Comparison of traditional and novel measures of body composition and vascular function in women with polycystic ovary syndrome
Women with polycystic ovary syndrome (PCOS) may be at increased risk of cardiovascular disease (CVD) compared to age matched controls (Cibula et al., 2000). However there is limited evidence as to how risk should be identified in this patient group, or the value of novel measures of body composition and vascular function. This study aimed to investigate the comparative ease of use, variability and validity of traditional and novel measures of blood pressure, body composition and vascular function in women at high and low risk of CVD (with and without PCOS). Methods:
An observational study involving 21 female subjects (n = 11 self reported PCOS; n = 10 controls) recruited from the general university population, quantified body composition and vascular function as markers of CVD risk using traditional [body mass index (BMI), waist and hip circumferences, blood pressure and novel measurement systems [bioimpedance analysis (BIA), Viscan, Vicorder]. The strength of agreement between traditional and novel measures was determined using correlation analyses. The chance-corrected measure of agreement between the novel and traditional measurement systems, and measure validity, was assessed using the kappa statistic. Results:
In a mixed sample, BMI was a strong indicator of BIA determined % body fat (r = 0.79, P < 0.001) and trunk fat % (r = 0.75, P < 0.001). Traditional waist circumference measures (taken at the midpoint) were also good indicators of % body and trunk fat, and were strongly correlated with peripheral augmentation index (pAI) in a high risk group (r = 0.66, P = 0.05). A body fat (by BIA) also correlated strongly with pAI (r = 0.67, P = 0.05) and pulse wave velocity (PWV) (brachial to femoral) (r = 0.72, P = 0.03) as measures of arterial stiffness in the high risk (PCOS) group. A trend towards a correlation between % body fat and carotid to femoral PWV was seen (r = 0.60, P = 0.09). BIA measures agreed well with most traditional measures in their ability to identify subjects at risk, including BMI (( = 0.61, P = 0.04), but underestimated risk in some individuals. The Viscan measurement of waist circumference was not significantly correlated with a traditional measure in a high risk group, and did not agree with traditional methods of identifying risk. Discussion:
Body fat distribution and abnormal vascular function are considered to be significant factors determining long-term health problems such as CVD. This ongoing study suggests that novel measures of body composition do not currently add value to risk assessment in women with PCOS, nor do they replace traditional measures; particularly as standardized reference ranges are not yet available. BMI is considered a good indicator of body fat levels and distribution in this patient group, but may be a poor predictor of vascular function. Traditional measures of waist circumference have the potential to predict arterial stiffness in this patient group and therefore facilitate the ‘correct’ identification of individuals at increased CVD risk (Han et al., 1995). It is agreed that waist circumference is a useful, reliable and convenient measure of risk in women with PCOS and should be implemented in routine clinical practice as an adjunct to BMI and blood pressure (RCOG, 2009). This would allow for targeted treatment, potentially reducing or reversing long term health problems in these women. Conclusions:
Novel measures of body composition and vascular function do not currently add value to a risk assessment in women with PCOS and a combination of traditional measures, including BMI, waist circumference and blood pressure should be used as CVD risk markers. References:
Cibula, D., Cifkova, R., Fanta, M. et al. (2000) Increased risk of non-insulin dependent diabetes mellitus, arterial hypertension and coronary artery disease in perimenopausal women with a history of the polycystic ovary syndrome. Hum. Reprod. 15, 785–9.
Han, T.S., van Leer, E.M., Seidell, J.C. & Lean, M.E.J. (1995) Waist circumference action levels in the identification of cardiovascular risk factors: prevalence study in a random sample. Br. Med. J. 311, 1401–5.
Royal College of Obstetricians and Gynaecologists (RCOG) (2009) Polycystic ovary syndrome (PCOS): what it means for your long-term health [online]. Available from: http://www.rcog.org.uk/womens-health/clinical-guidance/polycystic-ovary-syndrome-what-it-means-your-long-term-health [Accessed on 13 April 2010].
Document Type: Research Article
Publication date: 2011-06-01