Prescribing In General Practice Research Articles

Persistence and adherence with mirabegron versus antimuscarinics in overactive bladder: retrospective analysis of a UK General Practice Prescription Database

Persistence and adherence with mirabegron versus antimuscarinics in overactive bladder: retrospective analysis of a UK General Practice Prescription Database

Changing antibiotic prescribing in General Practice – The results of the SIMPle process evaluation

Objective: The Supporting the Improvement and Management of Prescribing for Urinary Tract Infections (SIMPle) study, a cluster randomized trial, sought to improve the quality of antibiotic prescribing for Urinary Tract Infections in General Practices located in the west of Ireland. This paper presents the process evaluation and intends to provide insights into the antibiotic prescribing behaviour of the General Practitioners (GPs) during the intervention. The paper discusses how the social marketing intervention developed as part of SIMPle resulted in GPs prescribing more first line antibiotics, the aim of the trial. However it also offers insights into why antibiotic prescriptions increased during the intervention period.Methods: Fifteen GP interviews and summative intervention components including monitoring practice participation and information provided to the study team. Thematic analysis was used to analyze transcripts.Results: GPs recognized the value of consultation coding to produce practice specific audit and feedback reports including current antibiotic prescribing and providing evidence which motivated change.Conclusions: The SIMPle study was successfully integrated into routine care. By simplifying GPs’ access to up to date evidence on their prescribing behaviors, GPs can be positively influenced beyond the context of an intervention.

Safer Prescribing and Care for the Elderly (SPACE): feasibility of audit and feedback plus practice mail-out to patients with high-risk prescribing.

INTRODUCTION High-risk prescribing in general practice is common and places patients at increased risk of adverse events. AIM The Safer Prescribing and Care for the Elderly (SPACE) intervention, comprising audit and feedback plus practice mail-out to patients with high-risk prescribing, was designed to promote medicines review and support safer prescribing. This study aims to test the SPACE intervention feasibility in general practice. METHODS This feasibility study involved an Auckland Primary Health Organisation (PHO), a clinical advisory pharmacist, two purposively sampled urban general practices, and seven GPs. The acceptability and utility of the SPACE intervention were assessed by semi- structured interviews involving study participants, including 11 patients with high-risk prescribing. Interviews were audio-recorded, transcribed verbatim and analysed using a general inductive approach to identify emergent themes. RESULTS The pharmacist said the SPACE intervention facilitated communication with GPs, and provided a platform for their clinical advisory role at no extra cost to the PHO. GPs said the feedback session with the pharmacist was educational but added to time pressures. GPs selected 29 patients for the mail-out. Some GPs were concerned the mail-out might upset patients, but patients said they felt cared for. Some patients intended to take the letter to their next appointment and discuss their medicines with their GP; others said there were already many things to discuss and not enough time. Some patients were confused by the medicines information brochure. DISCUSSION The SPACE intervention is feasible in general practice. The medicines information brochure needs simplification. Further research is needed to test the effect of SPACE on high-risk prescribing.

Social prescribing in general practice

Social prescribing in general practice

Validity of prescribing indicators for assessing quality of antibiotic use in Australian general practice.

The aim of this study was to assess the validity of a set of European quality indicators for assessing antimicrobial prescribing in Australian General Practice. A modified UCLA/RAND appropriateness method was used to assess the validity of 30 antimicrobial prescribing indicators. An expert panel of 12 general practitioners scored the validity of each indicator for measuring quality in Australian general practice. Four quality domains were considered: monitoring antibiotic resistance, benefit to individual patients, value for money and value to policymakers. Panelmembers were also asked to comment on the relevance to the Australian context and proposed benchmarks for each indicator. All panel members were in agreement regarding the validity of each indicator in each of the specified domains with exception of the indicator assessing the use of systemic antibiotics for pneumonia. The majority of the indicators and their associated benchmarks were considered valid for assessing quality in Australian General Practice, however, there were differences regarding the quality domain that each indicator was considered valid for. Monitoring quality considering individual patient benefit was the most problematic domain with respect to validity. This study demonstrates the validity of 30 European indicators for assessing quality of antimicrobial prescribing in general practice in a non-European setting and provides guidance regarding acceptable benchmarks for the indicators. With international concerns regarding misuse of antibiotics and global interest in prescribing quality, valid evidence-based antimicrobial prescribing indicators and associated benchmarks are an essential tool for assessing prescribing quality.

Antibiotic prescribing in Danish general practice 2004-13.

