"Up to 80 percent of people living with chronic pain are missing out on treatment that could improve their health and quality of life — due to a serious shortage of pain services. Patients with chronic pain face long waiting times to access multi-disciplinary pain services in public hospitals — frequently more than one year."...... from Painaustralia.
Painaustralia is a national not-for-profit body established to improve the treatment and management of pain in Australia.
They have recently released a very informative fact sheet on the pros and cons of using TENS therapy for pain relief. We recommend this resource to you as it could be very useful.