Assigning exposure duration to single prescriptions by use of the waiting time distribution

Geographic variation in sodium-glucose cotransporter 2 inhibitor and glucagon-like peptide-1 receptor agonist use in people with type 2 diabetes in New South Wales, Australia

AIM

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) improve glycaemic control and cardio-renal outcomes for people with type 2 diabetes (T2D). However, geographic and socio-economic variation in use is not well understood.

METHODS

We identified 367 829 New South Wales residents aged ≥40 years who dispensed metformin in 2020 as a proxy for T2D. We estimated the prevalence of use of other glucose-lowering medicines among people with T2D and the prevalence of SGLT2i and GLP-1RA use among people using concomitant T2D therapy (i.e. metformin + another glucose-lowering medicine). We measured the prevalence by small-level geography, stratified by age group, and characterized by remoteness and socio-economic status.

RESULTS

The prevalence of SGLT2i (29.7%) and GLP-1RA (8.3%) use in people with T2D aged 40-64 increased with geographic remoteness and in areas of greater socio-economic disadvantage, similar to other glucose-lowering medicines. The prevalence of SGLT2i (55.4%) and GLP-1RA (15.4%) among people using concomitant T2D therapy varied across geographic areas, with lower SGLT2i use in more disadvantaged areas and localized areas of high GLP-1RA use (2.5 times the median). Compared with people aged 40-64 years, the prevalence of SGLT2i and GLP-1RA use was lower in older age groups, but with similar patterns of variation across geographic areas.

CONCLUSIONS

The prevalence of SGLT2i and GLP-1RA use varied by geography, probably reflecting a combination of system- and prescriber-level factors. Socio-economic variation in GLP-1RA use was overshadowed by localized patterns of prescribing. Continued monitoring of variation can help shape interventions to optimize use among people who would benefit the most.

National surveillance using a clinical quality indicator for prolonged antipsychotic use among older Australians with dementia who access aged care services

OBJECTIVES

Dementia guidelines recommend antipsychotics are only used for behavioral and psychological symptoms when non-drug interventions fail, and to regularly review use. Population-level clinical quality indicators (CQIs) for dementia care in permanent residential aged care (PRAC) typically monitor prevalence of antipsychotic use but not prolonged use. This study aimed to develop a CQI for antipsychotic use >90 days and examine trends, associated factors, and variation in CQI incidence; and examine duration of the first episode of use among individuals with dementia accessing home care packages (HCPs) or PRAC.

METHODS

Retrospective cohort study, including older individuals with dementia who accessed HCPs (n = 50,257) or PRAC (n = 250,196). Trends in annual CQI incidence (2011-12 to 2015-16) and associated factors were determined using Poisson regression. Funnel plots examined geographical and facility variation. Time to antipsychotic discontinuation was estimated among new antipsychotic users accessing HCP (n = 2367) and PRAC (n = 15,597) using the cumulative incidence function.

RESULTS

Between 2011-12 and 2015-16, antipsychotic use for >90 days decreased in HCP recipients from 10.7% (95% CI 10.2-11.1) to 10.1% (95% CI 9.6-10.5, adjusted incidence rate ratio (aIRR) 0.97 (95% CI 0.95-0.98)), and in PRAC residents from 24.5% (95% CI 24.2-24.7) to 21.8% (95% CI 21.5-22.0, aIRR 0.97 (95% CI 0.96-0.98)). Prior antipsychotic use (both cohorts) and being male and greater socioeconomic disadvantage (PRAC cohort) were associated with higher CQI incidence. Little geographical/facility variation was observed. Median treatment duration in HCP and PRAC was 334 (interquartile range [IQR] 108-958) and 555 (IQR 197-1239) days, respectively.

CONCLUSIONS

While small decreases in antipsychotic use >90 days were observed between 2011-12 and 2015-16, findings suggest antipsychotic use among aged care recipients with dementia can be further minimized.

On- and off-label utilisation of antipsychotics in Australia (2000-2021): Retrospective analysis of two medication datasets

OBJECTIVE

To determine antipsychotic utilisation patterns in Australian adults from 2005 to 2021, with a focus on on-label and off-label prescriptions.

METHODS

We examined antipsychotic dispensing trends in adults from 2005 to 2021 using a 10% sample of the Pharmaceutical Benefits Scheme (PBS) dataset, which contains patient-level information on medicines dispensed throughout Australia. The lack of diagnostic information in PBS was substituted by analysing BEACH (Bettering the Evaluation And Care of Health) dataset, a cross-sectional national survey from 2000 to 2016, consisting of data from general practitioner-patient encounters.

RESULTS

There were 5.6 million dispensings for 164,993 patients in PBS throughout this period; 69% patients had >1 dispensing, with a median of 6 per patient. Calculating the estimated period of exposure gave a total of 693,562 treatment episodes, with a median duration of 80 days. There were steady increases in both the incidence and prevalence of antipsychotic dispensings, mainly due to oral second-generation antipsychotics. The most commonly prescribed antipsychotics were quetiapine, olanzapine and risperidone, with a significant portion of patients receiving low-dose quetiapine without dose titration. Analysis of diagnostic indications from BEACH indicated that 27% of antipsychotic prescriptions were off-label for indications such as depression, dementia, anxiety and insomnia, at much lower prescribed daily dosages.

CONCLUSION

The increasing prescribing and off-label use highlights concerns about chronic adverse effects caused by antipsychotics. The combined analysis of medication dispensings and the diagnostic indications for which they are prescribed is a novel approach and throws a spotlight on the need for additional monitoring of antipsychotics.

Association between long-term use of calcium channel blockers (CCB) and the risk of breast cancer: a retrospective longitudinal observational study protocol

INTRODUCTION

Calcium channel blockers (CCB), a commonly prescribed antihypertensive (AHT) medicine, may be associated with increased risk of breast cancer. The proposed study aims to examine whether long-term CCB use is associated with the development of breast cancer and to characterise the dose-response nature of any identified association, to inform future hypertension management.

METHODS AND ANALYSIS

The study will use data from 2 of Australia's largest cohort studies; the Australian Longitudinal Study on Women's Health, and the 45 and Up Study, combined with the Rotterdam Study. Eligible women will be those with diagnosed hypertension, no history of breast cancer and no prior CCB use at start of follow-up (2004-2009). Cumulative dose-duration exposure to CCB and other AHT medicines will be captured at the earliest date of: the outcome (a diagnosis of invasive breast cancer); a competing risk event (eg, bilateral mastectomy without a diagnosis of breast cancer, death prior to any diagnosis of breast cancer) or end of follow-up (censoring event). Fine and Gray competing risks regression will be used to assess the association between CCB use and development of breast cancer using a generalised propensity score to adjust for baseline covariates. Time-varying covariates related to interaction with health services will also be included in the model. Data will be harmonised across cohorts to achieve identical protocols and a two-step random effects individual patient-level meta-analysis will be used.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the following Human research Ethics Committees: Curtin University (ref No. HRE2022-0335), NSW Population and Health Services Research Ethics Committee (2022/ETH01392/2022.31), ACT Research Ethics and Governance Office approval under National Mutual Acceptance for multijurisdictional data linkage research (2022.STE.00208). Results of the proposed study will be published in high-impact journals and presented at key scientific meetings.

TRIAL REGISTRATION NUMBER

NCT05972785.

Potential drug-drug interactions due to concomitant medicine use among people living with HIV on antiretroviral therapy in Australia

AIMS

We quantified concomitant medicine use and occurrence of potential drug-drug interactions in people living with HIV in Australia who are treated with antiretroviral therapy (ART).

METHODS

In this cohort study using dispensing claims of a 10% random sample of Australians, we identified 2230 people dispensed ART between January 2018 and December 2019 (mean age 49.0 years, standard deviation 12.0 years, 88% male). We examined concomitant medicine use by identifying nontopical medicines dispensed within 90-days of any antiretroviral medicine dispensing during a 12-month follow-up period. For every antiretroviral and nonantiretroviral pair, we identified and classified possible drug-drug interactions using the University of Liverpool HIV drug interactions database.

RESULTS

A total of 1728 (78%) people were dispensed at least 1 and 633 (28%) 5 or more unique medicines in addition to ART in a 12-month period; systemic anti-infectives and medicines acting on the nervous system were the most common (68% and 56%, respectively). Among comedicated people, 1637 (95%) had at least 1 medicine combination classified as weak interactions, 558 (32%) interactions requiring close monitoring/dose adjustment and 94 (5%) that should not be coadministered. Contraindication or interactions requiring close monitoring/dose adjustment were more common among people receiving protease inhibitors (50-73% across different antiretrovirals), non-nucleoside reverse transcriptase inhibitors (35-64%), people using single-tablet combinations containing elvitegravir (30-46%) and those using tenofovir disoproxil (26-30%).