Antibiotic consumption in the primary care sector is often perceived as synonymous with consumption in general practice despite the fact that few countries stratify the primary care sector by providers' medical specialty. We aimed to characterize and quantify antibiotic use in Danish general practice relative to the entire primary care sector. This was a registry-based study including all patients who redeemed an antibiotic prescription between July 2004 and June 2013 at a Danish community pharmacy. Antibiotic use was expressed as DDDs and treatments/1000 inhabitants/day (DIDs and TIDs, respectively) and assessed according to antibiotic spectrum (narrow versus broad) and their anatomical therapeutic classification codes in total as well as in six age groups. The contribution of general practice to the entire antibiotic use in the primary care sector declined during the study period (TIDs, 79%-75%; DIDs, 77%-73%). Antibiotic use in general practice increased 8% when expressed as DIDs, while a 9% decrease was observed when expressed as TIDs. The use of broad-spectrum agents increased while narrow-spectrum agents decreased. The decline in antibiotic use was most prominent in children aged <5 years, while elderly patients were increasingly prescribed antibiotics. Using the entire primary care sector as a proxy for general practice prescribing is imprecise. Antibiotic use in general practice is at a stable high level, but DID and TID analyses show different trends and both should be applied when detailing changes in antibiotic consumption. While children are prescribed fewer narrow-spectrum agents, the observed increase in the use of broad-spectrum agents is worrisome and should be addressed in future interventions.

Dental consultations in UK general practice and antibiotic prescribing rates: a retrospective cohort study.

The frequency of consulting for dental problems in general medical practice, and antibiotic prescribing associated with these consultations, is poorly described. To describe consultation rates and antibiotic use for dental problems in UK general medical practice, and explore factors associated with antibiotic prescribing for dental conditions. A retrospective cohort study using Clinical Practice Research Datalink, a database of general practice patient records in the UK. All dental consultations between 2004 and 2013 were identified. The main outcome was the prescription of an antibiotic during a dental consultation. Multilevel logistic regression was conducted to examine factors associated with antibiotic prescription. In all, 288 169 dental consultations were included in the cohort. The average rate of dental consultations was 6.06 consultations per 1000 patient-years. Rates of dental consultation decreased from 6.84 consultations per 1000 patient-years in 2008, to 4.23 consultations per 1000 patient-years in 2013. Consultation rates were higher among females than males and highest in patients aged 20-29 years. An antibiotic was prescribed in 57.1% of consultations. Significant predictors (P<0.001) of antibiotic prescribing included: patient middle age, male sex, and previous consultations for tooth-related problems. Antibiotics were more likely to be prescribed during consultations in December (odds ratio [OR] 1.18, 95% confidence interval [CI] = 1.13 to 1.24, P<0.001, reference month: June) and on a Monday (OR 1.10, 95% CI = 1.07 to 1.13, P<0.001) or a Friday (OR 1.15, 95% CI = 1.12 to 1.18, P<0.001, reference day: Wednesday). Consultation rates for dental problems in UK general practice are relatively low but more than half result in the prescription of an antibiotic. This raises concerns about patient morbidity and contributions to antimicrobial resistance.

Assessing the uptake and effectiveness of a quick reference guide to antibiotic prescribing in Australian general practice.

Prescribing guidelines are an essential component of antimicrobial stewardship programs in Australian hospitals. Nonetheless, the majority of antibiotic prescribing occurs in the community and the effectiveness of guidelines developed specifically to meet the needs of Australian general practice is unknown. This study aims to assess the uptake and effectiveness of a quick reference guide to antibiotic prescribing among primary care prescribers. A quick reference guide to antibiotic prescribing was developed and prescribers in five Tasmanian practices were surveyed regarding use of this guide. Thirty-three surveys were returned and, of those answering specific sections, 75% were aware of the guide and 71% had used it within the last month. The guide affected the antibiotic prescribing practice of 74% of responding prescribers; most often on choice of antibiotic; but also on duration of treatment, dose and dosing frequency. A quick reference guide to antibiotic prescribing was well received by prescribers and may usefully support efforts to improve antimicrobial stewardship in the community.

Antibiotic prescribing and patient satisfaction in primary care in England: cross-sectional analysis of national patient survey data and prescribing data.

