The authors justified their selection of the comparators and they appear to have been appropriate. Iodine was the usual antiseptic in the operating theatre, while chlorhexidine was the new agent, which had advantages over iodine, but was more expensive.
A systematic search of the literature was used to identify the relevant sources of data and this was a valid method. The sole inclusion of head-to-head clinical trials should ensure the validity of the clinical evidence, given their robust design. The key details of the patient populations and clinical outcomes of the trials were reported and an appropriate meta-analysis was used to pool the clinical data. The authors considered the heterogeneity between trials, using appropriate statistical tests. Publication bias was investigated in a regression analysis and some bias was found in the risk of a positive skin culture after application. The authors judged the quality of the data sources, using a valid instrument that assessed randomisation, blinding, and patient retention; in general, moderate quality was observed. Intermediate clinical outcomes were used to assess the impact of the interventions on the patients’ health and these will not permit comparisons with the benefits of other health care interventions.
The cost categories were consistent with the perspective of the hospital. A hospital database was used to derive both the resource quantities and the unit costs, but the details were not reported separately. These data were representative of the authors’ context and a large sample of patients. The price year was implicitly reported, which will allow reflation exercises in other time periods. The cost estimates were treated deterministically, but alternative estimates were considered in the sensitivity analyses.
Analysis and results:
The results were clearly presented for both preventive strategies, but the costs and benefits were not synthesised and a cost-consequences analysis was conducted. The superior clinical and economic profiles of chlorhexidine mean it would have dominated iodine, if a cost-effectiveness ratio had been calculated. The uncertainty was considered in selected inputs for the model and the overall uncertainty was not assessed. The results appear to be specific to the authors’ setting and it is unclear whether they can be transferred to other settings.
The methods were valid and the available evidence was synthesised in an appropriate meta-analysis, which enhances the validity of the authors’ conclusions.