CONCLUSION

Concomitant medicine use is widespread among people living with HIV in Australia. Despite a relatively low prevalence of contraindicated medicines, almost a third received medicines that require close monitoring or dose adjustment.

Evidence-based medication adherence among seniors in the first year after heart failure hospitalisation and subsequent long-term outcomes: a restricted cubic spline analysis of adherence-outcome relationships

PURPOSE

Non-adherence to heart failure (HF) medications is associated with poor outcomes. We used restricted cubic splines (RCS) to assess the continuous relationship between adherence to renin-angiotensin system inhibitors (RASI) and β-blockers and long-term outcomes in senior HF patients.

METHODS

We identified a population-based cohort of 4234 patients, aged 65-84 years, 56% male, who were hospitalised for HF in Western Australia between 2003 and 2008 and survived to 1-year post-discharge (landmark date). Adherence was calculated using the proportion of days covered (PDC) in the first year post-discharge. RCS Cox proportional-hazards models were applied to determine the relationship between adherence and all-cause death and death/HF readmission at 1 and 3 years after the landmark date.

RESULTS

RCS analysis showed a curvilinear adherence-outcome relationship for both RASI and β-blockers which was linear above PDC 60%. For each 10% increase in RASI and β-blocker adherence above this level, the adjusted hazard ratio for 1-year all-cause death fell by an average of 6.6% and 4.8% respectively (trend p < 0.05) and risk of all-cause death/HF readmission fell by 5.4% and 5.8% respectively (trend p < 0.005). Linear reductions in adjusted risk for these outcomes at PDC ≥ 60% were also seen at 3 years after landmark date (all trend p < 0.05).

CONCLUSION

RCS analysis showed that for RASI and β-blockers, there was no upper adherence level (threshold) above 60% where risk reduction did not continue to occur. Therefore, interventions should maximise adherence to these disease-modifying HF pharmacotherapies to improve long-term outcomes after hospitalised HF.

Association between spironolactone use and COVID-19 outcomes in population-scale claims data: a retrospective cohort study

Background

Spironolactone has been proposed as a potential modulator of SARS-CoV-2 cellular entry. We aimed to measure the effect of spironolactone use on the risk of adverse outcomes following COVID-19 hospitalization.

Methods

We performed a retrospective cohort study of COVID-19 outcomes for patients with or without exposure to spironolactone, using population-scale claims data from the Komodo Healthcare Map. We identified all patients with a hospital admission for COVID-19 in the study window, defining treatment status based on spironolactone prescription orders. The primary outcomes were progression to respiratory ventilation or mortality during the hospitalization. Odds ratios (OR) were estimated following either 1:1 propensity score matching (PSM) or multivariable regression. Subgroup analysis was performed based on age, gender, body mass index (BMI), and dominant SARS-CoV-2 variant.

Findings

Among 898,303 eligible patients with a COVID-19-related hospitalization, 16,324 patients (1.8%) had a spironolactone prescription prior to hospitalization. 59,937 patients (6.7%) met the ventilation endpoint, and 26,515 patients (3.0%) met the mortality endpoint. Spironolactone use was associated with a significant reduction in odds of both ventilation (OR 0.82; 95% CI: 0.75-0.88; p < 0.001) and mortality (OR 0.88; 95% CI: 0.78-0.99; p = 0.033) in the PSM analysis, supported by the regression analysis. Spironolactone use was associated with significantly reduced odds of ventilation for all age groups, men, women, and non-obese patients, with the greatest protective effects in younger patients, men, and non-obese patients.

Interpretation

Spironolactone use was associated with a protective effect against ventilation and mortality following COVID-19 infection, amounting to up to 64% of the protective effect of vaccination against ventilation and consistent with an androgen-dependent mechanism. The findings warrant initiation of large-scale randomized controlled trials to establish a potential therapeutic role for spironolactone in COVID-19 patients.

A data-informed approach using individualised dispensing patterns to estimate medicine exposure periods and dose from pharmaceutical claims data

Pharmaceutical claims data are often used as the primary information source to define medicine exposure periods in pharmacoepidemiological studies. However, often critical information on directions for use and the intended duration of medicine supply are not available. In the absence of this information, alternative approaches are needed to support the assignment of exposure periods. This study summarises the key methods commonly used to estimate medicine exposure periods and dose from pharmaceutical claims data; and describes a method using individualised dispensing patterns to define time-dependent estimates of medicine exposure and dose. This method extends on important features of existing methods and also accounts for recent changes in an individual's medicine use. Specifically, this method constructs medicine exposure periods and estimates the dose used by considering characteristics from an individual's prior dispensings, accounting for the time between prior dispensings and the amount supplied at prior dispensings. Guidance on the practical applications of this method is also provided. Although developed primarily for application to databases, which do not contain duration of supply or dose information, use of this method may also facilitate investigations when such information is available and there is a need to consider individualised and/or changing dosing regimens. By shifting the reliance on prescribed duration and dose to determine exposure and dose estimates, individualised dispensing information is used to estimate patterns of exposure and dose for an individual. Reflecting real-world individualised use of medicines with complex and variable dosing regimens, this method offers a pragmatic approach that can be applied to all medicine classes.

Risk factors for cardiac implantable electronic device infections: a nationwide Danish study

AIMS

Cardiac implantable electronic device (CIED) infection is a severe complication to modern management of cardiac arrhythmias. The CIED type and the type of surgery are recognized as risk factors for CIED infections, but knowledge of patient-related risk factors is scarce. This study aimed to identify lifelong patient-related risk factors for CIED infections.

METHODS AND RESULTS

Consecutive Danish patients undergoing a CIED implantation or reoperation between January 1996 and April 2018 were included. The cohort consisted of 84 429 patients undergoing 108 494 CIED surgeries with a combined follow-up of 458 257 CIED-years. A total of 1556 CIED explantations were classified as either pocket (n = 1022) or systemic CIED infection (n = 534). Data were cross-linked with records from the Danish National Patient Registry and the Danish National Prescription Registry. Using multiple-record and multiple-event per subject proportional hazard analysis, specific patient-related risk factors were identified but with several variations amongst the subtypes of CIED infection. CIED reoperations were associated with the highest risk of pocket CIED infection but also CIED type, young age, and prior valvular surgery [hazard ratio (HR): 1.62, 95% confidence interval (CI): 1.29-2.04]. Severe renal insufficiency/dialysis (HR: 2.40, 95% CI: 1.65-3.49), dermatitis (HR: 2.80, 95% CI: 1.92-4.05), and prior valvular surgery (HR: 2.09, 95% CI: 1.59-2.75) were associated with the highest risk of systemic CIED infections. Congestive heart failure, ischaemic heart disease, malignancy, chronic obstructive pulmonary disease, and temporary pacing were not significant at multivariate analysis.

CONCLUSION

Specific comorbidities and surgical procedures were associated with a higher risk of CIED infections but with variations amongst pocket and systemic CIED infection. Pocket CIED infections were associated with CIED reoperations, young age and more complex type of CIED, whereas systemic CIED infections were associated with risk factors predisposing to bacteraemia.

Medicines use before and after comprehensive medicines review among residents of long-term care facilities: a retrospective cohort study

Background

Residential Medication Management Review (RMMR) is a subsidized comprehensive medicines review program for individuals in Australian residential aged care facilities (RACFs). This study examined weekly trends in medicines use in the four months before and after an RMMR and among a comparison group of residents who did not receive an RMMR.

Methods

This retrospective cohort study included individuals aged 65 to 105 years who first entered permanent care between 1/1/2012 and 31/12/2016 in South Australia, Victoria, or New South Wales, and were taking at least one medicine. Individuals with an RMMR within 12 months of RACF entry were classified into one of three groups: (i) RMMR within 0 to 3 months, (ii) 3 to 6 months, or (iii) within 6 to 12 months of RACF entry. Individuals without RMMRs were included in the comparison group. Weekly trends in the number of defined daily doses per 1000 days were determined in the four months before and after the RMMR (or assigned index date in the comparison group) for 14 medicine classes.

Results

113909 individuals from 1979 RACFs were included, of whom 55021 received an RMMR. Across all three periods examined, decreased use of statins and proton pump inhibitors was observed post-RMMR in comparison to those without RMMRs. Decreases in calcium channel blockers, benzodiazepines/zopiclone, and antidepressants were observed following RMMR provision in the 3–6 and 6–12 months after RACF entry. Negligible changes in antipsychotic use were also observed following an RMMR in the 6–12 months after RACF entry by comparison to those without RMMRs. No changes in use of opioids, ACE inhibitors/sartans, beta blockers, loop diuretics, oral anticoagulants, or medicines for osteoporosis, diabetes or the cognitive symptoms of dementia were observed post-RMMR.

