Studies using Australia's Pharmaceutical Benefits Scheme data for pharmacoepidemiological research: a systematic review of the published literature (1987-2013)

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.

Variation in clinical practice guideline recommendations for medication use in pregnancy in Australia: A systematic review

BACKGROUND

Medication use in pregnancy is common; however, it is unknown if clinical practice guideline (CPG) prescribing recommendations referred to in Australia at the state, national and international level are consistent.

AIMS

This systematic review aimed to: (1) identify sources of CPGs that inform prescribing during pregnancy in Australia; (2) assess CPG quality; and (3) evaluate variation within CPG recommendations for medication use in three common conditions in pregnancy: prophylactic antibiotics following premature rupture of membranes (PROM) at term, antidepressants in pregnancy and metformin in gestational diabetes mellitus (GDM).

MATERIALS AND METHODS

A literature search was conducted across PubMed, Scopus and EMBASE databases. Grey literature was identified through publicly available Australian policy statements. Prescribing recommendations for prophylactic antibiotics following PROM at term, antidepressants in pregnancy and metformin in GDM, were compared at the state, national and international levels. CPG quality was assessed using the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument.

RESULTS

We identified 39 CPG sources that inform prescribing during pregnancy in Australia. CPG quality varied between resources. There was minor variation in recommendations for antibiotic prophylaxis in PROM at term. Recommendations regarding metformin use in GDM were also variable, with CPGs either recommending its use as a first-line agent when lifestyle modifications are not effective or when insulin therapy is not practicable. Recommendations for antidepressant use were consistent across CPGs analysed.

CONCLUSION

Multiple CPGs exist to inform prescribing during pregnancy in Australia, with variation present within CPG quality and recommendations. These findings offer insight into potential sources of variation in maternal and neonatal health outcomes.

Investigating the impact of a national educational program on patient adherence to osteoporosis medications

Interrupted time series analysis (ITS) measured improvements in osteoporosis medication adherence after a national education program. The proportion of patients who were adherent to treatment increased following the program.

INTRODUCTION

The NPS MedicineWise osteoporosis program, implemented nationally in 2015-2016 in Australia, sought to improve adherence to osteoporosis medicines using evidence-based multifaceted large-scale educational interventions targeting general practitioners.

METHODS

We undertook a retrospective, observational study using ITS analysis from 1 December 2011 to 31 December 2019 using a 10% sample of Pharmaceutical Benefits Scheme (PBS) dispensing data for 71,093 patients ≥ 45 years. The adherence measure was the percentage of patients with a proportion of days covered (PDC) ≥ 80%.

RESULTS

The program significantly increased adherence to osteoporosis medicines. After 12 months, the estimated adherence rate with the program was 48.4% (95% CI, 47.4-49.4%). Without the program, adherence would have fallen to 43.5% (95% CI, 42.5-44.5%). There was a further increase in adherence by the end of the study period (44 months after the program). Among patients prescribed denosumab only, despite a significant increase in adherence following the program, adherence rates were overall sub-optimal (65.0% 12 months following the program).

CONCLUSIONS

The NPS MedicineWise osteoporosis program significantly increased osteoporosis medicine adherence. The program changed primary care prescriber behavior and improved treatment adherence. However, some patients had a period of treatment discontinuation, placing them at increased risk of fracture. A focused program emphasizing the importance of long-term adherence with denosumab (including switching to bisphosphonates if treatment is discontinued) may be warranted to further improve the quality use of osteoporosis treatment in Australia.

Dispensing of psychotropic medications to Australian children and adolescents before and during the COVID-19 pandemic, 2013-2021: a retrospective cohort study

OBJECTIVE

To determine longitudinal patterns of dispensing of antidepressant, anxiolytic, antipsychotic, psychostimulant, and hypnotic/sedative medications to children and adolescents in Australia during 2013-2021.

DESIGN

Retrospective cohort study; analysis of 10% random sample of Pharmaceutical Benefits Scheme (PBS) dispensing data.

PARTICIPANTS, SETTING

People aged 18 years or younger dispensed PBS-subsidised psychotropic medications in Australia, 2013-2021.

