Conducting pharmacoepidemiologic research in Denmark

Free-of-charge dispensing of antipsychotics for schizophrenia in Denmark: Impact on the nationwide prescription registry and redemption of somatic medications

OBJECTIVE

Free-of-charge dispensing of antipsychotics for schizophrenia was introduced in Denmark around 2008. However, free-of-charge dispensing is not recorded in the Danish National Prescription Register (DNPR), potentially introducing bias and misclassification.

METHODS

We identified all 30,275 individuals with a first-episode schizophrenia diagnosis in Denmark between 1 January 1999 and 1 March 2017 including all redeemed prescriptions registered in the DNPR during the two years after the schizophrenia diagnosis. For each calendar year, we calculated the proportion of individuals who had filled ≥1 prescription for psychotropic and/or somatic medications within the first two years after the schizophrenia diagnosis.

RESULTS

From 2007 to 2017, the proportion of individuals with prescription-records for any psychotropic medication during the two years after the schizophrenia diagnosis decreased from 88% to 74%, particularly antipsychotics (from 83% to 61%) and antidepressants (from 49% to 35%). This was particularly observed among those aged 18-30 years at the schizophrenia diagnosis. A similar decrease was not observed for prescription-records of somatic medications.

CONCLUSION

The introduction of free-of-charge antipsychotics has affected the redemption of specific psychotropic drugs in the DNPR in first-episode schizophrenia. This limitation needs to be considered in register-based studies and emphasizes the need to identify solutions.

Opioid maintenance treatment in the Czech Republic, Norway and Denmark: a study protocol of a comparative registry linkage study

INTRODUCTION

Opioid maintenance treatment (OMT) varies across settings and between countries. We plan to use data from several nationwide health and population registers to further improve the knowledge base established from earlier studies. Our aim is to study OMT adherence trajectories and to identify factors associated with improved outcomes for OMT patients across the Czech Republic, Norway and Denmark, in order to further improve OMT and our understanding of the key elements of treatment success.

METHODS AND ANALYSIS

The registry-based cohort approach across the three countries allows us to link data from a range of registers on the individual level, by using personal identifiers in nationwide cohorts of OMT and non-OMT patients and the general non-using populations. A total of ~21 500 OMT patients over the last two decades in all three countries will be included in the study. The following outcome variables (based on the International Classification of Diseases, 10th Revision codes) will be obtained from relevant registers: treatment adherence to OMT, comorbidity (somatic and mental health), and all-cause and cause-specific mortality. Outcomes of the country-specific analyses will be pooled.

ETHICS AND DISSEMINATION

The national OMT cohorts have been approved by the ethics committees in the respective countries. Data will be stored according to national and local guidelines and treated confidentially, and all data will be analysed separately for each country and compared across countries. Findings will be disseminated in peer-reviewed scientific journals, national and international conferences, and in briefings to inform clinical decision-making.

Intermediate-term and long-term mortality among acute medical patients hospitalized with community-acquired sepsis: a population-based study

OBJECTIVE

Admission with severe sepsis is associated with an increased short-term mortality, but it is unestablished whether sepsis severity has an impact on intermediate-term and long-term mortality following admission to an acute medical admission unit.

PATIENTS AND METHODS

This was a population-based study of all adults admitted to an acute medical admission unit, Odense University Hospital, Denmark, from September 2010 to August 2011, identified by symptoms and clinical findings. We categorized the mortality periods into intermediate-term (31-180 days) and long-term (181-365, 366-730, and 731-1096 days). Mortality hazard ratios (HRs), comparing patients admitted with sepsis with those of a well-defined background population, were estimated using multivariable Cox regression. HRs were presented with 95% confidence intervals.

RESULTS

In total, 621 (36.3%) presented with sepsis, 1071 (62.5%) presented with severe sepsis, and 21 (1.2%) presented with septic shock. Thirty-day all-cause mortality for patients with sepsis, severe sepsis, and septic shock was 6.1, 18.8, and 38.1%, respectively. The adjusted HR among patients with sepsis of any severity within the time periods 31-180, 181-365, 366-720, and 721-1096 days was 7.1 (6.0-8.5), 2.8 (2.3-3.5), 2.1 (1.8-2.6), and 2.2 (1.7-2.9), respectively. Long-term mortality was unrelated to sepsis severity [721-1096 days: sepsis HR: 2.2 (1.5-3.2), severe sepsis HR: 2.1 (1.5-3.0)].