Conclusions

For six of the 14 medicine classes investigated, modest changes in weekly trends in use were observed after the provision of an RMMR in the 6–12 months after RACF entry compared to those without RMMRs. Findings suggest that activities such as medicines reconciliation may be prioritized when an RMMR is provided on RACF entry, with deprescribing more likely after an RMMR the longer a resident has been in the RACF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03187-0.

Rationale and performances of a data-driven method for computing the duration of pharmacological prescriptions using secondary data sources

The assessment of the duration of pharmacological prescriptions is an important phase in pharmacoepidemiologic studies aiming to investigate persistence, effectiveness or safety of treatments. The Sessa Empirical Estimator (SEE) is a new data-driven method which uses k-means algorithm for computing the duration of pharmacological prescriptions in secondary data sources when this information is missing or incomplete. The SEE was used to compute durations of exposure to pharmacological treatments where simulated and real-world data were used to assess its properties comparing the exposure status extrapolated with the method with the “true” exposure status available in the simulated and real-world data. Finally, the SEE was also compared to a Researcher-Defined Duration (RDD) method. When using simulated data, the SEE showed accuracy of 96% and sensitivity of 96%, while when using real-world data, the method showed sensitivity ranging from 78.0 (nortriptyline) to 95.1% (propafenone). When compared to the RDD, the method had a lower median sensitivity of 2.29% (interquartile range 1.21–4.11%). The SEE showed good properties and may represent a promising tool to assess exposure status when information on treatment duration is not available.

Characteristics of New Users of Aclidinium Bromide, Aclidinium/Formoterol, and Other COPD Medications in the United Kingdom, Denmark, and Germany

Background and Objectives

Aclidinium bromide was approved in the European Union for the treatment of chronic obstructive pulmonary disease (COPD) in adult patients in 2012 and in a fixed-dose combination with formoterol in 2014. We characterised new users of aclidinium, aclidinium/formoterol and other COPD medications and evaluated off-label prescribing of these medications in three European populations.

Methods

We described demographic characteristics, comorbidities, comedications, COPD severity and off-label prescribing of new users of aclidinium, aclidinium/formoterol and other COPD medications in patients with COPD aged ≥ 40 years in the Clinical Practice Research Datalink (CPRD, UK), Danish National Health Databases, and German Pharmacoepidemiological Research Database (GePaRD) between 2015 and 2017.

Results

We included 17,668 new users of aclidinium (CPRD, 4871; Denmark, 2836; GePaRD, 9961) and 14,808 new users of aclidinium/formoterol (CPRD, 2153; Denmark, 2586; GePaRD, 10,069). Study patients were of similar age, except in GePaRD, where users of long-acting beta2-agonists (LABA)/inhaled corticosteroids were younger. Patients had multiple comorbidities and used multiple comedications—most frequently hypertension (50–79%) and short-acting beta2-agonists (26–84%). Aclidinium users in CPRD and long-acting anticholinergics/LABA users in Denmark and GePaRD had the highest frequency of severe/very severe COPD. Off-label prescribing of aclidinium (5.0% [CPRD]–8.9% [Denmark]) and aclidinium/formoterol (2.6% [GePaRD]–3.2% [CPRD]) was low, and the main reason was asthma without a COPD diagnosis.

Conclusions

Aclidinium and aclidinium/formoterol were mostly prescribed according to label, with preference given to older patients with more severe COPD and to patients with a high prevalence of comorbidities and comedication use.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40261-022-01120-2.

Antidepressant treatment trajectories and suicide attempt among Australians aged 45 years and older: A population study using individual prescription data

INTRODUCTION

Meta-analyses show antidepressant initiation has increased risk of suicidal behavior <25 years, no difference 25-64 years and reduced risk 65+ years. Estimating risks from RCTs has limitations and real-world population estimates are uncommon.

METHODS

A self-controlled case series reporting incidence rate ratio (IRR) between exposed and control periods for antidepressants associated with suicide attempt, in Australian older age adults. We included all cases with suicide attempt [hospital data for ICD codes (X60-X84)] and any antidepressant use (n = 689) by participants in the "45 and Up Study".

RESULTS

For all antidepressants the IRR for suicide attempt was elevated across all exposures, declining from 7.44 (95%CI 5.57-9.94) during the first 30 days, to 2.21 (1.73-2.81) at 91+ days. All four antidepressant sub-groups had higher IRRs for the first 30 day exposure: 2.43 (1.37-4.29) for TCAs, 4.06 (2.78-5.93) for SSRIs, 4.15 (2.65-6.50) for other antidepressants, and 4.92 (3.30-7.34) for SNRIs. Increased IRR persisted for 61- to 90-day exposures for SSRIs 2.42 (1.18-4.98) and SNRIs 2.66 (1.34-5.27).

CONCLUSION

Some older adults have increased risk of suicide attempt with antidepressant exposure, which may persist for months. Clinical guidelines should recommend a period of monitoring for treatment-emergent suicidal thoughts and behaviors in older adult patients.

The Risk of Preoperative Central Nervous System-Acting Medications on Delirium Following Hip or Knee Surgery: A Matched Case-Control Study

INTRODUCTION

Medicines acting on the central nervous system can increase the risk of postoperative delirium, but the specific medicines associated with greatest risk remain unclear.

OBJECTIVES

We aimed to examine the risk of individual central nervous system-acting medicines used preoperatively on delirium after hip or knee surgery.

METHODS

A matched case-control study was conducted using data from the Australian Government Department of Veterans' Affairs. We included people aged 65 years or older who had knee or hip surgery between 2000 and 2019. People with hip or knee surgery who developed postoperative delirium were cases and controls were people with hip or knee surgery but who did not develop postoperative delirium. Use of medicines including anxiolytics, sedatives, and hypnotics, opioid analgesics and antidepressants prior to surgery was compared between cases and controls.

RESULTS

A total of 2614 patient cases with postoperative delirium were matched by same sex, age (±2 years), and year of admission (±2 years) with 7842 controls without postoperative delirium. Cases were more likely to be exposed to nitrazepam (odds ratio [OR] = 1.81, 95% confidence interval [CI] 1.24-2.64), sertraline (OR = 1.50, 95% CI 1.20-1.87), mirtazapine (OR = 1.38, 95% CI 1.11-1.74), venlafaxine (OR = 1.42, 95% CI 1.02-1.98), citalopram (OR = 1.54, 95% CI 1.19-1.99), escitalopram (OR = 1.42, 95% CI 1.06-1.89) or fluvoxamine (OR = 5.01, 95% CI 2.15-11.68) prior to surgery than controls. At the class level, exposure to benzodiazepines (OR = 1.20, 95% CI 1.05-1.37) and antidepressants (OR = 1.64, 95% CI 1.47-1.83) prior to surgery was significantly higher in cases than in controls. The numbers needed to treat to harm for one additional delirium case were 43 for sertraline, 40 for citalopram, 57 for mirtazapine and 26 for nitrazepam. Whereas, the numbers needed to treat to harm were found to be 20 for sertraline, 17 for citalopram, 19 for mirtazapine and 10 for nitrazepam in the 85 years or older age group, indicating that the harmful effect of these medicines is pronounced as age advances.

CONCLUSIONS

People who developed delirium following hip or knee surgery were more likely to be exposed to nitrazepam, sertraline, mirtazapine, venlafaxine, citalopram, escitalopram or fluvoxamine at the time of admission for surgery. Planning to reduce use of these medicines well prior to surgery may decrease the risk of postoperative delirium.

A data visualisation method for assessing exposure misclassification in case-crossover studies: the example of tricyclic antidepressants and the risk of hip fracture in older people

Background

The case-crossover design is suited to medication safety studies but is vulnerable to exposure misclassification. Using the example of tricyclic antidepressants and the risk of hip fracture, we present a data visualisation tool for observing exposure misclassification in case-crossover studies.

Methods

A case-crossover study was conducted using Australian Government Department of Veterans’ Affairs claims data. Beneficiaries aged over 65 years who were hospitalised for hip fracture between 2009 and 2012 were included. The case window was defined as 1–50 days pre fracture. Control window one and control window two were defined as 101–150 and 151–200 days pre fracture, respectively. Patients were stratified by whether exposure status changed when control window two was specified instead of control window one. To visualise potential misclassification, each subject’s tricyclic antidepressant dispensings were plotted over the 200 days pre fracture.

Results

The study population comprised 8828 patients with a median age of 88 years. Of these subjects, 348 contributed data to the analyses with either control window. The data visualisation suggested that 14% of subjects were potentially misclassified with control window one while 45% were misclassified with control window two. The odds ratio for the association between tricyclic antidepressants and hip fracture was 1.18 (95% confidence interval = 0.91–1.52) using control window one, whereas risk was significantly increased (odds ratio = 1.43, 95% confidence interval = 1.11–1.83) using control window two.

Conclusions

Exposure misclassification was less likely to be present with control window one than with an earlier control window, control window two. When specifying different control windows in a case-crossover study, data visualisation can help to assess the extent to which exposure misclassification may contribute to variable results.

