A review of studies of adherence with antihypertensive drugs using prescription databases

Poor adherence with antihypertensive therapies is a major factor in the low rates of blood pressure control among people with hypertension. Patient adherence is influenced by a large number of interacting factors but their exact impact is not well understood, partly because it is difficult to measure adherence. Longitudinal prescription data can be used as a measure of drug supply and are particularly useful to identify interruptions and changes of treatment. Obtaining a medicine does not ensure its use; however, it has been established that continuous collection of prescription medications is a useful marker of adherence. We found 20 studies published in the last 10 years that used large prescription databases to investigate adherence with antihypertensive therapies. These were assessed in terms of patient selection, the definition of the adherence outcome(s), and statistical modeling. There was large variation between studies, limiting their comparability. Particular methodological problems included: the failure to identify an inception cohort, which ensures baseline comparability, in four studies; the exclusion of patients who could not be followed up, which results in a selection bias, in 17 studies; failure to validate outcome definitions; and failure to model the discrete-time structure of the data in all the studies we examined. Although the data give repeated measurements on patients, none of the studies attempted to model patient-level variability. Studies of such observational data have inherent limitations, but their potential has not been fully realized in the modeling of adherence with antihypertensive drugs. Many of the studies we reviewed found high rates of nonadherence to antihypertensive therapies despite differences in populations and methods used. Adherence rates from one database ranged from 34% to 78% at 1 year. Some studies found women had better adherence than men, while others found the reverse. Novel approaches to analyzing data from such databases are required to use the information available appropriately and avoid the problems of bias

Modelling compliance with antihypertensives and statins in Ireland, using a national prescription claims database

THESIS 7947Hypertension and high cholesterol, especially in the middle-aged and elderly, are fairly common, and pharmacological therapy is often required to control them. In spite of substantial knowledge of the consequences of uncontrolled blood pressure and high cholesterol (for example cardiovascular and cerebrovascular disease) and the proven benefits of treatment for these conditions, many patients continue to have uncontrolled blood pressure and cholesterol levels. It has been demonstrated in large clinical trials that treatment wth appropriate therapies substantially reduces the risk of morbidity and mortality. While lack of compliance is by no means the only reason for low control rates, many patients prescribed antihypertensives or lipid-lowering therapies do not continue to take them and therefore do not benefit. Previous studies of compliance have often not used the most appropriate methods to analyse drug discontinuations and thus have not been able to explore fully various characteristics of the problem- in particular the patterns of prescription claiming at the individual level, and their longitudinal dependencies. Determining appropriate models for the analysis of discontinuation and switching of statins and antihypertensives in the Irish population may help clinicians making decisions about what and how to prescribe

Estimating time-dependent contact: a multi-strain epidemiological model of SARS-CoV-2 on the island of Ireland

Mathematical modelling plays a key role in understanding and predicting the epidemiological dynamics of infectious diseases. We construct a flexible discrete-time model that incorporates multiple viral strains with different transmissibilities to estimate the changing patterns of human contact that generates new infections. Using a Bayesian approach, we fit the model to longitudinal data on hospitalisation with COVID-19 from the Republic of Ireland and Northern Ireland during the first year of the pandemic. We describe the estimated change in human contact in the context of government-mandated non-pharmaceutical interventions in the two jurisdictions on the island of Ireland. We take advantage of the fitted model to conduct counterfactual analyses exploring the impact of lockdown timing and introducing a novel, more transmissible variant. We found substantial differences in human contact between the two jurisdictions during periods of varied restriction easing and December holidays. Our counterfactual analyses reveal that implementing lockdowns earlier would have decreased subsequent hospitalisation substantially in most, but not all cases, and that an introduction of a more transmissible variant - without necessarily being more severe - can cause a large impact on the health care burden

Comparison between free serum thyroxine levels, measured by analog and dialysis methods, in the presence of perfluorooctane sulfonate and perfluorooctanoate.

