Effects of Simvastatin and Metformin on Polycystic Ovary Syndrome after Six Months of Treatment

Abstract

Context:

A randomized trial on women with polycystic ovary syndrome (PCOS) compared simvastatin, metformin, and a combination of these drugs.

Objective:

The aim of the study was to evaluate long-term effects of simvastatin and metformin on PCOS.

Design:

Women with PCOS (n = 139) were randomized to simvastatin (S), metformin (M), or simvastatin plus metformin (SM) groups. Evaluations were performed at baseline and at 3 and 6 months.

Setting:

The study was conducted at a university medical center.

Primary Outcome:

We measured the change of serum total testosterone.

Results:

Ninety-seven subjects completed the study. Total testosterone decreased significantly and comparably in all groups: by 25.6, 25.6, and 20.1% in the S, M, and SM groups, respectively. Both simvastatin and metformin improved menstrual cyclicity and decreased hirsutism, acne, ovarian volume, body mass index, C-reactive protein, and soluble vascular cell adhesion molecule-1. Dehydroepiandrosterone sulfate declined significantly only in the S group. Total cholesterol and low-density lipoprotein cholesterol significantly declined only in the S and SM groups. Ongoing reduction of ovarian volume, decreased hirsutism, acne and testosterone were observed between 0 and 3 months as well as between 3 and 6 months. Improvement of lipid profile, C-reactive protein, and soluble vascular cell adhesion molecule-1 occurred only during the first 3 months of treatment, with little change thereafter. Treatments were well tolerated, and no significant adverse effects were encountered.

Conclusions:

Long-term treatment with simvastatin was superior to metformin. Improvement of ovarian hyperandrogenism continued throughout the duration of the study.

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy affecting up to 10% of women of reproductive age (1–3). Among various definitions of PCOS that have been proposed, the most common diagnostic criteria include hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology. The etiology of PCOS remains unknown, and in view of the heterogeneous nature of the syndrome, it is likely to consist of a constellation of different disorders sharing various pathophysiological features. However, one of the most prominent features of PCOS is abnormal ovarian function characterized by excessive androgen production by a hyperplastic theca compartment. The typical polycystic ovary is enlarged, and individual theca cells produce greatly increased amounts of androgens, at least in part, due to excessive activity of several key enzymes involved in steroidogenesis (4, 5). In addition to dysfunction of the reproductive system, women with this condition often display a wide range of long-term metabolic derangements and cardiovascular risks including dyslipidemia, systemic inflammation, endothelial dysfunction, and insulin resistance (6–11).

Statins represent a potentially attractive group of medications with activities targeting several key pathophysiological aspects of PCOS. In addition to well-known beneficial effects on lipid profile and other cardiovascular risks, statins may also directly target ovarian theca cells. Studies in vitro have demonstrated that statins reduce theca cell androgen production, decrease cell proliferation, and induce apoptosis (12–15).

Several clinical trials have evaluated the effects of statins on both cardiovascular risks and reproductive-endocrine aspects of PCOS. In relatively short-term studies lasting from 6 wk to 3 months, simvastatin and atorvastatin exerted favorable effects on various features of PCOS, including reduction of androgen levels, improvement of lipid profile, and decreased systemic inflammation (16–22). However, long-term clinical and biochemical effects of statins on PCOS remain unknown.

This study evaluated the effects of simvastatin in comparison to metformin during a 6-month prospective, randomized trial. Initial outcomes of this trial after 3 months were recently published and demonstrated that both simvastatin and metformin improved hyperandrogenism and inflammation, whereas only simvastatin improved lipid profile (23). In this report, we present the final results of the trial demonstrating that the effects of simvastatin and metformin on PCOS are long lasting and that, overall, simvastatin is superior to metformin, as evidenced by improvement of both reproductive and cardiovascular features of the syndrome. In particular, for the first time, we show that simvastatin improves menstrual regularity, reduces ovarian volume, and induces progressive improvement of biochemical and clinical features of hyperandrogenism.

