Odense Pharmacoepidemiological Database: A Review of Use and Content

A comparative analysis of consumers' patterns of reimbursable prescription medications between online-only and community pharmacies

OBJECTIVES

Online pharmacies have emerged as a novel method for procuring reimbursable medicines. The study aimed to compare consumers' patterns of reimbursable prescription medications between online-only and community pharmacies in The North Denmark Region which is one of five regions in Denmark.

METHOD

The retrospective study used registered data for all reimbursable medicine prescriptions from pharmacies in 2022 across Denmark but specifically retrieved from patients residing in The North Denmark Region.

KEY FINDINGS

In 2022, 4414 and 395 438 patients obtained reimbursable medicines from 2 online-only and 240 community pharmacies, respectively. The age distribution of patients using online-only pharmacies was significantly different from community pharmacies (P < .001) as the proportion of patients in age groups 30-69 years was higher for online-only pharmacies. Whereas patients above the age of 70 were more likely to fill prescriptions from community pharmacies. The gender distribution of patients using online-only pharmacies was different from community pharmacies (P < .001) as a higher proportion of females filled prescriptions from online-only pharmacies. The distribution of patients' living areas differed between the two types of pharmacies (P < .001), where the proportion of patients from metropolitan municipalities was higher at online-only pharmacies. The distribution of prescriptions by anatomical therapeutic chemical code differed between the two types of pharmacies (P < .001).

CONCLUSION

Consumer patterns were different between online-only and community. These insights may inform pharmacy owners, ensuring both online and community pharmacies meet public health needs effectively in the future.

Aortic Root Replacement Procedures: A Validation Study of the Western Denmark Heart Registry from 1999 to 2022

Background/Objectives: We reviewed data from the Western Danish Heart Registry (WDHR), which collects mandatory information on heart surgeries in Western Denmark, to validate cases with aortic root replacement (ARR) and assess the validity of registered data for all recorded cases. Methods: Patients registered in the WDHR with Danish Health Care Classification System (SKS) codes KFC and KFM from January 1999 to April 2022 were reviewed using electronic medical records. All patients who underwent ARR were included, and clinical data from the WDHR were adjudicated against electronic medical records. Results: A total of 847 cases with ARR were identified. Missing values averaged 12.0% in baseline variables (range: 3.2-22.1%), 7.3% in EuroSCORE II variables (range: 0.8-48.9%), and 5.5% in postoperative outcome variables (range: 4.1-8.1%). After adjudication, unrecovered data averaged 6.5% for baseline variables (range: 0.1-11.7%), 5.3% for EuroSCORE II variables (range: 0-32.5%), and 0.5% for postoperative outcomes (range: 0-0.8%). Missing data among EuroSCORE II were lower from 2012 and beyond (2.9% (range: 0.6-14.3%)). The median EuroSCORE II according to the WDHR was 6.2% (95% confidence interval 1.4-6.3) and after adjudication 10.7% (95% confidence interval 3.3-13.3). The positive predictive value for arrhythmia, central nervous damage, dialysis, reoperation for bleeding, and reoperation for ischemia exceeded 95%. Conclusions: The WDHR demonstrated overall value for clinical epidemiological research in ARR, but cases require validation to differentiate between procedures due to insufficient coding, while adjudication resulted in significantly higher data completeness for the majority of the variables.

Estimating Type 2 Diabetes Prevalence: A Model of Drug Consumption Data

Observational, cross-sectional prevalence studies are costly and time-consuming. The development of indirect methods estimating prevalence used to obtain faster, less-expensive, and more robust results would be an advantage for several healthcare applications. This study aimed to use the drug dispensing data from community pharmacies to estimate the prevalence of Type 2 Diabetes mellitus (T2DM) in the Portuguese population. A cross-sectional study was conducted using a database of dispensed medicines with an indication for Diabetes mellitus in 2018 and 2021, stratified by geographic region. The methodology was based on a sequential method of acquiring prevalence estimates obtained through exposure to medicines using the daily doses defined per thousand inhabitants per day and adjusted to the rate of adherence to therapy, prescription patterns, and concomitance of antidiabetic drugs. The estimated overall T2DM prevalence in 2018 was 13.9%, and it was 14.2% for 2021. The results show the increased consumption of antidiabetic drugs, with fixed-dose combination antidiabetics and new antidiabetics being particularly important in 2021. This work allowed for the development of a model to obtain the estimated prevalence of T2DM based on drug consumption, using a simple, fast, and robust method that is in line with the available evidence. However, with the recent expanding indications for new antidiabetics, the inclusion of further data in the model needs to be studied.

