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An improved statistical method for assessing the efficacy of intrauterine contraception is presented. This method, called the log-rank method, is based on a daily life table, which yields the best estimates of the cumulative net termination probabilities. It provides a sensitive chi-square test statistic to detect differences among these probabilities for two or more contraceptive devices. When three or more devices are compared, the chi-square statistic may be partitioned into additive components representing comparisons among groups of devices. The log-rank method also permits adjusting for differences among subgroups by controlling for factors such as parity or age. Although calculations may be performed on a desk calculator, a FORTRAN-IV computer program is made available to interested researchers.

A case-control study of 150 ovarian cancer patients under the age of 50 and individually matched controls was done to study the influence of fertility and oral contraceptive use on the risk of ovarian cancer. The risk decreased with increasing numbers of live births, with increasing numbers of incomplete pregnancies, and with the use of oral contraceptives. These three factors can be amalgamated into a single index of protection--"protected time"--by considering them all as periods of anovulation. The complement of protected time--viz., "ovulatory age", the period between menarche and diagnosis of ovarian cancer (or cessation of menses) minus "protected time"--was strongly related to risk of ovarian cancer. Other factors found to be associated with increased ovarian cancer risk were obesity, cervical polyps, and gallbladder disease. Women who had an "immediate" intolerance to oral contraceptive use had a fourfold increased risk of ovarian cancer. 7 patients, but no controls, could recall a family history of ovarian cancer.

Oral contraceptives containing DL-norgestrel or norethindrone with ethinyl estradiol were administered by random assignment to 21 menstruating women, matched for anthropometric measurements, age, diet, alcohol consumption, smoking, and exercise habits. Pretreatment and 7-week treatment blood samples were obtained and assayed for serum cholesterol, triglyceride high-density lipoprotein cholesterol (HDL-C), and total high-density lipoprotein (HDL), HDL2a, HDL2b, and HDL3 subclasses by analytic ultracentrifugation. Subjects using the norethindrone oral contraceptive had a significant increase in HDL-C: baseline, 46 mg/dl; 7 weeks, 51 mg/dl. Values for the subjects using the norgestrel oral contraceptive were not significantly changed: 46 and 44 mg/dl, respectively. Users of the norethindrone oral contraceptive had significant elevations of total HDL and HDL3, while norgestrel oral contraceptive users demonstrated no significant changes. HDL2b increased with the norethindrone oral contraceptive and declined with the norgestrel oral contraceptive. The changes in HDL2b from baseline to treatment were not significant (p greater than 0.05), but the change with the norethindrone oral contraceptive did differ significantly from that with the norgestrel oral contraceptive (p less than 0.02). These changes may indicate oral contraceptive-induced alterations in HDL structure and metabolism that could be related to the risk of development of atherosclerosis.

Lipids and lipoproteins were studied in controls and women using contraceptive vaginal rings (CVRs). The groups were comparable for race, age, parity, obesity indices, alcohol ingestion, smoking, diet and exercise. Fasting blood samples were obtained twice before CVR treatment, after 2 and 7 weeks of treatment and 1 week thereafter. The women using the CVR had a significant incremental reduction of cholesterol from baseline to treatment which was distributed among all the lipoprotein classes. The cholesterol/HDL-C ratio was significantly increased with treatment. All mena changes were within the reference range. The reduction in HDL and especially in the subclasses HDL 2a and HDL 2b were significant and outside the reference range. The LDL/HDL ratio increased significantly, while the LDL/HDL 2a+2b ratio increased significantly outside the reference range with treatment. Of the lipid and lipoprotein measurements that changed significantly with treatment, HDL-C, HDL, HDL 2a LDL/HDL and LDL/HDL 2a+2b changed significantly towards baseline in the 1-week-off treatment. The potential reduction in predicted coronary risk with the use of the CVR suggested by a reduction in cholesterol was counterbalanced by a reduction in HDL-C and increases in the cholesterol/HDL-C and LDL/HDL ratios. The potential clinical implications of these findings remain to be determined.

A random sequential comparative study of three models of the Copper T intrauterine contraceptive device (IUD) was undertaken in 1,792 women. For 7 months, the TCu 300 and TCu 220C were randomly inserted, and then the TCu 380A and 220C were randomly inserted for the next 12 months. The log-risk method of life-table analysis of event rates was performed at the end of each of the first 3 years of use of each device. The TCu 380A had the lowest pregnancy rate during each year of use, although the difference was not significant. At the end of each of the first 2 years, the TCu 300 was removed significantly less than the TCu 220C and TCu 380A for bleeding and pain. At the end of three years, the rates of removal for bleeding and pain for the TCu 380A and TCu 300 were similar and lower than that for the TCu 220C, but the overall difference was not significant. There were no differences among the devices for any other relevant use-related reasons. The TCu 380A was removed for other medical reasons significantly more frequently than the other devices at the end of 2 and 3 years. Adjusting for parity did not alter the results. The findings of this study suggest that the copper sleeves along the horizontal arms together with copper wire on the vertical arm in the TCu 380A model provide greater protection against intrauterine pregnancy, whereas the copper sleeves along the vertical arm as in the TCu 220C caused increased removals for bleeding and pain. The TCu 380A should be studied in a larger number of patients for a longer period of time to determine its clinical effectiveness. It may become the IUD of choice for all women irrespective of parity.