A cross sectional study of psychotropic medicine use in Australia in 2018: A focus on polypharmacy

AIMS

To examine prescribed psychotropic medicine use on a given day in Australia (25 September 2018; World Pharmacists Day), with a focus on psychotropic polypharmacy.

METHODS

We used a 10% sample of individual-level nationwide dispensing claims to examine psychotropic medicine use on a given day. We estimated the prevalence of psychotropic medicine use in all ages stratified by age and sex. We also calculated the observed vs expected (had medicines been randomly combined) prevalence of psychotropic combinations used. We focused on combinations of clinical significance as well combinations of psychotropics with medicines prescribed to manage cardiovascular risk and disease.

RESULTS

Serotonin reuptake inhibitors, serotonin-noradrenalin reuptake inhibitors/noradrenaline reuptake inhibitors, tricyclic antidepressants and gabapentinoids dominated psychotropic use. The use of any psychotropic as a proportion of people in the Australian population increased with age, peaking at the 85-89 year age group and declining thereafter. Combinations of medicines from the same subclass generally occurred at lower than expected frequencies. However, combinations including atypical antipsychotics occurred more frequently than expected; e.g. 7.4× with anticonvulsants and 2.2× with other atypical antipsychotics. This was also the case for combinations of sedatives, e.g. anxiolytic with hypnotic benzodiazepines (3.8×). Lipid-lowering drugs and antidiabetic medicines were combined with psychotropics at frequencies close to those expected had they been randomly combined.

CONCLUSION

Psychotropic use in older adults and certain psychotropic combinations that are not well supported with evidence remain prevalent and greater consideration of the drivers of this potentially inappropriate prescribing is required.

Long-term trajectories of medicine use among older adults experiencing polypharmacy in Australia

AIMS

To explore longitudinal changes in the number and type of medicines used among older people who experience polypharmacy.

METHODS

We used pharmaceutical claims for a 10% sample of Australian Pharmaceutical Benefits Scheme beneficiaries to identify people aged 70 years and older who were exposed to 5 or more medicines on 15 February 2014. Using group-based trajectory modelling, we explored changes in the quarterly number and type of medicines used over a 5-year period (2014-2018).

RESULTS

In our cohort of 98 539 people, we identified 2 predominant groups of medicine use: sustained polypharmacy (77% of people, 4 trajectories); and decreasing medicine use (23%, 3 trajectories). Within the sustained polypharmacy group, people in trajectories with a lower mean number of medicines (e.g. 6 unique medicines) had relatively stable trajectories, while those using a higher number of medicines (e.g. 15 unique medicines) experienced greater seasonal variation in the number and type of medicines used. On average, people continued to use 2/3 of their medicines (chemical substance level) across adjacent quarters. Within groups of decreasing medicine use, the most common trajectory was a slight drop in medicines within 3 months. Overall, 79% of people still experienced polypharmacy after 1 year.

CONCLUSION

Polypharmacy among older people is a sustained phenomenon, reflecting the chronic nature of multimorbidity within this population. However, there is an underlying volatility in the nature of medicines involved, reflecting both changes in treatment and seasonal fluctuation in dispensing. Ongoing prescribing vigilance is required, particularly for patients using very large amounts of medicines.

A national study on prescribed medicine use in Australia on a typical day

PURPOSE

To describe Australians' prescribed medicine use on a typical day (September 25, 2018).

METHODS

We conducted a cross-sectional study using nationally representative dispensing claims data using the Australian Government Department of Human Services random 10% sample of all Australians eligible for prescription medicines subsidised through the Australian Pharmaceutical Benefits Scheme (PBS). Our main outcome measures were the number and proportion of people using at least one prescribed medicine and the specific medicine groups and classes on the day. We estimated the proportion of Australians using these medicines using the mid-year Australian population as the denominator. We quantified multiple medicine use by calculating the number and proportion of people experiencing polypharmacy (the use of 5 or more unique medicines) and hyper-polypharmacy (the use of 10 or more unique medicines).

RESULTS

We found that 9.0 million Australians used at least one PBS medicine on September 25, 2018; equating to 27.5 million medicines in use across Australia. "Cardiovascular system", "nervous system" and "alimentary tract and metabolism" medicines comprised the top three medicine groups. Over 1.8 million people experienced polypharmacy on the day, accounting for 13.6 million dispensed medicines. 1 022 590 (45%) people aged ≥70 years old experienced polypharmacy and 188 930 (8%) experienced hyper-polypharmacy.

CONCLUSIONS

Rates of polypharmacy were high, particularly in the people most susceptible to polypharmacy-related harm. Strategies to optimise the risk-benefit ratio of medicines and to reduce polypharmacy through "choosing wisely" and "de-prescribing" in this age group are needed. Australia's national data provides a benchmark to inform global medicine utilisation practices.

Long-Term Adherence to Renin-Angiotensin System Inhibitors and β-Blockers After Heart Failure Hospitalization in Senior Patients

AIMS

We investigated long-term adherence to renin-angiotensin system inhibitors (RASIs) and β-blockers, and associated predictors, in senior patients after hospitalization for heart failure (HF).

METHODS

A population-based data set identified 4488 patients who survived 60 days following their index hospitalization for HF in Western Australia from 2003 to 2008 with a 3-year follow-up. Their person-linked Pharmaceutical Benefits Scheme records identified medications dispensed during follow-up. Drug discontinuation was defined as the first break ≥90 days following the previous supply. Medication adherence was calculated using the proportion of days covered (PDC), with PDC ≥ 80% defined as being adherent. Multivariable logistic regression models were used to identify predictors of PDC < 80%.

RESULTS

In the cohort (57% male, mean age: 76.6 years), 77.4% were dispensed a RASI and 52.7% a β-blocker within 60 days postdischarge. Over the 3-year follow-up, 28% and 42% of patients discontinued RASI and β-blockers, respectively. Only 64.6% and 47.5% of RASI and β-blocker users, respectively, were adherent to their treatment over 3 years, with adherence decreasing over time (trend P < .0001 for RASI and trend P = .02 for β-blockers). Older age, increasing Charlson comorbidity score, chronic kidney disease, and chronic obstructive pulmonary disease were independent predictors of PDC < 80% for both drug groups.

CONCLUSION

Among seniors hospitalized for HF, discontinuation gaps were common for RASI and β-blockers postdischarge, and long-term adherence to these medications was suboptimal. Where appropriate, strategies to improve long-term medication adherence are indicated in HF patients, particularly in elderly patients with comorbidities.

Long-term use of proton-pump inhibitors: whole-of-population patterns in Australia 2013-2016

BACKGROUND

Proton-pump inhibitors (PPIs) are among the most prescribed medicines worldwide and concern about their long-term use is growing. We used dispensing claims for every person in Australia dispensed publicly subsidized PPIs between 2013 and 2016 to determine the incidence and prevalence of PPI use and to examine the patterns and durations of PPI treatment among individuals continuing treatment beyond the guideline-recommended maximum 12 weeks.

METHODS

We estimated annual prevalence and incidence per 100 people and duration of treatment for every Australian dispensed publicly subsidized PPIs between 2013 and 2016. We examined patterns of PPI treatment in three patient subgroups using PPIs for more than 12 weeks duration; people receiving maintenance, long-term continuous or long-term intermittent treatment. We calculated the proportion in each subgroup stepping down from higher to lower PPI strengths, stepping up from lower to higher PPI strength and discontinuing treatment.

RESULTS

PPIs were dispensed to 4,388,586 people; 60% were women; median age at initiation was 52 years [interquartile range (IQR): 36-65]. Standard and high strength PPIs accounted for 95% of dispensings. Annual incidence and prevalence were 3.9/100 and 12.5/100, respectively, in 2016 and highest among individuals over 65 years (prevalence range: 33-43/100). Most people (67%) stopped treatment after one dispensing; while 25%, 6% and 10% continued on maintenance, long-term continuous and long-term intermittent treatment, respectively. Median duration of treatment in people continuing treatment was 501 days (IQR: 180-not reached) for maintenance treated individuals and 'not reached' for long-term treated individuals. We observed 35%, 20% and 47% of people stepping down from higher to lower treatment strengths on maintenance, long-term continuous and long-term intermittent treatment, respectively.

CONCLUSIONS

Longer-term treatment with higher strength PPIs is common. Targeted regulation of PPI prescribing may improve the uptake of lower strength formulations and reduce both harms and costs associated with long-term PPI treatment.