Core Concepts in Pharmacoepidemiology: Fundamentals of the cohort and case-control study designs

In this review paper, I outline the principles of the cohort as a sampling frame and provide a basic introduction to the cohort study design and the case–control study design, two of the most important designs in the pharmacoepidemiologist's toolbox. Further, I discuss when to prefer one design over the other. The paper is intended as a primer for people new to the field of pharmacoepidemiology and contains a range of suggestions for additional reading regarding the study designs and related epidemiological topics.

Data Sources for Drug Utilization Research in Brazil-DUR-BRA Study

Background: In Brazil, studies that map electronic healthcare databases in order to assess their suitability for use in pharmacoepidemiologic research are lacking. We aimed to identify, catalogue, and characterize Brazilian data sources for Drug Utilization Research (DUR).

Methods: The present study is part of the project entitled, “Publicly Available Data Sources for Drug Utilization Research in Latin American (LatAm) Countries.” A network of Brazilian health experts was assembled to map secondary administrative data from healthcare organizations that might provide information related to medication use. A multi-phase approach including internet search of institutional government websites, traditional bibliographic databases, and experts’ input was used for mapping the data sources. The reviewers searched, screened and selected the data sources independently; disagreements were resolved by consensus. Data sources were grouped into the following categories: 1) automated databases; 2) Electronic Medical Records (EMR); 3) national surveys or datasets; 4) adverse event reporting systems; and 5) others. Each data source was characterized by accessibility, geographic granularity, setting, type of data (aggregate or individual-level), and years of coverage. We also searched for publications related to each data source.

Results: A total of 62 data sources were identified and screened; 38 met the eligibility criteria for inclusion and were fully characterized. We grouped 23 (60%) as automated databases, four (11%) as adverse event reporting systems, four (11%) as EMRs, three (8%) as national surveys or datasets, and four (11%) as other types. Eighteen (47%) were classified as publicly and conveniently accessible online; providing information at national level. Most of them offered more than 5 years of comprehensive data coverage, and presented data at both the individual and aggregated levels. No information about population coverage was found. Drug coding is not uniform; each data source has its own coding system, depending on the purpose of the data. At least one scientific publication was found for each publicly available data source.

Conclusions: There are several types of data sources for DUR in Brazil, but a uniform system for drug classification and data quality evaluation does not exist. The extent of population covered by year is unknown. Our comprehensive and structured inventory reveals a need for full characterization of these data sources.

Sampling in the case-time-control design among drug users when outcome prevents further treatment

PURPOSE

The objective of this paper is to advocate a new way of sampling controls in the case-time-control design in a cohort of drug users when the studied outcome prevents further treatment.

METHODS

Mathematically we demonstrate how a standard sampling of controls, where controls are sampled among all subjects without an event at end-of-study, leads to a biased effect estimate. We propose to add the requirement that controls initiate treatment before the calendar time of event of their matched case to circumvent this. The standard and proposed sampling methods are compared in a simulation study and in an empirical data example examining the effect of nonsteroidal anti-inflammatory drug usage on the risk of upper gastrointestinal bleeding.

RESULTS

When the controls are sampled the standard way, the case-time-control design confers a bias because cases and controls have a different time-trend of exposure. The bias has been upwards in all the scenarios we have investigated. The requirement we add to be a potential control ensures that cases and controls have the same time-trend of exposure when treatment and outcome are independent. The simulation study confirms that the proposed sampling method removes the bias between treatment and outcome. The proposed sampling method lowered the odds-ratio estimate from 3.72 to 3.26 in the data example.

CONCLUSION

The proposed sampling method makes it possible to use the case-time-control design in a cohort of subjects with registered use of a drug when outcome prevents further treatment.

The Validity of Danish Prescription Data to Measure Use of Aspirin and Other Non-Steroidal Anti-Inflammatory Drugs and Quantification of Bias Due to Non-Prescription Drug Use

Purpose

To evaluate the potential of Danish prescription registries to capture aspirin and non-aspirin non-steroidal anti-inflammatory drug (NSAID) use and to quantitatively evaluate the magnitude of bias from misclassification of true NSAID and aspirin use as apparent non-use in drug outcome studies.

