Prospective cohort study of the association between use of low-dose oral contraceptives and stroke in Chinese women

Absolute risk of ischemic and hemorrhagic stroke in Danish women using oral contraceptives

OBJECTIVE

Uncertainty exists for the absolute risk of ischemic and hemorrhagic stroke in users of oral contraceptives (OCs). Estimates greatly vary between countries. In Denmark, absolute risk of ischemic stroke (IS) is estimated to be 21 per 100,000 person-years. Risk of cerebral hemorrhage (CH) is unknown. Using the Danish Stroke Registry, we investigated absolute risk of IS and CH in users of OC.

MATERIAL AND METHODS

For the Danish female population aged 15-49 years during 2003-2011, we obtained information on hospital admission for IS and CH and current use of OC from Danish nationwide registries. We defined current use of OC as redeeming at least two OC prescriptions within the previous year.

RESULTS

The Danish female population years 2003-2011 consisted mean of 1,246,142 women per year. Of these, 29.6% were OC users. In the study period, OC users had 291 IS and 14 CH. Absolute risk of IS in OC users was 8.8 per 100,000 person-years and of CH it was 0.4 per 100,000 person-years.

CONCLUSIONS

In OC users, absolute risk of IS was 8.8 per 100,000 person-years. This is more than half that of the risk previously assumed in Denmark. Risk of CH in OC users was very low and 0.4 per 100,000 person-years.

Oral Contraceptive Use and Increased Risk of Stroke: A Dose-Response Meta-Analysis of Observational Studies

Background: Oral contraceptive (OCP) use might increase the risk of stroke in women. We examined a possible dose–response relation between OCP use and the risk of stroke in young and middle-aged women.

Methods: A retrieval of PubMed and EMBASE databases was performed. We selected observational studies that reported odds ratios (ORs) with 95% confidence intervals (CIs) for the risk of stroke in OCP users. A two-stage dose–response analysis was conducted using the random-effects model and the restricted spline model.

Results: A total of 6 cohort studies and 12 case–control studies were included, which involved 2,143,174 participants and 11,661 cases of stroke including ischemic stroke (IS), hemorrhagic stroke (HS), and stroke of unknown origin. The pooled ORs of total stroke were 1.19 (95% CI, 1.16–1.23) for every 10-μg increment in estrogen dosage, 1.20 (95% CI, 1.05–1.37) for every 5-years increment in duration of OCP use, and 0.82 (95% CI, 0.68–0.98) for every 5-years increment in duration of OCP cessation. The ORs of IS were 1.20 (95% CI, 1.17–1.22) in estrogen dosage, 1.24 (95% CI, 1.04–1.49) in duration of OCP use, and 0.78 (95% CI, 0.67–0.92) in duration of OCP cessation. The ORs of HS were 1.10 (95% CI, 1.04–1.16) in estrogen dosage, 1.13 (95% CI, 0.93–1.36) in duration of OCPs, and 0.71 (95% CI, 0.55–0.92) in duration of OCP cessation. The pooled ORs of total stroke from prospective studies (1.12; 95% CI, 1.01–1.24) were lower than those from retrospective studies (1.30; 95% CI, 1.01–1.67).

Conclusions: The higher estrogen dosage significantly increased the risks of total stroke, IS, and HS, respectively. The longer duration of OCP use significantly increased the risks of total stroke and IS, but its effects on HS risk were marginal. The longer duration of OCP cessation significantly decreased the risks of total stroke, IS, and HS, respectively. These findings affirm the contribution of estrogen dose and duration of OCP use to the increased risk of stroke, which may be critical for the instruction of OCP use and the prevention and management of cerebrovascular diseases.

Association between oral contraceptives and risk of hemorrhagic stroke: a meta-analysis of observational studies

OBJECTIVES

To estimate the risk of hemorrhagic stroke associated with current use of oral contraceptives (OCs), and to further depict how the risk was affected by study characteristics.

METHODS

We searched PubMed, Embase, and Cochrane Library for relevant articles published up to February 2017 that examined the association between OC use and risk of hemorrhagic stroke. Two investigators independently reviewed articles based on inclusion criteria. The Newcastle-Ottawa scale was employed to evaluate quality of studies. Random-effects meta-analysis model was used to generate summary risk estimates.