Cardioprotective medication adherence in Western Australians in the first year after myocardial infarction: restricted cubic spline analysis of adherence-outcome relationships

Adherence to cardioprotective medications following myocardial infarction (MI) is commonly assessed using a binary threshold of 80%. We investigated the relationship between medication adherence as a continuous measure and outcomes in MI survivors using restricted cubic splines (RCS). We identified all patients aged ≥65 years hospitalised for MI from 2003–2008 who survived one-year post-discharge (n = 5938). Adherence to statins, beta-blockers, renin angiotensin system inhibitors (RASI) and clopidogrel was calculated using proportion of days covered to one-year post-discharge (landmark date). Outcomes were 1-year all-cause death and major adverse cardiac events (MACE) after the landmark date. Adherence-outcome associations were estimated from RCS Cox regression models. RCS analyses indicated decreasing risk for both outcomes above 60% adherence for statins, RASI and clopidogrel, with each 10% increase in adherence associated with a 13.9%, 12.1% and 18.0% decrease respectively in adjusted risk of all-cause death (all p < 0.02). Similar results were observed for MACE (all p < 0.03). Beta-blockers had no effect on outcomes at any level of adherence. In MI survivors, increasing adherence to statins, RASI, and clopidogrel, but not beta blockers, is associated with a decreasing risk of death/MACE with no adherence threshold beyond 60%. Medication adherence should be considered as a continuous measure in outcomes analyses.

Antihypertensive polytherapy in Australia: prevalence of inappropriate combinations, 2013-2018

OBJECTIVES

To estimate the prevalence of inappropriate antihypertensive polytherapy in Australia.

METHODS

We used a nationally representative 10% sample of Pharmaceutical Benefits Scheme (PBS) eligible Australians and their dispensing history to identify people aged 18+ years exposed to at least one PBS-listed antihypertensive between 2012 and 2018. We measured prevalence of antihypertensive polypharmacy (≥40 days concomitant exposure), inappropriate antihypertensive combinations (against guideline recommendations; within-class polytherapy) and combinations to be used with caution.

RESULTS

Almost half (47.5%) of people using antihypertensives in 2018 experienced polytherapy. Among these, 2.4% had an inappropriate combination (1.5% against guidelines; 1.0% within-class polytherapy). Inappropriate combinations were more prevalent in people experiencing polytherapy with three (3.7%) or four (16.1%) antihypertensive medicines than people on dual therapy (0.7%). Inappropriate combinations occurred at a lower rate in people using fixed-dose rather than free-drug combinations for dual therapy (0 vs. 0.7%) and in those using three antihypertensives (2.4 vs. 7.3%); this was not the case for people using four or more antihypertensives (15.5 vs. 16.1%). Between 2013 and 2018, the prevalence of antihypertensive polytherapy was relatively stable (49-47%); however, the prevalence of inappropriate combinations among these patients halved (from 5.1 to 2.4%).

CONCLUSION

Antihypertensive polytherapy in Australia is common, but the prevalence of inappropriate combinations is low and decreasing over time, suggesting strong awareness of Australian clinical guidelines. However, in 2018, approximately 49 000 Australian adults experienced inappropriate polytherapy; prescribing of fixed-dose combinations in patients on dual or triple therapy may further reduce this inappropriate care, although increased vigilance treating patients with more than 3 antihypertensives is required.

Potentially inappropriate prescribing in people with dementia: An Australian population-based study

OBJECTIVE

To investigate the prevalence of potentially inappropriate prescribing (PIP) using the Screening Tool of Older Person's Prescriptions (STOPP) criteria in people with dementia compared with people without dementia.

METHODS

A retrospective cohort study was conducted using the Pharmaceutical Benefits Scheme 10% sample of pharmacy claims. People with dementia were defined as those dispensed a medicine for dementia (cholinesterase inhibitors, memantine, or risperidone for behavioural and psychological symptoms of dementia) between 1 January 2005 and 31 December 2015, aged 65 years or older at 1 January 2016 and alive at the end of 2016. An age- and gender-matched comparison cohort of people not dispensed medicines for dementia was identified. PIP prevalence was determined between 1 January 2016 and 31 December 2016.

RESULTS

In total, 8280 people dispensed medicines for dementia and 41 400 comparisons not dispensed medicines for dementia were included: 63% were female and the median age was 82 years. PIP prevalence was 79% among people with dementia compared with 70% among the comparison group (P < .0001). Use of anticholinergics, long-term use of high-dose proton pump inhibitors, and use of benzodiazepines were the most common instances of PIP in people with dementia. After adjustments for age, gender, comorbidity, and number of prescribers, people with dementia were more likely to be exposed to PIP than comparisons (adjusted OR 1.44, 95% CI, 1.35-1.53, P < .0001).

CONCLUSIONS

PIP was more common in people dispensed medicines for dementia than comparisons. These results highlight the need for effective interventions to optimize prescribing in people with dementia.

Initiation and continuation of antipsychotic medicines in older people following non-psychiatric hospital admission

Background Internationally, antipsychotics are frequently initiated during hospital admission for older patients and use often continues post-discharge without indication. We located no Australian studies on this topic. Objective to identify the hospital admissions (excluding psychosis) associated with antipsychotic initiation and continuation in older Australians. Setting Australian Government Department of Veterans' Affairs. Method Retrospective analysis of administrative claims data for people admitted to hospital from 1 January 2014 to 31 December 2014, aged ≥ 65 years, who were antipsychotic naïve. Main outcome measure number of admissions associated with antipsychotic initiation, and the major diagnosis groups for these admissions. Where antipsychotics were initiated, we determined the time to cessation of antipsychotics after discharge. Results There were 142,009 hospital admissions for 66,415 people with a median age of 86 years. 921 (0.65%) admissions were associated with antipsychotic initiation, most commonly where the primary diagnoses were for mental and behavioural disorders excluding psychosis (17.8%) and injuries (16%). Fourteen percent of antipsychotic initiations were for primary diagnoses of delirium or dementia. When secondary diagnoses were considered, 55% of antipsychotic initiations were associated with delirium, dementia or both. The median duration of use among people who used antipsychotics was 132 days, and 40% continued use until death or one year follow-up. Conclusion Initiation of antipsychotics during hospital admissions was not frequent in this Australian population. Amongst those who did initiate antipsychotics, for almost half no diagnosis corresponding with an approved indication for use was recorded and long-term use of up to one year was common.

Nonvitamin K Antagonist Oral Anticoagulants Versus Warfarin in Atrial Fibrillation Patients and Risk of Dementia: A Nationwide Propensity-Weighted Cohort Study

Background It is unclear whether nonvitamin K antagonist oral anticoagulants ( NOAC s) can mitigate dementia development in atrial fibrillation. We compared dementia development among users of NOACs or warfarin in patients with atrial fibrillation with no prior neurological diagnoses. Methods and Results We conducted a Danish nationwide cohort study including 33 617 new oral anticoagulant users with nonvalvular atrial fibrillation, of which 11 052 were aged 60 to 69 years, 13 237 were aged 70 to 79 years, and 9238 were aged 80 years and older. To exclude prevalent non -oral anticoagulants- associated dementia, we considered the at-risk population of patients alive and free of dementia at 180 days following inclusion. We compared rates of new-onset dementia by age and treatment regimen using inverse probability of treatment weighting to account for confounding. Approximately 60% of patients were NOAC users and 40% were warfarin users. Mean follow-up was 3.4 years. Dementia occurred in 41 patients aged 60 to 69 years, 276 patients aged 70 to 79 years, and 441 patients aged 80 years and older. Relative to warfarin users, dementia rates were nonsignificantly lower among NOAC users aged 60 to 69 years (0.11 events/100 person-years versus 0.12 events/100 person-years; weighted hazard ratio, 0.92 [95% CI, 0.48-1.72]) and NOAC users aged 70 to 79 years (0.64 events/100 person-years versus 0.78 events/100 person-years; weighted hazard ratio , 0.86 [95% CI, 0.68-1.09]), whereas NOAC s were associated with significantly higher dementia rates (2.16 events/100 person-years versus 1.70 events/100 person-years; weighted hazard ratio , 1.31 [95% CI, 1.07-1.59]) in patients 80 years and older. Conclusions This nationwide cohort of patients with atrial fibrillation revealed no clinically meaningful difference in dementia development between users of NOACs or warfarin apart from a higher risk in NOAC users 80 years and older, which may relate to residual confounding from selective prescribing and unobserved comorbidities.

Potentially inappropriate prescribing before and after initiation of medicines for dementia: An Australian population-based study

AIM

To evaluate the prevalence of potentially inappropriate prescribing (PIP), as defined by the internationally validated Screening Tool of Older Person's Prescriptions (STOPP) criteria, in 12 months before and after initiation of medicines for dementia.

METHODS

A retrospective cohort study was carried out involving people with their first claim for dispensing of medicines for dementia (cholinesterase inhibitor or memantine) between 1 January 2015 and 31 December 2015, aged ≥65 years at 1 January 2016 and alive at the end of 2016. The index date was defined as the date of first supply of medicines for dementia. PIP was identified using the Screening Tool of Older Person's Prescriptions criteria, and PIP prevalence was compared in the 12 months pre- and post-index date. The McNemar's test was used to test differences in the prevalence of PIP between the two time periods.