MAIN OUTCOME MEASURES

Population prevalence of dispensing of psychotropic medications to children and adolescents, by psychotropic class, gender, and age group (0-6, 7-12, 13-18 years).

RESULTS

The overall prevalence of psychotropic dispensing to children and adolescents was 33.8 per 1000 boys and 25.2 per 1000 girls in 2013, and 60.0 per 1000 boys and 48.3 per 1000 girls in 2021. The prevalence of psychotropic polypharmacy was 5.4 per 1000 boys and 3.7 per 1000 girls in 2013, and 10.4 per 1000 boys and 8.3 per 1000 girls in 2021. Prevalent dispensing during 2021 was highest for psychostimulants (boys, 44.0 per 1000; girls, 17.4 per 1000) and antidepressants (boys, 20.4 per 1000; girls, 33.8 per 1000). During 2021, the prevalence of dispensing was higher than predicted by extrapolation of 2013-2019 data for many classes, including antidepressants (boys: +6.1%; 95% CI, 1.1-11.1%; girls: +22.2%; 95% CI, 17.4-26.9%), and psychostimulants (boys: +14.5%; 95% CI, 8.0-21.1%; girls: +27.7%; 95% CI, 18.9-36.6%). The increases were greatest for girls aged 13-18 years (antidepressants: +20.3%; 95% CI, 16.9-23.7%; psychostimulants: +39.0%; 95% CI, 27.9-50.0%).

CONCLUSIONS

The prevalence of both psychotropic dispensing and psychotropic polypharmacy for children and adolescents were twice as high in 2021 as in 2013. The reasons and appropriateness of the marked increases in psychotropic dispensing during the COVID-19 pandemic, particularly to adolescent girls, should be investigated.

Restricting access to antibiotics: The effectiveness of a 'no repeats' government policy intervention

BACKGROUND

Australia has a high rate of antibiotic use. Government policy interventions are one strategy to optimise the use of antibiotics. On 1 April 2020, the Australian Government Department of Health introduced a policy intervention to increase the quality use of four antibiotics.

OBJECTIVES

To assess if the government policy intervention improved the appropriate supply of the four antibiotics amoxicillin, amoxicillin-clavulanic acid, cefalexin and roxithromycin.

METHOD

This study employed a retrospective cohort study design comparing a 10% sample (n = 345,018) of four antibiotics prescribed and dispensed in Australia during a three-month period (May, June, July) in 2019, and again in 2020 (after the policy intervention). The 10% sample of PBS data was obtained from the Australian Government Department of Health. Descriptive statistics, bivariate and multivariable logistic regression analysis were carried out.

RESULTS

The results suggest the policy change improved the appropriate supply of original prescriptions in 2020 compared to 2019 OR = 1.75 (95% CI = 1.68-1.82, p < 0.001), and appropriate supply of repeat prescriptions OR = 1.56 (95% CI = 1.25-1.96, p < 0.001). In 2020, the proportion of appropriate supply of original prescriptions increased by an absolute difference of 1.8% (95% CI = 1.6-1.9%; P < 0.001), and appropriate supply of repeat prescriptions increased by 3.9% (95% CI = 2.2-5.5%; P < 0.001). The total number of antibiotic prescriptions prescribed and dispensed in 2019 (N = 219,960) reduced in 2020 (N = 125,058) after the policy intervention.

CONCLUSION

The study provides evidence for the impact of a government policy intervention to improve the appropriate supply of antibiotics, although some of the reduction in antibiotic use was likely due to the concomitant COVID-19 pandemic. Further research is required to assess the impact of the intervention outside a pandemic.

Validity of three risk prediction models for dementia or cognitive impairment in Australia

BACKGROUND

no studies have compared the predictive validity of different dementia risk prediction models in Australia.

OBJECTIVES

(i) to investigate the predictive validity of the Australian National University-Alzheimer's Disease Risk Index (ANU-ADRI), LIfestyle for BRAin Health (LIBRA) Index and cardiovascular risk factors, ageing and dementia study (CAIDE) models for predicting probable dementia/cognitive impairment in an Australian cohort. (ii) To develop and assess the predictive validity of a new hybrid model combining variables from the three models.

