HIV/AIDS in New Zealand: an epidemic in decline?

OBJECTIVE: To describe the AIDS epidemic in New Zealand, and to discuss the reasons for an apparent decline in incidence. METHODS: The AIDS Epidemiology Group collects information on persons diagnosed with AIDS through a compulsory notification system. Data were presented on people diagnosed to the end of 1994, and reported by the end of September 1995. RESULTS: The cumulative incidence of AIDS in New Zealand was similar to that in some other Western countries, such as the United Kingdom, Germany and Sweden, before 1989, but has been declining since 1989. The epidemic is concentrated among men who have sex with men (89%). The median survival after diagnosis with AIDS is 13 months. CONCLUSIONS: The observed decline is not likely to be due to reporting delays or changes in reporting or diagnostic practices. The major factor was probably a rapid decline in HIV incidence among homosexual men a decade ago, and the effective prevention of epidemics in other subgroups. The epidemic in New Zealand started later than in other countries, enabling an earlier response, and there is evidence of behaviour change in high risk groups. Preventive efforts and monitoring must be maintained in order to ensure there is no reversal of this decline.

Geographic distribution of MS in New Zealand: evidence from hospital admissions and deaths.

We studied the occurrence of multiple sclerosis (MS) in residents of all regions of New Zealand by analyzing first hospital admissions and deaths. Maoris had a much lower proportion of first admissions and deaths than the proportion of Maoris in the general population. For non-Maoris, both first hospital admission and mortality rates increased steadily from the northern part of the country to the south, with one possible exception.

Breast cancer in Maori and non-Maori women.

BACKGROUND: Breast cancer is more common in Maori than in non-Maori women under the age of 40 years and is equally common in older women, despite Maori being generally of lower socioeconomic status and having had a higher fertility rate than non-Maori. METHODS: Data from a nationwide population-based case-control study of breast cancer in New Zealand women aged 25-54 years were used to compare the age-adjusted distribution of reproductive and other risk factors for breast cancer in self-identified Maori and non-Maori women from the control group. Separate analyses also were carried out for women aged 25-39 years and for those aged 40-54 years. The risk of breast cancer according to the proportion of Maori ancestry was estimated using multiple logistic regression simultaneously adjusting for several risk factors. RESULTS: Significant differences were found between self-identified Maori and non-Maori women in the age-adjusted frequencies for education level, socioeconomic status, age at first full-term pregnancy, parity, and duration of breastfeeding; the profile in all instances suggesting a lower risk of breast cancer for Maori than for non-Maori. There were no significant differences with respect to age at menarche, surgery for benign breast disease or a family history of breast cancer. Significantly more Maori than non-Maori were in the highest quartile of recent body mass index. Women self-identified as Maori has an approximately twofold higher risk of breast cancer than non-Maori women. CONCLUSIONS: Maori have high rates of breast cancer despite having a more favourable profile than non-Maori for most identified risk factors.

PIP: National statistics collected in New Zealand since the mid-1960s have identified higher rates of breast cancer in Maori women under 40 years of age than their non-Maori counterparts, despite their low socioeconomic status and high fertility. Data from a nationwide population-based case-control study of breast cancer in New Zealand women 25-54 years of age were used to compare the age-adjusted distribution of reproductive and other risk factors for breast cancer in self-identified Maori (n = 89) and non-Maori women (n = 1771) from the control group. Compared with women with no Maori ancestors, women 25-39 years old with at least half Maori ancestry had a two-fold higher risk of breast cancer after adjustment for known risk factors (odds ratio, 2.2; 95% confidence interval, 1.2-4.2). However, when data from the control group were analyzed, Maori women had a significantly more favorable profile in terms of breast cancer risk than their non-Maori counterparts in terms of education level, socioeconomic status, age at first full-term pregnancy, parity, and duration of breast feeding. The only exception to this pattern was body mass index. 62.1% of Maori controls 25-54 years old, compared with 23.1% of their non-Maori counterparts, were in the highest quartile of recent body mass index (p 0.001). The excess of breast cancer in young Maori may reflect unknown genetic factors that increase susceptibility.

