26 Impact of scientific evidence on regional differences in medical services provision is smaller than expected

In a first step, selected clinical guidelines were characterized according to certain criteria: does the guideline recommend or discourage the provision of a particular medical service? How strong is the underlying scientific evidence? In a second step, regional differences in the provision and utilisation of 24 selected medical services to which the guidelines referred were analysed on the basis of claims data from a large Swiss health insurer. In a third step, the relationship between the guidelines’ characteristics and geographic variation in the provision of the services was examined, while taking into account personal and insurance-related characteristics of the insured. The assumption was that strongly evidence-based guidelines would lead to less geographical variation in provision and utilization of medical services. In a fourth step, the relationship of compliance with clinical guidelines with level of health care costs and mortality was also analysed.

The provision and utilisation of medical services varies considerably both over time and in space. Large regional disparities can indicate under- or over-supply of population groups. This has significant repercussions for population health and for healthcare costs – particularly where chronic diseases are concerned. Until now, the influence of clinical guidelines on the choice of medical services is not well understood.

The first aim of the study was to describe geographic differences in the medical treatment of chronic diseases. Second, the study aimed at investigating how clinical guidelines affect treatment choices and related geographic differences.

The study found no evidence that strongly evidence-based clinical guidelines were followed more consistently than those with low evidence, or that they led to a reduction in geographic variation. However, it did show that guidelines encouraging a service tended to be followed more closely than those discouraging a service. For insured persons in managed care models, the provision of services tended to correspond more closely to the clinical guidelines than for insurees in other insurance models. At the same time, higher deductibles corresponded with lower utilisation of both recommended and non-recommended services. Finally, the study found adherence to clinical guidelines to be associated with lower health care costs. However, due to limitations of the data source, a correlation with lower mortality could not be shown.

The analysis of geographic variations in service provision is a first step for more in-depth research on the determinants of medical decision-making.

The influence of scientific evidence on regional differences in the provision of medical services is weaker than expected. Managed care models tend to support guideline-based care. Higher co-payments prevent the use of not only non-recommended but also recommended services. Refined financial incentives could contribute to a stronger consideration of evidence-based guidelines and recommendations.

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