RESULTS

The cohort included 1176 patients: 60% were women and the median age was 80 years. The overall PIP prevalence was 85% in the 12 months pre-initiation of medicines for dementia compared with 89% in the 12 months post-initiation (P < 0.0001). The median number of Screening Tool of Older Person's Prescriptions criteria was two (interquartile range 1-4) in the 12 months pre-initiation of medicines for dementia, increasing to three (range 2-4) in the 12 months post-initiation.

CONCLUSIONS

PIP was common in people dispensed medicines for dementia, with a significant increase in prevalence post-initiation of medicines for dementia compared with pre-initiation. These results highlight the need for targeted interventions to minimize inappropriate use of medicines in people with dementia. Geriatr Gerontol Int 2019; 19: 654-659.

Angiotensin II receptor blockers are safe in patients with prior angioedema related to angiotensin-converting enzyme inhibitors - a nationwide registry-based cohort study

BACKGROUND

It has long been suggested that angiotensin-converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (AT2s) have some degree of 'cross-reactivity' in causing angioedema. Therefore, caution has been advised when switching patients with ACEi-related angioedema to an AT2.

OBJECTIVES

To clarify whether AT2s can be used safely in patients with a history of angioedema during ACEi treatment and to estimate the incidence rate of angioedema in patients subsequently treated with other antihypertensive drugs (beta-adrenergic blockers, calcium channel blockers, thiazides and analogues) or no antihypertensives.

METHODS

This is a nationwide retrospective registry-based cohort study of the Danish population during the period 1994 to 2016, and it uses Danish health registries. Propensity score adjusted and conventional proportional hazards regression models have been employed.

RESULTS

A total of 1 106 024 ACEi users were identified. In total, 5 507 (0.5%) of these patients had experienced angioedema during ACEi treatment and were included in the study. The highest risk of angioedema recurrence was associated with continued ACEi use at an adjusted hazard ratio of 1.45 (95% CI, 1.19 to 1.78). An inverse association was found between AT2s and angioedema (adjusted hazard ratio, 0.39; 95% CI, 0.30 to 0.51) compared with other antihypertensives (adjusted hazard ratios, 0.77 to 0.97).

CONCLUSIONS

Compared with other antihypertensive drugs, AT2s do not increase the incidence of angioedema in patients with previous ACEi-related angioedema.

Patterns of use of antimuscarinic drugs to treat overactive bladder in Denmark, Sweden, and the United Kingdom

PURPOSE

To describe the use of antimuscarinic drugs to treat overactive bladder (OAB) in Denmark, Sweden, and the United Kingdom (UK).

METHODS

We identified new users of darifenacin, fesoterodine, oxybutynin, solifenacin, tolterodine, and trospium aged 18 years or older from the Danish National Registers (2004-2012), the Swedish National Registers (2006-2012), and UK Clinical Practice Research Datalink (2004-2012). Users were followed until disenrollment, cancer diagnosis, death, or study end. Treatment episodes, identified by linking consecutive prescriptions, were described with respect to duration, drug switch, and drug add-on.

RESULTS

Mean age of OAB drug users was 66 years in Denmark (n = 72,917) and Sweden (n = 130,944), and 62 years in the UK (n = 119,912); 60% of Danish and Swedish patients and 70% of UK patients were female. In Denmark, of 224,680 treatment episodes, 39% were with solifenacin, and 35% with tolterodine; 2% were with oxybutynin. In Sweden, of 240,141 therapy episodes, 37% were with tolterodine and 35% with solifenacin; 5% were with oxybutynin. In the UK, of 245,800 treatment episodes, 28% were with oxybutynin, 27% with solifenacin, and 26% with tolterodine. In the three countries, 49%-52% of treatment episodes comprised one prescription and over 80% of episodes ended because of no refill; less than 20% ended because of a switch to another antimuscarinic. During the study years, we observed a change in OAB treatment preference from tolterodine to solifenacin.

CONCLUSIONS

In these cohorts, persistence with antimuscarinic drugs was low. By 2012, the preferred drug was solifenacin; oxybutynin use was marginal in Nordic countries compared with the UK.

Measurement Error and Misclassification in Electronic Medical Records: Methods to Mitigate Bias

PURPOSE OF REVIEW

We sought to: 1) examine common sources of measurement error in research using data from electronic medical records (EMR), 2) discuss methods to assess the extent and type of measurement error, and 3) describe recent developments in methods to address this source of bias.

RECENT FINDINGS

We identified eight sources of measurement error frequently encountered in EMR studies, the most prominent being that EMR data usually reflect only the health services and medications delivered within the specific health facility/system contributing to the EMR data. Methods for assessing measurement error in EMR data usually require gold standard or validation data, which may be possible using data linkage. Recent methodological developments to address the impact of measurement error in EMR analyses were particularly rich in the multiple imputation literature.

SUMMARY

Presently, sources of measurement error impacting EMR studies are still being elucidated, as are methods for assessing and addressing them. Given the magnitude of measurement error that has been reported, investigators are urged to carefully evaluate and rigorously address this potential source of bias in studies based in EMR data.

Operationalization and validation of a novel method to calculate adherence to polypharmacy with refill data from the Australian pharmaceutical benefits scheme (PBS) database

Background

Electronic health care data contain rich information on medicine use from which adherence can be estimated. Various measures developed with medication claims data called for transparency of the equations used, predominantly because they may overestimate adherence, and even more when used with multiple medications. We aimed to operationalize a novel calculation of adherence with polypharmacy, the daily polypharmacy possession ratio (DPPR), and validate it against the common measure of adherence, the medication possession ratio (MPR) and a modified version (MPR_m).

Methods

We used linked health data from the Australian Pharmaceutical Benefits Scheme and Western Australian hospital morbidity dataset and mortality register. We identified a strict study cohort from 16,185 patients aged ≥65 years hospitalized for myocardial infarction in 2003–2008 in Western Australia as an illustrative example. We applied iterative exclusion criteria to standardize the dispensing histories according to previous literature. A SAS program was developed to calculate the adherence measures accounting for various drug parameters.

Results

The study cohort was 348 incident patients (mean age 74.6±6.8 years; 69% male) with an admission for myocardial infarction who had cardiovascular medications over a median of 727 days (range 74 to 3,798 days) prior to readmission. There were statins (96.8%), angiotensin converting enzyme inhibitors (88.8%), beta-blockers (85.6%), and angiotensin receptor blockers (13.2%) dispensed. As expected, observed adherence values were higher with mean MPR (median 89.2%; Q₁: 73.3%; Q_3: 104.6%) than mean MPR_m (median 82.8%; Q₁: 68.5%; Q_3: 95.9%). DPPR values were the most narrow (median 83.8%; Q₁: 70.9%; Q_3: 96.4%). Mean MPR and DPPR yielded very close possession values for 37.9% of the patients. Values were similar in patients with longer observation windows. When the traditional threshold of 80% was applied to mean MPR and DPPR values to signify the threshold for good adherence, 11.6% of patients were classified as good adherers with the mean MPR relative to the DPPR.

Conclusion

In the absence of transparent and standardized equations to calculate adherence to polypharmacy from refill databases, the novel DPPR algorithm represents a valid and robust method to estimate medication possession for multi-medication regimens.

Use of beta-blockers and risk of serious upper gastrointestinal bleeding: a population-based case-control study

BACKGROUND

Some studies indicate a reduced risk of serious upper gastrointestinal bleeding (UGIB) for users of beta-blockers, but the association remains to be confirmed in larger studies and characterized with respect to differences among beta-blockers. We aimed to assess whether beta-blocker use decreases the risk of UGIB.

METHODS

We conducted a register-based, population-based case-control study in Denmark. We identified cases with a first validated discharge diagnosis of UGIB during the period 1995-2006. Controls were selected by risk-set sampling in a ratio of 10:1. We estimated crude and adjusted odds ratios (ORs) of the association between current beta-blocker use and the risk of UGIB by using conditional logistic regression and further stratified by selective and non-selective beta-blockers, respectively.

RESULTS

We identified 3571 UGIB cases and 35,582 controls. Use of beta-blockers was not found to be associated with a decreased risk of UGIB (adjusted OR 1.10; 95% CI: 1.00-1.21). The association remained neutral after stratification by selective and non-selective beta-blockers, and by single beta-blocker substances. Similarly, we found no association between current beta-blocker use and the risk of UGIB within different subgroups.

CONCLUSIONS

We found no association between beta-blocker use and UGIB.

Comparison of cardiovascular events among treatments for overactive bladder: a Danish nationwide cohort study

PURPOSE

The purpose of this study is to explore the cardiovascular safety of antimuscarinic drugs to treat overactive bladder (OAB) in Denmark.

