Objectives To identify factors associated with the decisions of the Federal Department of Home Affairs concerning coverage with evidence development (CED) for contested novel medical technologies in Switzerland.

Design Quantitative, retrospective, descriptive analysis of publicly available material and prospective, structured, qualitative interviews with key stakeholders.

Setting All 152 controversial medical services decided on by the Federal Commission on Health Insurance Benefits within the framework of the new federal law on health insurance in Switzerland from 1997 to 2013, with focus on 33 technologies assigned initially to CED and 33 to evidence development without coverage.

Main outcome measures Factors associated with numbers and type of contested services assigned to CED per year, the duration and final outcome of the evaluations and perceptions of key stakeholders.

Results The rate of CED decisions (82 total; median 1.5/year; range 0–9/year), the time to final decision (4.5 years median; 0.75 to +11 years) and the probability of a final ‘yes’ varied over time. In logistic regression models, the change of office of the commission provided the best explanation for the observed outcomes. Good intentions but absence of scientific criteria for decisions were reported as major comments by the stakeholders.

Conclusions The introduction of CED enabled access to some promising technologies early in their life cycle, and might have triggered establishment of registries and research. Impact on patients’ outcome and costs remain unknown. The primary association of institutional changes with measured end points illustrates the need for evaluation of the current health technology assessment (HTA) system.