Monitoring of patients for the development of adverse reactions to antihypertensive drugs in general practice

McDowell, Sarah Elizabeth (2011). Monitoring of patients for the development of adverse reactions to antihypertensive drugs in general practice. University of Birmingham. Ph.D.


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Guidelines generally recommend the monitoring of serum electrolyte and creatinine concentrations in patients treated with antihypertensive therapy in order to detect potential adverse reactions to treatment. However, it is not well known to what extent these guidelines are followed in primary care.

I undertook a retrospective analysis of 74096 adult patients from the General Practice Research Database with newly diagnosed hypertension and prescribed a single antihypertensive agent. Baseline biochemical testing was undertaken in 31094 patients (42%) and 37365 (50%) patients had at least one biochemical monitoring test in the year after starting antihypertensive treatment. Monitoring was significantly more likely in patients treated with angiotensin-converting enzyme inhibitors than thiazide diuretics, older patients, and patients with diabetes mellitus. These patient factors were significantly associated with monitoring when multiple imputation was used to control for the potential bias introduced by missing data. In general, follow-up monitoring was infrequent, irregular, and did not change in response to events such as abnormal test results.

Patients who were monitored after the initiation of antihypertensive treatment were significantly more likely to be admitted to hospital and discontinue therapy, which is likely a result of reactive instead of planned monitoring. Using propensity score methods to control for confounding, I demonstrated a decreased risk of these same adverse outcomes in patients with baseline testing, which may be because these patients were less likely to have any follow-up monitoring and not the protective effect of the baseline testing.

I described several barriers to biochemical monitoring including the lack of consensus in published guidelines, uncertain responsibility for monitoring, patient nonadherence, and absence of alerts or reminders to monitor. More work is needed to improve the primary evidence base for monitoring and to improve the guidelines on the nature and frequency of monitoring for adverse drug reactions, particularly in patients at greater risk of drug-induced harm.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
College/Faculty: Colleges (2008 onwards) > College of Medical & Dental Sciences
School or Department: School of Clinical and Experimental Medicine
Funders: None/not applicable
Subjects: R Medicine > R Medicine (General)
R Medicine > RA Public aspects of medicine > RA0421 Public health. Hygiene. Preventive Medicine


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