**1. Introduction**

The earliest form of telehealth was via telephone, which has included patientdoctor consultation, doctor-doctor (specialist) for advice and referral, and clinician (nurse) led structured telephone support, with the first reports of management of chronic disease appearing in 1995 [1]. This review [1] shows a steady increase in the number of reports from telehealth from 1995 to 2011 (**Figure 1**), with the greater number of reports being on management of diabetes, followed by congestive heart failure (CHF) and chronic obstructive pulmonary disease (COPD), with smaller numbers for asthma and hypertension. There has been continued growth and the Covid pandemic of 2020 has caused significant increase in its use.

Telehealth has mainly been favoured in locations where significant distance between parties is involved, such as between primary and secondary/tertiary care, with most of the results being reported from countries such as USA and Australia, where significant distance between sites is involved. In a review [2], more than 50% of reported results were from USA.

Telehealth has been applied in many applications. **Figure 2** shows the range identified in a review of reported successes and failures [3], together with the perceived advantages that were provided in the studies in **Figure 3**.

**Figure 1.** *Telehealth publications by year [1].*

**Figure 2.** *Advantages of telehealth by application [3].*

**Figure 3.** *Advantages of Telehealth by application [3].*

However the application of telehealth remains intermittent and patchy and its use has been determined primarily where economic advantage can be demonstrated. This is most frequently demonstrated where the economic benefits of introduction can be gained elsewhere within the same organisation through savings in travel or impact on the provision of services across the organisation. This is most clearly seen in the introduction of telehealth in the indigenous health programs in the USA, such as in Indian Health Service (IHS) providing services to reservations and the Alaska Federal Health Care Access Network (AFHCAN) providing services to remote Inuit communities [4]. These have exploited store-and-forward telehealth to support services such as diabetic retinopathy (IHS), and a wide range of services including ENT, dermatology, and ECG examinations (AFHCAN), for which a purpose cart was designed.

The Veterans Administration (VA) is a US Federal programme that provides health care to those who have served in any of the US armed forces and their families, whilst in the forces and upon discharge anywhere within the US. Many of retired return or settle in small communities throughout the US, which may be far from VA clinical facilities. In order to serve these patients, the VA instigated a programme of telehealth that included many approaches that included video clinic telehealth and store-and-forward being used for home monitoring and capturing retinal images to manage diabetic retinopathy. The use of the programme between 1994 and 2014 is reported in [5] and the increasing number of encounters using the store-and-forward is shown in **Figure 4**.

The growth in use of telehealth within the VA continues, with the latest release of a request for procurement in 2021 for over \$1 billion, accelerated in response to the Covid pandemic, with most patients preferring to consult with their doctor from home [6].

There are similar experiences of an increase in the use of telehealth during the Covid pandemic. For example the NHS in the UK turned to online and telephone consultations with GPs (family doctor). It is to be seen how delivery of health will evolve post Covid.

**Figure 4.** *Veterans Health Affairs store-and-forward telehealth encounters, fiscal years 2006–2013 [5].*
