Harland Austin

A follow-up study of methods of contraception, sexual activity, and rates of trichomoniasis, candidiasis, and bacterial vaginosis

A randomized, clinical trial was conducted to evaluate the spermicidal agent nonoxynol 9 as prophylaxis for sexually transmitted diseases. Eight hundred eighteen women using birth control who attended a sexually transmitted disease clinic were evaluated monthly for trichomoniasis, candidiasis, and bacterial vaginosis for 6 months. Women using the active spermicide experienced a somewhat lower incidence rate of trichomoniasis (relative rate 0.83; 95% confidence interval 0.61 to 1.12) and bacterial vaginosis (relative rate 0.86; 95% confidence interval 0.69 to 1.12) as compared with placebo users. The rate of candidiasis was nearly identical for spermicide and placebo users (relative rate 1.02; 95% confidence interval 0.77 to 1.35). The number of sexual partners during the preceding month was related directly to the occurrence of trichomoniasis (p = 0.047) and bacterial vaginosis (p = 0.009) but not candidiasis (p = 0.99). Subjects using oral contraceptives experienced a statistically significant lower rate of trichomoniasis than did women using an intrauterine contraceptive device or who had had a tubal ligation (relative rate 0.56; 95% confidence interval 0.39 to 0.81).

Oral contraceptive use and the risk of chlamydial and gonococcal infections.

Oral contraceptive users were compared with nonusers with respect to the rate of cervical infections by Chlamydia trachomatis and Neisseria gonorrhoeae. The comparison was adjusted for differences in demographic and behavioral characteristics between the two groups. The rates of infection among oral contraceptive users were increased by approximately 70% (statistically significant) for both pathogens. Cervical ectopy was implicated in the increased rate of chlamydia but not gonorrhea. Rates of gonorrheal infection differed significantly among oral contraceptive formulations; rates were higher for formulations containing more androgenic progestins.

A case-control study of endometrial cancer in relation to cigarette smoking, serum estrogen levels, and alcohol use

OBJECTIVES The purpose of this study was to evaluate the effect of cigarette smoking and alcohol use on the risk of endometrial cancer. The impact of smoking on serum estrone, estradiol, and androstenedione levels also was examined. STUDY DESIGN This hospital-based case-control study included 168 women with endometrial carcinoma and 334 control women. RESULTS Women who were current smokers had a lower risk of endometrial cancer than did women who did not smoke (relative rate 0.69; 95% confidence interval 0.40-1.19), whereas women who were exsmokers and women who had never smoked had similar rates (relative rate 0.83; 95% confidence interval 0.46-1.48). There was little overall association between serum estrogen levels and cigarette smoking, although estradiol levels in overweight control subjects were lower among women who were current smokers than among women who had never smoked. Androstenedione levels were slightly higher among women in the control group who smoked than among women in the control group who did not smoke, but the difference was not statistically significant (p = 0.28, two-tailed). Alcohol use was unrelated to endometrial cancer in this study. CONCLUSIONS The study provides additional support for the hypothesis that smoking is inversely related to endometrial cancer. The inverse smoking association with endometrial cancer may be more directly related to higher serum androstenedione levels than to lower serum estrogen levels except, perhaps, among overweight women.

Cigarette smoking and leukemia

THE REPORT of the Surgeon General of the United States cites cigarette smoking as a major cause of cancers of the lung, larynx, oral cavity, and esophagus, and as a contributory factor in the etiology of cancers of the bladder, kidney, and pancreas [ 11. It is also indicated in this report that cigarette smoking may be related to stomach and cervical cancer. Leukemia is not considered a tobacco-related cancer, although the report mentions that several epidemiologic studies have reported higher leukemia risks among smokers compared with non-smokers [2]. This evidence was judged inconclusive because no dose-response relationship between leukemia mortality and the amount smoked was found in these studies. This paper reviews briefly the epidemiologic evidence pertinent to an evaluation of the relationship between cigarette smoking and leukemia and suggests strategies for the further evaluation of this relationship.

