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First Consensus Meeting on Menopause in the East Asian Region

The menopause in Hong Kong

C. J. Haines
Department of Obstetrics and Gynaecology, Chinese University of Hong Kong,
Prince of Wales Hospital, New Territories, Hong Kong

Hong Kong population statistics

The population of Hong Kong is predominantly Chinese, with the 1996 census showing that 60.3% of the inhabitants had been born in Hong Kong, 32.6% in China and 7.1% elsewhere [1]. By nationality, 59.6% of the population were British but with right of abode only in Hong Kong, and 34.4% were Chinese with Hong Kong as their place of domicile. The Cantonese dialect is the usual language of 88.7% of the population, whilst 7.0% speak other Chinese dialects and 1.1% speak Putonghua (Mandarin). English is the usual language of only 2.2% of the population.

Despite a reduction in the rate of natural increase over the last decade, the Hong Kong population has continued to expand, partly due to greater longevity. The estimated mid-year population in Hong Kong in 1994 was 6,061,400, which represented an 11.1% increase from the figure of 5,456,200 recorded in 1985 [2]. Population figures for those years are shown in Table I.

Table I: Estimated mid-year population, birth rates, death rates and infant mortality rates in Hong Kong.

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Although the number of women over the age of 50 years increased during this 10-year period, there was a relatively greater rise in the number of men. In 1985 there were 551,000 men aged 50 years or more and 586,100 women. These figures had increased to 657,500 for men and 650,300 for women by 1994. The number of males per 1,000 females in the age group 65 years and over increased from 683 in 1981 to 784 in 1991 [1]. From 1985 until 1994, the crude birth rate decreased from 14.0/1,000 to 11.9/1,000 population, whilst the crude death rate increased from 4.6 to 5.0/1,000 population.

Expectation of life in Hong Kong increased from 20.5 years in 60-year-old women in 1971 to 23.2 years in 1991. In 80-year-old women, there was an increase from 7.1 to 8.8 years. From 1985 to 1994, the overall increase was from 73.8 to 75.9 years in males and from 79.2 to 81.2 years in females. This increase is expected to continue into the next century (Table II).

Table II: Expectation of life at birth for Hong Kong and selected countries: 1991-2011

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From 1991 to 2011 the life expectancy of males is expected to increase from 74.9 to 77.7 years, and the increase is expected to be slightly greater for men than for women. This trend is similar to that of the United States and United Kingdom; however, life expectancy for women in Hong Kong (83.0 years) will still remain lower than in Japan (projected 83.5 years) and the United States (projected 83.9 years), but will remain higher than in the United Kingdom (projected 80.4 years).

A reduction in the number of high order births and a postponement in low-order births which has been observed in western countries has also been found in Hong Kong [1]. The total fertility rate steadily declined over the 20-year period from 1971 onwards. In 1971 the total fertility rate was 3,460/1000 women, and this figure had declined to 1,211/1,000 by 1990. This compares with figures of 1,790/1000 in 1989 in Singapore, 1,570/1,000 in Japan and 1,810/1,000 in England and Wales.

The rate of natural increase in population decreased from 9.3/1,000 in 1985 to 6.9/1,000 in 1994. The increase in population during this period was affected by immigration, especially by those entering Hong Kong from mainland China. However, a negative balance of net migration of 3,300 persons per annum is projected for the years 1992-2001, but this figure is expected to become positive by 2002. There is, however, some uncertainly in the estimation of migration figures for Hong Kong due to the handover of sovereignty from Great Britain to China in 1997. As a
result of the low birth rate and the anticipated migration figures, the projected mid-year population for the year 2000 is 6,039,500, comprising 3,021,600 males and 3,017,900 females [3].