Projections of cervical cancer mortality and incidence in New Zealand: the possible impact of screening.

STUDY OBJECTIVE: The aim was to estimate the likely burden of cervical cancer in New Zealand over the next two decades, according to whether cervical screening services are made more effective. DESIGN: The study was based on national mortality and incidence data for the periods 1954-87 and 1954-86, respectively. An age-period-cohort model was used to estimate the contributions of age, time period, and birth cohort effects to the occurrence of cervical cancer. Using age specific estimates of the future female population of New Zealand, projections of cervical cancer mortality and incidence until the year 2008 were derived from the model. Projections were made assuming either that screening services will not be improved, or that an immediate improvement in the organisation of screening will lead to a decline in period effects for incidence of 15% per five year time period (with a slightly delayed effect on mortality). It was also assumed either that the risk in new birth cohorts will be similar to that in recent cohorts, or that their risk will be halved as a result of changes in sexual behaviour (due to education about AIDS or other factors). Combining these assumptions produced four sets of estimates, reflecting a range of possible scenarios. SETTING: Both the data used and the projections obtained related to the entire population of New Zealand women. MAIN RESULTS: For both mortality and incidence, projections were made of age specific rates, cumulative rates, and absolute numbers of deaths or new cases. With the first assumption about new birth cohorts, it was estimated that both mortality and incidence rates will increase if screening services are are not improved. In absolute terms, the present 100 deaths per year could increase to about 148 deaths per year, while there could be a much larger increase in incidence from 235 per year to about 440 per year). With improved screening, there could be a reduction in age specific mortality rates and a modest decline in the number of deaths, while a reduction in incidence rates would be accompanied by about the same number of new cases as at present. In comparison with improvements in screening, changes in the underlying risk in new birth cohorts would have much smaller effects on the occurrence of cervical cancer over the next two decades. CONCLUSIONS: Plausible improvements in cervical screening are likely to be accompanied by only small changes in the burden of cervical cancer over the next two decades. If screening services are not improved, however, there will be striking increases in both mortality and incidence.

Record linkage for drug monitoring.

A study was carried out to assess the feasibility of using record linkage for drug monitoring. For two years, three types of records were collected for a total of 43 117 people: (1) details of basic attributes, such as sex and age; (2) details of prescriptions dispensed; and (3) records of hospital admissions, obstetric deliveries, and deaths. The records about each person were linked together, and analyses were performed to reveal associations between drugs and diagnoses. The study suggested that record linkage would be useful both for generating and for testing hypotheses about the adverse effects of drugs. The method would be especially valuable for detection of delayed effects (such as the induction of cancer), sudden deaths outside hospital, and effects of the fetus-all of which are difficult to study by other means. A full-scale project would need to cover a large population, and some of the practical issues that would arise are discussed.

Is there seasonal variation in the prescribing of antidepressants in the community?

The prescribing of antidepressants by general practitioners might be expected to reflect the incidence of depression in the community. In a two-year study of the prescriptions issued by English general practitioners to a population of 40,000 people, the rates of initiating treatment with antidepressants were analysed by month. There was seasonal variation in new antidepressant prescribing for men (p less than 0.025), with peaks in early June and early December, but no significant seasonality for women. The bimodal pattern in men was similar to a recently reported seasonal variation in general practice consultations for depression.

Assessment of the "E' book as a tool for drug monitoring.

For two years, the following records were linked for 10 453 people: (1) basic attributes; (2) details of prescriptions; and (3) information about illnesses recorded by general practitioners (GPs) in an "E' book. Analyses were performed to reveal association between drugs and diagnoses. Although the "E' book has certain disadvantages for drug monitoring, the methods proved to be capable of detecting adverse effects of drugs. Unfortunately the number of practitioners using "E' books would be too small for detection of most serious hazards such as the induction of cancer. Hence it is concluded that the first priority should be to establish a record linkage scheme covering hospital admissions, obstetric deliveries, and deaths.

Frequency of moles in a defined population.