METHODS

the Hunter Community Study (HCS) included 3,306 adults aged 55-85 years with a median follow-up of 7.1 years. Probable dementia/cognitive impairment was defined using Admitted Patient Data Collection, dispensing of cholinesterase inhibitors or memantine, or a cognitive test. Model validity was assessed by calibration and discrimination. A hybrid model was developed using deep neural network analysis, a machine learning method.

RESULTS

120 (3.6%) participants developed probable dementia/cognitive impairment. Mean calibration by ANU-ADRI, LIBRA, CAIDE and the hybrid model was 19, 0.5, 4.7 and 3.4%, respectively. The discrimination of the models was 0.65 (95% CI 0.60-0.70), 0.65 (95% CI 0.60-0.71), 0.54 (95% CI 0.49-0.58) and 0.80 (95% CI 0.78-0.83), respectively.

CONCLUSION

ANU-ADRI and LIBRA were better dementia prediction tools than CAIDE for identification of high-risk individuals in this cohort. ANU-ADRI overestimated and LIBRA underestimated the risk. The new hybrid model had a higher predictive performance than the other models but it needs to be validated independently in longitudinal studies.

Using electronic admission data to monitor temporal trends in local medication use: Experience from an Australian tertiary teaching hospital

Background and aims: Medication usage varies according to prescribing behavior, professional recommendations, and the introduction of new drugs. Local surveillance of medication usage may be useful for understanding and comparing prescribing practices by healthcare providers, particularly in countries such as Australia that are in the process of enhancing nationwide data linkage programs. We sought to investigate the utility of electronic hospital admission data to investigate local trends in medication use, to determine similarities and differences with other Australian studies, and to identify areas for targeted interventions.

Methods: We performed a retrospective longitudinal analysis using combined data from a hospital admissions administrative dataset from a large tertiary teaching hospital in Adelaide, South Australia and a hospital administrative database documenting medication usage matched for the same set of patients. All adult admissions over a 12-year period, between 1 January 2007 and 31st December 2018, were included in the study population. Medications were categorized into 21 pre-defined drug classes of interest according to the ATC code list 2021.

Results: Of the 692,522 total admissions, 300,498 (43.4%) had at least one recorded medication. The overall mean number of medications for patients that were medicated increased steadily from a mean (SD) of 5.93 (4.04) in 2007 to 7.21 (4.98) in 2018. Results varied considerably between age groups, with the older groups increasing more rapidly. Increased medication usage was partly due to increased case-complexity with the mean (SD) Charlson comorbidity index increasing from 0.97 (1.66) in 2007-to-2012 to 1.17 (1.72) in 2013-to-2018 for medicated patients. Of the 21 medication classes, 15 increased (p < 0.005), including antithrombotic agents; OR = 1.18 [1.16–1.21], proton pump inhibitors; OR = 1.14 [1.12–1.17], statins; OR = 1.12; [1.09–1.14], and renin-angiotensin system agents; OR = 1.06 [1.04–1.08], whilst 3 decreased (p < 0.005) including anti-inflammatory drugs (OR = 0.55; 99.5% CI = 0.53–0.58), cardiac glycosides (OR = 0.81; 99.5% CI = 0.78–0.86) and opioids (OR = 0.82; 99.5% CI = 0.79–0.83). The mean number of medications for all admissions increased between 2007 and 2011 and then declined until 2018 for each age group, except for the 18-to-35-year-olds.

Conclusion: Increased medication use occurred in most age groups between 2007 and 2011 before declining slightly even after accounting for increased comorbidity burden. The use of electronic hospital admission data can assist with monitoring local medication trends and the effects of initiatives to enhance the quality use of medicines in Australia.