Medical services in Hong Kong

In response to the growth in size of the Hong Kong population, the total number of beds increased from 24,638 in 1985 to 27,836 in 1994, despite a reduction in the number of medical institutions from 90 to 87. This represented approximately a 13% increase in beds for an 11% population increase. The Hospital Authority (government) hospitals provided 23,461 of these beds in 13 institutions on Hong Kong Island, 11 on the Kowloon peninsula and 13 in the Hong Kong New Territories. Other figures demonstrate the increased load which was placed on health care facilities. From 1990/91 to 1994/95, the number of public hospital discharges increased from 632,335 to 832,281 [4]. The bed occupancy rate increased from 74.8% to 77.8% and the average length of stay increased from 7.3 to 7.8 days. There were 4,874,565 specialist outpatient attendances and 741,298 general outpatient attendances.

As far as medical personnel are concerned, the total number of registered/licensed doctors increased from 4,887 in 1985 to 7,670 in 1994. The number of registered nurses also increased from 14,178 to 23,018 over the same period. There are currently 341 doctors in Hong Kong with a recognized degree in Obstetrics and Gynaecology (predominantly a specialist degree from the United Kingdom, Australia, the United States or Canada) who are members or fellows of the Hong Kong College of Obstetricians and Gynaecologists. Of these, 280 have completed their training requirements and are recognized specialists registered with the Hong Kong Academy of Medicine.

There are few services offered solely for the education and care of postmenopausal women. Gynaecologists provide the only specialized public clinics for postmenopausal women, but they may also be seen in general medical, endocrine, geriatric and community medicine clinics. The first hospital-based public clinic devoted entirely to the care of postmenopausal women was established by the Chinese University of Hong Kong at the Prince of Wales Hospital in the New Territories in 1990. Resources are only available to operate one clinic each week which sees approximately 30 patients and has a waiting list of over 6 months. In order to reduce the waiting time, a shared care arrangement with a nearby Family Planning Association of Hong Kong clinic commenced in 1996, and under this arrangement, those women who are stable on hormone replacement therapy can be referred to this clinic for ongoing care. A second hospital-based public clinic opened in 1996 at the Tsan Yuk Hospital on Hong Kong island which has two menopause sessions each week. Well Women clinics which also offer services to postmenopausal women are offered by the Family Planning Association of Hong Kong, by the Hospital Authority and by the Department of Health.

Cardiovascular disease in Hong Kong

The prevalence of diseases and the major causes of death in Asian populations have a different distribution to that of many of the developed countries. In Hong Kong, neoplasms account for more deaths than heart disease in both males and females. In 1994 there were 2,331 cancer-related deaths in women and 2,022 deaths from heart diseases, including hypertensive heart disease. Cerebrovascular disease accounted for another 1,455 deaths. As expected, deaths due to coronary artery disease (CAD) increase with advancing age, and statistics from 1992 showed CAD death rates of 13.9/100,000 for males in their forties, 67.9/100,000 for males in their fifties and 205.8/100,000 for males in their sixties [5]. Heart diseases were responsible for 15.6% of all deaths compared with 31.1% for cancer. Over the last 20 years, the crude death rate due to CAD in Hong Kong almost doubled, from 28.4/100,000 population in 1972 to 54.7/100,000 in 1992 [5]. This occurred in association with a longer life expectancy as well as the development of a more atherogenic lipid profile. The problem of cardiovascular disease appears to be increasing, with the ratio of deaths from heart diseases compared with cancer having risen from 0.65 in 1985 to 0.87 in 1994 in women and from 0.45 to 0.56 in men. In addition, women appear to be affected more by the increase in risk than do men. The age-specific mortality rate from ischaemic heart disease increased from 402.30/100,000 women in the period 1979-1983 to 445.95/100,000 in the years 1989-1993 [6] (Table III).

Table III: Sex-age specific mortality rate (1 per 100,000) of IHD in Hong Kong (1989-1993) [6]

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The menopause has a similar effect on the incidence of CAD in postmenopausal Chinese women in Hong Kong as in most other populations. The sex ratio (M:F) is 5.1 in the 30–49-year-old age group but decreases to 1.2 in those aged 65 years or more. However, at all ages the gender difference in the incidence of cardiovascular diseases in Hong Kong is not as great as in most western countries. In the 40–69-year-old age group, for example, the ratio is 2.8 in the United States and 3.3 in England and Wales, but in Hong Kong it is only 2.4 [7]. Women in Hong Kong therefore appear to be at relatively greater risk of developing CAD at a younger age.

