Data analysis

To analyze the sample, the characteristics of the women participating in the study were described using absolute and relative frequencies for qualitative measures and summary measures (mean, standard deviation, median, minimum and maximum) for quantitative measurements.

Qualitative characteristics were described according to MS, and the association was verified with the use of chi-square tests or likelihood ratio test; quantitative characteristics were described according to metabolic syndrome and compared using Student t-tests.

With the objective of analyzing the relationships between the population characteristics and the FSFI questionnaire domains, generalized linear models with a gamma distribution and identity link function were created to compare the scores according to the categories of interest adjusted for age, educational level, race/color, marital status, and religion.

The FSFI questionnaire scores were described based on the presence or absence of MS and compared using the Mann-Whitney test. The analyses were performed using IBM-SPSS software for Windows version 20.0 (IBM, Chicago, IL). Microsoft Excel 2003 software was used to store the data and results, and the statistical package statistiXL (Statistical Power for MS Excel version 1.8, 2007) was used for the statistical analyses. The tests were performed with a significance level of 5%.

The sample size calculation was based on a confidence level (1-alpha) = 95, a power (% of probability of detection) = 80, a ratio of controls to cases = 1, a hypothetical proportion of controls with exposure = 40, a hypothetical proportion of cases with exposure = 57.14, and a least extreme odds ratio to be detected = 2.00, resulting in a sample size of 288 patients (144 cases and 144 controls).