• Outcomes research
• Patient perspective
• Epidemiology

Multiple instruments to assess the patient's perception of disease activity and other critical domains are used in rheumatology to evaluate treatment response and guide clinical decisions. These instruments, known as patient-reported outcomes (PROs), allow to incorporate the patient's perspective.1 Despite PROs being increasingly recognised as important measures, there is great heterogeneity in their use.2 In order to overcome the difficulty in accessing validated PROs and the heterogeneity in its use,3 an initiative to generate a repository of the main cross-culturally validated PROs in rheumatic and musculoskeletal diseases (RMDs) was endorsed by the European League Against Rheumatism (EULAR). The main idea was to develop a structured Outcome Measures Library (OML) that would include a comprehensive database of validated PROs.

The international taskforce defined in 2011 the scope, aims, users and ways to collect the data using standardised forms to summarise the relevant information on each PRO. The data collected include the instrument itself, languages in which it is validated, relevant references, developer contact information and psychometric properties based on the Consensus-based Standards for the selection of health status Measurement Instruments (COSMIN) checklist.4 PROs included have evidence of documented validity published in a peer-reviewed journal and have been validated at least in English.

In 2012–2013, specialists from each field of RMDs performed different systematic reviews. The included PROs cover any domain of health, with an emphasis on those of the International Classification of Functioning framework.5 PROs are generic (across diseases) or specific, with a special focus on rheumatoid arthritis, osteoarthritis, spondylarthritis, low back pain, systemic lupus, gout, osteoporosis, fibromyalgia and paediatric measures.

A total of 15 methodological collaborators and 11 reviewers participated in this project. In total, 236 instruments were identified through 9 systematic reviews (106 generic and 130 specific). This is an in-progress library led by rheumatologists freely available online since November 2013 (http://oml.eular.org/) (figure 1) and connected to the main EULAR website. PROs search can be performed by disease, domain or language. A glossary with validation aspects is also included for educational support. The EULAR OML will be regularly updated using search strategy alerts in PubMed on a yearly basis and creating a network of volunteers, in as many European countries as possible, who may propose the inclusion of new instruments. We invite everyone to contact us if potential gaps on diseases, domains or validation are detected.

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Figure 1

European League Against Rheumatism (EULAR) Outcome Measures Library website (http://oml.eular.org/).

Over the first part of 2014, the EULAR OML accumulated 1685 page views and 706 visits, with the European countries with most users being France (106 visits), the UK (105), Belgium (82), Germany (78) and Spain (71). Interestingly, other non-European countries are also users of the Library, in particular the USA (1047), China (165) and Japan (123).

Important goals for this Library are to reduce variability in PROs use, to improve the knowledge and interest of the rheumatology community on PROs and validation, to highlight the importance of using the right tool in the appropriate way and to detect gaps on cross-cultural adaptation.

In summary, we present the new EULAR OML as a freely available website with structured access to a growing database of validated PROs. We expect that unified access to PROs will not only contribute to improve research but also enhance the use of these measures in clinical practice.