RESULTS

Fifteen independent studies (5 cohort studies and 10 case-control studies) with 4271 hemorrhagic stroke cases were included in this meta-analysis. The overall summary odds ratio (OR) for hemorrhagic stroke (HS) in relation to current OC use was 1.39 [95% confidence interval (CI), 1.05-1.83]. Subgroup analyses on hemorrhagic stroke types showed that OC use was associated with subarachnoid hemorrhage (SAH) (OR 1.68; 95% CI 1.21-2.12), but not with intracerebral hemorrhage (ICH) (OR 0.92; 95% CI 0.33-2.54). The risk of hemorrhagic stroke was increased slightly among current OC users with high-dose estrogen (OR 1.60; 95% CI 1.12-2.27). The risk of hemorrhagic stroke was further increased in OC users with additional risk factors including current smoking, hypertension, and history of migraine.

CONCLUSIONS

This meta-analysis of observational studies suggests that current use of OCs could contribute to a small increased risk of hemorrhagic stroke, and the increased risk is related to subarachnoid hemorrhage, but not intracerebral hemorrhage.

Influence of hormonal contraceptives and the occurrence of stroke: integrative review

ABSTRACT Objective: To identify scientific evidence regarding the influence of hormonal contraceptive use and the occurrence of stroke. Method: Integrative review of the literature, through database search using the descriptors "contraceptive agents", "contraceptive devices", "contraceptives, Oral" and "Stroke". Original studies in Portuguese, Spanish and English, published in full and available online were included. Studies that did not answer our guiding questions and duplicated studies were excluded. Results: Women using combined oral contraceptives have higher risk of stroke, even with a lower hormonal dosage and different types of progestogen, regardless of the duration of use. The use of contraceptives associated with smoking, hypertension, migraine, hypercholesterolemia, obesity and sedentary lifestyle increases the chance of stroke. Contraceptive patch and vaginal ring are associated to increased risk. Conclusion: Use of combined hormonal contraceptives, except for the injectable and the transdermal ones, increases the chance of occurrence of the event. Progestogen-only contraceptives were considered safe.

Chinese health care system and clinical epidemiology

China has gone through a comprehensive health care insurance reform since 2003 and achieved universal health insurance coverage in 2011. The new health care insurance system provides China with a huge opportunity for the development of health care and medical research when its rich medical resources are fully unfolded. In this study, we review the Chinese health care system and its implication for medical research, especially within clinical epidemiology. First, we briefly review the population register system, the distribution of the urban and rural population in China, and the development of the Chinese health care system after 1949. In the following sections, we describe the current Chinese health care delivery system and the current health insurance system. We then focus on the construction of the Chinese health information system as well as several existing registers and research projects on health data. Finally, we discuss the opportunities and challenges of the health care system in regard to clinical epidemiology research. China now has three main insurance schemes. The Urban Employee Basic Medical Insurance (UEBMI) covers urban employees and retired employees. The Urban Residence Basic Medical Insurance (URBMI) covers urban residents, including children, students, elderly people without previous employment, and unemployed people. The New Rural Cooperative Medical Scheme (NRCMS) covers rural residents. The Chinese Government has made efforts to build up health information data, including electronic medical records. The establishment of universal health care insurance with linkage to medical records will provide potentially huge research opportunities in the future. However, constructing a complete register system at a nationwide level is challenging. In the future, China will demand increased capacity of researchers and data managers, in particular within clinical epidemiology, to explore the rich resources.

Combined oral contraceptives: the risk of myocardial infarction and ischemic stroke

BACKGROUND

Combined oral contraceptives (COCs) have been associated with an increased risk of arterial thrombosis, i.e. myocardial infarction or ischemic stroke. However, as these diseases are rare in young women and as many types of combined oral contraception exist, the magnitude of the risk and the effect of different hormonal contents of COC preparations remain unclear.

OBJECTIVES

To estimate the risk of myocardial infarction or ischemic stroke in users compared with non-users of different types, doses and generations of combined oral contraception.

SEARCH METHODS

We searched electronic databases (MEDLINE (1966 to July 08, 2015), EMBASE (1980 to July 08, 2015), Popline (1970 to July 08, 2015) and LILACS (1985 to July 08, 2015) for eligible studies, without language restrictions.