Concerns about adverse effects on patient satisfaction may be an important obstacle to attempts to curtail antibiotic prescribing. To determine the relationship between antibiotic prescribing in general practice and reported patient satisfaction. Retrospective cross-sectional study of general practices in England. Data were obtained from the General Practice Patient Survey (GPPS) in 2012 (2.7 million questionnaires in England; 982 999 responses; response rate 36%); the national Quality and Outcomes Framework dataset for England, 2011-2012 (8164 general practices); and general practice and demographic characteristics. Standardised measures of antibiotic prescribing volumes were obtained for each practice in England during 2012-2013, together with 12 other nationally available prescribing variables. The role of antibiotic prescribing volume was identified as a determinant of GPPS scores and adjusted for demographic and practice factors using multiple linear regression. The final dataset consisted of 7800 (95.5%) practices. A total of 33.7 million antibiotic prescriptions were issued to a registered population of 53.8 million patients. Antibiotic prescribing volume was a significant positive predictor of all 'doctor satisfaction' and 'practice satisfaction' scores in the GPPS, and was the strongest predictor of overall satisfaction out of 13 prescribing variables. A theoretical 25% reduction in antibiotic prescribing volume would be associated with 0.5-1.0% lower patient satisfaction scores, a drop of 3-6 centile points in national satisfaction ranking. Patients were less satisfied in practices with frugal antibiotic prescribing. A cautious approach to antibiotic prescribing may require a trade-off in terms of patient satisfaction.

Examining variations in prescribing safety in UK general practice: cross sectional study using the Clinical Practice Research Datalink

Study question What is the prevalence of different types of potentially hazardous prescribing in general practice in the United Kingdom, and what is the variation between practices? Methods A cross...

Antibiotic prescribing in UK general dental practice: a cross-sectional study.

To assess the extent to which antibiotic prescribing in general dental practice conforms to clinical guidelines and to describe factors associated with antibiotic prescription in the absence of spreading infection or systemic involvement. A cross-sectional study of the management of adult patients with acute dental conditions by General Dental Practitioners (GDPs) in Wales, UK. Clinical information on the management of patients was compared to clinical and prescribing guidelines published by the Scottish Dental Clinical Effectiveness Programme and the Faculty of General Dental Practice (UK). Multilevel logistic regression was used to identify patient, practitioner and consultation characteristics predictive of antibiotic prescribing in the absence of infection. Antibiotics were prescribed to 57.4% of 568 patients. Over half of antibiotics (65.6%) were prescribed in situations where there was no evidence of spreading infection, and 70.6% were used without the provision of an operative intervention. Only 19.0% of antibiotics were prescribed in situations where their use was indicated by clinical guidelines. Factors associated (P < 0.05) with antibiotic prescription in the absence of infection were failure of previous operative treatment (Odds Ratio (OR) 13.57), shortage of clinical time to undertake treatment (OR 10.21), patients who were unable or unwilling to accept operative treatment (OR 4.89), patient requests for antibiotics (OR 3.69) and acute periodontal conditions (OR 3.37). A high level of inappropriate antibiotic prescribing was observed amongst the GDPs studied. Features of the healthcare environment, such as clinical time pressures, and patient-related characteristics, such as expectations for antibiotics and refusal of operative treatment, are associated with antibiotic prescribing in the absence of infection. Individuals responsible for the commissioning and delivery of dental services should seek to develop targeted interventions addressing these issues in order to ensure optimal antimicrobial stewardship within dentistry.

Measuring prevalence, reliability and variation in high-risk prescribing in general practice using multilevel modelling of observational data in a population database