Patients and Methods

In a population-based cohort study, we retrieved sales statistics for NSAIDs and aspirins based on nationwide data from the Danish Health Data Authority and the Danish National Prescription Registry. We estimated prevalence of recorded and non-recorded NSAID use in the prescription registry and resulting proportions of true NSAID and aspirin use misclassified as apparent non-use from 1999 to 2019 at population and patient levels.

Results

The prevalence of true use misclassified as non-use (mainly due to over-the-counter use) peaked at 4.7% in 2012 for NSAIDs overall, 5.5% in 2012 for ibuprofen, and at 5.9% in 2002 for high-dose aspirin. Misclassification of other individual NSAIDs was near null. Misclassification of true low-dose aspirin use as non-use declined during the study period but remained around 1% since 2005. In subgroups of cardiac patients, the highest prevalence of true NSAID use misclassified as non-use was 5.0% in 2002 and 4.3% in 2017. Quantitative bias analyses showed how such misclassification of true NSAID and aspirin use as non-use remained minimal both at population and patient levels. In hypothetical examples simulating real study populations with differing exposure prevalence and prevalence of true NSAID and aspirin use misclassified as apparent non-use, the approximate percentage change due to misclassification of use as non-use did not exceed 5% and in most scenarios stayed around 1%.

Conclusion

The Danish prescription registries are valid data sources for assessing the effects of aspirin and NSAID use. The influence of non-recorded NSAID and aspirin use on estimates of association is virtually negligible.

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.

Cost Analysis of a Dedicated Outpatient Clinic in Patients With Newly Diagnosed Atrial Fibrillation

AIMS

The aim of this study was to assess healthcare utilization costs of a dedicated outpatient clinic for patients with atrial fibrillation (AF).

METHODS

We conducted a registry-based retrospective study in patients with a first-time AF diagnosis from 2009 to 2011 (control group) and 2013 to 2015 (intervention group). The control group had physician-led usual care, and the intervention group received multidisciplinary care. The primary outcome was total costs of AF-related resource utilization. Exploratory outcomes were ischemic stroke, intracranial hemorrhage, and all-cause mortality. Multiple regression methods were used to control for confounders in the assessment of effects on outcomes.

RESULTS

A total of 1552 patients were included, hereof 850 in the intervention group. Total AF-related costs were €2746 for the control group and €3154 for the intervention group, which was not statistically significant. Average outpatient costs were significantly higher in the control group than in the intervention group (€522 vs €344, respectively; P = .003). There was no difference in the number of AF-related hospital admissions and outpatient visits between the control group and the intervention group (incidence risk ratio, 1.03 vs 0.85; and 95% confidence interval, 0.92-1.16 vs 0.69-1.05, respectively). There was a trend toward reduced all-cause mortality (hazard ratio, 0.86; 95% confidence interval, 0.63-1.16) in the intervention group, which was not statistically significant.

CONCLUSION

Total expenses for AF-related hospital resource utilization in the intervention group were higher, but the expenses for AF-related outpatient visits were significantly lower. There was a trend toward lower all-cause mortality in the intervention group, although the differences were not statistically significant. More research is needed investigating whether a multidisciplinary AF clinic is cost-effective.

Is tranexamic acid use in patients with a hip fracture safe?

AIMS

To assess the safety of tranexamic acid (TXA) in a large cohort of patients aged over 65 years who have sustained a hip fracture, with a focus on transfusion rates, mortality, and thromboembolic events.

METHODS

This is a consecutive cohort study with prospectively collected registry data. Patients with a hip fracture in the Region of Southern Denmark were included over a two-year time period (2015 to 2017) with the first year constituting a control group. In the second year, perioperative TXA was introduced as an intervention. Outcome was transfusion frequency, 30-day and 90-day mortality, and thromboembolic events. The latter was defined as any diagnosis or death due to arterial or venous thrombosis. The results are presented as relative risk (RR) and hazard ratio (HR) with 95% confidence intervals (CIs).

