Analytical approach:
The cost-effectiveness analysis was based on the results of a randomised controlled trial. The time horizon was one year. The authors stated that they adopted a UK NHS perspective.
Effectiveness data:
The primary measure of efficacy, for the economic evaluation, was the EQ-5D score, which was from questionnaires given to trial participants at the start of the trial, and every three months, up to the one-year follow-up. The results were presented both with and without adjustments for baseline differences, and with missing values imputed. The main results were those without adjustment, and without imputation.
Monetary benefit and utility valuations:
The EQ-5D scores were converted to utility values using UK preference rates. Quality-adjusted life-years (QALYs) were calculated, for each patient, using the area under the curve, and assuming a linear utility change between points.
Measure of benefit:
The summary measure of benefit was QALYs.
Cost data:
Resource use data were collected from GP records for a period of 15 months, including the three months before the trial, and the 12 months of follow-up. Four categories of unit costs were assessed: GP, hospital, other health professional, and acupuncture. The unit costs were from the Personal Social Services Research Unit, NHS reference costs, or the NHS Choices website (for acupuncture). Analyses were conducted for all costs, and for only those related to irritable bowel syndrome. The results were presented with and without baseline adjustments. The price year was 2010, and costs were in UK £.
Analysis of uncertainty:
Probabilistic sensitivity analysis was conducted and the results were presented as cost-effectiveness planes, and cost-effectiveness acceptability curves, with and without adjustments for baseline differences. Only patients with complete outcome and cost data were included in the probabilistic sensitivity analysis.