The occurrence of moles was studied in a community survey of 872 adults, using criteria that allowed comparison with two earlier surveys. Men and women had similar numbers of moles-on average, 15 moles of diameter 2 mm or greater, and 39 moles of all sizes. The frequency of moles declined with age and varied according to body site. Comparison of the findings with those of previous surveys-in New York in about 1950 and in Sydney in about 1970-suggested that the frequency of moles has increased as malignant melanoma has become more common. Little is known about the epidemiology of moles, which may hold the key to the explanation of the rising incidence of melanoma in many countries.

HIV surveillance by testing saliva from injecting drug users: a national study in New Zealand.

OBJECTIVE: To determine whether the prevalence of HIV infection among injecting drug users in New Zealand has remained low since the introduction of a needle and syringe exchange scheme in May 1988. DESIGN: Anonymous survey of intravenous drug users attending outlets of the exchange scheme, based on questionnaires and saliva testing. SETTING: Twelve pharmacies and community outreach organisation in six cities. SUBJECTS: Altogether 620 people provided saliva specimens and completed questionnaires. These represented 73% of those who visited exchange scheme outlets during a three month period in 1992. MAIN OUTCOME MEASURE: Saliva was tested for antibodies to HIV-1 and HIV-2 using an IgG-capture enzyme linked immunosorbent assay (GACELISA). RESULTS: Of 591 specimens eligible for inclusion, only three (0.5%) were repeatedly reactive in the GACELISA test, while two of these were also positive in a Western blot test. CONCLUSIONS: Although surveys show that sharing of needles and syringes was common in New Zealand until recently, the prevalence of HIV infection in intravenous drug users has remained low. This can probably be attributed to the success of educational campaigns and legislative action to allow a needle and syringe exchange scheme to be set up.

Monthly combined injectable contraceptives and neoplasia.

Monthly injectable contraceptives, containing a combination of a long-acting progestogen and an estrogen, have been used in Latin America and China for many years. While knowledge about the effects of other hormonal contraceptives on cancer risk is relevant, close analogies with monthly injectables cannot be made. The relation between use of these preparations and cancers of the breast and cervix has been examined in case-control studies, but no firm conclusions can be drawn because of limitations in sample size. Adequate studies of the influence of monthly injectable contraceptives on risk of neoplasia need to be carried out.

PIP: Monthly injectable contraceptives containing long-acting progestogen and estrogen have been used in Latin America and China for many years. In Mexico and some other Latin American countries, several proprietary preparations containing dihydroxyprogesterone acetophenide and estradiol enanthate are available, with injections often administered by pharmacists. It is estimated that in the early 1980s more than one million ampoules per year were sold privately through pharmacies in Mexico. A large body of evidence exists, however, about the relationship between oral contraceptives and, to a lesser extent, DMPA and the risk of various tumors. The nature of the relationship between using the above monthly preparations and the risk of breast and cervical cancer remains to be determined. Toxicological studies in animals have proved to be of limited value in predicting the effects of contraceptive steroids on cancer risk in humans, but results have nonetheless delayed the introduction of monthly injectables in the US and other developed countries. The only studies which have examined associations between the use of monthly injectable contraceptives and cancer risk in women have been handicapped by limitations in sample size. There is clearly a significant and urgent need to conduct studies on the influence of monthly injectable contraceptives on the risk of cancer.

Oral contraceptives and neoplasia: an introduction.

PIP: A reassessment of the risks of using oral contraceptives regarding cancer of the cervix, endometrium, ovary, breast and biliary system was commissioned in the form of a series of reviews, published in the journal Contraception, June 1991: this is the introduction to the reports. Since 1977, the risks of developing epithelial ovarian cancer and endometrial cancer have been clearly shown to be reduced and that protection persists for years even in ex-pill users. The chance of getting hepatocellular carcinoma is slightly higher in developed countries, still extremely rare; while not noticeably increased in those developing countries that have high liver cancer rates. The likelihood of getting cervical cancer is increased in some studies but not in others, reflecting the difficult problem of controlling of patterns of sexual behavior in this area. Even though broad analyses of breast cancer risks are reassuring, some detailed studies that focus on certain age groups of women do find increased breast cancer. A special multi-center, hospital-based, case-control study in developing countries, sponsored by WHO, concluded that the results of studies on cancer from developing countries are applicable to developing countries as well. So the overall benefits of using oral contraceptives outweigh the risks, both for women in areas where maternal morbidity and mortality are high, because of the effectiveness of the pill in preventing pregnancy; and in industrialized areas, where the benefits of preventing ovarian cancer alone is enough to make pill use safer than other methods, such as the condom. There appears to be no way to predict cancer risks for any subgroup of women who should avoid taking the pill.^ieng

Risk assessment issues in breast cancer.