BackgroundHigh-risk primary care prescribing is common and is known to vary considerably between practices, but the extent to which high-risk prescribing varies among individual general practitioners (GPs) is not known.ObjectivesTo create prescribing safety indicators usable in existing electronic clinical data and to examine (1) variation in high-risk prescribing between patients, GPs and practices including reliability of measurement and (2) changes over time in high-risk prescribing prevalence and variation between practices.DesignDescriptive analysis and multilevel logistic regression modelling of routine data.SettingUK general practice using routine electronic medical record data.Participants(1) For analysis of variation and reliability, 398 GPs and 26,539 patients in 38 Scottish practices. (2) For analysis of change in high-risk prescribing, ≈ 300,000 patients particularly vulnerable to adverse drug effects registered with 190 Scottish practices.Main outcome measuresFor the analysis of variation between practices and between GPs, five indicators of high-risk non-steroidal anti-inflammatory drug (NSAID) prescribing. For the analysis of change in high-risk prescribing, 19 previously validated indicators.ResultsMeasurement of high-risk prescribing at GP level was feasible only for newly initiated drugs and for drugs similar to NSAIDs which are usually initiated by GPs. There was moderate variation between practices in total high-risk NSAID prescribing [intraclass correlation coefficient (ICC) 0.034], but this indicator was highly reliable (&gt; 0.8 for all practices) at distinguishing between practices because of the large number of patients being measured. There was moderate variation in initiation of high-risk NSAID prescribing between practices (ICC 0.055) and larger variation between GPs (ICC 0.166), but measurement did not reliably distinguish between practices and had reliability &gt; 0.7 for only half of the GPs in the study. Between quarter (Q)2 2004 and Q1 2009, the percentage of patients exposed to high-risk prescribing measured by 17 indicators that could be examined over the whole period fell from 8.5% to 5.2%, which was largely driven by reductions in high-risk NSAID and antiplatelet use. Variation between practices increased for five indicators and decreased for five, with no relationship between change in the rate of high-risk prescribing and change in variation between practices.ConclusionsHigh-risk prescribing is common and varies moderately between practices. High-risk prescribing at GP level cannot be easily measured routinely because of the difficulties in accurately identifying which GP actually prescribed the drug and because drug initiation is often a shared responsibility with specialists. For NSAID initiation, there was approximately three times greater variation between GPs than between practices. Most GPs with above average high-risk prescribing worked in practices which were not themselves above average. The observed reductions in high-risk prescribing between 2004 and 2009 were largely driven by falls in NSAID and antiplatelet prescribing, and there was no relationship between change in rate and change in variation between practices. These results are consistent with improvement interventions in all practices being more appropriate than interventions targeted on practices or GPs with higher than average high-risk prescribing. There is a need for research to understand why high-risk prescribing varies and to design and evaluate interventions to reduce it.FundingFunding for this study was provided by the Health Services and Delivery Research programme of the National Institute for Health Research.

Is drug choice by general practitioners influenced by exposure to specialists? Record-linkage study in Italy.

To investigate whether previous drug prescriptions by, or exposure to, specialists influence general practitioners' prescribing (using the example of inhibitors of the renin-angiotensin system). Drug prescriptions in GP and specialist care, hospital records and outpatient visits in the Emilia-Romagna region (northern Italy) were linked to assess, among patients who in 2013 had been prescribed Angiotensin Converting Enzyme (ACE)-inhibitors or Angiotensin Receptor Blocker (ARBs) in general practice for the first time, whether those who had been previously prescribed these drugs by specialists (or have been recently exposed to cardiovascular, diabetes or nephrology specialists) were more likely to be prescribed an ARB or a patented ACE-inhibitor/ARB. A cohort of 88,926 patients was identified of whom 52,666 had not been exposed to specialists. Of these patients, 77.6% were initially prescribed ACE-inhibitors and 87.2% a non-patented drug. Higher prescription of ACE-inhibitors (82.0%) and of non-patented drugs (95.8%) in general practice were observed in the 10,243 the patients who had already been prescribed these drugs by a specialist compared to unexposed patients (p < 0.001 in both cases) and in the 14,648 patients exposed to specialists in the 90 days preceding the first prescription in general practice (79.0% and 89.6%, respectively, p < 0.001 in both cases). Exposure to specialists was not associated with higher prescription of ARBs and of patented drugs in this Region of Italy. The hypothesis of prescribing induction by specialists is not supported by these data. This kind of analysis can provide help inform local prescribing agreements.

PWE-249 Impact of switching from a brand to a generic macrogol on prescriptions and doses for patients with chronic constipation in the UK

