Future projections of opioid use and cost in patients with chronic osteoarthritis pain in Spain.

• Opioids are widely used in chronic pain which is non-responsive to standard analgesics. Prescriptions have increased in Europe, although remain lower than in USA. Osteoarthritis (OA) is a degenerative joint disease usually accompanied by pain. Despite not recommended, opioids use in OA have been expanded because this health condition is increasing with ageing and, also, because physicians both primary and specialist boosted their use.• This study aimed to quantify the current burden of opioids used for chronic moderate-to-severe OA pain by estimating the number of defined daily doses per 1000 inhabitants per day (DHD) and associated costs, and to forecast the likely burden on the National Health System (NHS) in Spain for the years 2020-2029.• In 2010, an estimated 5.67 DHDs were dispensed for the equivalent of 217,076 chronic OA pain patients per day. From these trends, the projected number of DHDs is expected to increase more than threefold to 17.98 DHDs by the year 2029 for the equivalent of 727,356 chronic OA pain patients per day; 41.8% on strong opioids. The estimated cost was €116.9m in 2010 rising by 222% to €376.1m by 2029.• Chronic OA-pain-related opioid dispensing and costs to the NHS are set to increase substantially (threefold to more than fourfold) from 2010 to 2029 in Spain. Thus, using opioids for OA pain is concerning given disease chronicity, aging population and other related costs not computed in these projections. Our findings can inform payors and clinicians about ongoing discussions on appropriate analgesic management for longer-term OA pain, including resource requirements at a national level. Clinicians who prescribe opioids for OA pain should consider the potential implications of side effects such as sedation, cognitive deterioration, incremental need of caregivers, particularly in older people, and carefully consider the risk-benefit balance.