CONCLUSION

Patients admitted with community-acquired sepsis showed high intermediate-term mortality, increasing with sepsis severity. Long-term mortality was increased two-fold compared with sepsis-free individuals, but might be explained by unmeasured confounding. Further, long-term mortality was unrelated to sepsis severity.

Risk of lactic acidosis in type 2 diabetes patients using metformin: A case control study

BACKGROUND

Metformin constitutes first-line treatment of type 2 diabetes mellitus. It is presumed to have lactic acidosis as a dangerous, but rare, side effect.

OBJECTIVES

To estimate the incidence rate of lactic acidosis in patients with type 2 diabetes mellitus as well as to estimate the relative risk of lactic acidosis associated with metformin treatment.

METHODS

This is a population-based combined cohort and case-control study among patients with type 2 diabetes mellitus who were acutely admitted with lactic acidosis at Odense University Hospital, Denmark; in the period from 1st June 2009 to 1st October 2013. The patients included as cases were all acutely hospitalized with lactic acidosis (pH <7.35 and lactate ≥2.0 mmol/l). For each case, we identified 24 age- and sex-matched controls sampled from the same cohort with type 2 diabetes mellitus. The use of metformin identified by using a prescription database. Analyses included multivariable logistic regression and adjusting for predefined confounding: renal function, HbA1c, comorbidity and diabetes duration.

RESULTS

Our cohort included 10,652 patients with type 2 diabetes mellitus with a median age of 74 years, and 51.5% were male. During follow-up, 163 individuals were hospitalized with lactic acidosis, corresponding to an incidence rate of 391/100,000 person years. Use of metformin was not associated with lactic acidosis: adjusted odds ratio was 0.79 (95%CI 0.54-1.17).

CONCLUSION

Among patients with type 2 diabetes mellitus, the incidence rate of acute hospitalization with lactic acidosis was 391/100,000 person years. Use of metformin did not increase the risk of lactic acidosis. However, comorbidity seems to be an important risk factor.

Initiation of glucose-lowering treatment decreases international normalized ratio levels among users of vitamin K antagonists: a self-controlled register study

ESSENTIALS: It is not known if initiation of glucose-lowering drugs alters the efficacy of vitamin K antagonists (VKA). We examined if glucose-lowering drugs affected international normalized ratio (INR) in VKA-treated patients. Upon initiating glucose-lowering drugs, 51% of patients had INR values below the therapeutic window. Monitoring of INR levels should be intensified upon initiation of glucose-lowering drugs.

BACKGROUND

It is not known whether initiation of antidiabetic treatment affects the effect of vitamin K antagonists (VKAs). It was previously shown that metformin affects the effect of one VKA, phenprocoumon.

OBJECTIVES

The aim of this study was to determine if initiation of glucose-lowering treatment affects the international normalized ratio (INR) and dose requirements of the anticoagulant VKAs warfarin and phenprocoumon.

PATIENTS/METHODS

We performed a self-controlled retrospective register-based study. A total of 118 patients commencing glucose-lowering treatment while being treated with warfarin or phenprocoumon were included in the study. We compared INR, dose/INR and proportion of patients with at least one sub-therapeutic INR measurement before and after initiation of glucose-lowering treatment.

RESULTS

Initiation of glucose-lowering treatment caused mean INR to decrease from 2.5 to 2.2 (decrease of -0.3 [95% CI: -0.1; -0.5]) and led to more than half of the patients having at least one sub-therapeutic INR measurement. Six to 12 weeks later, the VKA dose/INR was increased by 11%, indicating a weakened effect of the VKA.

CONCLUSION

Initiation of glucose-lowering treatment reduces the anticoagulant effect of VKAs to an extent that is likely to be clinically relevant. This finding needs confirmation and mechanistic explanation.