Subjects and Methods

Subjects

All subjects fulfilled PCOS criteria as defined by the Rotterdam consensus and had at least two of the following: 1) clinical or chemical hyperandrogenism; 2) oligo- or amenorrhea; and/or 3) polycystic ovaries as viewed by transvaginal ultrasound (24, 25). Congenital adrenal hyperplasia was excluded on the basis of morning follicular phase 17-hydroxyprogesterone below 2 ng/ml. None of the subjects had elevated prolactin, thyroid disease, Cushing disease, or diabetes mellitus. All subjects had normal baseline renal function tests, bilirubin, and aminotransferases.

All subjects were recruited at Poznan University of Medical Sciences between December 2006 and March 2009. Informed consent was obtained from all participants. Approval of the study was obtained from the Institutional Review Board at the Poznan University of Medical Sciences and the Institutional Review Board at the University of California-Davis. The study was registered at www.clinicaltrials.gov with the identifier NCT00396513.

During the last 3 months before the study, none of the study subjects used any form of oral contraceptives, other steroid hormones, or any other treatments likely to affect ovarian function, insulin sensitivity, or lipid profile.

Procedures

The flowchart of the study is summarized in Fig. 1. A total of 150 women were screened, and 139 (93%) were randomly assigned to three treatment groups: simvastatin alone (20 mg/d orally; S group), metformin alone (850 mg orally twice a day; M group), and simvastatin plus metformin (20 mg/d orally and 850 mg orally twice a day, respectively; SM group). Simvastatin (Simvachol) was obtained from Polfa Grodzisk (Grodzisk Mazowiecki, Poland) and metformin (Metformax) was provided by Polfa Kutno SA (Kutno, Poland). Randomization was performed using 1:1:1 allocation ratio with blocks of random size (6, 9, or 12 subjects per block).

Fig. 1.

Flow diagram of the trial.

Patient allocation and block size were obtained using random number tables. At the time of randomization, sequentially numbered, sealed envelopes were opened. Allocation to study group was concealed until a consent was obtained and inclusion/exclusion criteria verified. The randomization list was kept locked, and the allocation numbers were generated and sealed in the envelopes by one of the authors (R.Z.S.). Allocation of the patients was performed only by the author who was blinded to the randomization schedule. Because commercially available pills were used, there was no blinding after randomization; consequently, investigators and patients could identify the actual treatment. The primary endpoint was change of total testosterone.

Study design and assays

All participants were evaluated at baseline during the follicular phase of a natural cycle or after medroxyprogesterone-induced menses. Clinical assessments included determinations of body mass index (BMI), of hirsutism using Ferriman and Gallwey score (26), and of acne score (27). Acne was scored using a four-point scale: 0, no acne; 1, minor acne on face only; 2, moderate acne on face only; and 3, severe acne, face and back or chest. Transvaginal ultrasonographic examination was performed; ovaries were measured recording three perpendicular diameters. Ovarian volume was determined using the prolate ellipsoid formula. Endocrine and metabolic tests were performed after 3 d of carbohydrate intake of 300 g/d to standardize conditions before glucose tolerance test. Venous blood was collected between 0700 and 0800 h after an overnight fast. Serum specimens were stored at −70 C until analysis was performed.

A 2-h oral glucose tolerance test was performed with determinations of glucose and insulin in the fasting state as well as after a 75-g glucose load at 30, 60, 90, and 120 min. Glucose was determined using enzyme electrode in the EBIO (enzymatic amperometric principle, enzyme glucose oxidase; Eppendorf-Netheler-Hin, Hamburg, Germany). Insulin, total testosterone, LH, FSH, prolactin, SHBG, and dehydroepiandrosterone sulfate (DHEAS) were determined by specific electrochemiluminescence assays (automated Elecsys 2010 immunoanalyser; Roche Diagnostics GmbH, Mannheim, Germany). Free testosterone was determined as described by Vermeulen et al. (28). 17-Hydroxyprogesterone was measured using ELISA assay (DRG Instruments GmBH, Marburg/Lahn, Germany). Insulin sensitivity index was calculated using glucose and insulin levels obtained during an oral glucose tolerance test as described by Matsuda and DeFronzo (29); this measure reflects both hepatic and peripheral tissue sensitivity to insulin.