RESULTS

A total of 3,097 patients were included: 1,558 in the control group and 1,539 in the TXA group.31% (n = 477) of patients had transfusions in the control group compared to 27% (n = 405) in the TXA group yielding an adjusted RR of 0.83 (95% CI 0.75 to 0.91). TXA was not associated with increased 30-day mortality with an adjusted HR of 1.10 (95% CI 0.88 to 1.39) compared to the control group as well as no association with increased risk of 90-day mortality with a per protocol adjusted HR of 1.24 (95% CI 0.93 to 1.66). TXA was associated with a lower risk of thromboembolic events after 30 days (RR 0.63 (95% CI 0.42 to 0.93)) and 90 days (RR 0.72 (95% CI 0.52 to 0.99)). A subanalysis on haemoglobin demonstrated a median 17.7 g/L (interquartile range (IQR) 11.3 to 27.3) decrease in the control group compared to 17.7 g/L (IQR 9.7 to 25.8) in the per protocol TXA group (p = 0.060 on group level difference).

CONCLUSION

TXA use in patients with a hip fracture, was not associated with an increased risk of mortality but was associated with lower transfusion rate and reduced thromboembolic events. Thus, we conclude that it is safe to use TXA in this patient group. Cite this article: Bone Joint J 2021;103-B(3):449-455.

Feasibility Study of Advanced Cardiovascular Screening in Middle-Aged Patients with Diabetes

Purpose

Cardiovascular mortality remains high among patients with diabetes compared with the general population. The primary aim was to evaluate the interest in and demand for advanced cardiovascular screening in patients with diabetes; the secondary aim was to explore its efficiency in detecting unprotected subclinical cardiovascular disease (CVD).

Patients and Methods

In a cross-sectional design, randomly selected 40–60-year-old men and women with diabetes were invited to the screening trial. Screening encompassed (1) a comprehensive medical interview; (2) non-contrast computed tomography scanning to quantify coronary artery and aortic valve calcification, to measure left atrial size, to assess heart rhythm and to detect aortic and iliac dilatations; (3) ankle and brachial blood pressure measurements; and (4) blood and urine samples for measurements of HbA_1c, lipid profile, renal function, NT-pro B-type natriuretic peptide (pro-BNP) and albuminuria. Primary outcome was participation rate; secondary outcome was rate of unprotected subclinical CVD.

Results

Of 465 invited patients, 191 (41.1%) attended screening. The participation rate was 40% (95% CI:33–47) for males and 42% (95% CI:36–48) for females. Twenty-four patients were excluded due to previous CVD. The remaining patients’ mean age was 52 years; 58% were males. Subclinical CVD was found in 64%, with a male preponderance (males 75% (95% CI:66–83; females 49% (95% CI:37–60)). Presence of severe coronary artery calcification (score ≥ 400) showed a male preponderance (males 19% (95% CI:12–27); females 7% (95% CI:3–16)). Aortic valve calcification, enlarged left atrial volume, atrial fibrillation, aortic dilatations, peripheral artery disease or increased pro-BNP were uncommon, and without any sex differences. Unprotected subclinical CVD was very common, and medical treatment was intensified in 60% (95% CI:53–68) of patients.

Conclusion

We propose a feasible cardiovascular screening examination from which middle-aged patients with diabetes may benefit. However, the participation rate may be too low to warrant screening.

Adherence to adrenaline autoinjector prescriptions in patients with anaphylaxis

This study evaluates adherence to adrenaline autoinjector prescriptions in a cohort of well-characterized anaphylaxis patients. The overall retrieval rate was 76% with the highest rate in patients with severe anaphylaxis. Special attention is needed in patients with unknown elicitors and in young adults, comprising the largest proportion of non-adherent patients.

Trial registration No intervention performed. Retrospective data used with permission from the Danish Data Protection Agency and Regional Committees on Health Research Ethics

The Danish health care system and epidemiological research: from health care contacts to database records

Denmark has a large network of population-based medical databases, which routinely collect high-quality data as a by-product of health care provision. The Danish medical databases include administrative, health, and clinical quality databases. Understanding the full research potential of these data sources requires insight into the underlying health care system. This review describes key elements of the Danish health care system from planning and delivery to record generation. First, it presents the history of the health care system, its overall organization and financing. Second, it details delivery of primary, hospital, psychiatric, and elderly care. Third, the path from a health care contact to a database record is followed. Finally, an overview of the available data sources is presented. This review discusses the data quality of each type of medical database and describes the relative technical ease and cost-effectiveness of exact individual-level linkage among them. It is shown, from an epidemiological point of view, how Denmark’s population represents an open dynamic cohort with complete long-term follow-up, censored only at emigration or death. It is concluded that Denmark’s constellation of universal health care, long-standing routine registration of most health and life events, and the possibility of exact individual-level data linkage provides unlimited possibilities for epidemiological research.