Comparison of the Five Danish Regions Regarding Demographic Characteristics, Healthcare Utilization, and Medication Use--A Descriptive Cross-Sectional Study

Background

While Denmark is well known for its plethora of registers. Many studies are conducted on research databases that only cover parts of Denmark, and regional differences could potentially threaten these studies’ external validity. The aim of this study was to assess sociodemographic and health related homogeneity of the five Danish regions.

Methods

We obtained descriptive data for the five Danish regions, using publicly available data sources: Statbank Denmark, the Danish Ministry of Economic Affairs, and Medstat.dk. These data sources comprise aggregate data from four different nationwide registers: The Danish National Patient Register, The Danish Civil Registration System, The Danish Register of Medicinal Product Statistics, and The Danish National Health Service Register for Primary Care. We compared the Danish regions regarding demographic and socioeconomic characteristics, health care utilization, and use of medication. For each characteristic, one-year prevalence was obtained and analyses were performed for 2013 and 2008 to account for possible change over time.

Results

In 2013, 5,602,628 persons were living in Denmark. The mean age was 40.7 years in the entire Danish population and ranged between 39.6 to 42.4 years in the five regions (coefficient of variation between regions [CV] = 0.028). The proportion of women in Denmark was 50.4% (CV = 0.009). The proportion of residents with low education level was 28.7% (CV = 0.051). The annual number of GP contacts was 7.1 (range: 6.7–7.4, CV = 0.040), and 114 per 1,000 residents were admitted to the hospital (range: 101–131, CV = 0.107). The annual number of persons redeeming a prescription of any medication was 723 per 1,000 residents (range: 718–743, CV = 0.016). Analyses for 2008 showed comparable levels of homogeneity as for 2013.

Conclusions

We found substantial homogeneity between all of the five Danish regions with regard to sociodemographic and health related characteristics. Epidemiologic studies conducted on regional subsets of Danish citizens have a high degree of generalizability.

The potential drug-drug interaction between proton pump inhibitors and warfarin

BACKGROUND

Proton pump inhibitors (PPIs) have been suggested to increase the effect of warfarin, and clinical guidelines recommend careful monitoring of international normalized ratio (INR) when initiating PPI among warfarin users. However, this drug-drug interaction is sparsely investigated in a clinical setting. The aim was to assess whether initiation of PPI treatment among users of warfarin leads to increased INR values.

METHODS

The study was an observational self-controlled study from 1998 to 2012 leveraging data on INR measurements on patients treated with warfarin from primary care and outpatient clinics and their use of prescription drugs. Data were analyzed in 2015. We assessed INR, warfarin dose, and dose/INR ratio before and after initiating PPI treatment using the paired student's t-test.

RESULTS

We identified 305 warfarin users initiating treatment with PPIs. The median age was 71 years (interquartile range 63-78 years), and 64% were men. The mean INR in the 70 days prior to PPI initiation was 2.6 (95%CI 2.5-2.8) and 2.6 (95%CI 2.5-2.7) in the period 1-3 weeks after PPI initiation (p = 0.67). Further, neither mean warfarin dose nor the dose/INR ratios were significantly different before and after PPI initiation. Sensitivity analyses revealed no differences among individual PPIs.

CONCLUSIONS

We found no evidence of a clinically meaningful drug-drug interaction between PPIs and warfarin in a Northern European patient population of unselected patients from an everyday outpatient and primary care clinical setting. Thus, we do not support the recommendation to "cautiously monitor" users of warfarin initiating PPI treatment.

Birth Weight and Social Trust in Adulthood: Evidence for Early Calibration of Social Cognition

Social trust forms the fundamental basis for social interaction within societies. Understanding the cognitive architecture of trust and the roots of individual differences in trust is of key importance. We predicted that one of the factors calibrating individual levels of trust is the intrauterine flow of nutrients from mother to child as indexed by birth weight. Birth weight forecasts both the future external environment and the internal condition of the individual in multiple ways relevant for social cognition. Specifically, we predicted that low birth weight is utilized as a forecast of a harsh environment, vulnerable condition, or both and, consequently, reduces social trust. The results of the study reported here are consistent with this prediction. Controlling for many confounds through sibling and panel designs, we found that lower birth weight reduced social trust in adulthood. Furthermore, we obtained tentative evidence that this effect is mitigated if adult environments do not induce stress.