A Survey of Gynecologists Concerning Menorrhagia: Perceptions of Bleeding Disorders as a Possible Cause

We sought to determine perceptions and practices of American gynecologists when treating with a woman complaining of menorrhagia, specifically with regard to an underlying bleeding disorder as a potential cause. A mail survey of Georgia members of the American College of Obstetricians and Gynecologists was conducted. The survey response was 52%, and the analysis includes 376 physicians who reported seeing at least one gynecological patient per week. On average, respondents were in practice 20 years and reported that 8% of their patient population complain of menorrhagia. Virtually all physicians reported employing a menstrual history as a starting point for the workup for menorrhagia, and 95% order a hemoglobin/hematocrit determination. About 50% of physicians considered saturating three tampons/pads per 4 hours as excessive, although the criterion varied widely (range 0-24 per 4 hours, SD = 3). The diagnoses considered most likely among reproductive age women were anovulatory bleeding or benign lesions or that the heavy bleeding was within normal limits. Only 4% of physicians would consider von Willebrand disease (VWD) for this age group (women of reproductive age). Among girls near menarche, physicians overwhelmingly consider anovulatory bleeding or bleeding within normal limits the likely diagnoses, and 16% would consider VWD in this age group. Only rarely (3%) do surveyed physicians refer menorrhagia patients to other specialists. Most respondents believe that most menorrhagia is caused by anovulation or is within normal limits. Bleeding disorders are believed to be a rare cause of menorrhagia.

An efficient procedure for computing exact confidence limits for a standardized mortality ratio

Abstract An efficient computing procedure is described for obtaining exact confidence limits for the mean of a Poisson distribution. It is shown how this procedure can be used to obtain the exact confidence limits for a standardized mortality ratio, a parameter of great interest to epidemiologists. An example is presented illustrating the technique.

The identification of confounders in case-control studies

THE SELECTION of a control group for a case-control study is probably the most important and most difficult decision confronting an investigator. Although there are a number of sources from which controls may be obtained, they are usually chosen either from among other patients at the hospital where the cases are identified (hospital-based) or from among healthy members of the same communities in which the cases reside (population-based). In the preceding paper Stavraky and Clarke report a recent case-control study which used both hospital and population-based controls. The authors compare these two control groups in the hope of clarifying some of the issues involved in choosing between them. However, the study is limited and does not appreciably add to our understanding of the issues involved in choosing between hospital and population-based controls. The first limitation is that the hospital controls are from London (Ontario) while the neighborhood controls are from Ontario. Although each control group may be appropriate for its respective case series, there is no reason to believe that they are comparable to each other. Indeed, controls are usually selected from the same locale as cases because the prevalence of many exposures differs according to geographic area. The authors apparently recognize this problem, in fact, they explain some of the differences between the two control groups on this basis, but choose largely to ignore it. This is not one case-control study with two control groups, but rather two case-control studies each with its own control group. It is not relevant to the evaluation of the choice between hospital or population-based controls. The second limitation of the study is more subtle. It relates to case-control studies in general and to what issues are and are not important in selecting controls. However, to put the discussion in perspectives, I would like first to make a few general comments about case-control studies. Many scientists view case-control studies with extreme skepticism. This skepticism may arise because such studies are perceived as “unnatural” because they look back from effects to causes and because of the difficulties involved in obtaining unbiased estimates of the exposure frequencies of cases and controls. These aspects of case-control studies have led some to maintain that they are inherently non-scientific and that their validity can be enhanced by considering as their goal the duplication of the results of a randomized controlled trial. However, case-control studies differ from randomized controlled trials in that the latter are experimental whereas the former are non-experimental scientific investigations. The goal of a case-control study should be to obtain a valid estimate of the disease frequency among exposed persons relative to that among the non-exposed, not to mimic a randomized trial. This concern with their supposed unscientific nature has fostered a need to do something to enhance their validity and many epidemiologists believe that this need is fulfilled by controlling for many extraneous factors. In fact, the identification and control of confounding has become a preoccupation in case-control studies. However, although much is known about methods for controlling confounding, often little thought is given to what factors need to be controlled in case-control studies.