The Medicines Intelligence Centre of Research Excellence: Co-creating real-world evidence to support the evidentiary needs of Australian medicines regulators and payers

Regulators and payers play a pivotal role in facilitating timely and affordable access to safe and efficacious medicines. They use evidence generated from randomised clinical trials (RCTs) to support decisions to register and subsidise medicines. However, at the time of registration and subsidy approval, regulators and payers face uncertainty about how RCT outcomes will translate to real-world clinical practice. In response to this situation, medicines policy agencies worldwide have endorsed the use of real-world data (RWD) to derive novel insights on the use and outcomes of prescribed medicines. Recent reforms around data availability and use in Australia are creating unparalleled data access and opportunities for Australian researchers to undertake large-scale research to generate evidence on the safety and effectiveness of medicines in the real world. Highlighting the critical importance of research in this area, Quality Use of Medicines and Medicine Safety was announced as Australia's 10th National Health Priority in 2019. The National Health and Medical Research Council, Medicines Intelligence Centre of Research Excellence (MI-CRE) has been formed to take advantage of the renewed focus on quality use of medicines and the changing data landscape in Australia. It will generate timely research supporting the evidentiary needs of Australian medicines regulators and payers by accelerating the development and translation of real-world evidence on medicines use and outcomes. MI-CRE is developing a coordinated approach to identify, triage and respond to priority questions where there are significant uncertainties about medicines use, (cost)-effectiveness, and/or safety and creating a data ecosystem that will streamline access to Australian data to enable researchers to generate robust evidence in a timely manner. This paper outlines how MI-CRE will partner with policy makers, clinicians, and consumer advocates to leverage real-world data to co-create real-world evidence, to improve quality use of medicines and reduce medicine-related harm.

Generating Real-World Evidence on the Quality Use, Benefits and Safety of Medicines in Australia: History, Challenges and a Roadmap for the Future

Australia spends more than $20 billion annually on medicines, delivering significant health benefits for the population. However, inappropriate prescribing and medicine use also result in harm to individuals and populations, and waste of precious health resources. Medication data linked with other routine collections enable evidence generation in pharmacoepidemiology; the science of quantifying the use, effectiveness and safety of medicines in real-world clinical practice. This review details the history of medicines policy and data access in Australia, the strengths of existing data sources, and the infrastructure and governance enabling and impeding evidence generation in the field. Currently, substantial gaps persist with respect to cohesive, contemporary linked data sources supporting quality use of medicines, effectiveness and safety research; exemplified by Australia's limited capacity to contribute to the global effort in real-world studies of vaccine and disease-modifying treatments for COVID-19. We propose a roadmap to bolster the discipline, and population health more broadly, underpinned by a distinct capability governing and streamlining access to linked data assets for accredited researchers. Robust real-world evidence generation requires current data roadblocks to be remedied as a matter of urgency to deliver efficient and equitable health care and improve the health and well-being of all Australians.

Effect of a state hospital formulary on medicines utilisation in Australia

ObjectiveThe provision of medicines through state public hospitals is comparatively restrictive compared with the federally funded Pharmaceutical Benefits Scheme (PBS). Individual states are progressively moving towards statewide medicines formularies. Although a statewide formulary has existed in Queensland for some time. The effects of hospital formularies on medicines utilisation and policy in Australia has not been quantified. Thus, the aim of the present study was to quantify the effects of the Queensland Health List of Approved Medicines (LAM) on medicines utilisation in Queensland at a state and PBS-purchasing level and describe the implications for medicines policy.MethodsThis study used a quasi-experimental design with an interrupted time series (with control for PBS) examining utilisation effects of medicines within the therapeutic classes of proton pump inhibitors and non-vitamin K oral anticoagulants with LAM listing or delisting.ResultsThe LAM was demonstrated to be highly effective at controlling utilisation within Queensland Health purchasing. Effects on PBS utilisation were evident, resulting in increases in generic utilisation (where available) and associated reduced total costs both within Queensland Health and to the PBS. The full benefit is likely underestimated due to limitations in the PBS datasets.ConclusionThe LAM is a highly effective state medicines policy tool with demonstrable effects on PBS utilisation. With increased use of statewide medicines formularies, this will be an increasingly relevant aspect of Australia's overall medicines policy.What is known about the topic?State medicines policy is comparatively restrictive compared with the federal PBS. Most Australian states have, or are developing, statewide medicines formularies.What does this paper add?By examining several classes of medicines, a substantial quantitative effect of the Queensland state formulary on both state and PBS medicines utilisation can be demonstrated. Increased use of generic medicines and reduced costs are seen.What are the implications for practitioners?With increased use of state medicines formularies, state medicines formularies will become increasingly relevant to medicines policy makers and advocates at both the state and federal level.

