L Villard-Mackintosh

The epidemiology of hysterectomy: findings in a large cohort study

Objective To examine patterns of hysterectomy in the Oxford‐Family Planning Association (Oxford‐FPA) study in relation to age, parity, social class and calendar period (–1974, 1975–79. 1980–84, 1985–89).

Oral contraceptives, cigarette smoking and other factors in relation to arthritis

The data on oral contraceptive use and arthritis in the Oxford-Family Planning Association contraceptive study have been analysed. For rheumatoid arthritis, the rate of first referral to hospital was 0.33 per 1000 woman-years in those who never used oral contraceptives (27 cases), 0.33 per 1000 woman-years in ex-users of oral contraceptives (29 cases) and 0.44 per 1000 woman-years in current users of oral contraceptives (22 cases). Likewise, there was no important association between oral contraceptive use and other forms of arthritis. An unexpected finding was a strong association between referral to hospital for rheumatoid arthritis and cigarette smoking; the rate in women never smoking was 0.27 per 1000 woman-years (34 cases) and in those smoking 15 or more cigarettes per day was 0.64 per 1000 woman-years (19 cases).

Epidemiology of endometriosis in women attending family planning clinics.

OBJECTIVE--To describe the epidemiology of endometriosis in women attending family planning clinics with special reference to contraceptive methods. DESIGN--Non-randomised cohort study with follow up of subjects for up to 23 years. Disease was measured by first hospital admission rates since endometriosis can be diagnosed with accuracy only at laparotomy or laparoscopy. SETTING--17 family planning centres in England and Scotland. SUBJECTS--17,032 married white women aged 25-39 years at entry during 1968-74 who were taking oral contraceptives or using an intrauterine device or diaphragm. About 99% of the women approached agreed to participate and annual loss to follow up was about 0.3%. MAIN OUTCOME MEASURES--Diagnosis of endometriosis, age, parity, and history of contraceptive use. RESULTS--Endometriosis was significantly related to age, peaking at ages 40-44 (chi 2 for heterogeneity = 30.9, p < 0.001). Endometriosis was not linked to duration of taking oral contraceptives. Nevertheless, the risk of endometriosis was low in women currently taking oral contraceptives (relative risk 0.4; 95% confidence interval 0.2 to 0.7), but higher in women who had formerly taken them (1.8; 1.0 to 3.1 in women who had stopped 25-48 months previously) compared with women who had never taken the pill. A similar pattern was seen for use of intrauterine devices (relative risk 0.4 (0.2 to 0.7) in current users and 1.4 (0.4 to 3.2) in users 49-72 months previously compared with never users). No association was found between endometriosis and use of the diaphragm. CONCLUSIONS--Oral contraceptives seem to temporarily suppress endometriosis. Endometriosis may be diagnosed late in women using intrauterine devices as pain and bleeding occur with both.

Oral contraceptives and reproductive factors in multiple sclerosis incidence.

Data from the Oxford.FPA prospective study show that oral contraceptive use and pregnancy have no discernible effect on the risk of developing multiple sclerosis (MS). Women of parity 0-2 developed MS twice as often as women of parity 3 or more but the difference did not reach statistical significance. Smoking may be a risk factor for developing MS. A nested case-control analysis did not identify any associations between MS onset and preceding illnesses.

Mortality among oral contraceptive users : 20 year follow up of women in a cohort study

OBJECTIVE--To see whether the use of oral contraceptives influences mortality. DESIGN--Non-randomised cohort study of 17,032 women followed up on an annual basis for an average of nearly 16 years. SETTING--17 Family planning clinics in England and Scotland. SUBJECTS--Women recruited during 1968-74. At the time of recruitment each woman was aged 25-39, married, a white British subject, willing to participate, and either a current user of oral contraceptives or a current user of a diaphragm or intrauterine device (without previous exposure to the pill). MAIN OUTCOME MEASURES--Overall mortality and cause specific mortality. RESULTS--238 Deaths occurred during the follow up period. The main analyses concerned women entering the study while using either oral contraceptives or a diaphragm or intrauterine device. The overall relative risk of death in the oral contraceptive users was 0.9 (95% confidence interval 0.7 to 1.2). Though the numbers of deaths were small in most individual disease categories, the trends observed were generally consistent with findings in other reports. Thus the relative risk of death in the oral contraceptive users was 4.9 (95% confidence interval 0.7 to 230) for cancer of the cervix, 3.3 (95% confidence interval 0.9 to 17.9) for ischaemic heart disease, and 0.4 (95% confidence interval 0.1 to 1.2) for ovarian cancer. There was a linear trend in the death rates from cervical cancer and ovarian cancer (in opposite directions) with total duration of oral contraceptive use. Death rates from breast cancer (relative risk 0.9; 95% confidence interval 0.5 to 1.4) and suicide and probable suicide (relative risk 1.1; 95% confidence interval 0.3 to 3.6) were much the same in the two contraceptive groups. In 1981 the relative risk of death in oral contraceptive users from circulatory diseases as a group was reported to be 4.2 (95% confidence interval 2.3 to 7.7) in the Royal College of General Practitioners oral contraception study. The corresponding relative risk in this study was only 1.5 (95% confidence interval 0.7 to 3.0). CONCLUSIONS--These findings contain no significant evidence of any overall effect of oral contraceptive use on mortality. None the less, only small numbers of deaths occurred during the study period and a significant adverse (or beneficial) overall effect might emerge in the future. Interestingly, the mortality from circulatory disease associated with oral contraceptive use was substantially less than that found in the Royal College of General Practitioners study.