Breast cancer is the most common malignancy affecting women, and its incidence has been increasing in many countries. The aetiology of breast cancer is poorly understood, so there is concern as to which factors in our environment or lifestyle are responsible for the increase. There is a need for reliable risk assessment, which involves the steps of hazard identification, hazard evaluation, exposure evaluation and risk estimation. Short-term laboratory tests and long-term tests in animals are useful for priority-setting, but quantitative human risk assessment should preferably involve observations of humans. Epidemiological studies vary in the degree of reliance that can be placed on their results. The main types of epidemiological investigation are illustrated by recent examples from the literature on breast cancer. Careful judgement is required in assessing whether any association between a factor and a disease is likely to be causal. The injectable contraceptive, depot medroxyprogesterone acetate (DMPA, 'Depo-Provera'), has been controversial because it caused malignant mammary tumours in beagle dogs. Two recent case-control studies found no overall association between DMPA and the risk of breast cancer in women. There was some evidence of increased risk in certain sub-groups of women, which could be interpreted with more confidence if there were a better understanding of the biology of human breast cancer. Nevertheless, the results do not support the prediction from beagle experiments that DMPA might increase the overall risk of breast cancer.

Depot medroxyprogesterone acetate. Patterns of use and reasons for discontinuation.

Little information is available from outside clinic settings about the acceptability of depot medroxyprogesterone acetate (DMPA, Depo-Provera) as an injectable contraceptive. In this national, population-based study, New Zealand women aged 25 to 54 years were selected at random from voter rolls. The 1864 subjects were interviewed by telephone after an initial approach by letter. More than 1 in 8 women (13.7%) had used DMPA at some time. The proportion was higher among Maori women and among those of lower income and education, but DMPA had been used by a substantial proportion of all socioeconomic groups. A quarter of all users reported receiving only a single injection of DMPA, and only 53% had used this method for a total of 12 months or more. Only 5 (1.6%) of discontinuations were attributed to contraceptive failure; this corresponds to a contraceptive failure rate of 0.9 per 100 woman-years. Side effects were given as the most common reasons for stopping, with menstrual disturbances and weight gain being cited most often. Other reasons for stopping included no further need for contraception or doubts about the appropriateness of DMPA. In this developed country population, DMPA is widely used for short periods but its acceptability is limited by the occurrence of side effects.

High prevalence of vasectomy in New Zealand.

The aim of this study was to examine the prevalence of vasectomy and associated factors in New Zealand, based on interviews with men. Participants were randomly selected from European men, aged between 40 and 74 years, on the general electoral roll. Telephone interviews were completed with 1225 men between 1997 and 1999. Overall, the prevalence of vasectomy was 44% (95% CI, 37-52%), adjusted to the age distribution of all New Zealand men aged 40-74 years. The prevalence ranged from 57% of men aged 40-49 years to 15% of those aged 70-74 years. Catholic men had a significantly lower odds of vasectomy, and there was a trend in increasing odds of vasectomy with increasing number of marriages and level of education of the wife. The results confirm a very high prevalence of vasectomy among New Zealand men. Comparison with earlier surveys based on interviews of women showed an increasing prevalence of vasectomy in each birth cohort from the 1920s to the 1950s. Vasectomy has been popular with men across all socioeconomic groups. New Zealand is an ideal country in which to study consequences of vasectomy.

The changing patterns of disease.