Development and Validation of a Model to Identify Alzheimer's Disease and Related Syndromes in Administrative Data

BACKGROUND

Administrative data are used in the field of Alzheimer's Disease and Related Syndromes (ADRS), however their performance to identify ADRS is unknown.

OBJECTIVE

i) To develop and validate a model to identify ADRS prevalent cases in French administrative data (SNDS), ii) to identify factors associated with false negatives.

METHODS

Retrospective cohort of subjects ≥ 65 years, living in South-Western France, who attended a memory clinic between April and December 2013. Gold standard for ADRS diagnosis was the memory clinic specialized diagnosis. Memory clinics' data were matched to administrative data (drug reimbursements, diagnoses during hospitalizations, registration with costly chronic conditions). Prediction models were developed for 1-year and 3-year periods of administrative data using multivariable logistic regression models. Overall model performance, discrimination, and calibration were estimated and corrected for optimism by resampling. Youden index was used to define ADRS positivity and to estimate sensitivity, specificity, positive predictive and negative probabilities. Factors associated with false negatives were identified using multivariable logistic regressions.

RESULTS

3360 subjects were studied, 52% diagnosed with ADRS by memory clinics. Prediction model based on age, all-cause hospitalization, registration with ADRS as a chronic condition, number of anti-dementia drugs, mention of ADRS during hospitalizations had good discriminative performance (c-statistic: 0.814, sensitivity: 76.0%, specificity: 74.2% for 2013 data). 419 false negatives (24.0%) were younger, had more often ADRS types other than Alzheimer's disease, moderate forms of ADRS, recent diagnosis, and suffered from other comorbidities than true positives.

CONCLUSION

Administrative data presented acceptable performance for detecting ADRS. External validation studies should be encouraged.

The changing face of Australian data reforms: impact on pharmacoepidemiology research

OBJECTIVE

A wealth of data is generated through Australia's universal health care arrangements. However, use of these data has been hampered by different federal and state legislation, privacy concerns and challenges in linking data across jurisdictions. A series of data reforms have been touted to increase population health research capacity in Australia, including pharmacoepidemiology research. Here we catalogued research leveraging Australia's Pharmaceutical Benefits Scheme (PBS) data (2014-2018) and discussed these outputs in the context of previously implemented and new data reforms.

METHODS

We conducted a systematic review of population-based studies using PBS dispensing claims. Independent reviewers screened abstracts of 4,996 articles and 310 full-text manuscripts. We characterised publications according to study population, analytical approach, data sources used, aims and medicines focus.

RESULTS

We identified 180 studies; 133 used individual-level data, 70 linked PBS dispensing claims with other health data (66 across jurisdictions). Studies using individual-level data focussed on Australians receiving government benefits (87 studies) rather than all PBS-eligible persons. 63 studies examined clinician or patient practices and 33 examined exposure-outcome relationships (27 evaluated medicines safety, 6 evaluated effectiveness). Medicines acting on the nervous and cardiovascular system account for the greatest volume of PBS medicines dispensed and were the most commonly studied (67 and 40 studies, respectively). Antineoplastic and immunomodulating agents account for approximately one third of PBS expenditure but represented only 10% of studies in this review.

CONCLUSIONS

The studies in this review represent more than a third of all population-based pharmacoepidemiology research published in the last three decades in Australia. Recent data reforms have contributed to this escalating output. However, studies are concentrated among specific subpopulations and medicines classes, and there remains a limited understanding of population benefits and harms derived from medicines use. The current draft Data Availability and Transparency legislation should further bolster efforts in population health research.

Examining the dispensing patterns of antipsychotics in Australia from 2006 to 2018 - A pharmacoepidemiology study

BACKGROUND

Antipsychotic medications can be prescribed in Australia by medical and nurse practitioners under the Pharmaceutical Benefits Scheme (PBS). The current pharmacoepidemiology study aims to determine the dispensing rates of antipsychotic medicines in Australia, and to produce and examine a time-trend of the dispensing patterns of these medicines.