SELECTION CRITERIA

We included observational studies that recruited women in the reproductive age group (18 to 50 years) and compared the risk of myocardial infarction or ischemic stroke between users and non-users of COCs.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected relevant studies and extracted data. We pooled relative risks ()(combined odds ratios and one incidence rate ratio) and 95% confidence intervals (CIs) for myocardial infarction or ischemic stroke in users versus non-users of COCs.We combined the outcomes of myocardial infarction and ischemic stroke and also analysed these outcomes separately. Analyses were stratified according to estrogen dose and progestagen type.

MAIN RESULTS

In total, we identified 1298 publications through the search strategy. We included 28 publications reporting on 24 studies. COC users were at increased risk of myocardial infarction or ischemic stroke compared with non-users: relative risk (RR) 1.6 (95% CI 1.3-1.9).These RRs were similar for myocardial infarction (1.6, 95% CI 1.2 to 2.1) and ischemic stroke (1.7, 95% CI 1.5 to 1.9). The risks did not vary clearly according to the generation of progestagen or according to progestagen type. When we stratified preparations according to estrogen dose, the risk of myocardial infarction or ischemic stroke seemed to increase with higher doses of estrogen.

AUTHORS' CONCLUSIONS

This meta-analysis showed that the risk of myocardial infarction or ischemic stroke was 1.6-fold increased in women using COCs . The risk was highest for pills with > 50 microgram estrogen. When combined with the results of studies on the risk of venous thrombosis in COC users, it seems that the COC pill containing levonorgestrel and 30 μg of estrogen is the safest oral form of hormonal contraception.

Pai-1 gene variants and COC use are associated with stroke risk: a case-control study in the Han Chinese women

Genetic variants of plasminogen activator inhibitor type 1 (PAI-1) gene have been suggested to influence the PAI-1 transcription activity and PAI-1 levels as well as might be involved in the pathophysiology of stroke. The aims of this study are to investigate whether the polymorphisms at the PAI-1 gene are associated with the risk of stroke and to explore the combined effects of PAI-1 variants and combined oral contraceptive (COC) use for stroke risk. We conducted a nested case-control study using 453 first-ever female stroke cases and 919 age- and region-matched controls that were recruited from our prospective surveillance cohort. SNP rs1799889 was genotyped by allele-specific polymerase chain reaction (PCR), and SNPs rs7242 and rs2227631 were detected by the TaqMan SNP genotyping assay. We identified that rs1799889 5G allele conferred a protective effect against ischemic stroke while 4G allele conferred an increased risk of ischemic stroke. But we failed to suggest associations of rs7242 and rs2227631. COC users had a 1.31-fold (OR=1.31, 95% CI=1.01-1.71) increased risk of stroke compared with the non-users. Furthermore, COC users with rs1799889 4G5G/5G5G genotype had a decreased risk of ischemic stroke (OR=0.53, 95% CI=0.34-0.83). Moreover, haplotype G-5G-T was associated with an increased risk of overall stroke (OR=1.28, 95% CI=1.01-1.62). In contrast, haplotype A-4G-G and haplotype G-5G-T were slightly associated with the protection from ischemic stroke (OR=0.61, 95% CI=0.46-0.82; OR=0.61, 95% CI=0.44-0.85, respectively). The study assessed the associations of three PAI-1 SNPs and also suggested combined effects of these PAI-1 gene variants and COC use on stroke risk in the Han Chinese women.

Hormonal contraceptives and arterial disease: an epidemiological update

The cardiovascular safety of widely used combined hormonal contraceptives is still debated. Newer generations of oral formulations as well as non-oral contraceptives (transdermal and vaginal) have been recently evaluated in the context of cardiovascular disease. This review provides a summary of the association between combined oral contraceptives (COCs) and arterial diseases, with an emphasis on new formulations of hormonal contraceptives, as well as routes of administration. A systematic search of the Medline database was performed to find all relevant articles which included women who had widely use third generation pills, and the development of new progestins. Eligible articles published in English and reporting risk of arterial events (myocardial infarction [MI] and stroke) among users of hormonal contraceptives were reviewed. A quantitative assessment was made from included studies. Overall, current use of oral combined contraceptives increased the risk of MI and ischemic stroke (pooled OR: 1.7; 95% confidence interval [95% CI]: 1.2-2.3 and OR: 1.8; 95% CI: 1.2-2.8, respectively), but this was not associated with the risk of hemorrhagic stroke (OR: 1.1; 95% CI: 0.7-1.9). The increase in ischemic arterial disease was higher among first generation pill users compared with second or third generation pill users. In contrast, risk of ischemic arterial disease among current users of second or third generation pill was similar (p = 0.23 for MI risk and 0.99 for ischemic stroke). In conclusion, newer generation formulations of COCs, as well as the non-oral hormonal contraceptive, do not seem to be safer than second generation hormonal contraceptives.