Total cholesterol and triglycerides were determined by enzymatic colorimetric assays (Roche Diagnostics GmbH). High-density lipoprotein (HDL) was separated by precipitating apolipoprotein-B (Roche Diagnostics GmbH). LDL was calculated using the Friedwald formula. High-sensitivity C-reactive protein (hs-CRP) was determined using a specific electrochemiluminescence assay (automated Elecsys 2010 immunoanalyzer; Roche Diagnostics GmbH). Soluble vascular cell adhesion molecule 1 (sVCAM) was determined using a human Quantikine ELISA kit from R&D Systems (Minneapolis, MN).

The above evaluations were repeated after 3 and 6 months of treatment.

Statistical analysis

Comparisons between groups were performed by ANOVA, and repeat measures ANOVA was used to evaluate change of values for individual variables (at 3 months compared with baseline, at 6 months compared with baseline, and at 6 months compared with 3 months). Post hoc comparisons of individual pairs included t tests with Bonferroni correction. In the absence of a normal distribution (tested by Shapiro-Wilk test), logarithmic transformations or nonparametric testing was carried out.

Results

Baseline evaluations and dropouts

Table 1 summarizes baseline characteristics of 139 subjects enrolled in the study. Hirsutism (defined as Ferriman and Gallwey score ≥8) was observed in 79% of subjects, acne in 82%, and hyperandrogenemia (total testosterone >70 ng/ml) in 69% of subjects. At least one feature of hyperandrogenism (hirsutism, acne, or hyperandrogenemia) was present in 96% of subjects. Oligomenorrhea (no more than eight spontaneous cycles per year) was reported by 86% of subjects. The average age (mean ± sd) was 25.9 ± 4.0 yr; 20% of the subjects were overweight (BMI, 25–30 kg/m²), and 14% were obese (BMI > 30 kg/m²). Fasting hyperinsulinemia (>16 μU/ml) was detected in 4%.

Table 1.

Baseline parameters in individual groups

Variable	Simvastatin (S)	Metformin (M)	Simvastatin + metformin (SM)	Comparison between groups, P value (pair-wise comparisons)
n	48	47	44
Age (yr)	26.3 ± 0.6	26.0 ± 0.6	25.3 ± 0.6	0.49
No. of spontaneous menses per 6 months	2.4 ± 0.2	3.0 ± 0.2	2.6 ± 0.2	0.07
Volume of both ovaries (ml)	21.9 ± 1.0	21.3 ± 1.4	20.6 ± 0.9	0.22
BMI (kg/m2)	23.5 ± 0.6	24.7 ± 0.7	24.8 ± 0.8	0.32
Hirsutism (Ferriman/Gallwey score)	9.1 ± 0.3	9.7 ± 0.3	8.7 ± 0.3	0.07
Acne (score)	1.19 ± 0.12	1.21 ± 0.12	1.55 ± 0.15	0.11
Total testosterone (ng/ml)	0.84 ± 0.03	0.84 ± 0.04	0.85 ± 0.04	0.99
Free testosterone (ng/dl)	1.32 ± 0.09	1.47 ± 0.10	1.52 ± 0.10	0.30
DHEAS (μmol/ml)	9.26 ± 0.42	9.26 ± 0.41	9.00 ± 0.49	0.85
SHBG (nmol/liter)	49.3 ± 3.6	41.4 ± 2.9	40.3 ± 3.4	0.11
LH (IU/liter)	10.4 ± 0.7	9.9 ± 0.8	9.2 ± 0.7	0.57
FSH (IU/liter)	6.0 ± 0.2	6.0 ± 0.2	5.3 ± 0.2	0.02 (SM vs. M, P = 0.04)
Prolactin (ng/ml)	18.1 ± 1.2	16.9 ± 1.2	18.5 ± 1.2	0.61
Total cholesterol (mg/dl)	190.7 ± 5.4	174.4 ± 4.1	184.3 ± 4.8	0.06
LDL cholesterol (mg/dl)	107.6 ± 4.9	96.6 ± 4.2	101.6 ± 4.4	0.22
HDL cholesterol (mg/dl)	69.0 ± 2.2	60.4 ± 2.2	64.7 ± 2.2	0.03 (S vs. M, P = 0.02)
Triglycerides (mg/dl)	72.2 ± 3.1	79.0 ± 6.7	93.0 ± 7.9	0.06
hs-CRP (mg/liter)	1.4 ± 0.5	2.5 ± 0.5	2.5 ± 0.7	0.34
sVCAM (μg/liter)	680 ± 25	749 ± 34	686 ± 27	0.17
Fasting glucose (mg/dl)	84.2 ± 1.5	84.9 ± 1.7	84.4 ± 1.7	0.95
Fasting insulin (μU/ml)	6.9 ± 0.7	8.1 ± 0.6	8.1 ± 0.8	0.34
Insulin sensitivity index	7.1 ± 0.5	5.7 ± 0.4	6.6 ± 0.6	0.15

Each value represents mean ± sem.

