Increased thrombin generation in women with polycystic ovary syndrome: A pilot study on the effect of metformin and oral contraceptives

doi:10.1016/j.metabol.2015.06.011

Metabolism

Volume 64, Issue 10, October 2015, Pages 1272-1278

https://doi.org/10.1016/j.metabol.2015.06.011 Get rights and content

Abstract

Objective

Polycystic ovary syndrome (PCOS) is associated with risk factors for cardiovascular disease (CVD) which may be modified by the use of metformin and oral contraceptives (OC). Thrombin generation (TG) measures are risk markers of CVD and address the composite of multiple factors that influence blood coagulation. This prospective, randomized, intervention study evaluated the potential influence of PCOS on TG measures and the effect of OC and/or metformin on TG measures in women with PCOS.

Material and methods

Ninety patients with PCOS and 35 controls were included. Patients were randomized to 12 months of treatment with metformin, metformin + OC or OC alone. C-reactive protein (CRP), fibrinogen, total cholesterol, trunk fat mass, body mass index, estradiol, testosterone, sex hormone binding globulin (SHBG) as well as TG measures, i.e. the lag time for formation of thrombin, the endogenous thrombin potential (ETP), peak thrombin concentration (peak) and time to peak were determined at baseline and after 12 months of treatment.

Results

CRP and total testosterone were significantly higher and SHBG significantly lower in PCOS women than in controls (P = 0.012, P < 0.001 and P = 0.008, respectively). The TG measures ETP, peak and lag time were increased in women with PCOS compared to controls (P < 0.01). Significant correlations were observed between TG measures and fibrinogen, CRP, SHBG and fat trunk mass (P>0.01). ETP (P = 0.006), peak (P = 0.003) and lag time (P = 0.023) remained increased after adjustment for these potential confounders. Treatment with OC and metformin + OC further increased ETP (P < 0.001) and peak (P < 0.005) and reduced time to peak (P < 0.04). The increase in ETP was significantly lower in the metformin + OC group than in the OC group (P < 0.05). Metformin alone did not affect TG significantly.

Conclusions

PCOS is associated with increase in TG measures independent of other risk factors of CVD. OC increase TG measures further and may thus add to the increased risk of CVD already present in women with PCOS.

Introduction

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age affecting 5%–10% of premenopausal women. The clinical identification of women with PCOS, as defined in the Rotterdam criteria, is based on anovulation, hyperandrogenism and polycystic ovaries and at least two of these three criteria must be accomplished to establish the PCOS diagnosis [1], [2]. PCOS is associated with insulin resistance and enhanced risk of type 2 diabetes. Patients with PCOS have increased levels of cardiovascular risk markers [3] increased risk of venous thromboembolism [4], [5] and significant subclinical atherosclerosis compared with healthy controls [6], [7], [8].

Life style intervention and treatment with metformin are applied to reduce insulin resistance and improve ovulation rates in women with PCOS [9]. Treatment with metformin may have beneficial effects on cardiovascular events [10], but no long term studies are available in patients with PCOS. The menstrual irregularities and hirsutism associated with PCOS are often treated with oral contraceptives (OC). Treatment with OC increases the risk of cardiovascular disease (CVD) in women without PCOS [11]. A comparable thrombogenic effect of OC treatment has been reported in women with PCOS [4], although recent studies have indicated that OC-treatment is without effect or may even reduce the cardiovascular risk in women with PCOS [5], [7], [12].

Measures of thrombin generation (TG) address the combined effect of multiple haemostatic risk markers for venous and arterial thrombotic disease [13], [14], [15], [16]. Elevated TG measures are associated with idiopathic and pregnancy related thrombosis [13], [16] and thrombin formation contributes to vascular calcification and atherosclerosis progression [17]. Age, body mass index (BMI), total cholesterol, trunk fat mass and low grade inflammation are shown to be potential confounders of measures of TG [18], [19] and several studies have indicated that also sex hormones may have significant impact on TG [20], [21], [22], [23]. It is of particular interest that OC treatment has been demonstrated to elevate measures of TG [24], whereas the function of thrombin is reduced in diabetic patients treated with metformin [25], [26]. TG has rarely been studied in women with PCOS [27] and no previous studies have addressed the long term effect of OC and/or metformin on TG measures in this group of women.

In the present study we evaluated the impact of PCOS on measures of TG by comparison with control subjects of similar age and BMI after adjustment for the effect of the confounders. Furthermore we evaluated whether 12 months’ treatment with metformin and/or OC affected TG measures in women with PCOS.

