Statistical analyses and cost-effectiveness study
Categorical data were expressed as proportions, whereas continuous data were expressed as means and standard-deviations (SD).
Both time without failure and time without complications were considered as censored data and were analyzed using a Kaplan-Meier survival method and compared with a log-rank test. For each patient, occurrence of a failure and its delay since the initial menorrhagia surgery were tracked from the initial surgery date until death or last follow-up date (31thDecember 2015). If no failure occurred, the patient was considered as having no failure (censored) at last follow-up date. The occurrence of severe complication was tracked from the initial surgery date until failure, death or last follow-up date (31th December 2015).
The cost-effectiveness analysis was performed comparing each surgical strategy to the 2G one. Groups were both compared in terms of incremental cost (\euro) and of incremental effectiveness(rate of patients without failure) of the different surgical strategies, as compared to the 2G one, during the 18 months following the initial surgery. Sensitivity analyses were performed by varying the horizon time at 60 months, but the analysis was restricted to the patients with at least this follow-up in the study (as patients with a follow-up less than 60 months may have an underestimation of costs). Secondary analyses were also performed by varying the effectiveness criteria, using the complication rate alone. Analyses were performed by using the R statistical software (version 3.2.3).