The pattern of disease in New Zealand is changing and will continue to do so. Some trends are predictable, while others (such as the epidemic of AIDS) may be unexpected. Analysis of past improvements in health suggests that medical research would be more productive if greater attention were paid to the external influences and personal behaviour which are the chief determinants of health. Apart from such general implications, analysis of the changing patterns of disease is vital as a stimulus and guide for medical research of all kinds. More effective monitoring of disease trends in New Zealand will require improvement in the quality and timeliness of routine health statistics, and training of adequate numbers of epidemiologists to analyse and interpret the data. Such developments are essential if medical research is to make a full contribution to the health of New Zealanders.

Alcaligenes faecalis septicaemia.

A case of Alcaligenes faecalis septicaemia occurring after appendicectomy is described, and previous reports of this condition are briefly reviewed. Alcaligenes is frequently found in the faeces of healthy people and systemic infections appear to be very uncommon. Nevertheless, if the organism is cultured from the blood it should not be dismissed as a contaminant without careful investigation.

Trends in cervical cancer in New Zealand.

Analysis of mortality and incidence rates over a 30-year period discloses differing trends in the risk of cervical cancer in older and younger women. Age-specific rates have been declining in older women, but there has been a marked rise in incidence among women under 40. Birth-cohort analyses show declining risks in successive cohorts of women born from late in the last century until the 1930's, except that risks were slightly elevated in the generation who were young adults during the Second World War. The risk of cervical cancer has increased very rapidly in cohorts born since the 1930s. A mathematical model suggests that women born around 1957 may have over three times the risk experienced by women born around 1932. The numbers of New Zealand women developing, and dying from, cervical cancer will increase strikingly over the next few decades unless effective control measures are introduced.

Cervical smear histories of Maori women developing invasive cervical cancer.

AIMS: To locate problems with the implementation of cervical screening for Maori women by investigating the histories of women with invasive cervical cancer, and determining why their disease had not been detected by screening and treated at an intraepithelial stage. METHODS: In a national study, the screening histories of 46 Maori women with invasive cervical cancer were ascertained by interview and from hospital, general practitioner and cytology laboratory records. RESULTS: Possible reasons for failure of cervical screening were never having had a smear (54%), infrequent smear tests (22%) and previous abnormal smears without appropriate follow-up (4%). Only six women (13%) had one or more normal smears in the three years before diagnosis. CONCLUSIONS: The main factor underlying the onset of invasive cancer was an absence of cervical screening or infrequent smear tests. Although no slide review was done, false negative reporting could have been a factor in only a small number of cases. Ways need to be found to encourage Maori women to be screened and to recall women regularly.

Childhood cancer in New Zealand: incidence and survival, 1961-1976.

Mortality from cancer in New Zealand children is higher than in most other western countries. This paper reports an analysis of the incidence and survival of all cases of childhood cancer registered in New Zealand from 1961 to 1976. The overall incidence was very similar to that reported by American registries, but higher than in Britain. Survival rates in New Zealand for children with lymphoma and leukaemia were rather poorer than in Britain as a whole, and appreciably worse than in Manchester and in selected regions of the USA. For most other malignancies, survival rates were similar to those in Britain. Survival rates in New Zealand were improving during the period of this study. The possible advantage of centralising treatment was examined by comparing the survival of children treated in the largest centre (Auckland--with 32% of all cases) and in other parts of the country. Children treated in Auckland generally had a longer remission, but experienced no significant advantage in five-year survival. This lack of advantage was not due to referrals from outside the region or to differences in racial composition.

Contraceptive practice in New Zealand.

A survey of contraceptive practice in New Zealand was carried out using a population-based sample of women, aged 25 to 54, selected as control subjects in a national case-control study. The results showed that sterilisation has become the most common means of family limitation. Overall, 45% of women aged 25 to 54 were in a union where one or the other partner had been sterilised. Vasectomy was the most common method of contraceptive sterilisation. The frequency of hysterectomy contributed to the high rates of sterilisation; 12% of women had had a hysterectomy. Over 80% of New Zealand women had used an oral contraceptive at some time, but only 11% were using the pill at the time of the survey. Comparison with earlier studies of contraceptive use in New Zealand show there has been a marked increase in the prevalence of contraceptive sterilisation, and a marked decrease in the use of oral contraceptives.