*2.1. Service Description*

The four studied telemedicine programs all operate in a similar manner: the primary care physician or nurse (salaried sta ff employed by the Catalan public healthcare system) uploads a file (such as a photograph) to the patient's electronic health record together with their clinical notes; hospital specialists access the patient's electronic health record, view the images and sugges<sup>t</sup> treatment or an action plan; the primary care physician or nurse reviews the instructions and makes a phone call to the patient to give them the results of the consultation; if the specialist has any doubts, they can ask the primary care professional to arrange a face-to-face consultation with the patient (Figure 1). In other words, we can describe the process as medical record-based, store and forward and provider-to-provider asynchronous telemedicine between primary and hospital care. The Catalan healthcare system, which provides publicly financed universal health coverage, is free at the point of access, and thus, no fee is charged for the either face-to-face visits or the telemedicine service. We will assume that a telemedicine consultation avoids a face-to-face referral if it does not result in a referral for the same matter within the following 3 months. It has been shown that this telemedicine setting reduces waiting lists while improving access to GPs [14].

**Figure 1.** Patient flow: telemedicine vs. usual care.
