Assessment of transparency of cost estimates in economic evaluations of patient safety programmes

Transparency of costing is essential for decision-makers who require information on the efficiency of a health care programme, because effective decisions depend largely on applicability to their settings. The main objectives of this study were to assess published studies for transparency of cost estimates.

We first developed criteria with two axes by reviewing publications dealing with economic evaluations and cost accounting studies: clarification of the scope of costing and accuracy of method evaluating costs. We then performed systematic searches of the literature for studies which estimated prevention costs and assessed the transparency and accuracy of costing based on our criteria.

Forty studies met the inclusion criteria. Half of the studies reported data for both the quantity and unit price of programmes in regard to prevention costs. Although 30 studies estimated costs of adverse events, 19 of these described the scope of costing only, and just five studies used a micro-costing method. Among 30 studies that estimated 'gross cost savings' and 'net cost savings', there was a huge discrepancy in labels.

Even if a cost study was conducted in accordance with existing techniques of economic evaluation which mostly paid attention to internal validity of cost estimates, without adequate explanation of the process of costing, reproducibility cannot be assured and the study may lose its value as scientific information. This study found that there is tremendous room for improvement.