Analytical approach:
The analysis was based on data from a single study with a one-month time horizon. The authors stated that the perspectives of both the National Health Service (NHS) and society were considered.
Effectiveness data:
The clinical data came from a prospective randomised controlled trial (RCT), carried out at a single hospital between September 2004 and February 2007. The inclusion and exclusion criteria were reported. The sample included 72 patients, with 36 in the early laparoscopic cholecystectomy group and 36 in the conventional group. The median age was 52 years in the early group and 53 years in the conventional group. The number of women was 26 in the early group and 21 in the conventional group. The length of follow-up was one month after surgery. The key clinical endpoint was the change in health status.
Monetary benefit and utility valuations:
The utility valuations were derived using the European Quality of life (EQ-5D) questionnaire for all patients in the RCT at 30 to 35 days after surgery.
Measure of benefit:
Quality-adjusted life-years (QALYs) were the summary benefit measure.
Cost data:
The economic analysis considered the costs of in-patient, out-patient, and community services, including hospital stay, surgery, diagnostic and laboratory tests, prescriptions, out-patient visits, and general practitioner and district nurse visits. The resource use data were collected alongside the RCT. The unit costs were derived from official NHS sources, such as NHS Reference Costs, Unit Costs of Health and Social Care, the Hospital Finance Department, and the British National Formulary. Overhead and capital charges were included. All costs were in UK pounds sterling (£) and the price year was 2007. A non-parametric bootstrapping approach was used to deal with the skewed distribution of costs. In a supplementary analysis, the societal costs related to time off work, travel to and from hospital, visits to primary care facilities related to gallbladder disease, and over-the-counter or prescription drugs were also included.
Analysis of uncertainty:
A nonparametric percentile bootstrap method with 2,000 replications was used to generate confidence intervals (CIs) around the incremental cost-utility ratios. The impact of using an imputation method for the QALYs was also investigated.