Oral contraceptives and breast cancer: latest findings in a large cohort study.

During the interval 1968-74, 17,032 women aged 25-39 years were recruited to the Oxford-Family Planning Association contraceptive study, more than half of whom were using oral contraceptives. These women have been followed up over the years and breast cancer has been diagnosed in 189 of them. We have analysed the available data in two ways. First, we have calculated standardised breast cancer incidence rates in non-users and users of oral contraceptives according to total duration of use, interval since first use, interval since last use, duration of use before first term pregnancy and duration of use before age 25. Secondly, we have conducted case-control within cohort analyses to examine the possible effects of different types of pill and to search for evidence of a latent effect of oral contraceptive use before first term pregnancy on breast cancer risk. We have found no evidence of any adverse effect of oral contraceptive use on the risk of breast cancer in this study. There was, however, little exposure to the pill before first term pregnancy among the participants and virtually no such exposure at a very young age (i.e. below 20 years). Accordingly, the results of this study strengthen the evidence that oral contraceptive use by mature women does not increase breast cancer risk, but add little to the uncertainty about the effects of early use.

The effects of oral contraceptives and parity on ovarian cancer trends in women under 55 years of age

Summary. Mortality from epithelial ovarian cancer is falling in women under 55 years of age in England and Wales. The decline does not appear to be a treatment effect nor to be attributable to changes in the rate of oophorectomy. Case‐control studies have shown that high parity and oral contraceptive use are protective against the disease. We suggest that the decrease in mortality is compatible in timing and magnitude with exposure to oral contraceptives. No obvious effect on mortality attributable to parity was apparent in this analysis. Oral contraceptives may prove to be a widely acceptable means of preventing ovarian cancer, providing they do not increase breast cancer risk.

Myocardial infarction and angina pectoris in young women.

The Oxford-Family Planning Association contraceptive study has now followed 17,000 women, predominantly of childbearing age, for a total of more than 200,000 woman-years. The incidence of myocardial infarction and angina in women aged less than 50 years has been low: 0.03/1,000 woman-years at ages 25-34 rising to 0.67/1,000 woman-years at ages 45-49. However, the overall incidence in women who were smokers at entry to the study is more than three times that in women who were non-smokers, the increase in individual risk being proportional to the number of cigarettes smoked. Observations on other risk factors must be treated with caution in view of the small numbers involved: in general, the differences and trends reported are not statistically significant. However, a consistent positive relation is observed between incidence rates and both relative weight and parity after adjustment for age and smoking, while no consistent trend is observed for social class. Ever use of oral contraceptives is associated with a twofold increased risk of myocardial infarction (not statistically significant), but there is no increased risk in current users as was suggested by earlier studies. This may reflect the adoption of lower dose preparations and the positive selection of healthy women for oral contraception.

ORAL CONTRACEPTIVES AND PREGNANCY IN RELATION TO PEPTIC ULCER

There is evidence in the scientific literature that peptic ulceration occurs less frequently during pregnancy than at other times. This encouraged us to examine the pattern of hospitalisation for peptic ulcer in the Oxford-Family Planning Association contraceptive study. In total, 175 women in the study had been hospitalised for peptic ulcer; 105 had duodenal disease, 55 had gastric disease and 22 had disease of unspecified site (some had disease at more than one location). Hospitalisation for peptic ulcer increased with age, parity and cigarette smoking. In addition, hospitalisation was at a low rate during pregnancy and was not seen at all during the 12 months following delivery. There was no relationship between hospitalisation for peptic ulcer and total duration of oral contraceptive use. Likewise, there was no significant relationship with recency of oral contraceptive use, but the lowest rate of hospitalisation was in current users of the pill.

Epidemiology of endometriosis in women attending family planning clinics

of CA-125 secreted increases significantly from the early to the late luteal phase in all treatment groups. When compared with controls, the endometrium of women with endometriosis secreted two to four times more CA-125 in all treatment groups, in both the early and late luteal phase. Conclusions: When compared with control endometrium; the endometrium of women with advanced endometriosis secretes significantly more CA-125 and represents a potential source of the elevated serum levels of CA-125 seen in these women.