To examine the risk of multiple sclerosis in users of combined oral contraceptives.
Design
Cohort study conducted between 1968 and 1996 using diagnostic data supplied by general practitioners
Setting
General practices throughout the United Kingdom.
Population
Royal College of General Practitioners' Oral Contraception Study cohort of initially 46,000 women recruited during the late 1960s.
Methods
Directly standardised incidence rates of multiple sclerosis were calculated for current, former and never-users of oral contraceptives using first ever cases of multiple sclerosis reported by the general practitioners. The standardisation variables were age, parity, social class and smoking history. Five-year survival rates in the different contraceptive groups were calculated using standard life table techniques.
Results
One hundred and fourteen first ever cases of multiple sclerosis had been reported by November 1996 during 564,000 woman-years of observation. The incidence rate in both current and former users was not materially different to that in never-users. Although based on limited evidence there was no suggestion that the five-year survival was affected by a woman's use of combined oral contraceptives.
Conclusions
These findings do not suggest a greatly elevated risk of multiple sclerosis during, or after, use of combined oral contraceptives.
oral contraceptives multiple sclerosis risk cohort study, combined oral contraceptive autoimmune disease multiple sclerosis, Thorogood Hannaford RCGP oral contraception study MS, Royal College General Practitioners contraception cohort study, oral contraceptive use neurological disease incidence women, multiple sclerosis incidence current former never users OC, hormonal contraception autoimmune risk long-term follow-up, five-year survival multiple sclerosis oral contraceptive users, standardised incidence rate MS contraceptive exposure UK cohort
PMID 9883921 9883921 DOI 10.1111/j.1471-0528.1998.tb10008.x 10.1111/j.1471-0528.1998.tb10008.x
Cite this article
Thorogood, M., & Hannaford, P. C. (1998). The influence of oral contraceptives on the risk of multiple sclerosis. British journal of obstetrics and gynaecology, 105(12), 1296-1299. https://doi.org/10.1111/j.1471-0528.1998.tb10008.x
Thorogood M, Hannaford PC. The influence of oral contraceptives on the risk of multiple sclerosis. Br J Obstet Gynaecol. 1998;105(12):1296-1299. doi:10.1111/j.1471-0528.1998.tb10008.x
Thorogood, M., and P. C. Hannaford. "The influence of oral contraceptives on the risk of multiple sclerosis." British journal of obstetrics and gynaecology, vol. 105, no. 12, 1998, pp. 1296-1299.
Several environmental and genetic factors have been implicated to date in the development of Crohn's disease (CD) and ulcerative colitis (UC). The aim of this study was to provide a quantification of the risk of oral contraceptive pill (OCP) use in the etiology of inflammatory bowel disease. A literature search was performed to identify comparative studies reporting on the association of oral contraceptive use in the etiology of UC and CD between 1983 and 2007. A random-effect meta-analysis was used to compare the incidence of UC or CD between the patients exposed to the OCP and nonexposed patients. The results were adjusted for smoking. A total of 75,815 patients were reported on by 14 studies, with 36,797 exposed to OCP and 39,018 nonexposed women. The pooled relative risk (RR) for CD for women currently taking the OCP was 1.51 (95% confidence interval [CI] 1.17-1.96, P= 0.002), and 1.46 (95% CI 1.26-1.70, P < 0.001), adjusted for smoking. The RR for UC in women currently taking the OCP was 1.53 (95% CI 1.21-1.94, P= 0.001), and 1.28 (95% CI 1.06-1.54, P= 0.011), adjusted for smoking. The RR for CD increased with the length of exposure to OCP. Moreover, although the RR did not reduce once the OCP was stopped, it was no longer significant once the OCP was stopped (CI contains 1), both for CD and for UC. This study provides evidence of an association between the use of oral contraceptive agents and development of IBD, in particular CD. The study also suggests that the risk for patients who stop using the OCP reverts to that of the nonexposed population.
Mutations in the methylenetetrahydrofolate reductase (MTHFR) gene (677C>T, 1298A>C) cause elevated plasma homocysteine concentrations and have been linked to fatal outcomes after nitrous oxide anesthesia. This study tested the hypothesis that patients with common MTHFR 677C>T or 1298A>C mutations develop higher plasma homocysteine concentrations after nitrous oxide anesthesia than wild-type patients. In this prospective, observational cohort study with blinded, mendelian randomization, the authors included 140 healthy patients undergoing elective surgery. All patients received 66% nitrous oxide for at least 2 h. The main outcome variable, plasma total homocysteine, and folate, vitamin B12, and holotranscobalamin II were measured before, during, and after surgery. After completion of the study, all patients were tested for their MTHFR 677C>T or 1298A>C genotype. Patients with a homozygous MTHFR 677C>T or 1298A>C mutation (n = 25) developed higher plasma homocysteine concentrations (median [interquartile range], 14.9 [10.0-26.4] microm) than wild-type or heterozygous patients (9.3 [7.5-15.5] microm; n = 115). The change in homocysteine after nitrous oxide anesthesia was tripled in homozygous patients compared with wild-type (5.6 microm [+60%] vs. 1.8 microm [+22%]). Only homozygous patients reached average homocysteine levels considered abnormal (> 15 microm). Plasma 5-methyl-tetrahydrofolate concentrations increased uniformly by 20% after nitrous oxide anesthesia, indicating the inactivation of methionine synthase and subsequent folate trapping. Holotranscobalamin II concentrations remained unchanged, indicating no effect of nitrous oxide on vitamin B12 plasma concentrations. This study shows that patients with a homozygous MTHFR 677C>T or 1298A>C mutation are at a higher risk of developing abnormal plasma homocysteine concentrations after nitrous oxide anesthesia.
Bone HealthOsteoporosis Incidence and PrevalenceProspective CohortFracture Risk Assessment
Relatively little is known about the factors in Canada which lead to osteoporosis and its concomitant fractures. The Canadian Multicentre Osteoporosis Study (CaMos) is a prospective cohort study which will estimate the incidence and prevalence of declining bone mass and fractures. The impact of osteoporosis in Canada will be assessed, including regional variation and the effect of various risk factors. The study will provide information for developing prevention programs. The cohort has been drawn from a random population-based sample of non-institutionalized men and women 25 years old or more and living within 50 km. of nine cities in Canada. Through telephone interviews 9,423 participants have been recruited. All answered an extensive questionnaire, and had physical measurements related to bone quality taken. This paper details the CaMos baseline and five-year follow-up protocol.
We used rosters of the Crohn's and Colitis Foundation of America to identify potential cases and peer-nominated controls to explore the reported association between oral contraceptives and inflammatory bowel disease. Overall, women who used oral contraceptives were at increased risk of developing Crohn's disease (odds ratio = 1.49, 95% confidence interval (CI) = 0.99-2.26). The findings persisted after adjustment for age at symptom onset, decade of onset, education, marital status, and location of disease. There was an interaction with cigarette smoking; the risk associated with oral contraceptives was elevated in current smokers (odds ratio = 2.64, 95% CI = 1.22-5.75), but not in former smokers or never-smokers. The risk was not elevated for ulcerative colitis (odds ratio = 1.10, 95% CI = 0.65-1.85).