As presented in Fig. 1, 114 of 139 subjects (82%) completed the first 3 months of the study, whereas 97 of 139 subjects (70%) completed the entire 6 months of the study. All treatment groups were comparable with regard to the primary outcome (total testosterone) and other studied variables, with the exception of modest differences in levels of FSH and HDL cholesterol. Six subjects using metformin experienced transient gastrointestinal side effects including diarrhea; however, these side effects did not result in discontinuation of treatment. Baseline levels of FSH were 0.7 U/liter lower in the SM group than in the M group, whereas baseline HDL-cholesterol was 8.6 mg/dl lower in the M group than in the S group.

Final outcomes

Effects of treatments on clinical, endocrine, and metabolic parameters during the entire 6-month trial are summarized in Table 2. Subjects in all treatment groups experienced a significant improvement of menstrual regularity, with the greatest increase in the number of menses observed in women receiving simvastatin (S and SM groups). Subjects receiving metformin alone (M group) also experienced an increase in the number of menses, but this effect was significantly lower than that observed in other groups. Multiple linear regression analysis revealed that the change in the number of spontaneous menstrual cycles correlated independently with changes in BMI (P = 0.009), changes in total cholesterol level (P = 0.01), and changes in ovarian volume (P = 0.006). Ovarian volume declined significantly in the S and SM groups, whereas the decline in the M group was of borderline statistical significance. All groups experienced modest, but statistically significant deceases of BMI, with the greatest effect detected in the M group.

Table 2.

Change of parameters after 6 months of treatment in comparison to baseline values