Increased risk of stroke in oral contraceptive users carried replicated genetic variants: a population-based case-control study in China

Combined oral contraceptives (COC) use is a unique risk factor for stroke in women, and may modify the associations between genetic polymorphisms and stroke. To investigate whether the genetic variants identified in a recent genome-wide association study (GWAS) could be replicated in Chinese women, as well as, whether related risk was different in COC users, 451 stroke cases and 831 age- and region-matched controls were recruited from our cohort. Genotyping of 3 SNPs (rs700651, rs10958409, and rs1333040) was performed by the polymerase chain reaction assay with TaqMan probes. The history of contraceptive use and relevant information were obtained from a face-to-face interview. Odds ratios (OR) with 95 % confidence interval (CI) were estimated under conditional logistic regression model after adjustment for cardiovascular covariates. Our study replicated the associations of rs10958409 and rs1333040, with the risk of stroke, especially hemorrhagic subtype, but failed to confirm association of rs700651. COC use was associated with a 1.56-fold (OR 1.56, 95 % CI 1.21-2.01) increased risk of stroke. COC users with rs10958409 GA/AA or rs1333040 CT/TT genotypes had an increased risk of overall stroke by 1.59-fold (OR 2.59, 95 % CI 1.59-4.19) and 3.24-fold (OR 4.24, 95 % CI 1.71-10.49), respectively, compared with the non-users with wild-type genotypes. Moreover, the risk of hemorrhagic stroke increased by 4.81- and 15.06-fold when risk allele carriers of rs10958409 or rs1333040 who took COC. Our results confirmed the associations of two GWAS SNPs, also suggested combination effects of these genetic variants and COC use on stroke risk.

General and central obesity, combined oral contraceptive use and hypertension in Chinese women

BACKGROUND

Asians have different body fat distributions and disease characteristics compared with Caucasians. The purpose of this study was to evaluate general and central obesity, combined oral contraceptive (COC) use, and their joint effects on the risk of hypertension in Chinese women.

METHODS

A case-control study including 1,760 women (878 hypertensive cases and 882 normotensive controls) was conducted in China. Body weight, height, waist circumference (WC), blood pressure, serum lipids, and apolipoproteins were measured. History of contraceptive use and relevant factors were investigated. Odds ratio (OR) with 95% confidence interval (CI) was estimated for hypertension-related factors under unconditional logistic regression model.

RESULTS

Our study showed that increased body mass index (BMI), increased WC, and COC use were risk factors for hypertension with an OR (95% CI) of 2.19 (1.69-2.83), 1.46 (1.13-1.88), and 1.26 (1.02-1.56), respectively. Compared with WC, BMI was more strongly associated with hypertension risk (OR 3.40, 95% CI 2.28-5.05, for highest vs. lowest quartile) and was a better predictor for blood pressure. COC users had a 1.39-fold (OR 1.39, 95% CI 1.14-1.69) increased risk compared with the nonusers, while stopping COC was associated with a 36% reduced risk (OR 0.64, 95% CI 0.42-0.98). The risk increased dramatically in combination of COC use with a BMI ≥28 kg/m(2) or WC ≥90 cm (OR 8.02, 95% CI 5.05-12.74; OR 5.76, 95% CI 3.65-9.12, respectively).

CONCLUSIONS

General and central obesity, COC use, and their joint effects significantly increased the risk of hypertension in Chinese women.

Estrogen receptor beta genetic variants and combined oral contraceptive use as relates to the risk of hypertension in Chinese women

BACKGROUND AND AIMS

Estrogen receptor beta (ESR2) plays an important role in cardiovascular physiology and blood pressure regulation, whereas estrogens may influence gene expression, growth, and cellular differentiation in target tissues by activating estrogen receptors. This study aims to investigate the association between common genetic variants of ESR2 gene and the risk of hypertension and to explore the combined effected of ESR2 variants and combined oral contraceptive (COC) use for hypertension risk.

METHODS

A population-based case-control study was conducted in 621 female hypertensive patients and 621 female normotensive controls.