Results from animal studies have shown that negative associations between serum levels of free thyroxine (FT4) and perfluorooctane sulfonate (PFOS) at concentrations much higher than those reported for any exposed population may be due to bias in analog methods used for measuring FT4. We aimed to assess if there is evidence of differences between human FT4 measurements in serum by an analog and a dialysis method due to the presence of PFOS or perfluorooctanoate (PFOA) in a population of 50 adults with typical US serum PFOS concentrations but higher PFOA concentrations. Mean analog-dialysis difference was -0.02 (95% CI=-0.06, 0.02). Regressing the difference between FT4 measurements on either PFOA or PFOS serum concentrations yielded slopes close to zero. The present findings do not indicate any observable bias from the use of the analog with respect to the dialysis method, across the range of PFOS and PFOA concentrations in this population

Stroke Associated with Atrial Fibrillation – Incidence and Early Outcomes in the North Dublin Population Stroke Study

BACKGROUND: Prospective population-based studies are important to accurately determine the incidence and characteristics of stroke associated with atrial fibrillation (AF), while avoiding selection bias which may complicate hospital-based studies. METHODS: We investigated AF-associated stroke within the North Dublin Population Stroke Study, a prospective cohort study of stroke/transient ischaemic attack in 294,592 individuals, according to recommended criteria for rigorous stroke epidemiological studies. RESULTS: Of 568 stroke patients ascertained in the first year, 31.2% (177/568) were associated with AF (90.4%, i.e. 160/177 ischaemic infarcts). The crude incidence rate of all AF-associated stroke was 60/100,000 person-years (95% CI = 52-70). Prior stroke was almost twice as common in AF compared to non-AF groups (21.9 vs. 12.8%, p = 0.01). The frequency of AF progressively increased across ischaemic stroke patients stratified by increasing stroke severity (NIHSS 0-4, 29.7%; 5-9, 38.1%; 10-14, 43.8%; >or=15, 53.3%, p < 0.0001). The 90-day trajectory of recovery of AF-associated stroke was identical to that of non-AF stroke, but Rankin scores in AF stroke remained higher at 7, 28 and 90 days (p < 0.001 for all). DISCUSSION: AF-associated stroke occurred in one third of all patients and was associated with a distinct profile of recurrent, severe and disabling stroke. Targeted strategies to increase anticoagulation rates may provide a substantial benefit to prevent severe disabling stroke at a population level

Heartwatch: the effect of a primary care-delivered secondary prevention programme for cardiovascular disease on medication use and risk factor profiles.

BACKGROUND: Heartwatch is a secondary prevention programme of coronary heart disease (CHD) in primary care in Ireland. The aim was to further examine the effect of the Heartwatch programme on cardiovascular risk factors and treatments of patients with a follow-up of 3.5 years. DESIGN: Prospective cohort study of 12,358 patients with established CHD (myocardial infarction, percutaneous cardiac intervention, coronary artery bypass graft) recruited by participating general practitioners; patients invited to attend on a quarterly basis, with continuing care implemented according to defined clinical protocols. METHODS: Changes in risk factors and treatments at 1, 2, 3 and 3.5-year follow-up from baseline were made using paired t-test for continuous and McNemar's test for categorical data. RESULTS: Important changes in systolic and diastolic blood pressure, total and low-density lipoprotein cholesterol and smoking status were observed at 1, 2, 3 and 3.5 years (P < 0.0001) with significant increase in proportions of patients within the target. However, changes in body mass index were small, with no significant improvement in waist circumference. There was a significant increase in prescription of secondary preventive medications and good patient compliance. Males were more likely to be within the target for systolic blood pressure, total cholesterol, waist circumference and exercise level at 3.5 years, but less likely for body mass index. CONCLUSION: Studies of cardiac rehabilitation without any follow-up programmes show that over time patients revert in part to previous lifestyle habits; this primary care-delivered programme has shown sustained improvements in major risk factors, particularly smoking, blood pressure and cholesterol, and treatments for CHD. Weight management presents a greater challenge