Variable	Simvastatin (S)	Effect of S vs. baseline P value	Metformin (M)	Effect of M vs. baseline P value	Simvastatin + metformin (SM)	Effect of SM vs. baseline P value	Comparison between groups P value (pair-wise comparisons)
n	28		33		36
No. of spontaneous menses per 6 months	+1.6 ± 0.2 (71.3%)	<0.001	+1.1 ± 0.2 (33.1%)	<0.001	+1.7 ± 0.2 (73.3%)	<0.001	0.02 (S vs. M, P = 0.03; SM vs. M, P = 0.02; S vs. SM, P = 0.86)
Volume of both ovaries (ml)	−2.99 ± 0.67 (−14.1%)	<0.0001	−1.24 ± 1.31 (−5.4%)	0.06	−1.49 ± 0.80 (−7.3%)	0.04	0.42
BMI (kg/m2)	−0.35 ± 0.15 (−1.4%)	0.03	−0.93 ± 0.14 (−4.0%)	<0.0001	−1.35 ± 0.34 (−5.3%)	0.0003	0.02 (S vs. M, P = 0.09; SM vs. M, P = 0.21; S vs. SM, P = 0.005)
Hirsutism (Ferriman/Gallwey score)	−1.1 ± 0.1 (−12%)	<0.0001	−0.84 ± 0.35 (−8.9%)	<0.0001	−1.0 ± 0.15 (−11.7%)	<0.0001	0.52
Acne (score)	−0.93 ± 0.13 (−76%)	<0.0001	−0.75 ± 0.12 (−62%)	<0.0001	−1.06 ± 0.14 (−67%)	<0.0001	0.23
Total testosterone (ng/ml)	−0.22 ± 0.03 (−25.6%)	<0.0001	−0.15 ± 0.04 (−25.6%)	0.0002	−0.16 ± 0.03 (−20.1%)	<0.0001	0.42
Free testosterone (ng/dl)	−0.28 ± 0.06 (−20.3%)	<0.0001	−0.30 ± 0.08 (−23.2%)	0.001	−0.27 ± 0.08 (−17.5%)	0.003	0.97
DHEAS (μmol/ml)	−1.64 ± 0.43 (−17.1%)	0.0007	0.54 ± 0.37 (6.1%)	0.15	0.59 ± 0.31 (6.7%)	0.07	0.0001 (S vs. M, P = 0.0001; SM vs. M, P = 0.92; S vs. SM, P = 0.0001)
SHBG (nmol/liter)	−5.19 ± 2.20 (−10.7%)	0.03	2.27 ± 1.96 (5.2%)	0.25	0.43 ± 1.78 (1.1%)	0.81	0.03 (S vs. M, P = 0.01; SM vs. M, P = 0.50; S vs. SM, P = 0.05)
LH (IU/liter)	0.15 ± 1.16 (1.4%)	0.90	−1.9 ± 0.77 (−19.6%)	0.03	−0.09 ± 1.1 (−0.9%)	0.93	0.35
FSH (IU/liter)	−0.56 ± 0.26 (−9.2%)	0.04	−0.67 ± 0.29 (−10.7%)	0.03	0.12 ± 0.31 (2.3%)	0.71	0.12
Prolactin (ng/ml)	−1.60 ± 1.80 (−9.1%)	0.38	−2.24 ± 0.94 (−12.9%)	0.02	−5.00 ± 0.97 (−26.7%)	<0.0001	0.12
Total cholesterol (mg/dl)	−35.4 ± 6.1 (−18.9%)	<0.0001	2.81 ± 4.63 (1.6%)	0.55	−34.5 ± 5.6 (−18.9%)	<0.0001	<0.0001 (S vs. M, P = 0.0001; SM vs. M, P = 0.0001; S vs. SM, P = 0.91)
LDL cholesterol (mg/dl)	−32.6 ± 5.0 (−31.6%)	<0.0001	2.40 ± 4.20 (2.5%)	0.57	−31.8 ± 4.4 (−31.9%)	<0.0001	0.0001 (S vs. M, P = 0.0001; SM vs. M, P = 0.0001; S vs. SM, P = 0.91)
HDL cholesterol (mg/dl)	−2.62 ± 2.74 (−3.7%)	0.35	0.55 ± 2.13 (0.9%)	0.80	−0.79 ± 1.8 (−1.2%)	0.66	0.61
Triglycerides (mg/dl)	−3.38 ± 4.20 (−5.0%)	0.42	12.8 ± 7.5 (17.5%)	0.09	−13.4 ± 7.3 (−15.0%)	0.07	0.02 (S vs. M, P = 0.11; SM vs. M, P = 0.006; S vs. SM, P = 0.31)
hs-CRP (mg/liter)	−0.55 ± 0.29 (−33.5%)	0.03	−1.32 ± 0.66 (−55.7%)	0.01	−0.83 ± 0.78 (−33.5%)	0.10	0.78
sVCAM (μg/liter)	−85.7 ± 25.6 (−12.7%)	0.003	−62.2 ± 23.6 (−8.2%)	0.01	−68.5 ± 23.0 (−10.1%)	0.005	0.79
Fasting glucose (mg/dl)	−2.85 ± 2.37 (−3.4%)	0.23	−3.13 ± 2.05 (−3.8%)	0.13	−3.36 ± 2.12 (4.0%)	0.12	0.99
Fasting insulin (μU/ml)	−0.29 ± 0.57 (−4.1%)	0.62	0.72 ± 1.00 (11.1%)	0.47	−1.73 ± 0.76 (−20.9%)	0.02	0.08
Insulin sensitivity index	0.31 ± 0.55 (5.1%)	0.58	0.34 ± 0.47 (6.0%)	0.47	0.31 ± 0.54 (5.1%)	0.56	0.99

Each value represents mean ± sem (percentage change).

In all treatment groups, there was a significant decrease of hirsutism, acne, total testosterone, and free testosterone; these effects were comparable in all groups. In contrast, a significant decrease of DHEAS was observed only in the S group, whereas the M group and the SM group experienced a modest, but statistically insignificant increase of DHEAS. SHBG declined slightly in the S group. LH and FSH were not affected by any treatments, whereas prolactin declined significantly only in subjects receiving metformin (M and SM groups).

