Chapter 2 Measures against Lifestyle Related Diseases
|1. Creation of a new paradigm of "lifestyle related diseases"
Chronic diseases such as cancer, cardiovascular diseases were once referred to as "aging related diseases" because the incidence increases with aging.
However the new paradigm of "lifestyle related diseases" was proposed by a report by the Public Health Committee in 1996 to emphasize primary prevention over secondary prevention.
The rationale for creating the new paradigm of "lifestyle related diseases" in place for "aging related diseases" is that the latter may give a false impression that such diseases are inevitable with aging and a sense of resignation that they are not preventable and can only be countered with early detection at best.
|2. Current status of major lifestyle related diseases
Majority of diabetic patients in Japan are of type II or NIIDM, which is heavily dependent on lifestyle. Although its rank in the immediate cause of death is only the 10th in vital statistics, it also contribute to other major causes of death such as cardiovascular diseases or cerebrovascular diseases as major risk factors. Diabetes also contributes to various forms of disability such as renal failure and blindness.
Diabetic nephropathy accounted for 36.6% of newly initiated dialysis patients in 2000 and the number is increasing still. Also, as many as 3,000 people lose vision due to diabetic retinopathy making it the largest cause of blindness.
For the first time in November 1997, a nation wide survey on prevalence of diabetes was conducted as part of the National Nutritional Survey. According to the survey result applied to the national population, the number of suspected cases of diabetes defined as "HbA1C 6.1% or over plus patients already under medical treatment" is estimated to be 6.9 million and the number of potential cases defined as "HbA1C 5.6% or over" is estimated to be 13.7 million (more than 10% of the total population).
According to the result of the 5th National Survey on Cardiovascular Diseases conducted in 2000, the prevalence of hypertension has increased slightly in the total number except men aged 60 years or over and women over 40. On the other hand the percent of people with hypertension who are currently under medical treatment has increased possibly due to the effective mass-screening program rigorously conducted for a last decade.
Japan used to have a high prevalence of cerebral apoplexy until as late as 1970s. The health indices concerning apoplexies as measured by mortality and prevalence have since then improved dramatically thanks to the great effort to control high blood pressure.
A series of nation-wide sampling surveys to elucidate the secular trend of blood pressure of the Japanese have been conducted at 10 years interval for 5 times 1961-2000. Each time BP was measured on subjects aged 30 years or older randomly sampled from the entire population. Tracing the long-term trend of BP bears witness to the yield of public health activities.
The average systolic pressure (SP) of men aged 60 to 69 was nearly 160 mmHg, but it has consistently declined to 143 in 2000. What is noteworthy about BP is that diastolic pressure (DP), which has not declined as drastically as SP. In other words, the difference or pulse pressure (PP) has shrunk. More recently, PP is increasingly considered to reflect atherosclerosis or elasticity of blood vessel, then this tend my suggest that the BP of male Japanese has declined while suppressing atherosclerosis.
According to the Patient Survey conducted in October 1996, the number of patients under treatment for hyperlipidemia per age group is peaked in the age group of 70 to 74 at around 280 patients per 100,000. This figure severely underestimates the actual number of hyperlipidemia patients. Cautions should be taken because the survey is a cross sectional covering only three days and the number reflects only patients with hyperlipidemia as their primary diagnoses. Majority of hyperlipidemia patients are receiving treatment for the disease as secondary to other primary diagnoses.
Japan Obesity Association defines the obesity as BMI 26.4 or higher. According to this definition, the National Nutritional Survey conducted in 2000 revealed that 25.5% of men and 20.5% of women aged 15 years old or over were obese.
When compared with 20 years ago, there is a marked increase of obesity among men in all age groups but not in women. Since the prevalence of obesity will increase in the later stage of life, obesity should be considered as a major public health concern in combating lifestyle related diseases.
(5) Cerebral Vascular diseases
Cerebral vascular diseases used to occupy the most common cause of death until 1980. However it is now ranked in the 3rd place thanks to a sharp decline of the mortality especially due to a dramatic decline of cerebral bleeding because of better blood pressure control. Ironically enough, the improved survival of cerebral vascular diseases increased the number of surviving patients under treatment and the subsequent disabled people.
Primary prevention of cerebral vascular diseases and tertiary prevention from disability such as acute phase rehabilitation remains a major challenge for Japan's public health.
(6) Heart diseases
Japan used to have a high prevalence of rheumatic heart diseases but ischemic heart diseases are increasing even as the age-adjusted cause of death since 1993. As the incidence of ischemic heart diseases increases, some questions were raised as to the unsatisfactory rescue rate in the acute phase of onset. In addition to primary prevention, improvement of rescue and survival of acute phase should be emphasized.
Cancer has been the leading cause of death since 1981. Age-adjusted mortality shows a slight but gradual increase for male, while a slight decrease is observed for female. Site-specific cancer mortality shows that while mortality of stomach and uterine cancer are declining, lung and colon cancer mortality are on the rise suggesting effects of lifestyle changes.
Incidence of cancer can not be known from vital statistics especially when the survival of cancer improves. According to some cancer registry such as the one being conducted in Osaka suggests that stomach cancer is still by far the commonest cancer for men and second for women. However stomach cancer slipped from the top of the mortality for men thanks to improved survival. For women, stomach cancer is still the largest killer.