Abstract
Background
Many epidemiological questions need to be answered regarding dementia, including the causes, prognosis, comorbidities, and treatment of the condition and complications. A routine electronic primary care dataset provides a way of investigating some of the complicated factors with rich information. However, there has been concern regarding whether dementia is recorded well enough.
Methods
This study has therefore explored this by conducting a systematic review to understand how dementia has been identified previously in primary care databases in the UK, and added to this by exploring additional terms and symptoms, and medications that might be helpful in identifying people with dementia. The study estimated the prevalence and incidence rates of dementia in The Health Improvement Network (THIN) database and compared with other longitudinal studies using the comprehensive list of diagnostic codes.
Results
The estimated incidence rates per 1,000 person-years for the 60+ age group who had any of the first diagnosis among the Quality Outcomes Framework (QOF) defined codes, Other diagnoses, Dementia symptoms and Prescribed medications were 2.5, 4.7, and 15.9 in 1995, 2004, and 2015 respectively. The estimated prevalence were 2.8, 3.2, and 10.2 in 1995, 2004, and 2015 respectively.
Conclusions
The codes related to dementia symptoms (represented by mini-mental state examination, the six item cognitive impairment test, referral to memory clinic and behaviour assessment) seem to cover a broad definition of dementia or pre-existing dementia population in the UK primary care records. At least, using of the Other diagnoses (represented by dementia annual review, senile/presenile dementia and dementia monitoring) in addition to the QOF defined codes, and Prescribed medications were evidenced that will not missing out a number of people with dementia.
Key messages
The codes related to dementia symptoms seem to cover a broad definition of dementia or pre-existing dementia population in electronic primary care records in the UK. Nevertheless, the codes about non-specific or temporary symptoms may need to be used carefully as it is possible for memory or cognitive function to be impaired temporarily due to other factors.