Introduction Patients with constipation switching from a branded to a generic macrogol may require a higher number of prescriptions (i.e. scripts) and doses (defined as packs of 20 sachets). Repeated switching on the basis of cost savings alone can irritate patients and can erode trust and compliance (GPC 2013 1 ). This analysis compares the number of prescriptions and doses for patients with chronic constipation who switched from a branded macrogol (MOVICOL ® ) to a generic macrogol (LAXIDO ® ), and those who switched back to the branded macrogol. Method Retrospective real world, longitudinal patient and prescribing data were collected from 397 GP practices (2,186 GPs and 13,567 patients in the database during the period Jan to Dec 2013) across the UK (sourced from Cegedim Strategic Data Ltd.). Two patient cohorts were selected for the analysis: (1) patients with chronic constipation prescribed the branded macrogol who switched to the generic; and (2) patients with chronic constipation prescribed the branded macrogol, who switched to the generic and returned to the brand. Patients in each cohort were tracked from initiation to end of treatment. The change in annualised prescriptions and doses per patient in each cohort were analysed using the one- and two-sided t-test for two-sample assuming unequal variances. Results Males and females aged ≥13 years were included in the analysis. Patient Cohort (1), N=3109, M=0.63, SD=8.29, chronic patients initiated on the brand and switched to the generic, showed on average an increased number of prescriptions (+8%) and doses (+13%) per patient per year. The +0.6 and +1.7 absolute increase in number of prescriptions and doses respectively were significant (p Patient Cohort (2), N=91, M=−3.41, SD=1.65, chronic patients initiated on the brand who switched to the generic (Switch 1) and switched back to the brand (Switch 2), showed on average a reduced number of prescriptions (−24%) and doses (−11%) per patient per year during Switch 2. In addition, the +5.0 and +4.9 absolute increase in number of prescriptions and doses at Switch 1 from the branded to generic macrogol was significant (p Conclusion Amongst patients with chronic constipation, those who switched away from the branded to a generic macrogol required a significantly higher number of prescriptions and doses than they had been used to having. Conversely, patients who were switched back from the generic to the branded macrogol required fewer. Factors impacting changes in prescription for example, efficacy, convenience, and compliance require further investigation. Disclosure of interest V. Bajaj Employee of: Norgine Limited, A. Naidoo Employee of: Norgine Limited. Reference Prescribing in General Practice, General Practitioners Committee (GPC), BMA, May 2013

A real-world, data-driven view of general practice prescribing.

A real-world, data-driven view of general practice prescribing.

Post-diagnostic prescriptions for low-dose aspirin and breast cancer-specific survival: a nested case-control study in a breast cancer cohort from the UK Clinical Practice Research Datalink

IntroductionRecent observational studies indicate that post-diagnostic use of aspirin in breast cancer patients may protect against cancer progression perhaps by inhibiting cyclooxygenase-2 dependent mechanisms. Evidence also supports a crucial role for interactions between tumour cells and circulating platelets in cancer growth and dissemination, therefore, use of low-dose aspirin may reduce the risk of death from cancer in breast cancer patients.MethodsA cohort of newly diagnosed breast cancer patients (1998 to 2006) were identified in the UK Clinical Practice Research Datalink (and confirmed by cancer registry linkage). Cancer-specific deaths were identified up to 2011 from Office for National Statistics mortality data. A nested case-control analysis was conducted using conditional logistic regression to compare post-diagnostic aspirin exposure using General Practice prescription data in 1,435 cases (breast cancer deaths) with 5,697 controls (matched by age and year of diagnosis).ResultsAfter breast cancer diagnosis, 18.3% of cancer-specific deaths and 18.5% of matched controls received at least one prescription for low-dose aspirin, corresponding to an odds ratio (OR) of 0.98 (95% CI 0.83, 1.15). Adjustment for potential confounders (including stage and grade) had little impact on this estimate. No dose response relationship was observed when the number of tablets was investigated and no associations were seen when analyses were stratified by receipt of prescriptions for aspirin in the pre-diagnostic period, by stage at diagnosis or by receipt of prescriptions for hormone therapy.ConclusionsOverall, in this large population-based cohort of breast cancer patients, there was little evidence of an association between receipt of post-diagnostic prescriptions for low-dose aspirin and breast cancer-specific death. However, information was not available on medication compliance or over-the-counter use of aspirin, which may have contributed to the null findings.

Implementing guidelines for depression on antidepressant prescribing in general practice: a quasi-experimental evaluation

BackgroundInternationally, guidelines for depression recommend a stepped care approach, implying that antidepressant medication should not be offered as a first step treatment to patients with sub-threshold or mild depression. In the Netherlands, antidepressant prescribing rates in general practice as a first treatment step are considered to be high. The aim of this study was to evaluate the implementation of guideline recommendations on antidepressant prescribing.MethodsA quasi-experimental study with a non-equivalent naturalistic control group and three years follow-up was performed in the general practice setting in the Netherlands. General Practitioners (GPs) participated in a national Quality Improvement Collaborative (QIC), focusing on the implementation of a guideline based model for a stepped care approach to depression. The model consisted of self-help and psychological treatment options for patients with milder symptoms as an alternative to antidepressants in general practice. Changes in antidepressant prescription rates of GPs were documented for a three-year period and compared to those in a control group of GPs, selected from an ongoing national registration network.ResultsA decrease of 23.3% (49.4%-26.1%) in antidepressant prescription rates for newly diagnosed patients with depressive symptoms was found within the intervention group, whereas no difference occurred in the reference group (50.3%-52.6%). The decrease over time was significant, compared to the usual care group (OR 0.44, 95% CI: 0.21-0.92).ConclusionsAn implementation program using stepped care principles for the allocation of depression interventions resulted in reduced antidepressant prescription rates in general practice. GPs can change prescribing behaviour within the context of a QIC.