METHODS

Dispensing counts of antipsychotic medication from 2006 to 2018 were accessed from the PBS dataset. All of the antipsychotic medicines dispensed were included for time trend analysis. Cumulative dispensing counts and defined daily dose (DDD) per 1000 concessional population days (DPD) were analysed for the purpose of time trend analysis.

RESULTS

Sixteen antipsychotic medications were assessed and had a total cumulative dispensing count of 33, 732, 404. Olanzapine had the highest cumulative prescription count and Quetiapine experienced the highest average dispensing count and rate as determined by DPD. Twelve out of the sixteen medications were second-generation antipsychotics (SGAs). Overall, eleven out of the sixteen medications (aripiprazole, asenapine, brexpiprazole, clozapine, flupentixol, lurasidone, olanzapine, paliperidone, quetiapine, ziprasidone, zuclopenthixol) had an increase in both dispensing count and rate, as expressed per DPD.

CONCLUSIONS

The current study highlights the increasing prescription rates of SGAs and the stagnation of FGA prescription among Australian health practitioners. This is observed through particularly large increase in the dispensing rates of Olanzapine and Quetiapine. Further interdisciplinary investigation is required to ensure that these medications are being prescribed under the appropriate medical rationale, particularly to groups that are vulnerable to the adverse effects of the medications.

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.

Pharmacological treatment initiation for type 2 diabetes in Australia: are the guidelines being followed?

AIM

To determine the patterns and predictors of pharmacological treatment initiation for type 2 diabetes and whether treatment initiation is consistent with Australian clinical practice guidelines that recommend metformin monotherapy.

METHODS

Individuals aged 40-99 years initiating a non-insulin type 2 diabetes medication between July 2013 and February 2018 were identified from a 10% random national sample of pharmacy dispensing data. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the predictors of initiating sulfonylurea monotherapy, non-guideline monotherapy and combination therapy compared with metformin monotherapy. Predictors included age, sex, initiation year and comorbidities determined using the Rx-Risk comorbidity index.

RESULTS

Of the 47 860 initiators, [47% women, mean age 60.7 (sd 12.1) years], 85.8%, 4.6%, 1.9% and 7.7% received metformin monotherapy, sulfonylurea monotherapy, non-guideline monotherapy and combination therapy, respectively. Increasing age was associated with increasing odds of initiating sulfonylurea monotherapy and non-guideline monotherapy. Combination therapy initiation was less likely in women (OR 0.74, 95% CI 0.69-0.79) and people with more comorbidities (e.g. OR 0.36, 95% CI 0.29-0.44 for seven or more comorbidities vs. no comorbidities) but more likely in congestive heart failure (OR 1.42, 95% CI 1.22-1.65), cerebrovascular disease (OR 1.50, 95% CI 1.32-1.69) and dyslipidaemia (OR 1.29, 95% CI 1.19-1.40).

CONCLUSION

Treatment initiation in Australia is largely consistent with clinical practice guidelines, with 86% of individuals initiating metformin monotherapy. Initiation on combination therapy was more common in men and in those with fewer comorbidities.

Identifying incident cancer cases in dispensing claims: A validation study using Australia's Repatriation Pharmaceutical Benefits Scheme (PBS) data

Introduction

Dispensing claims are used commonly as proxy measures in pharmacoepidemiological studies; however, their validity is often untested.

Objectives

To assess the performance of a proxy for identifying cancer cases based on the dispensing of anticancer medicines and estimate the misclassification of cancer status and potential for bias researchers may encounter when using this proxy.

Methods

We conducted our validation study using Department of Veterans’ Affairs (DVA) client data linked with the New South Wales (NSW) Cancer Registry and Repatriation Pharmaceutical Benefits Scheme data. We included DVA clients aged ≥65 years residing in NSW between July 2004 and December 2012. We matched clients with a cancer diagnosis to clients without a diagnosis based on demographic characteristics and available observation time. We used dispensing claims for anticancer medicines dispensed between July 2004 and December 2013 as a proxy to identify clients with cancer and calculated sensitivity, specificity, positive predictive values and negative predictive values compared with cancer registrations (gold standard), overall and by cancer site. We illustrated misclassification by the proxy in a cohort of people initiating opioid therapy. Using the proxy, we excluded people with cancer from the cohort, in an attempt to delineate people potentially using opioids for cancer rather than chronic non-cancer pain.