Despite the increasing incidence of CAD in Hong Kong and in other Chinese communities in Asia, the prevalence of this disease remains considerably lower than in the majority of urbanized western societies (approximately 200-350/100,000 population). In the 1950s it was estimated that CAD mortality in mainland China was
15–20 years behind that of the developed countries [8], and in the mid-1980s, crude
death rates due to CAD of 36.9/100,000 and 15.6/100,000 were reported in urban and rural mainland Chinese populations respectively [9]. At that time the number of deaths from CAD in Hong Kong and in Taiwan was also relatively low (44.4/100,000 and 30/100,000 population respectively) [10], but it was acknowledged that this number was increasing in all of these predominantly Chinese communities. In China, the increase was recognized in the late 1950’s [11], and subsequent studies have confirmed a progressive rise in CAD deaths throughout the country [12]. This has taken place when the trend in most developed countries has been in the reverse direction. In Taiwan, coronary mortality increased from 5.7/100,000 to in 1971 to 30/100,000 in 1978 [13], but these figures may have been influenced by the underreporting of deaths due to CAD prior to this time. An increase was also documented in Singapore, where the standardized death rate rose from 40/100,000 population in 1970 to 62/100,000 in 1988 [14]. Heart disease therefore remains a significant problem in Chinese populations, and there is no evidence at present to suggest that the number of CAD deaths in Hong Kong is likely to decrease in the immediate future.

Osteoporosis in Hong Kong

As is the case for cardiovascular disease, the incidence of osteoporosis is also increasing. Between 1960 and 1985, the incidence of hip fracture in elderly Chinese more than doubled, from 153 to 353 per 100,000 population [15]. This increase was thought to be related to the increase in urbanization in Hong Kong, and the fracture rates became closer to those found in other developed countries (Table IV). The estimated incidence for women aged over 80 years is 1,521/100,000 per year and is 32/100,000 in those aged 50-59 years [16].

Table IV: Incidence rates a of hip fracture by country and sex (b) (Research on the menopause in the 1990s. Report of a WHO scientific group. WHO Technical Report Series 866, 1996:42).

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The age-specific fracture rates remained relatively stable between 1985 and 1989 [17]. An increase in the number of fractures has also been found in other Asian countries, including Japan and Singapore [18].

Approximately half of all patients with fractures admitted to district hospitals in Hong Kong are elderly women [16] who have been reported to suffer an associated 40% mortality over a 4-year period [19]. Whilst the prevalence of osteoporosis is increasing, some studies have suggested that the incidence of hip fracture in Asian women is still almost half of that of white women from the United States [20,21]. However, the bone mineral density of Chinese premenopausal women has been reported to be lower than that of Caucasians of a similar age [20], although more recent evidence suggests that after controlling for factors such as weight and height, these differences may disappear [22]. One of the factors which may reduce the risk of fracture in Asian women is their shorter stature and hip axial length, which on anatomical grounds may make a fracture less likely than in a taller woman [23]. In addition, Asian women have a narrower angle of the femoral neck, and this may also reduce the risk of fracture for a given fall [24].

As in other populations, a low bone mineral density is a risk factor for fractures in Hong Kong Chinese women [25]. Studies of our own and of others have consistently shown that the intake of calcium in postmenopausal women in Hong Kong is below the recommended daily allowance [26,27]. The relative risk of hip fracture in Hong Kong is significantly higher in those with a low dietary calcium intake [17], and dietary calcium supplements have been shown to be effective in preventing bone loss in the femoral neck [25].

As far as other diseases are concerned, the death rate from breast cancer increased from 9.9 to 11.1/100,000 population from 1985 to 1994, but the number of deaths due to carcinoma of the cervix decreased from 5.3/100,000 to 4.6/100,000 population.

