(P-324) Prescribing Trends of Antihypertensive Drug Classes in a Hong Kong Dementia Cohort

Background: Ageing is a major public health issue and the most important risk factor for morbidities such as hypertension and dementia. Midlife and late-life hypertension is associated with an increased risk of incident dementia and whether exposure to all antihypertensive drugs or a specific class is protective against dementia is unclear.

Objectives: The objective of the study is to describe the prescribing trends of patients exposed to different classes of antihypertensive drugs among a dementia cohort using pilot data in Hong Kong.

Methods: This is a descriptive study using electronic health data from Clinical Data Analysis and Reporting System (CDARS), a territory-wide medical database in Hong Kong. The target population are those aged 40 years or older, who are users of antihypertensive drugs and were diagnosed with dementia. The pilot data includes approximately half of the expected cohort, randomly selected from those with an incident diagnosis of dementia from 2001-2010. The exposure and outcome of interest are those with antihypertensive drug prescriptions from 2001-2010. For statistical analysis, the proportion of patients over the entire study cohort with antihypertensive drug prescriptions before, continued after and started after incident dementia were described. The annual prescribing prevalence was evaluated between antihypertensive drug classes from 2001-2010. For patients prescribed with multiple classes, counts may be doubled due to concurrent medications.

Results: The pilot study included 80,000 patients diagnosed with dementia from 2001-2010. 67,022 (83.8%) of whom were prescribed with at least one antihypertensive drug over the follow-up period from 2001-2010. 51,992 (65.0%) of the study cohort started antihypertensives before their incident dementia diagnosis, 45,751 (57.2%) of them continued on or after the incident diagnosis date and 15,030 (18.8%) patients started on or after incident dementia. For annual prescription prevalence, antihypertensive drug prevalence ranged from 56.9% to 110.8% from 2001-2010. Calcium channel blockers and 2 or more antihypertensive combination were the most prevalent groups, ranging from 12.8% to 25.1% and 12.4% to 25.0%, respectively.

Conclusions: This pilot study described the prescribing patterns of antihypertensives among dementia patients in Hong Kong. A large proportion of patients started antihypertensives before receiving a dementia diagnosis and further studies are needed to investigate the potential effects of different antihypertensive classes on the risk of incident dementia. However, the full dataset is needed along with refinements on the exposure definitions to warrant the present findings.