Results

We identified 15,679 new cancer diagnoses in 14,112 DVA clients from the cancer registry and 62,663 clients without a diagnosis. Sensitivity of the proxy based on dispensing claims was 30% for all cancers and around 20% for specific cancers (range: 10-67%). Specificity was above 90% for all cancers. The dispensing proxy correctly identified 26% of people with a cancer diagnosis who initiated opioid therapy and failed to identify 74% those with a cancer diagnosis; the proxy was most robust for clients with breast cancer where 61% were correctly identified by proxy.

Conclusions

Using dispensing of anticancer medicines to identify people with a cancer diagnosis performed poorly. Excluding patients with evidence of anticancer medicine use from cohort studies may result removal of a disproportionate number of women with breast cancer. Researchers excluding or otherwise using anticancer medicine dispensing to identify people with cancer in pharmacoepidemiological studies should acknowledge the potential biases introduced to their findings.

Keywords

cancer, diagnosis, proxy, dispensing records, validation study

Assessment of Medication Safety Using Only Dispensing Data

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of the published studies that have been used to generate evidence on the safety of medicine use when only medication dispensing data are available.

RECENT FINDINGS

Medication dispensing databases are increasingly available for research on large populations, particularly in countries that provide universal coverage for medicines. These data are often used for drug utilisation studies to identify inappropriate medicine use at the population level that may be associated with known safety issues. Lack of coded diagnoses, to identify outcomes, and lack of data on confounders can limit use of these data in practice for medication safety assessment. To overcome these issues, studies have exploited the fact that symptoms of adverse effects of medications can be treated with other medications, for example antidepressants to treat depression or oxybutynin to treat urinary incontinence. The challenge of unmeasured confounding has been addressed by implementing self-controlled study designs that use within-person comparisons and provide inherent control for confounding. Prescription sequence symmetry analysis (SSA) is a within-person study design that has been demonstrated as a useful tool for safety signal generation in dispensing data.

SUMMARY

Using medicine initiation as a proxy for the development of adverse events can help to generate evidence of the safety of medicines when only medication dispensing data are available. Careful consideration, however, should be given to the sensitivity and specificity of the proxy medicine for the adverse event and potential for time-varying confounding due to trends in medicine utilisation. Data-mining approaches using dispensing data have the potential to improve safety assessments; however, the challenge of unmeasured confounding with these methods remains to be investigated.

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.

A methodological protocol for selecting and quantifying low-value prescribing practices in routinely collected data: an Australian case study

Background

Growing imperatives for safety, quality and responsible resource allocation have prompted renewed efforts to identify and quantify harmful or wasteful (low-value) medical practices such as test ordering, procedures and prescribing. Quantifying these practices at a population level using routinely collected health data allows us to understand the scale of low-value medical practices, measure practice change following specific interventions and prioritise policy decisions. To date, almost all research examining health care through the low-value lens has focused on medical services (tests and procedures) rather than on prescribing. The protocol described herein outlines a program of research funded by Australia’s National Health and Medical Research Council to select and quantify low-value prescribing practices within Australian routinely collected health data.

Methods

We start by describing our process for identifying and cataloguing international low-value prescribing practices. We then outline our approach to translate these prescribing practices into indicators that can be applied to Australian routinely collected health data. Next, we detail methods of using Australian health data to quantify these prescribing practices (e.g. prevalence of low-value prescribing and related costs) and their downstream health consequences. We have approval from the necessary Australian state and commonwealth human research ethics and data access committees to undertake this work.

Discussion

The lack of systematic and transparent approaches to quantification of low-value practices in routinely collected data has been noted in recent reviews. Here, we present a methodology applied in the Australian context with the aim of demonstrating principles that can be applied across jurisdictions in order to harmonise international efforts to measure low-value prescribing. The outcomes of this research will be submitted to international peer-reviewed journals. Results will also be presented at national and international pharmacoepidemiology and health policy forums such that other jurisdictions have guidance to adapt this methodology.

Electronic supplementary material

The online version of this article (doi:10.1186/s13012-017-0585-9) contains supplementary material, which is available to authorized users.

