Osteoarthritis (OA) is a slow, progressive joint disease causing mobility problems resulting in reduced quality of life and a major cause of time off work. Around 8.5 million people have been diagnosed with symptomatic OA in the UK. This figure is, however, an underestimate as it fails to include the significant number of us with undiagnosed, asymptomatic OA. Major confounding factors here are that many with joint destruction do not experience pain (so are unlikely to visit their GP), whilst many others self-medicate with painkillers since there are currently no treatments for OA other than pain relief.
For many years, OA has been regarded as an inevitable consequence of getting old, simple “wear and tear” of our joint cartilage and bone. Although ageing is a key risk factor for OA, data from experimental models of OA now indicate that there are in fact distinct biological pathways underpinning the observed joint destruction. This research offers new hope and opportunities for the development of drugs that actually modify the disease process. A significant obstacle for any drug that targets our cartilage is that this somewhat unusual tissue does not have a blood supply. Drugs we take as tablets are ‘delivered’ via the blood but the biology of some targets identified by research will hinder our ability to design drugs that could be taken as tablets. However, these could be formulated to be delivered by injection (such as intravenous infusion, into muscle or fat, or directly into the affected joint). Such drugs, especially delivered directly to a joint such as hip or knee (the most commonly affected joints), will undoubtedly have the best outcome. Due to their chemical composition, which would be incompatible as a tablet, they will reside in the joint for quite some time which should reduce the need for frequent injections.
Current research therefore offers the exciting potential to generate treatments for OA that could prevent further joint damage and delay or even avoid the need for joint replacement which today is the eventual outcome for many OA sufferers. However, it is vital that scientists develop drugs that patients find acceptable in terms of the route of administration as well as frequency. Non-adherence to medications is a problem in OA treatments which is mainly due to upset stomach caused by many painkillers. Some drugs could have dual action, targeting both joint destruction and pain. In this case, it may be that relatively infrequent hospital visits for injections, as is the case for many rheumatoid arthritis sufferers, represents an acceptable alternative for many OA patients especially as their joint pain increases as disease progresses.
Researchers at Newcastle University are interested to discover what the preferences of OA patients, as well as the public, would be for different delivery routes for drugs specifically designed to stop further joint destruction in OA. We all have to balance the perceived risk of any treatment with its expected benefits. The pain experienced by OA patients typically increases as the disease progresses, and we are also interested in how preferences may change as pain increases. Public engagement is therefore an essential component of future research that aims to generate novel, cutting edge treatments for a highly debilitating disease that affects an increasing number of our ageing population. The research and development of drugs for OA today needs to be relevant and appropriate for tomorrow’s patients.