Examining the Evidence
Q Should all obese women be screened for PCOS?
<huc>A</huc> Probably. In this evaluation of 113 consecutive premenopausal women referred to a university hospital in Madrid for treatment of overweight or obesity, 32 (28.3%) were diagnosed as having PCOS according to the National Institutes of Health criteria of unexplained hyperandrogenic chronic anovulation. This is a marked increase over the 5.5% incidence of PCOS found in lean women in Spain in an earlier study by the same researchers.1
Polycystic ovary syndrome (PCOS) is often accompanied by obesity, and the obesity epidemic appears to have been accompanied by a PCOS epidemic. Rather than focus on obesity’s effects on PCOS, Àlvarez-Blasco and colleagues looked for stigmata of PCOS in an unselected obese population.
Findings in line with earlier studies
This study adds credence to other investigations that have found women with a metabolic abnormality more likely than an unselected sample of the same population to have PCOS. Another study found a similar prevalence of PCOS—26.7%—among premenopausal women with type 2 diabetes.2
Obesity per se is associated with metabolic abnormalities, and the investigators showed an increasing prevalence of the metabolic syndrome and its components with increasing obesity among the study cohort. The components of metabolic syndrome are:
- waist circumference >88 cm
- triglyceride level >150 mg/dL
- HDL cholesterol ≤50 mg/dL
- blood pressure ≥130/85 mm Hg
- fasting glucose ≥100 mg/dL
Interestingly, the incidence of PCOS did not increase as the degree of obesity increased. Among women with a body mass index (BMI) of 25 to 29, the incidence of PCOS was 40%, but it was 23% among those with a BMI of 30 to 34, and 27% among women with a BMI of 35 to 39. These findings suggest that factors other than obesity are associated with PCOS stigmata, or perhaps that increasing metabolic morbidity may mask or suppress PCOS symptoms.
Strengths and weaknesses
The prospective design, size of the cohort, and full phenotyping performed on all subjects are strengths of this study.
The major weakness is the referral bias of a university-based endocrine clinic that is likely to attract women who are obese and also have endocrine abnormalities such as PCOS. (Endocrinology and nutrition are a single medical specialty in Spain.)
The best prevalence study of PCOS in the US general population involved asymptomatic women applying for employment at a university medical center.3 A similar study design and findings would strengthen the investigators’ recommendations to routinely screen for PCOS in an obese population.
This study did not use the revised Rotterdam criteria, which incorporate ultrasonographic size and morphology of the ovaries into the diagnosis. Preliminary studies show that these revised criteria tend to increase the prevalence of PCOS by about 50% among women with oligomenorrhea,4 so Álvarez-Blasco and colleagues likely underdetected PCOS by these criteria.
Bottom line: Screen obese patients for PCOS and metabolic syndrome
This study adds evidence of obesity’s adverse effects on reproduction, and suggests that routine screening of obese women for both PCOS and the metabolic syndrome is a high-yield procedure (25–30% for both).
1. Escobar-Morreale HF, Roldan B, Barrio R, et al. High prevalence of the polycystic ovary syndrome and hirsutism in women with type 1 diabetes mellitus. J Clin Endocrinol Metab. 2000;85:4182-4187.
2. Peppard HR, Marfori J, Iuorno MJ, et al. Prevalence of polycystic ovary syndrome among premenopausal women with type 2 diabetes. Diabetes Care. 2001;24:1050-1052.
3. Azziz R, Woods KS, Reyna R, Key TJ, Knochenhauer ES, Yildiz BO. The prevalence and features of the polycystic ovary syndrome in an unselected population. J Clin Endocrinol Metab. 2004;89:2745-2749.
4. Broekmans FJ, Knauff EA, Valkenburg O, Laven JS, Eijkemans MJ, Fauser BC. PCOS according to the Rotterdam consensus criteria: change in prevalence among WHO-II anovulation and association with metabolic factors. BJOG. 2006;113:1210-1217.