RESULTS

ESR2 G1082A heterozygote genotype (GA) was in significant relationship with hypertension (crude odds ratio [OR] = 1.38, 95% CI: 1.09-1.76; adjusted odds ratio [OR] = 1.38, 95% CI: 1.09-1.76). No association was observed for ESR2 G1730A polymorphism. Furthermore, the joint effects of the heterozygote of G1082A polymorphism (heterozygote model: GG/AA vs. GA) and cumulative COC use time ≥15 years significantly increased the risk of hypertension [adjusted odds ratio (OR) = 2.19, 95% CI: 1.49-3.24], and the interaction effects between those two risk factors were significant (p = 0.0001).

CONCLUSIONS

The heterozygote GA genotype of ESR2 gene G1082A polymorphism may be a risk genotype for hypertension in Chinese women, and the GA genotype (heterozygote model: GG/AA vs. GA) of G1082A locus together with COC use simultaneously contributed to hypertension development.

Dyslipidaemia, combined oral contraceptives use and their interaction on the risk of hypertension in Chinese women

The objective of the study was to assess the associations of dyslipidaemia, combined oral contraceptive (COC) use and their interaction on the risk of hypertension in Chinese women. In a case-control study, we evaluated 665 hypertensive women and 665 normotensive women matched on region and age in China. Hypertensive women had a higher prevalence of dyslipidaemia and higher levels of total cholesterol, triglyceride, low-density lipoprotein-cholesterol and lipoprotein a than normotensive ones (P<0.05). The risk of hypertension gradually increased with the increasing cumulative time of COC use in women (P=0.0043), especially significantly increased among those with cumulative time of COC use 15-20 and ≥20 years (adjusted odds ratio (OR)=1.46, 95% confidence interval (CI): 1.00-2.15; OR=1.49, 95% CI: 1.06-2.11), but gradually decreased from stopping use of COC (P<0.0001). The multiplicative interaction between dyslipidaemia and accumulative time of COC use ≥15 years, dyslipidaemia and family history of hypertension, or family history of hypertension and accumulative time of COC use ≥15 years was confirmed and the interaction analyses showed that they can significantly increased the risk of hypertension (adjusted OR=2.82, 95% CI: 1.59-3.27; OR=4.33, 95% CI: 3.10-6.06; OR=4.56, 95% CI: 3.07-6.77). It is concluded that dyslipidaemia, accumulative time of COC use ≥15 years and their interaction increased the risk of hypertension.

Copper containing intra-uterine devices versus depot progestogens for contraception

BACKGROUND

Highly effective contraception is essential to reduce unintended pregnancies and the effect these have on individuals, society and public health resources. Intrauterine devices (IUDs) and depot progestogens are two commonly used long-acting, reversible contraceptive methods with different risk and benefit profiles.

OBJECTIVES

To compare the contraceptive and non-contraceptive benefits and risks of using the copper-containing IUD versus depot progestogens for contraception.

SEARCH STRATEGY

In June 2009 we searched the Cochrane Pregnancy and Childbirth Group Trials Register, the Cochrane Central Register of Controlled Trials, Pubmed, Popline, Clinical Trials.gov, the Current Controlled Trials metaRegister, EMBASE and LILACS, and contacted study authors.

SELECTION CRITERIA

Randomized trials comparing women using copper-containing IUDs with women using depot progestogens.

DATA COLLECTION AND ANALYSIS

We assessed eligibility and trial quality, extracted and double-entered data.

MAIN RESULTS

Two studies were included in the review. In the one study in HIV infected women, the IUD was compared with depot progestogen or the oral contraceptive, according to the women's choice. As the majority of women chose depot progestogen, we have included this study in the review, within a mixed hormonal contraception sub-group.Overall, the copper IUD was more effective than depot progestogens/hormonal contraception at preventing pregnancy (risk ratio (RR) 0.45; 95% confidence interval (CI) 0.24 to 0.84). HIV disease progression was reduced in the IUD group (RR 0.58; 95% CI 0.39 to 0.87). There was no significant difference in pelvic inflammatory disease rates between the two groups. Discontinuation of the allocated method was less frequent with the IUD in one study, and less frequent with hormonal contraception in the other study (in which women were allowed to switch between various hormonal methods).

AUTHORS' CONCLUSIONS

In the populations studied, the IUD was more effective than hormonal contraception with respect to pregnancy prevention. High quality research is urgently needed to compare the effects, if any, of these two commonly used contraception methods on HIV acquisition/seroconversion and HIV/AIDS disease progression.