Assessing comparability of dressing disability in different countries by response conversion

Background: Comparability of health data is a major challenge within the context of the Health Monitoring Programme of the European Commission. A common problem in surveys is that many variations of essentially the same question exist. Methods: Response conversion is a new method for improving comparability by scaling the data onto a common scale. Comparisons between member states can then be made in terms of the common scale. A first step is the construction of a conversion key. This is a relatively complex activity, but needs to be done only once. The second step is the actual data transformation. This is simple, and can be repeatedly done on a routine basis as new information arrives. Construction of the key is only possible if enough overlapping information can be found. Results: The method is illustrated for dressing disability from five European countries. Differences occur between countries, between sexes and between age groups. These were similar in magnitude. Conclusion: Response conversion is a new method for enhancing comparability among existing data. Conversion can only be done if a key is available. More work is needed to establish the technique. Future implications within the Health Monitoring Programme are discussed.