METHODS

This was a cohort study using data recorded in Danish registries from patients newly exposed to darifenacin, fesoterodine, oxybutynin, solifenacin, tolterodine, or trospium in 2004-2012. We estimated crude and standardized incidence rates (IRs) for acute myocardial infarction (AMI); stroke; cardiovascular mortality; major adverse cardiac events (MACE, a combined endpoint of the previous three outcomes); and all-cause death for the individual and combined drugs. We also estimated crude, standardized, and propensity score-stratified incidence rate ratios (IRRs) comparing individual antimuscarinic drugs to tolterodine as the reference.

RESULTS

Among 72,917 new users of OAB drugs (mean age, 66 years; 60% women), the standardized IR (95% confidence interval) per 1000 person-years for current use of any OAB drug was 2.7 (2.5-2.9) for AMI, 1.3 (1.2-1.5) for stroke, 7.8 (7.5-8.1) for MACE, 4.8 (4.5-5.0) for cardiovascular mortality, and 15.2 (14.8-15.6) for all-cause mortality. Propensity score-stratified IRRs for current use (reference, tolterodine) were close to the null for all drugs and endpoints.

CONCLUSIONS

We did not identify differences in the risk of cardiovascular events or mortality among users of individual antimuscarinic OAB drugs.

Psychotropic polypharmacy in Australia, 2006 to 2015: a descriptive cohort study

AIMS

To describe psychotropic polypharmacy in Australia between 2006 and 2015.

METHODS

We used pharmaceutical claims from a national 10% sample of people with complete dispensing histories to estimate the annual prevalence of the combined use (overlap of >60 days exposure) of ≥2 psychotropics overall and within the same class or subclass (class and subclass polypharmacy). We also estimated the proportion of polypharmacy episodes involving one, two, three and four or more unique prescribers.

RESULTS

The prevalence of class polypharmacy between 2006 and 2015 in people dispensed specific psychotropic classes was 5.9-7.3% for antipsychotics, 2.1-3.7% for antidepressants and 4.3-2.9% for benzodiazepines. The prevalence of antipsychotic polypharmacy was higher than expected given the prevalence of antipsychotic exposure and combinations of sedating agents were notably common. Overall, 26.7% of polypharmacy episodes involved multiple prescribers but having multiple prescribers occurred more frequently for class and subclass polypharmacy and people with four or more concomitant psychotropics.

DISCUSSION

Psychotropic polypharmacy is common, despite limited evidence of risks and benefits. Increases in polypharmacy with multiple prescribers may be due to poor communication with patients and between health care professionals.

Using probability of drug use as independent variable in a register-based pharmacoepidemiological cause-effect study-An application of the reverse waiting time distribution

BACKGROUND

In register-based pharmacoepidemiological studies, each day of follow-up is usually categorized either as exposed or unexposed. However, there is an underlying continuous probability of exposure, and by insisting on a dichotomy, researchers unwillingly force a nondifferential misclassification into their analyses. We have recently developed a model whereby probability of exposure can be modeled, and we tested this on an empirical case of nonsteroidal anti-inflammatory drug (NSAID)-induced upper gastrointestinal bleeding (UGIB).

METHODS

We used a case-controls data set, consisting of 3568 cases of severe UGIB and 35 552 matched controls. Exposure to NSAID was based on 3 different conventional dichotomous measures. In addition, we tested 3 probabilistic exposure measures, a simple univariate backward-recurrence model, a "full" multivariable model, and a "reduced" multivariable model. Odds ratios (ORs) and 95% confidence intervals for the association between NSAID use and UGIB were calculated by conditional logistic regression, while adjusting for preselected confounders.

RESULTS

Compared to the conventional dichotomous exposure measures, the probabilistic exposure measures generated adjusted ORs in the upper range (4.37-4.75) while at the same time having the most narrow confidence intervals (ratio between upper and lower confidence limit, 1.46-1.50). Some ORs generated by conventional measures were higher than the probabilistic ORs, but only when the assumed period of intake was unrealistically short.

CONCLUSION

The pattern of high ORs and narrow confidence intervals in probabilistic exposure measures is compatible with less nondifferential misclassification of exposure than in a dichotomous exposure model. Probabilistic exposure measures appear to be an attractive alternative to conventional exposure measures.

Psychotropic medication use in Australia, 2007 to 2015: Changes in annual incidence, prevalence and treatment exposure

OBJECTIVE

To examine changes in annual patterns of psychotropic medication use in Australia from 2007 to 2015.

METHODS

We used a 10% sample of individual-level nationwide dispensing claims for concessional beneficiaries dispensed psychotropic medications (stratified by class, subclass) to investigate annual trends and changes in the incidence and prevalence of use, median annual duration of exposure, proportion of people with single psychotropic dispensing and median defined daily doses per person dispensed each medicine per year.

RESULTS

Over the study period, there was a 26.1% decrease in the incidence and a 2.6% increase in the prevalence of all psychotropic medicine use. We observed a decrease in the annual incidence and prevalence of antidepressants (11.6% and 16.8%, respectively) but increases in the median annual duration of exposure (7.4%). Amitriptyline had the highest proportion of single dispensings of all antidepressants throughout the study period (26.5% in 2015) and defined daily doses per person dispensed each medicine per year increased by 20% for antidepressants overall. Benzodiazepine use decreased across all measures over the study period apart from long-term use (exposure for >240 days of the year), which in 2015 was 23.6% of those dispensed a benzodiazepine. We observed a relative increase in the incidence and prevalence of antipsychotic use (14.2% and 26.8%, respectively), and haloperidol had the highest proportion of single dispensings of any antipsychotic throughout the study period (47.5% in 2015). We observed a relative increase in the incidence and prevalence of attention-deficit hyperactivity disorder medication use of 114.0% and 101.8%, respectively, over the study period.

CONCLUSION

Increasing doses and treatment durations of antidepressants warrants further investigation due to concerns about overuse. Single dispensings of amitriptyline and haloperidol may indicate off-label use and long-term use of benzodiazepines remains problematic. Despite increases in attention-deficit hyperactivity disorder medication use, prevalence of use is still much lower than the estimated prevalence of attention-deficit hyperactivity disorder in the adult population.

The Risk of Hip Fracture Due to Mirtazapine Exposure When Switching Antidepressants or Using Other Antidepressants as Add-On Therapy

Background

Antidepressants are associated with adverse effects such as sedation and hypotension, which can result in falls and fractures. Few studies have assessed the risk of hip fracture due to mirtazapine, and no known studies have assessed whether the risk of hip fracture is higher in patients taking other antidepressant medicines in combination with mirtazapine.

Objectives

This study aimed to examine the risk of hip fracture in older people due to mirtazapine use as well as switching between or concurrently using mirtazapine and other antidepressants.

Method

A matched case–control study was conducted. Cases were people aged over 65 years who were eligible for Australian Government Department of Veterans’ Affairs (DVA) benefits and who sustained a hip fracture between 2009 and 2012. Each case was matched with up to four randomly selected controls of the same gender and age (± 2 years). Multivariable conditional logistic regression was used to estimate associations between antidepressant use and hip fracture. In order to assess whether combined antidepressant effects differed from the sum of individual effects, the relative excess risk due to interaction (RERI) was calculated.

Results

The study population comprised 8828 cases and 35,310 controls. The median age of these participants was 88 years and 63% were women. The risk of hip fracture was increased for mirtazapine (continuous use: odds ratio [OR] 1.27, 95% confidence interval [CI] 1.12–1.44). The combinations associated with increased odds of hip fracture were addition of selective serotonin reuptake inhibitors (SSRIs) to mirtazapine (OR 11, 95% CI 2.2–51; RERI 7.7, 95% CI −9.0 to 24), addition of tricyclic antidepressants (TCAs) to mirtazapine (OR 14, 95% CI 1.4–132; RERI 12, 95% CI −19 to 43) and continuous use of both SSRIs and mirtazapine (OR 2.4, 95% CI 1.4–4.2; RERI 0.4, 95% CI −0.9 to 1.7). RERIs indicated that the effect of each antidepressant pair equalled the sum of the effects of individual antidepressant use. There was no evidence of dispensing of lower strength mirtazapine upon introducing TCAs and SSRIs.

Conclusions

Our results show elevated risk of hip fracture following use of mirtazapine alone and in combination with other antidepressants. The overlapping use of antidepressants may reflect the treatment of comorbidities (e.g. anxiety), switching from mirtazapine to other antidepressants, or add-on therapy. Our results highlight the risks of employing add-on therapy or switching antidepressants in older people, providing further evidence to support cautious cross-tapering where switching between antidepressants is required.

Electronic supplementary material

The online version of this article (doi:10.1007/s40801-017-0120-y) contains supplementary material, which is available to authorized users.

Risk of Hip Fracture in Older People Using Selective Serotonin Reuptake Inhibitors and Other Psychoactive Medicines Concurrently: A Matched Case-Control Study in Australia

Background

Few studies have assessed the risk of hip fracture following concurrent use of psychoactive medicines, and none has investigated combinations with selective serotonin reuptake inhibitors.

