The use of general practice consultation databases in rheumatology research.

Clinicians, health service planners and public health policy-makers all understand the value of data which describe the occurrence of disease in the community. Routinely collected mortality statistics, for example, have made an enormous contribution to understanding the causes of disease, measuring the impact of prevention and health-care, and the planning of health services. However, a modern rheumatological readership will understand the point made forcibly in the 1980 Black Report on Inequalities in Health, that ‘undue dependence on mortality rates can induce comparative indifference towards problems of chronic illness’, since such indifference is still evident in health policy and research priorities today. The report emphasized the need for statistics on morbidity, especially chronic disease. The problem with morbidity is that, unlike death, much of the everyday experience of illness is not routinely recorded, whilst periodic surveys of the health of the general population, such as those carried out by the Office of National Statistics, whilst important, only provide a snapshot of the occurrence of selected problems at certain times. One source of routine and continuing data on morbidity in the UK is general practice. More than 95% of people are registered with a general practice and the patient records held by those practices provide a picture of morbidity from cradle to grave. Furthermore, general practice is the first point of access to the National Health Service for most non-emergency care in the UK. Although many people with musculoskeletal symptoms seek advice and care from other sources, such as friends and neighbours, pharmacists, complementary therapists or private practitioners, most also use general practice. Most general practices in Britain are now recording at least some data electronically. This means that information on events arising from consultations in this setting—such as diagnosis, drugs prescribed, tests and referrals, as well as lifestyle data such as smoking status and body mass index—are becoming more readily available. Whilst this brings benefits for the organization and monitoring of clinical practice, such consultation data also provide an important source of information on the occurrence of symptoms and disease, and their treatment and care, and an important resource for researchers. The growing importance of general practice databases is evidenced by the number of research articles generated from one of the largest samples of archived consultations in the UK, the General Practice Research Database (GPRD). Since 1990, 450 papers have been published using the GPRD. However, most have been about pharmacological issues, and the number of musculoskeletal research papers using GPRD or other similar databases is small. Researchers in rheumatology are, however, beginning to exploit the information which can be yielded by such consultation archives. The paper by Linsell and colleagues on a prospective study of patients consulting with shoulder problems using the Mediplus database [1] and a study by the same authors on patients with hip and knee problems [2] are examples of this. GPRD and Mediplus are just two of an increasing number of large anonymized UK sets of routinely collected consultation data potentially available to researchers. For example, the GPRD contains data from around 300 practices across the country, covering an equivalent of 5% of the UK population. Others include the Weekly Returns Service run by the Royal College of General Practitioner’s Birmingham Research Unit [3], QRESEARCH [4] and the Doctor’s Independent Network (DIN) [5]. There are also regionally organized databases, such as our local North Staffordshire Consultations in Primary Care Archive (CiPCA), which contains validated data from 10 local practices [6]. General practice data routinely recorded about every contact offer the attractive possibility of charting the full range of musculoskeletal morbidity and how it is managed over time. There are caveats to this optimism, however, and as these databases become more widely available the positive reasons to use them must be considered in the context of potential constraints on their quality and interpretation. The strengths and weaknesses of specific databases have been discussed previously [7], but researchers need to be aware of aspects of general practice consultation recording that may be considered as limiting its value for research. The first and most obvious point is that many general practices may not yet be recording all patient contacts on their computerized systems or systematically coding the reasons for those contacts. Various methods have been used to assess the quality of morbidity recording in general practice [8]. For example, Hassey et al. cross-referenced diagnostic codes with relevant drug prescriptions and a recorded seropositive rheumatoid factor to check on the completeness of records of rheumatoid arthritis in one practice [9]. The quality of prescription recording has tended to be better than that for recording morbidity [10]. However, the situation is improving as general practitioners (GPs) become more familiar with electronic recording. Computerized morbidity data are now being used by the government to assess the quality of care being provided and to renumerate practices on that basis. This should encourage both the completeness of computerized recording of patient contacts and the accuracy of coding. One of the claims of some of the large systematically organized databases is that they only use data from practices signed up to training and rules about regular recording of contacts. However, each database follows rather different rules which may not necessarily reflect what the average GP does. In the GPRD, for example, GPs only have to code morbidities on the first occasion and when a treatment is first issued. Whilst the GPRD appears an excellent resource for pharmacology research, these instructions mean that its use in exploring patterns of consultation may be more limited than that of other databases. The second issue—and one that creates more doubts for the specialist rheumatologist than the first—is that there are no standardized methods of applying diagnostic labels in general practice. GPs are faced with an array of alternative codes for the same or similar conditions. One of the advantages of the coding systems used in practice is that the label applied can be a presenting symptom (‘shoulder pain’), but a disadvantage is that the basis for applying a diagnostic label, such as subacromial bursitis, may vary from GP to GP. The decision to use a label of joint pain rather than osteoarthritis may be down to habit or to whether the GP has decided to refer the patient for X-ray.