Section snippets

Patients

The study design has recently been published [28]. In brief, 90 white, non-diabetic women aged 18–39 years fulfilling the Rotterdam criteria for PCOS were included in the study. It should be noticed that TG as outcome measure was not defined in the original study [28], which was planned ultimo 2006. The power of the study was calculated using the area under the curve for insulin during two hours OGTT as the primary end point. No previous studies examined the effect of metformin and/or OC on TG

The Association Between PCOS and Measures of TG

Controls and patients with PCOS were comparable at baseline with respect to age (P = 0.29), BMI (P = 0.30), fibrinogen (P = 0.051), total cholesterol (P = 0.31) and trunk fat mass (P = 0.45). CRP, total testosterone and SHBG were log10-transformed to obtain normal distribution. CRP and total testosterone were significantly higher in women with PCOS than controls (P = 0.01 and P < 0.001, respectively), Table 1. The concentration of SHBG was significantly lower in women with PCOS than in controls (P = 0.008).

Discussion

The first part of this study, focusing on measures of TG in women with PCOS and controls, demonstrates that the TG potential, measured as ETP and peak thrombin concentration, is significantly higher, and that the lag time is significantly longer in women with PCOS than in healthy women with comparable age and BMI.

Previous studies have shown that age, BMI, total cholesterol, trunk fat mass and low grade inflammation are potential confounders of measures of TG [18], [19]. Additional studies have

Funding

Financial grants for the studies were provided by Jacob Madsen’s and Olga Madsen’s Foundation, Institute of Clinical Research, Odense University Hospital, Kolding Hospital, AP Møller’s Foundation, Bernhard and Marie Kleins Foundation, The Novo Nordisk Foundation, and The Danish Medical Association. Oral contraceptive pills and metformin tablets were sponsored by Sandoz. Sandoz was not involved in study planning or writing of article.

Conflict of Interest

None of the authors have any conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Supplementary data

The following are the Supplementary data to this article.

. CONSORT 2010 checklist of information to include when reporting a randomized trial

. Flow chart of included and excluded subjects and study design. Data are presented as number of participants (number of normal weight + overweight patients). NW, normal weight, BMI less than 25 kg/m2; OW, overweight, BMI 25 kg/m2 or greater; dropouts, NW, 14 of 36 = 38.8%; dropouts, OW, 11 of 54 = 20.3%, P = 0.06.

Acknowledgments

The authors thank Anette Riis Madsen, Lotte Hørlyck, Steffanie Anthony Christensen, Jane Nielsen, Donna Arbuckle-Lund, Elizabeth Hanmann, Jeannette Fogh Lindegaard, Mette Brøchner Hansen, Anne Mette Hangaard, Susanne Møller Pedersen, Geraldine Rasmussen, Thon Kowall Andersen, Anette Larsen and Kathrine Overgaard for excellent technical assistance.

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Clinical ScienceIncreased thrombin generation in women with polycystic ovary syndrome: A pilot study on the effect of metformin and oral contraceptives

Abstract

Objective

Material and methods

Results

Conclusions

Introduction

Section snippets

Patients

The Association Between PCOS and Measures of TG

Discussion

Funding

Conflict of Interest

Supplementary data

Acknowledgments

Am J Obstet Gynecol

Metabolism

JACC Cardiovasc Imaging

Atherosclerosis

Thromb Res

Blood

J Thromb Haemost

Consensus on women's health aspects of polycystic ovary syndrome (PCOS): the Amsterdam ESHRE/ASRM-Sponsored 3rd PCOS Consensus Workshop Group

Fertil Steril

An update on the pathogenesis, inflammation, and metabolism in hirsutism and polycystic ovary syndrome

Gynecol Endocrinol

Meta-analysis of cardiovascular disease risk markers in women with polycystic ovary syndrome

Hum Reprod Update

Risk of venous thromboembolism in women with polycystic ovary syndrome: a population-based matched cohort analysis

CMAJ

Polycystic ovarian syndrome and the risk of cardiovascular disease and thrombosis

Semin Thromb Hemost

Carotid artery intima-media thickness in polycystic ovary syndrome: a systematic review and meta-analysis

Hum Reprod Update

Metformin in reproductive health, pregnancy and gynaecological cancer: established and emerging indications

Hum Reprod Update

Effects of metformin versus glipizide on cardiovascular outcomes in patients with type 2 diabetes and coronary artery disease

Diabetes Care

Different combined oral contraceptives and the risk of venous thrombosis: systematic review and network meta-analysis

BMJ

Adverse effects of the common treatments for polycystic ovary syndrome: a systematic review and meta-analysis

J Clin Endocrinol Metab

Differential haemostatic risk factors for pregnancy-related deep-vein thrombosis and pulmonary embolism: a population-based case–control study

Thromb Haemost

Is thrombin a key player in the 'coagulation-atherogenesis' maze?

Cardiovasc Res

Clinical Science
Increased thrombin generation in women with polycystic ovary syndrome: A pilot study on the effect of metformin and oral contraceptives