Use of hormone replacement therapy in Hong Kong

The relatively small number of women using hormone replacement therapy in Hong Kong is likely to result from two main factors. The first of these is the low incidence of acute menopausal symptoms. This was confirmed in a prospective study of Chinese women undergoing a surgical menopause, where the incidence of hot flushes was 24.2%, which is considerably lower than the 70% or so which may be expected in Caucasians [28]. In addition, Chinese women in Hong Kong have very little knowledge of the effects of the menopause or the treatments which are available [29]. The combination of a low incidence of symptoms and a lack of awareness of the possible long-term complications of the menopause means that Chinese women in Hong Kong may be less likely to seek advice about the menopause from a medical professional than Caucasian women.

The cost of treatment is unlikely to be contributing to the low number of women using HRT. The cost of a visit to a Hospital Authority outpatient clinic is $44 (approximately USD 5.68). This sum includes the cost of drugs which can be prescribed for six months at each visit. It is difficult to estimate the number of postmenopausal women in Hong Kong who are using hormone replacement therapy. Unofficial estimates suggest that the figure lies somewhere between 3 and 6%. A wide range of preparations have been approved and are readily available. Conjugated equine oestrogens (Premarin, Wyeth; Conjugated Oestrogens Jean-Marie, Jean-Marie) are the most commonly prescribed oral oestrogens, but oral estradiol (Estrofem, Novo Nordisk; Progynova, Schering) and oral estriol (Ovestin, Organon) are also used. Non-oral oestrogen is available in patches (Estraderm TTS, Ciba) and as a percutaneous gel (Oestrogel, Besins). There are a wide variety of combined cyclical oral preparations (Prempak, Wyeth; Trisequens, Novo Nordisk; Femoston, Solvay; Climen, Schering; Dilena, Organon) and continuous combined treatment is also available (Kliogest, Novo Nordisk, Livial, Organon). Combined treatment is also available in patches (Estracomb TTS, Ciba). Another unofficial estimate suggests that sales of hormone replacement therapy products currently amount to approximately HKD 10,867,000 per annum, and are increasing by more than 25% each year.

Future research directions

There are a number of areas relating to the menopause and the use of hormone replacement therapy which apply especially to Chinese and other Asian women and which are deserving of further research effort.

The first of these is the study of the most appropriate doses of HRT for women in this region. The doses of oestrogen which are most commonly prescribed for HRT are those which have been shown to prevent osteoporosis in postmenopausal Caucasian women. Chinese and other Asian women tend to be of smaller stature than Caucasians, and there is some preliminary evidence to suggest that doses lower than those used in Caucasians may be more appropriate [30]. Chinese women have fewer problems with acute menopausal symptoms, and at present have a relatively low coronary artery disease risk. In addition, a significant number may be taking Chinese herbal medicines or else may have a high phytoestrogen content in their diet, and these factors could also mean that the oestrogen dose could be reduced. This is particularly important in view of the recent data which suggest that the risk of venous thrombosis and stroke in Asians who are using oral contraceptives is higher than in other populations [31,32]. It is not known whether Asian women using hormone replacement therapy are also at greater risk of these conditions.

A high dietary intake of phytoestrogens may also be one of the reasons for the relatively low incidence of breast and endometrial carcinoma in Asian women, and whilst there is already some evidence to support this [33], further studies on phytoestrogens in different Asian populations would be interesting as diets differ widely between countries.

Nearly all studies concerning the most appropriate dose of progestogens have also been performed in Caucasian women, and partly for the reasons mentioned above, lower doses of progestogens than those currently recommended may prove to be safe in postmenopausal Asian women.

It has yet to be determined whether postmenopausal women from different parts of Asia suffer from the same variety of acute symptoms as Caucasian women. Although Asian women experience fewer of the symptoms which are common in Caucasians, there have been no studies in Asian populations using open-ended questioning, and it may be that they exhibit a different type or frequency of symptoms as a result of racial, cultural or environmental differences.

It is also our impression that Chinese women are relatively poorly informed about the menopause, and that this contributes to the low usage of HRT in these populations. This warrants further investigation, as it appears as if cardiovascular disease will increasingly affect Chinese women in future years, and it is important that they are given as much information as possible so that they have the choice about whether to use HRT as a preventive measure against the development of osteoporosis and cardiovascular disease.

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