Objectives

To assess the risk of hip fracture in older people as a result of concurrent use of selective serotonin reuptake inhibitors and other psychoactive medicines.

Methods

A matched case–control design was employed. Cases were Australian Government Department of Veterans’ Affairs beneficiaries aged over 65 years who experienced a hip fracture between 2009 and 2012. Each case was matched with up to four randomly selected controls of the same age (±2 years) and sex. Medicine-hip fracture associations were estimated via conditional logistic regression. The relative excess risk due to interaction (RERI) was calculated to determine whether combined effects differed from the sum of individual effects.

Results

There were 8828 cases and 35,310 controls. The median age of subjects was 88 years and 63% were women. The risk of hip fracture was elevated for all medicines assessed individually, most notably selective serotonin reuptake inhibitors (initiation: odds ratio [OR] = 2.7, 95% confidence interval [CI] 2.1, 3.6) and opioids (initiation: OR = 2.3, 95% CI 1.9, 2.9). Combinations associated with an increased odds of hip fracture included addition of benzodiazepines to selective serotonin reuptake inhibitor therapy (OR = 3.0, 95% CI 1.9, 4.8; RERI = 0.9, 95% CI −0.5, 2.3), concurrent use of both opioids and selective serotonin reuptake inhibitors (OR = 2.2, 95% CI 1.9, 2.6; RERI = 0.1, 95% CI −0.3, 0.5), addition of opioids to selective serotonin reuptake inhibitor therapy (OR = 3.2, 95% CI 1.8, 5.5; RERI = −0.1, 95% CI −2.0, 1.7), and initiation of both benzodiazepines and selective serotonin reuptake inhibitors (OR = 4.7, 95% CI 1.7, 13; RERI = 1.3, 95% CI −3.8, 6.3). The RERI results suggested that the effect of each of these medicine combinations equalled the sum of the effects of individual medicine use.

Conclusions

In older people, the concurrent use of selective serotonin reuptake inhibitors and other psychoactive medicines increased the risk of hip fracture as much as the sum of the risks owing to individual medicine use. Our results highlight the need for prescribers to consider the sedative burden of medicines in each older patient as well as the potential for an additive risk of hip fracture when initiating additional psychoactive therapy.

Refining estimates of prescription durations by using observed covariates in pharmacoepidemiological databases: an application of the reverse waiting time distribution

PURPOSE

The study aimed to develop an automated method to estimate prescription durations in pharmacoepidemiological studies that may depend on patient and redemption characteristics.

METHODS

We developed an estimation algorithm based on maximum likelihood estimation for the reverse waiting time distribution (WTD), which is the distribution of time from the last prescription of each patient within a time window to the end of the time window. The reverse WTD consists of two distinctly different components: one component for prevalent users and one for patients stopping treatment. We extended the model to allow parameters of the reverse WTD to depend on linear combinations of covariates to obtain estimates and confidence intervals for percentiles of the inter-arrival density (time from one prescription to the subsequent). We applied the method to redemptions of warfarin, using the amount of drug filled, patient sex and patient age as covariates.

RESULTS

The estimated prescription durations increased with redeemed amount and age. Women generally had longer prescription durations, which increased more with age than men. For 70-year-old women redeeming 300+ pills, we predicted a 95th percentile of the inter-arrival density of 225 (95%CI: 201, 249) days. For 50-year-old men redeeming 100 pills, the corresponding prediction was 97 (88, 106) days.

CONCLUSIONS

The algorithm allows estimation of prescription durations based on the reverse WTD, which can depend upon observed covariates. Statistical uncertainty intervals and tests allow statistical inference on the influence of observed patient and prescription characteristics. The method may replace ad hoc decision rules. Copyright © 2017 John Wiley & Sons, Ltd.

Odense Pharmacoepidemiological Database: A Review of Use and Content

The Odense University Pharmacoepidemiological Database (OPED) is a prescription database established in 1990 by the University of Southern Denmark, covering reimbursed prescriptions from the county of Funen in Denmark and the region of Southern Denmark (1.2 million inhabitants). It is still active and thereby has more than 25 years of continuous coverage. In this MiniReview, we review its history, content, quality, coverage, governance and some of its uses. OPED's data include the Danish Civil Registration Number (CPR), which enables unambiguous linkage with virtually all other health-related registers in Denmark. Among its research uses, we review record linkage studies of drug effects, advanced drug utilization studies, some examples of method development and use of OPED as sampling frame to recruit patients for field studies or clinical trials. With the advent of other, more comprehensive sources of prescription data in Denmark, OPED may still play a role as in certain data-intensive regional studies.

Persistent User Bias in Case-Crossover Studies in Pharmacoepidemiology

Studying the effect of chronic medication exposure by means of a case-crossover design may result in an upward-biased odds ratio. In this study, our aim was to assess the occurrence of this bias and to evaluate whether it is remedied by including a control group (the case-time-control design). Using Danish data resources from 1995-2012, we conducted case-crossover and case-time-control analyses for 3 medications (statins, insulin, and thyroxine) in relation to 3 outcomes (retinal detachment, wrist fracture, and ischemic stroke), all with assumed null associations. Controls were matched on age, sex, and index date, and exposure over the preceding 12 months was ascertained. For retinal detachment, the case-crossover odds ratio was 1.60 (95% confidence interval (CI): 1.42, 1.80) for statins, 1.40 (95% CI: 1.02, 1.92) for thyroxine, and 1.53 (95% CI: 1.04, 2.24) for insulin. Estimates for the retinal detachment controls were similar, leading to near-null case-time-control estimates for all 3 medication classes. For wrist fracture and stroke, the odds ratios were higher for cases than for controls, and case-time-control odds ratios were consistently above unity, thus implying significant residual bias. In case-crossover studies of medications, contamination by persistent users confers a moderate bias upward, which is partly remedied by using a control group. The optimal strategy for dealing with this problem is currently unknown.

Long-term use of secondary prevention medications for heart failure in Western Australia: a protocol for a population-based cohort study

INTRODUCTION

Heart failure (HF) is a chronic, debilitating and progressive disease associated with high morbidity and mortality. Evidence-based medications (EBMs) are the cornerstone of management of patients with HF. In Australia, these EBMs are subsidised by the Commonwealth Government under the Pharmaceutical Benefits Scheme. Suboptimal dispensing and non-adherence to these EBMs have been observed in patients with HF. Our study will investigate trends in dispensing patterns, as well as adherence and persistence of EBMs for HF. We will also identify factors influencing these patterns and their impact on long-term clinical outcomes.

METHODS AND ANALYSIS

This whole population-based cohort study will use longitudinal data for people aged 65-84 years who were hospitalised for HF in Western Australia between 2003 and 2008. Linked state-wide and national data will provide patient-level information on medication dispensing, medical visits, hospitalisations and death. Drug dispensing trends will be described, drug adherence and persistence estimated and the association with all-cause/cardiovascular death and hospitalisations reported.

ETHICS AND DISSEMINATION

This project has received approvals from the Western Australian Department of Health Human Research Ethics Committee and the Western Australian Aboriginal Health Ethics Committee. Results will be published in relevant cardiology journals and presented at national and international conferences.

Determining prescription durations based on the parametric waiting time distribution

PURPOSE

The purpose of the study is to develop a method to estimate the duration of single prescriptions in pharmacoepidemiological studies when the single prescription duration is not available.

METHODS

We developed an estimation algorithm based on maximum likelihood estimation of a parametric two-component mixture model for the waiting time distribution (WTD). The distribution component for prevalent users estimates the forward recurrence density (FRD), which is related to the distribution of time between subsequent prescription redemptions, the inter-arrival density (IAD), for users in continued treatment. We exploited this to estimate percentiles of the IAD by inversion of the estimated FRD and defined the duration of a prescription as the time within which 80% of current users will have presented themselves again. Statistical properties were examined in simulation studies, and the method was applied to empirical data for four model drugs: non-steroidal anti-inflammatory drugs (NSAIDs), warfarin, bendroflumethiazide, and levothyroxine.

RESULTS

Simulation studies found negligible bias when the data-generating model for the IAD coincided with the FRD used in the WTD estimation (Log-Normal). When the IAD consisted of a mixture of two Log-Normal distributions, but was analyzed with a single Log-Normal distribution, relative bias did not exceed 9%. Using a Log-Normal FRD, we estimated prescription durations of 117, 91, 137, and 118 days for NSAIDs, warfarin, bendroflumethiazide, and levothyroxine, respectively. Similar results were found with a Weibull FRD.

CONCLUSIONS

The algorithm allows valid estimation of single prescription durations, especially when the WTD reliably separates current users from incident users, and may replace ad-hoc decision rules in automated implementations. Copyright © 2016 John Wiley & Sons, Ltd.