Significant improvement of lipid profile (decline of total and LDL cholesterol) occurred only among subjects receiving simvastatin. HDL cholesterol and triglyceride levels were not significantly altered by any of the treatments. Measures of systemic inflammation (hs-CRP) and endothelial function (sVCAM) were improved to a comparable degree by simvastatin and by metformin. In contrast, fasting glucose and insulin sensitivity were not affected by any treatment. Fasting insulin declined significantly in the SM group only.

Time-course of changes

To evaluate the time-course of changes in selected clinical, endocrine, and metabolic parameters of PCOS, we compared changes observed during two consecutive 3-month intervals: 1) between values at baseline and at 3 months of treatment; and 2) between values at 3 and 6 months of treatment. As presented in Fig. 2, it is apparent that simvastatin alone or together with metformin led to decreased of ovarian volume during the first 3 months of treatment followed by a further decrease during the subsequent 3 months. In contrast, treatment with metformin alone led to a significant decrease of ovarian volume only during the first 3 months of treatment, with no significant change thereafter.

Fig. 2.

Time-course of effects of simvastatin (S), metformin (M) and simvastatin plus metformin (S+M) on selected parameters of PCOS during the first 3 months of treatment (values at baseline in comparison to 3 months; hatched bars) and during the second 3 months (values at 3 months in comparison to values at 6 months; gray bars) of the trial. Each bar represents mean ± sem. *, P < 0.05. Different ranges and different scales are used for presentation of individual parameters.

Simvastatin alone induced a significant and progressive decrease of all studied measures of hyperandrogenism (hirsutism, acne, total and free testosterone). Comparable, albeit not always statistically significant, effects were observed in subjects receiving only metformin or metformin in combination with simvastatin.

An entirely different pattern was observed with regard to the time-course of changes in metabolic parameters. Total cholesterol and LDL cholesterol declined in subjects receiving simvastatin during the first 3 months of treatment, with no significant change during the next 3 months. Similarly, in the S group, significant reduction of hs-CRP and sVCAM was observed only during the first 3 months of the study. Insulin sensitivity index improved significantly also only in S group and only during the first 3 months.

Normal transaminases and creatinine kinase levels were documented every 3 months in all subjects.

Discussion

The present study demonstrates for the first time that in women with PCOS: 1) long-term treatment with simvastatin results in progressive reduction of ovarian volume and improvement of hyperandrogenism; 2) simvastatin improves menstrual regularity, and this effect is superior to that of metformin; and 3) improvement of metabolic parameters such as lipid profile and level of hs-CRP occurs within the first 3 months of treatment, with no further significant change thereafter.

Abnormal ovarian function, including excessive androgen production, is considered to be one of the key pathophysiological features of PCOS. Ovaries of women with PCOS are typically enlarged, and individual follicles contain a greatly increased number of layers of androgen-producing theca cells (30). Furthermore, individual theca cells from women with PCOS produce significantly greater amounts of androgens than theca cells obtained from healthy women; this effect is associated with increased expression of key genes involved in androgen production, including the CYP11A gene encoding cholesterol side chain cleavage and the CYP17 gene encoding 17α-hydroxylase/17,20-desmolase (4, 5).

In our previous in vitro studies evaluating rat and human theca cells, statins reduced cell proliferation, increased apoptosis, and inhibited testosterone production (12, 14, 15). These actions of statins may be responsible for the presently observed decrease of ovarian volume and testosterone level as well as improvement of clinical manifestations of androgen actions including hirsutism and acne. Although it is not feasible to directly evaluate the effects of statins on ovarian histology, it is likely that a decrease of ovarian volume occurs in parallel with a reduction in the number of theca cells, resulting in decreased androgen production. Reduction of ovarian volume may also be due to a decrease in the number of antral follicles; however, this end-point was not recorded in this study. The above concepts are consistent with the gradual, ongoing decrease of testosterone concentration observed during both the first and second 3-month period of simvastatin treatment (Fig. 2).

