Abstract
Background Ankylosing spondylitis (AS) often has a long period from first symptom presentation to diagnosis. We examined the occurrence of symptoms, prescriptions and diagnostic tests in primary care electronic records over time prior to a diagnosis of AS.Methods Nested case-control study using anonymised primary care electronic health records from Scotland. Cases were 100 adults with a first diagnosis of AS between 1994 and 2010. Controls were matched for age, sex and GP practice: (a) 400 randomly selected adults (b) 236 adults whose records contained codes indicating spinal conditions or symptoms. We extracted clinical features (symptoms, AS-related disorders, prescriptions and diagnostic tests). Conditional logistic regression was used to examine the association between clinical features (both individually and in combinations) and diagnosis of AS. We examined the associations between clinical features and diagnosis over time prior to diagnosis.Results Several new composite pointers were predictive of AS: including distinct episodes of axial pain separated by more than 6 months (OR 3.7, 95% CI 1.8 to 7.5) and the co-occurrence of axial pain with either large joint symptoms (OR 2.7, 95% CI 1.1 to 6.3) or tendon symptoms within the same year (OR 3.6, 95% CI 1.3 to 10.3). Coded episodes of axial pain increased steadily over the three years before diagnosis. In contrast, large joint symptoms and enthesopathy showed little or no time trend prior to diagnosis.Conclusions We identified novel composite pointers to a diagnosis of AS in GP records. These may represent valuable targets for diagnostic support systems.
The risk of pancreatic cancer in symptomatic patients in primary care: a large case–control study using electronic records