Twenty-five years of prescription opioid use in Australia: a whole-of-population analysis using pharmaceutical claims

AIM

The aim of this paper is to investigate 25-year trends in community use of prescribed opioid analgesics in Australia, and to map these trends against major changes to opioid registration and subsidy.

METHODS

We obtained dispensing data from 1990 to 2014 from two sources: dispensing claims processed under Australia's national drug subsidy programme, the Pharmaceutical Benefits Scheme, including under co-payment records from 2012; and estimates of non-subsidized medicine use from a survey of Australian pharmacies (until 2011). Utilization was expressed in defined daily doses (DDD)/1000 population/day.

RESULTS

Opioid dispensing increased almost four-fold between 1990 and 2014, from 4.6 to 17.4 DDD/1000 pop/day. In 1990, weak, short-acting or orally administered opioids accounted for over 90% of utilization. Use of long-acting opioids increased over 17-fold between 1990 and 2000, due primarily to the subsidy of long-acting morphine and increased use of methadone for pain management. Between 2000 and 2011, oxycodone, fentanyl, buprenorphine, tramadol and hydromorphone use increased markedly. Use of strong opioids, long-acting and transdermal preparations also increased, largely following the subsidy of various opioids for noncancer pain. In 2011, the most dispensed opioids were codeine (41.1% of total opioid use), oxycodone (19.7%) and tramadol (16.1%); long-acting formulations comprised approximately half, and strong opioids 40%, of opioid dispensing.

CONCLUSIONS

Opioid utilization in Australia is increasing, although these figures remain below levels reported in the US and Canada. The increased use of opioids was largely driven by the subsidy of long-acting formulations and opioids for the treatment of noncancer pain.

Use of prescription medicines in Australian women of child-bearing age

Background

This study aimed to examine current utilisation of prescribed medicines amongst Australian women of child-bearing age, with a particular focus on the extent of use of medicines in Category D and X risk groups, which are moderate and high risk teratogens, respectively. The use of those medicines may pose risk of birth defects in pregnant women.

Methods

A retrospective cross-sectional study was undertaken involving all women of child-bearing age (15 to 44 years) who were dispensed medicines in 2013 using the 10 % random sample of dispensing data from the Australian Government Department of Human Services. Dispensing patterns were reported by medicine, therapeutic class, pregnancy risk category and women’s age.

Results

Over one-third of women aged 15 to 44 years received at least one prescribed medicine in 2013. Psychoanaleptics, antibiotics and analgesics were the top three classes. Around 9 % of all dispensings were for medicines from risk category D, with statins, agents acting on renin-angiotensin system, and some anti-epileptic agents being the most commonly used. Both statins and agents acting on renin-angiotensin system showed increasing use with age, estimated to be 35,600 women nationally for each group. Collectively between 2 % and 4 % of women used anti-epileptics from risk category D in each year of age, with overall use estimated to be 51,000 women nationally. Below 1 % of all dispensings were for category X medicines, mainly isotretinoin.

Conclusions

It is important for medical practitioners to offer counselling around pregnancy planning and the risk of birth defects when prescribing moderate or high risk teratogens to women in child-bearing age. For the antihypertensives and some anti-epileptics, alternative medicines with lower risk categorization are available.

The Australian Pharmaceutical Benefits Scheme data collection: a practical guide for researchers

Background

The Pharmaceutical Benefits Scheme (PBS) is Australia’s national drug subsidy program. This paper provides a practical guide to researchers using PBS data to examine prescribed medicine use.

Findings

Excerpts of the PBS data collection are available in a variety of formats. We describe the core components of four publicly available extracts (the Australian Statistics on Medicines, PBS statistics online, section 85 extract, under co-payment extract). We also detail common analytical challenges and key issues regarding the interpretation of utilisation using the PBS collection and its various extracts.

Conclusions

Research using routinely collected data is increasing internationally. PBS data are a valuable resource for Australian pharmacoepidemiological and pharmaceutical policy research. A detailed knowledge of the PBS, the nuances of data capture, and the extracts available for research purposes are necessary to ensure robust methodology, interpretation, and translation of study findings into policy and practice.