Changes to inhaled corticosteroid dose when initiating combination inhaler therapy in long-acting β agonist-naïve patients with asthma: a retrospective database analysis

Retrospective prescribing data were obtained from 46 general practice surgeries in NHS Scotland. Patients with asthma who were naïve to previous long-acting β agonist therapy and initiated combination inhaler therapy...

The Aston Medication Adherence Study: mapping the adherence patterns of an inner-city population

The Aston Medication Adherence Study was designed to examine non-adherence to prescribed medicines within an inner-city population using general practice (GP) prescribing data. To examine non-adherence patterns to prescribed oral medications within three chronic disease states and to compare differences in adherence levels between various patient groups to assist the routine identification of low adherence amongst patients within the Heart of Birmingham teaching Primary Care Trust (HoBtPCT). Patients within the area covered by HoBtPCT (England) prescribed medication for dyslipidaemia, type-2 diabetes and hypothyroidism, between 2000 and 2010 inclusively. HoBtPCT's population was disproportionately young, with seventy per cent of residents from Black and Minority Ethnic groups. Systematic computational analysis of all medication issue data from 76 GP surgeries dichotomised patients into two groups (adherent and non-adherent) for each pharmacotherapeutic agent within the treatment groups. Dichotomised groupings were further analysed by recorded patient demographics to identify predictors of lower adherence levels. Results were compared to an analysis of a self-report measure of adherence [using the Modified Morisky Scale(©) (MMAS-8)] and clinical value data (cholesterol values) from GP surgery records. Adherence levels for different patient demographics, for patients within specific longterm treatment groups. Analysis within all three groups showed that for patients with the following characteristics, adherence levels were statistically lower than for others; patients: younger than 60 years of age; whose religion is coded as "Islam"; whose ethnicity is coded as one of the Asian groupings or as "Caribbean", "Other Black" and "African"; whose primary language is coded as "Urdu" or "Bengali"; and whose postcodes indicate that they live within the most socioeconomically deprived areas of HoBtPCT. Statistically significant correlations between adherence status and results from the selfreport measure of adherence and of clinical value data analysis were found. Using data from GP prescribing systems, a computerised tool to calculate individual adherence levels for oral pharmacotherapy for the treatment of diabetes, dyslipidaemia and hypothyroidism has been developed. The tool has been used to establish nonadherence levels within the three treatment groups and the demographic characteristics indicative of lower adherence levels, which in turn will enable the targeting of interventional support within HoBtPCT.

Adherence to inhaled corticosteroids by asthmatic patients: measurement and modelling

Background Poor adherence to inhaled corticosteroids (ICS) is known as the main cause for therapeutic failure in asthma treatment and associated morbidity. To improve adherence, targetted and effective interventions need to be developed ideally based on using longitudinal follow-up of a large study cohort to establish patterns and influences on adherence. Objective To develop an annual measure of asthma patients’ adherence to ICS using primary care prescribing data over consecutive annual intervals, and to statistically model ICS adherence controlling for a range of patient factors. Setting A retrospective cohort study between 1997 and 2010 using United Kingdom general practice prescribing data on asthma patients aged between 12 and 65 years, without a diagnosis of chronic obstructive pulmonary disease. Method Patient’s ICS prescriptions are used to calculate the ‘number of days prescribed during calendar year’ divided by ‘number of days in the interval’ to form an annual prescription possession ratio (PPR) for each patient. Several definitions of PPR are considered and compared when calculating numerator and denominator. Adherence, measured by the preferred PPR, is then modelled to estimate the effect of asthma exacerbation, severity, control and other patient factors on adherence. Main outcome measure PPR, being a proxy measure for adherence. Results Annual PPR by all strategies gave a similar frequency profile. ICS were either over- or under-prescribed for over half of the follow-up time. Adherence was lower in younger patients, those newer to the study timeframe, those with less severe asthma, those with good control, with lower previous adherence, and who had not previously experienced an exacerbation. Conclusion The chosen PPR simulated clinical use of ICS most closely; including overlapping days, excess days passed to the next interval, considering gaps in the denominator, with censoring at 100 %. The PPR is a useful measure for signalling or measuring adherence changes over time. The modelling results identified many characteristics which would indicate which asthma patients and at what points in their treatment cycle they would be at increased risk of low adherence.