heart and kidneys leading to strokes, heart attacks, heart failure and kidney failure. Obesity has also been reported to increase the risk of kidney stones and is also an established risk factor for kidney cancer.

The major factors associated with the increasing worldwide epidemic of obesity are a combination of a sedentary lifestyle, high caloric intake and lack of exercise. The issue of the source of calories, specifically carbohydrates in the form of highly absorbed carbohydrates/starch products or fructose-based products used in the production of soft drinks and as components of fast food products, are areas of intensive interest currently and some countries have taken measures to reduce availability of such product to the consumer.

Economic implications

The increasing numbers of obese persons worldwide and more specifically, nationally, have significant import for the health care budget.

Obesity is a largely preventable disease, but difficult to treat. Pharmaceutical treatments have significant adverse effects and studies have found that sustainable weight loss is an elusive goal; the recent introduction of various forms of gastric (stomach) bypass surgery have been shown to be effective and in some cases have reversed protein loss in the urine and also diabetes.

The costs that will have to be incurred with this modality of surgery to an increasing population need to be considered along with the potential for adverse effects. There have been estimates that the number of new patients that will progress to end stage kidney failure and require dialysis or transplantation in the Bahamas, is between 200 and 300 per year. The direct cost of one year of haemodialysis treatment, without hospitalisation considerations, is more than $86,000 per patient; a kidney transplant operation only has a direct cost of close to $100,000, not including the cost of medications required to prevent rejection of the transplanted kidney, which are required for the life-time of the transplant.

With the total number of dialysis-dependent patients currently around 400 to 450, the anticipated increase in numbers for the future due to obesity-induced diabetes and hypertension, could well eclipse $20m per year. Any plans for considering kidney failure as a candidate for catastrophic care by the proposed NHI, will need to take cognisance of this hard fact.

The only effective strategy to meet this epidemic of obesity and obesity-related kidney disease is prevention by education of parents and children of the negative impact of obesity on health; the undertaking of initiatives on a national scale, to reduce the availability of the foods that contribute to obesity, f such as fast foods and high sugar-calorie drinks; the implementation of weight-reduction and increased exercise programmes from a young age; and reducing daily calorie intake efforts to abolish the local myth that increased body mass is a sign of health.

• Dr Adrian Sawyer is the Director and Chief Nephrologist at The Dialysis Centre Bahamas