Association between the level of municipality healthcare services and outcome among acutely older patients in the emergency department: a Danish population-based cohort study

OBJECTIVES

This study aims to describe the association between use of municipality healthcare services before an emergency department (ED) contact and mortality, hospital reattendance and institutionalisation.

DESIGN

Population-based prospective cohort study.

SETTING

ED of a large university hospital.

PARTICIPANTS

All medical patients ≥65 years of age from a single municipality with a first attendance to the ED during a 1-year period (November 2013 to November 2014).

PRIMARY AND SECONDARY OUTCOME MEASURES

Patients were categorised as independent of home care, dependent of home care or in residential care depending on municipality healthcare before ED contact. Patients were followed 360 days after discharge. Outcomes were postdischarge mortality, hospital reattendance and institutionalisation.

RESULTS

A total of 3775 patients were included (55% women), aged (median (IQR) 78 years (71-85)). At baseline, 48.9% were independent, 34.9% received home care and 16.2% were in residential care. Receiving home care or being in residential care was a strong predictor of mortality, hospital reattendance and institutionalisation. Among patients who were independent, 64.3% continued being independent up to 360 days after discharge. Even among patients ≥85 years, 35.4% lived independently in their own house 1 year after ED contact.

CONCLUSION

Prehospital information on municipality healthcare is closely related to patient outcome in older ED patients. It might have the potential to be used in risk stratification and planning of needs of older acute medical patients attending the ED.

Disability and morbidity among older patients in the emergency department: a Danish population-based cohort study

OBJECTIVES

The objective was to describe the prevalence of geriatric conditions among older medical patients in the emergency department (ED) and the association with admission, mortality, reattendance and loss of independency.

DESIGN

Population-based prospective cohort study.

SETTING

ED of a large university hospital.

PARTICIPANTS

All medical patients ≥65 years of age from a single municipality with a first attendance to the ED during a 1-year period (November 2013 to November 2014).

PRIMARY AND SECONDARY OUTCOME MEASURES

Based on information from healthcare registers, we defined geriatric conditions as disability, recently increased disability, polypharmacy and comorbidity. Outcomes were admission, length of admission, 30 days postdischarge mortality, 30 days hospital reattendance and home care dependency 0-360 days following ED contact.

RESULTS

Totally, 3775 patients (55% women) were included, age 78 (71-85) years (median (IQR)). No patients were lost to follow-up. The prevalence of 0-4 geriatric conditions was 14.9%, 27.3%, 25.2%, 22.3% and 10.3%, respectively. The number of conditions was significantly associated with hospital admission, length of admission, 30 days postdischarge mortality and 30 days hospital reattendance. Among patients with no geriatric conditions, 70% lived independent all 360 days after discharge, whereas all patients with ≥3 conditions had some dependency or were dead within 360 days following discharge.

CONCLUSION

Among older medical patients in the ED, 50% had two or more geriatric conditions which were associated with poor health outcomes. This highlights the need for studies of the effect of geriatric awareness and competences in the ED.

Treatment Failure of TNF-α Inhibitors in Obese Patients With Inflammatory Bowel Disease-A Cohort Study

BACKGROUND

In treatment of inflammatory bowel disease (IBD) with anti-tumor necrosis factor-α agents (anti-TNF-α), obesity has been suspected as a cause of accelerated loss of response (LOR). We sought to determine whether overweight IBD patients have accelerated LOR when treated with anti-TNF-α agents, compared with normal weight IBD patients.

METHODS

We identified a cohort of adult IBD patients treated with anti-TNF-α agents at a Danish university hospital. Patients were grouped according to body mass index (BMI), and our main outcome was time to LOR. We performed survival analyses on LOR and calculated hazard ratios (HRs) with the normal weight group as the reference, while adjusting for confounders.

RESULTS

Of 210 eligible patients, 92 (44%) experienced LOR. One hundred eighty patients were treated with infliximab and 30 with adalimumab, 114 (54%) were normal weight, 51 (24%) were overweight, and 45 (21%) were obese. Regression analysis produced the following adjusted HRs, compared with the normal weight group: overweight 0.89 (95% confidence interval [CI], 0.51-1.56) and obese 1.31 (95% CI, 0.76-2.24), thus showing no statistically significant association between BMI and time to LOR. Subgroup analyses produced similar results, except for obese ulcerative colitis patients having an adjusted HR of 2.42 (95% CI, 1.03-5.70).

