Oral contraceptives and mortality from circulatory system diseases: an epidemiologic study in Taiwan

The Use of Deceased Controls in Epidemiologic Research: A Systematic Review

Scholarly debate on the use of deceased controls in epidemiologic research continues. This systematic review examined published epidemiologic research using deceased persons as a control group. A systematic search of 5 major biomedical literature databases (MEDLINE, CINAHL, PsycINFO, Scopus, and EMBASE) was conducted, using variations of the search terms "deceased" and "controls" to identify relevant peer-reviewed journal articles. Information was sought on study design, rationale for using deceased controls, application of theoretical principles of control selection, and discussion of the use of deceased controls. The review identified 134 studies using deceased controls published in English between 1978 and 2015. Common health outcomes under investigation included cancer (n = 31; 23.1%), nervous system diseases (n = 26; 19.4%), and injury and other external causes (n = 22; 16.4%). The majority of studies used deceased controls for comparison with deceased cases (n = 95; 70.9%). Investigators rarely presented their rationale for control selection (n = 25/134; 18.7%); however, common reasons included comparability of information on exposures, lack of appropriate controls from other sources, and counteracting bias associated with living controls. Comparable accuracy was the most frequently observed principle of control selection (n = 92; 68.7%). This review highlights the breadth of research using deceased controls and indicates their appropriateness in studies using deceased cases.

Serum lipids in Chinese patients using oral contraceptive pills

Eighty-four Chinese patients attending the Family Planning Association of Hong Kong for contraception with oral contraceptive pills were randomized into 2 groups. The first group received pills containing 0.15 mg levonorgestrel and 0.03 mg ethinyl oestradiol. The second group received pills containing 0.15 mg desogestrel and 0.03 mg ethinyl oestradiol. Blood was taken after overnight fast before the use of pills for assay of serum total lipids, triglycerides, total cholesterol and high density lipoprotein cholesterol (HDL-C). The tests were repeated at 1 month, 3 months and 6 months after the use of pills. There was a significant increase in the serum total lipids in the levonorgestrel group but not in the desogestrel group. The serum triglycerides showed a significant increase in the desogestrel group but not in the levonorgestrel group. There was no significant change in the serum total cholesterol levels in both groups. There was a significant decrease in the HDL-C in the levonorgestrel group but there was no significant change in the desogestrel group.

Oral contraceptives and cardiovascular disease: a critique of the epidemiologic studies

Observational study designs used to investigate the relationship of oral contraceptive use to the occurrence of venous thromboembolism, stroke, myocardial infarction, and cardiovascular death include case-control, cohort, and mortality statistics studies. This analysis catalogs the findings of each of these epidemiologic studies, its statistical significance, and its performance with regard to scientific methodologic standards. An association between current oral contraceptive use and incidence of venous thromboembolism without predisposition has been consistently observed in case-control and cohort studies. Associations are less consistent for various types of stroke and for myocardial infarction. Only the Royal College of General Practitioners study found a significantly elevated risk of cardiovascular death with oral contraceptive use. The majority of mortality statistics studies offer little support for a relationship between oral contraceptive use and cardiovascular events. Major systematic problems in the epidemiologic studies include potential for bias in the detection of cardiovascular events and differences in the prognostic susceptibility of compared groups. Bias in the ascertainment of drug exposure is an unresolved issue for most of the case-control studies. Because of possible biases arising from methodologic deficiencies in these epidemiologic studies, questions as to the validity of the observed associations between oral contraceptive use and cardiovascular events should remain.