- Complications 1. week, 1 month, 3 and 6 months after placement (Form E): HRQL questionnaires Analysis Descriptive statistics, including graphical displays, will be used to summarize all study variables. The unit of analysis will be the patient. For continuous variables, means, medians, standard deviations, percentiles, ranges, box plots and histograms will be generated. For categorical variables, frequencies and proportions will be generated. The investigators will examine all variables to determine if parametric distributional assumptions (e.g. normality for the continuous variables) are valid.