CONCLUSIONS

In IBD patients treated with anti-TNF-α agents, we found no overall association between increased BMI and accelerated LOR.

Empirical validation of the reverse parametric waiting time distribution and standard methods to estimate prescription durations for warfarin

PURPOSE

In many prescription databases, the duration of treatment for the single prescription is not recorded. This study aimed to validate 2 different types of approaches for estimating prescription durations, using the oral anticoagulant warfarin as a case.

METHODS

The approaches undergoing empirical validation covered assumptions of a fixed daily intake of either 0.5 or 1.0 defined daily dose (DDD), as well as estimates based on the reverse parametric waiting time distribution (rWTD), with different sets of covariates. We converted estimates of prescription duration to daily dose and compared them to prescribed daily dose as recorded in a clinical registry (using Bland-Altman plots). Methods were compared based on their average prediction error (logarithmic scale) and their limit of agreement ratio (ratio of mean error ± 1.96 SD after transformation to original scale).

RESULTS

Estimates of daily doses were underestimated by 19% or overestimated by 62% when assumptions of 0.5 or 1.0 DDD were applied. The limit of agreement ratio was 6.721 for both assumptions. The rWTD-based approaches performed better when using the estimated mean value of the inter-arrival density, yielding on average negligible bias (relative difference of 0 to 2%) and with limit of agreement ratios decreasing upon additional covariate adjustment (from 6.857 with no adjustment to 4.036 with the fully adjusted model).

CONCLUSIONS

Comparing the different methods, the rWTD algorithm performed best and led to unbiased estimates of prescribed doses and thus prescription durations and reduced misclassification on the individual level upon inclusion of covariates.

Using the "proportion of patients covered" and the Kaplan-Meier survival analysis to describe treatment persistence

PURPOSE

Standard Kaplan-Meier (KM) survival analysis is often used to study treatment persistence estimating the proportion of patients who have not yet experienced a treatment break by a given day after treatment initiation. This method only allows patients to be studied until their first treatment break. The "proportion of patients covered" (PPC) method is another approach to study treatment persistence. It measures the proportion of live patients currently covered by treatment. We aimed to describe the PPC method, show how the KM survival analysis and the PPC method can describe treatment persistence, and discuss the interpretation/application of the methods.

METHODS

We identified new users of statins, selective serotonin reuptake inhibitors, hormone replacement therapy, and ibuprofen. We used KM estimates and the PPC to describe persistence in the 3 years post treatment initiation, using a grace period of 90 days to define a treatment break.

RESULTS

Three years after statin initiation, approximately 40% of patients were still in continuous treatment (KM survival) and 60% of patients still alive were in current treatment (PPC). Corresponding numbers were 12% and 25% for selective serotonin reuptake inhibitors and 9% and 29% for hormone replacement therapy. At 1 year, numbers were 5% and 10% for ibuprofen. The PPC showed markedly less variability than the KM survival analysis with different choices of grace periods.

CONCLUSIONS

The KM survival analysis and the PPC method can be used to study different aspects of treatment persistence. Together, they provide a more complete picture of treatment persistence and drug use patterns.

Introduction of national guidelines for restrictive blood transfusion threshold for hip fracture patients--a consecutive cohort study based on complete follow-up in national databases

Background

Randomized controlled trials have demonstrated that a restrictive red blood cell (RBC) transfusion strategy lowers transfusion frequency without affecting mortality. However, the external validity of these trials has not been tested in a large cohort. The purpose was to estimate the effect of introducing a National Clinical Guideline (NCG) for a restrictive hemoglobin transfusion threshold on transfusion frequency and mortality in hip fracture patients > 65 years old.

Methods

A consecutive cohort study of hip fracture patients > 65 years old residing in the southern region of Denmark was conducted using prospectively gathered data from registers during two separate 1-year time periods. The first period from October 1, 2012, to September 30, 2013, included 1494 patients and used a liberal transfusion threshold, whereas the second period from October 1, 2015, to September 30, 2016, including 1414 participants used a restrictive threshold from the NCG. Participant data for age, sex, body mass index, Charlson Comorbidity Index, time to surgery, and death were retrieved from the Danish Interdisciplinary Registry of Hip Fractures and were merged with RBC transfusion and medication data extracted from the Danish Transfusion and Odense Pharmacoepidemiological Databases, respectively. Cox proportional hazards models were used to test relative mortality risk for the restrictive group compared with the liberal group at 30 and 90 days.

