Using secondary costing data to inform priority setting: a survey of current approaches for TB

Estimation of unit costs is essential for priority setting and programme planning. Cost analyses commonly use secondary data for some or all cost inputs. However, little is known about how practitioners select and adapt secondary cost estimates. The objective of this study was to describe the current practice in applying secondary unit cost data to estimate the unit costs for national prioritisation exercises.We developed a survey for current costing practitioners, using TB as a case study. Our approach included: defining a conceptual framework for analysis; developing a survey instrument; conducting key informant interviews with costing practitioners; and analysing interview responses using descriptive statistics and narrative synthesis.We surveyed 22 respondents. Cost analyses were mostly used for investment cases, national strategic plans, and budgeting and financial planning. Analyses were generally completed in small teams and used a range of data sources, with preference given to locally produced cost data. Data availability and accuracy were the most common drivers in selecting cost estimates. Most respondents transferred evidence from other settings by adjusting for intervention relevance, time, and scale.The findings from this study complement existing costing guidance by describing how secondary cost analysis is done in practice. Further practical guidance on conducting secondary cost analysis, including practical methodological instructions, would benefit practitioners..