**1. Introduction**

Although at present there is no clear consensus as to the economic impact of telemedicine [1,2], recent evidence has shown it can be effective, provide efficient care at a lower cost [3–7] and enjoy a high degree of acceptance among users. Moreover, telemedicine reduces journeys by road and therefore decreases the environmental impact of atmospheric pollutants emitted by vehicles [8]. Published studies have already provided some insights as to the acceptance drivers. Eddy et al. reported high patient satisfaction with teledermatology and amongs<sup>t</sup> physicians, although this satisfaction was higher in primary care doctors than in dermatologists [9]. McKoy et al. used questionnaires to assess the acceptance of a teledermatology service and reported that 82% of users saw it as a valid alternative to face-to-face consultations [10]. In another qualitative study using semi-structured interviews with 32 healthcare professionals, MacNeill et al. showed mixed points of view: while it was broadly welcomed by nursing staff, some primary care physicians were worried that telemedicine could increase their workload and it could potentially undermine their professional autonomy [11]. A comprehensive systematic review recently published by Mounessa et al. reported that patients and healthcare providers were in general highly satisfied with the two types of telemedicine: store-and-forward and real time telemedicine [11]. Whilst all the studies provided valuable inputs to help understand the complex heterogeneous effect of the participants' acceptance of new healthcare models, it is of the utmost importance that any published evidence uses validated questionnaires to perform reliable and comprehensive evaluations [12].

The Technology Acceptance Model (TAM) proposed by Davis (1989) [11] is based on the two main concepts of ease of use and perceived usefulness, and comprises three dimensions: the individual context, the technological context and the implementation or organizational context. Based on his benchmark, studies have adapted their methodology to create validated questionnaires. For example, Orruño et al. (2011) evaluated teledermatology adoption by healthcare professionals using a modified 33-item version of this model grouped into eight theoretical dimensions. The Cronbach's alpha for each theoretical variable and internal consistency of the questionnaire reported good results which sugges<sup>t</sup> the proposed questionnaire is a valid tool for assessing acceptance in this setting [13].

In the REgioNs of Europe WorkINg toGether for HEALTH (RENEWING HEALTH) project, Kidholm et al. reviewed the scientific literature to find questionnaires used in European telemedicine projects to assess the stakeholders' perceptions. One such questionnaire was used in the EU project Health Optimum (Delivery OPTIMisation through telemedicine) [14,15]. This questionnaire for healthcare professionals includes eight general questions irrespective of their medical specialty and focuses on the physicians' perception of the quality of the telemedicine service, their convenience, technical and other difficulties and potential effects on the health of the patients using the service (see Appendix A). The questionnaire was not validated and although it does not strictly use the TAM, it adopts some of its dimensions. An easy-to-answer questionnaire increases the response rate but no other short validated questionnaire using the TAM to assess healthcare professionals' perceptions of asynchronous telemedicine services was found.

Whilst the Catalan Ministry of Health is putting a lot of effort into developing telemedicine, the degree of acceptance of these tools has ye<sup>t</sup> to be investigated using validated questionnaires.

It is not possible to deploy telehealth services without first carrying out a thorough assessment of practitioner's perceptions of their usefulness, a factor which is critical in fostering their deployment in public and private healthcare systems. Brief questionnaires are preferable as a means to improve response rates as studies using long questionnaires based on the TAM have reported low response rates [16,17]. For these reasons, the aim of our study is the statistical validation of the Catalan version of the EU project Health Optimum telemedicine acceptance questionnaire.