Results

Overall RBC transfusions decreased from 42 to 30% (p < 0.001). The 30-day mortality rate (95% CI) was 9% (8;11) in the restrictive group and 13% (11;14) in the liberal group (p < 0.008), whereas the adjusted relative mortality risk was 0.72 (0.57;0.91). The 90-day mortality rate was 15% (13;17) in the restrictive group and 19% (17;21) in the liberal group, whereas the adjusted relative mortality risk was 0.78 (0.65;0.94).

Conclusion

These data suggest that the introduction of an NCG on restrictive blood transfusion leads to lower transfusion frequency in hip fracture patients > 65 years old. Even though this reduction is associated with decreased mortality at both 30 and 90 days, it may be explained by other issues than restrictive transfusion strategy. There has been an improvement in the mortality of hip fracture patients in Denmark, and we suggest that a restrictive transfusion strategy does not lead to increased mortality.

Explaining trends in coronary heart disease mortality in different socioeconomic groups in Denmark 1991-2007 using the IMPACTSEC model

AIM

To quantify the contribution of changes in different risk factors population levels and treatment uptake on the decline in CHD mortality in Denmark from 1991 to 2007 in different socioeconomic groups.

DESIGN

We used IMPACTSEC, a previously validated policy model using data from different population registries.

PARTICIPANTS

All adults aged 25-84 years living in Denmark in 1991 and 2007.

MAIN OUTCOME MEASURE

Deaths prevented or postponed (DPP).

RESULTS

There were approximately 11,000 fewer CHD deaths in Denmark in 2007 than would be expected if the 1991 mortality rates had persisted. Higher mortality rates were observed in the lowest socioeconomic quintile. The highest absolute reduction in CHD mortality was seen in this group but the highest relative reduction was in the most affluent socioeconomic quintile. Overall, the IMPACTSEC model explained nearly two thirds of the decline in. Improved treatments accounted for approximately 25% with the least relative mortality reduction in the most deprived quintile. Risk factor improvements accounted for approximately 40% of the mortality decrease with similar gains across all socio-economic groups. The 36% gap in explaining all DPPs may reflect inaccurate data or risk factors not quantified in the current model.

CONCLUSIONS

According to the IMPACTSEC model, the largest contribution to the CHD mortality decline in Denmark from 1991 to 2007 was from improvements in risk factors, with similar gains across all socio-economic groups. However, we found a clear socioeconomic trend for the treatment contribution favouring the most affluent groups.

Statins and polyneuropathy revisited: case-control study in Denmark, 1999-2013

AIM

In a previous study, we found a positive association between statin use and polyneuropathy risk. Other studies reported equivocal results. The present study aimed to confirm our findings with a design similar to that used in our previous study but with a larger data set.

METHODS

We searched medical registry data to identify patients diagnosed with incident polyneuropathy of no known cause (idiopathic polyneuropathy) between 1999 and 2013; we verified diagnoses through medical records. For each case, we recruited 20 general population controls with no previous history of polyneuropathy. Controls were matched to their respective case for age and gender. We ascertained the prior statin use of cases and controls through a prescription registry. Based on this information, exposure to statins was categorized into 'ever use' or 'never use'. Ever use of statins was classified by how recently they had been used ('current use' or 'past use'); current use was further classified into long-term use (5+ years) and high- or low-intensity use. We used conditional logistic regression to calculate odds ratios (ORs) with 95% confidence intervals (CIs) to examine associations between polyneuropathy and statin use.

RESULTS

We included 370 validated cases and 7400 controls. Ever use of statins was not associated with an elevated risk of polyneuropathy (OR 1.14, 95% CI 0.84, 1.54). Similarly, we found no associations between polyneuropathy risk and current use (OR 1.11, 95% CI 0.79, 1.53), long-term use (OR 1.13, 95% CI 0.66, 1.92) or high-intensity statin use (OR 1.05, 95% CI 0.59, 1.84).

CONCLUSION

Statin use was not associated with an increased risk of idiopathic polyneuropathy.