A different time-course was observed with regard to metformin, whereby reduction of ovarian volume was observed only during the first 3 months of treatment, with no significant changes thereafter. It is possible that the effects of metformin on reduction of testosterone level may be related not only to changes of ovarian volume, but may also be due to direct actions of metformin on androgen production by theca cells. Indeed, metformin has been shown to inhibit androstenedione and testosterone production by cultured human theca cells (31, 32). Metformin also reduced expression of steroidogenic acute regulatory (StAR) protein and 17α-hydroxylase/17,20-desmolase (CYP17) (31).

Improvement of hyperandrogenism occurred in parallel with a significant increase in the number of spontaneous menses in all treatment groups. Simvastatin alone or in combination with metformin induced a greater increase in the number of menses than treatment with metformin alone. At present, the mechanisms involved in the restoration of menstrual function and the causes of superiority of simvastatin treatment remain unclear. It is difficult to attribute this effect to reduction of androgen levels alone because testosterone level declined to a comparable degree in all treatment groups. It is likely that menstrual cyclicity has a complex relationship with other parameters of PCOS; indeed, multiple linear regression modeling indicates that the improvement in menstrual cyclicity correlates independently with changes of total cholesterol level, BMI, and ovarian volume, but not with changes of testosterone. Importantly, the finding of the increase in the number of spontaneous menses should be interpreted with caution and should not be equated with resumption of ovulatory function because possible episodes of anovulatory bleeding cannot be excluded.

In contrast to the effects of simvastatin on ovarian volume and androgens, simvastatin-induced improvement of lipid profile and decrease of hs-CRP occurred only during the first 3 months of treatment, with no further changes during the second 3 months of therapy (Fig. 2). The rapid effect on total and LDL cholesterol levels may be explained by the primary mode of action of statins, i.e. immediate and direct competitive inhibition of the rate-limiting step of cholesterol synthesis via 3-hydroxy-3methylglutaryl-coenzyme A reductase (33). Similarly, the action of simvastatin on reduction of hs-CRP is likely to be a direct effect on cell function: decreased hs-CRP production by hepatocytes due to reduced protein geranylgeranylation (34).

In this study, treatment with metformin alone had no significant effect on lipid profile; this observation is consistent with our preliminary findings at 3 months and with some other clinical trials (23, 35, 36). However, other reports, including a previous study of ours on a different population of women with PCOS, have shown beneficial effects of metformin on lipids (37, 38). This discrepancy may be due, at least in part, to different inclusion criteria used in individual studies. In the present trial, nearly all subjects were normoinsulinemic and conformed to broader and more inclusive Rotterdam diagnostic criteria of PCOS, whereas our previous trial demonstrating beneficial effects of metformin on lipids evaluated only subjects with fasting hyperinsulinemia, fulfilling strict National Institutes of Health criteria (37).

Limitations of the present study are noted. First, this trial did not include a placebo group, and hence some of the observed effects may not be due to the use of medications, but may be related to other changes such as lifestyle modifications leading to weight loss. However, it is difficult to attribute the observed improvements only to weight changes because, for example, women in the simvastatin group lost significantly less weight than those in the metformin group and yet had a greater improvement in several parameters. Consequently, we may speculate that weight loss may be one of the mechanisms of action of metformin, but it is less likely to explain the effects of simvastatin. Another limitation of the study is the absence of blinding, whereby both subjects and treating physicians were aware of the nature of treatments.

On a cautionary note, whereas statins are generally considered to be safe, their use, especially in the long-term, is not risk-free (39–42). Rarely, statins, especially at higher doses, may cause elevation of transaminases, myopathy, and rhabdomyolysis (39). Statins may interact with some other drugs such as cyclosporin, nefazodone, fibrates, azole antifungals, macrolide antibiotics, antiarrhythmics, and protease inhibitors (39). In view of potential risks of teratogenicity, the use of statins is also contraindicated in pregnancy, and sexually active women should use reliable contraception (43).

In conclusion, the present study has demonstrated that long-term treatment of PCOS by simvastatin resulted in significant improvement of several key features of this condition, with results superior to those achieved by metformin monotherapy. Furthermore, addition of metformin to simvastatin offered no significant benefit beyond the effects achieved using simvastatin alone. These findings extend previous short-term observations and are highly encouraging; however, further long-term trials evaluating different statins in various populations of women with PCOS are needed before the use of statins can be recommended in standard clinical practice.