Polycystic ovary syndrome (PCOS) is a frustrating experience for an increasing number of women, a complex syndrome for managing clinicians, and a scientific challenge for researchers. As research in the area is rapidly advancing and a greater understanding of the condition evolving, it is important that this information is provided to women with PCOS and healthcare professionals alike.

PCOS is the most common endocrinopathy of reproductive-aged women. The only PCOS community based prevalence study published including all current international diagnostic criteria, recently reported prevalence of 8.7 per cent (NIH), 11.9 per cent (Rotterdam) and 10.2 per cent (AES) in Australian women 27–34 years of age (n = 728)¹. The prevalence of Rotterdam diagnosed PCOS increased to 17.8 per cent on imputation for those not consenting to ovarian ultrasounds. Disturbingly, this study also reported that around 70 per cent of PCOS cases are currently undiagnosed in Australia¹. Using the NIH criteria², other studies have reported that PCOS affects 4-8 per cent of women worldwide^3-6. In an unselected obese population, 28 per cent had PCOS, compared to 5 per cent of lean women⁷ and another study suggested approximately 21 per cent of indigenous women are affected by PCOS in Australia⁸.

Obesity and excess weight is a major chronic disease in Western countries. Obesity increases hyperandrogenism, hirsutism, infertility and pregnancy complications both independently and by exacerbating PCOS. Obesity also increases the risk of type 2 diabetes and cardiovascular disease. Indeed, obesity is known to exacerbate most features of PCOS, and its rising prevalence is reflected in the apparent increasing prevalence of the short- and long-term clinical features of PCOS. Overall, PCOS is a common condition and with increasing rates of obesity, known to precipitate or exacerbate PCOS, prevalence is expected to rise.

Based on US data, the anticipated economic burden of PCOS in Australia in 2006 was $40 million (menstrual dysfunction 31 per cent, infertility 12 per cent and PCOS-associated diabetes 40 per cent of total costs), representing a major health and economic burden⁹. Estimated cost per birth in infertile, obese, Australian women with PCOS was $0.5million¹⁰. Lifestyle intervention reduces insulin resistance and improves fertility - Where successful, birth costs are closer to $20,000¹⁰.

Definition of PCOS

Until recently, no universally accepted clinical definition existed for PCOS. During the past three decades research has revealed that PCOS is a heterogeneous condition. The initial National Institutes of Health (NIH) diagnostic criteria based on oligomenorrhoea/amenorrhoea and clinical or biochemical hyperandrogenism² were broadened in the 2003 Rotterdam criteria to include polycystic ovaries (PCO) at ultrasound in the key diagnostic criteria. 25 per cent of young women have PCO on ultrasound, and the inclusion of PCO in the diagnostic criteria has increased the prevalence of PCOS. More recently the Androgen Excess Society suggested the diagnostic criteria should be modified to exclude those without symptoms, that is, those with PCO on ultrasound and oligomenorrhoea/amenorrhoea but no hyperandrogenism^11,12, in whom other causes such as hypogonadotrophic hypogonadism are common.

However, the Rotterdam criteria are currently the accepted criteria and require two of the following three features; hyperandrogenism, irregular anovulatory cycles or polycystic ovaries (PCO) on ultrasound, with exclusion of related reproductive disorders¹³ in order to diagnose PCOS. It should be noted that PCOS is a diagnosis of exclusion, and conditions such as thyroid dysfunction, hyperprolactinaemia and late-onset congenital adrenal hyperplasia should be excluded biochemically, while rarer conditions should primarily be excluded clinically (Cushing’s syndrome, virilising tumours, etc).

With the three key diagnostic features (oligomenorrhoea/amenorrhoea, clinical or biochemical hyperandrogenism and PCO on ultrasound), there are 16 different presentations which are grouped into four main phenotypes (table 1). The possible phenotypes shown in table 1 demonstrate the heterogeneity of the condition based on the key diagnostic features. Phenotypes are also influenced by life stage, genotype, ethnicity and environmental factors including lifestyle and body weight.

Obesity, insulin resistance and metabolic syndrome are key features of the condition but are not currently part of the diagnostic criteria. However, hyperinsulinaemia drives hyperandrogenism through several different mechanisms (table 2). Measurement of insulin resistance remains flawed and is not recommended in clinical practice. This is one of the key reasons it is not currently included in the diagnostic criteria.

There is also ongoing uncertainty surrounding the metabolic features of women only diagnosed by Rotterdam/AES criteria. These women have, by definition, milder reproductive features and appear also to have milder metabolic features¹⁴. No natural history studies have charted long term outcomes in AES and Rotterdam PCOS. Overall, studies suggest the more severe the reproductive abnormalities (represented by the NIH criteria) the worse the metabolic features¹⁵. This was confirmed in a recent literature review by our group, which concluded that NIH-diagnosed PCOS have greater insulin resistance in addition to greater total and abdominal obesity and have more severe risk factors for diabetes and CVD than Rotterdam PCOS. Where differences in metabolic features existed between the phenotypes, they were generally related to the degree of total and abdominal obesity [reviewed in ¹⁴]. Thus, while it has been established that NIH PCOS has a more adverse metabolic profile, the metabolic features including insulin resistance and long-term sequelae of the new milder reproductive categories of PCOS have not yet been established and research and debate are ongoing.

The reason for the evolving diagnostic criteria and the ongoing controversy relate back to the lack of a clear understanding of the aetiology of PCOS. However, currently the Rotterdam criteria are the agreed diagnostic criteria for defining PCOS. Further research is needed to clarify the aetiology of PCOS and to allow further definition of the condition, including division into different subcategories.

This article first appeared in Australian Doctor, How to treat on 29 August 2008 and has been reproduced here with permission.

 Australian Doctor - How to treat: Polycystic ovary syndrome 437.44 Kb

Content updated 7 September 2009