Analytic strategy
- Univariate analysis: Descriptive statistics appropriate to the nature
of each variable were estimated, including the measures of central
tendency, dispersion, and tables of the absolute and relative
frequencies of each variable.
- Bivariate analysis: a contrast analysis was used to test the
relationship between the variables, employing Chi-squared tests to
examine relationships between categorical variables, correlation tests
to examine relationships between quantitative variables, and a
comparison of means using Student’s t-tests, Analysis of variance
(ANOVA) or their non-parametric equivalents (Mann-Whitney U test and
Kruskall-Wallis H test).
- The evolution of the episodes over time was modelled out using the
mean episodes suffered during each year of the follow-up, reflecting
this evolution in a similar way to routine clinical practice. On some
occasions, the incidence rate was the parameter used in each follow-up
period (number of episodes suffered/time elapsed since the last
visit).
The statistical package SPSS® v.22 was used for the statistical
analysis.
4.RESULTS
During the course of the longitudinal study, data were collected from
327 patients with unilateral UMD, of which 87 (26.6%) were followed up
from the onset of the disease.