Statistical analysis
Statistical analyses were performed using Statistical Package for Social
Sciences version 24 (IBM Corp., Armonk, NY). According to the
Kolmogorov-Smirnov test, continuous variables were divided into normally
and non-normally distributed variables. Normally distributed continuous
variables were reported as mean ± standard deviation, whereas
non-normally distributed continuous variables were reported as median
(quartile spacing). Differences between the PCOS and control groups were
examined using an independent sample t-test (normally distributed
variables) or the Mann-Whitney U test (non-normally distributed
variables). One-way analysis of variance (ANOVA) with Tukey’s or
Dunnett’s post-hoc test (two-sided) was conducted for multi-group
comparisons. Logistic regression analysis was used to determine the odds
ratios (OR) with 95% confidence intervals (CI) for various
characteristics associated with hyperuricemia in PCOS. All tests were
two-sided, and statistical significance was defined as P< 0.05.
Restricted cubic splines (RCS) were conducted using R software (version
4.0.2, using packages “segmented,” “splines,” “Hmisc,” “rms,”
and “ggplot2”) to assess the relationship between serum uric acid and
fructose levels in PCOS. We prespecified three knots located at the
10th, 50th, and 90th percentiles of serum uric acid, as recommended by
Stone and Koo.17 The RCS is a smoothly joined sum of
polynomial functions, which can avoid inappropriate linearity
assumptions.18 The advantages of RCS include its
ability to relate to the natural shape of the relationship and the
detected sensitivity of nonlinear relationships.19, 20