Risk factors for hospitalization due to community-acquired sepsis - a population-based case-control study

Background

The aim of the study was to estimate risk factors for hospitalization due to sepsis and to determine whether these risk factors vary by age and gender.

Methods

We performed a population-based case-control study of all adult patients admitted to a medical ED from September 2010 to August 2011. Controls were sampled within the hospital catchment-area. All potential cases were manually validated using a structured protocol. Vital signs and laboratory values measured at arrival were registered to define systemic inflammatory response syndrome and organ dysfunction. Multivariable logistic regression was used to elucidate which predefined risk factors were associated with an increased or decreased risk hospitalization due to sepsis.

Results

A total of 1713 patients were admitted with sepsis of any severity. The median age was 72 years (interquartile range: 57–81 years) and 793 (46.3%) were male. 621 (36.3%) patients were admitted with sepsis, 1071 (62.5%) with severe sepsis and 21 (1.2%) with septic shock. Episodes with sepsis of any severity were associated with older age (85+ years adjusted OR 6.02 [95%CI: 5.09–7.12]), immunosuppression (4.41 [3.83–5.09]), alcoholism-related conditions (2.90 [2.41–3.50]), and certain comorbidities: psychotic disorder (1.90 [1.58–2.27]), neurological (1.98 [1.73–2.26]), respiratory (3.58 [3.16–4.06]), cardiovascular (1.62 [1.41–1.85]), diabetes (1.82 [1.57–2.12]), cancer (1.44 [1.22–1.68]), gastrointestinal (1.71 [1.44–2.05]) and renal (1.46 [1.13–1.89]). The strength of the observed associations for comorbid factors was strongest among younger individuals.

Conclusions

Hospitalization due to sepsis of any severity was associated with several independent risk factors, including age and comorbid factors.

Systolic blood pressure and short-term mortality in the emergency department and prehospital setting: a hospital-based cohort study

Introduction

Systolic blood pressure is a widely used tool to assess circulatory function in acutely ill patients. The systolic blood pressure limit where a given patient should be considered hypotensive is the subject of debate and recent studies have advocated higher systolic blood pressure thresholds than the traditional 90 mmHg. The aim of this study was to identify the best performing systolic blood pressure thresholds with regards to predicting 7-day mortality and to evaluate the applicability of these in the emergency department as well as in the prehospital setting.

Methods

A retrospective, hospital-based cohort study was performed at Odense University Hospital that included all adult patients in the emergency department between 1995 and 2011, all patients transported to the emergency department in ambulances in the period 2012 to 2013, and all patients serviced by the physician-staffed mobile emergency care unit (MECU) in Odense between 2007 and 2013. We used the first recorded systolic blood pressure and the main outcome was 7-day mortality. Best performing thresholds were identified with methods based on receiver operating characteristics (ROC) and multivariate regression. The performance of systolic blood pressure thresholds was evaluated with standard summary statistics for diagnostic tests.

Results

Seven-day mortality rates varied from 1.8 % (95 % CI (1.7, 1.9)) of 112,727 patients in the emergency department to 2.2 % (95 % CI (2.0, 2.5)) of 15,862 patients in the ambulance and 5.7 % (95 % CI (5.3, 6.2)) of 12,270 patients in the mobile emergency care units. Best performing thresholds ranged from 95 to 119 mmHg in the emergency department, 103 to 120 mmHg in the ambulance, and 101 to 115 mmHg in the MECU but area under the ROC curve indicated poor overall discriminatory performance of SBP thresholds in all cohorts.

Conclusions

Systolic blood pressure alone is not sufficient to identify patients at risk regardless of the defined threshold for hypotension. If, however, a threshold is to be defined, a systolic blood pressure threshold of 100 to 110 mmHg is probably more relevant than the traditional 90 mmHg.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0884-y) contains supplementary material, which is available to authorized users.

Time to initial antibiotic administration, and short-term mortality among patients admitted with community-acquired severe infections with and without the presence of systemic inflammatory response syndrome: a follow-up study

BACKGROUND

The prognosis for patients with severe infection is related to early treatment, including early administration of antibiotics. The study aim was to compare the short-term mortality among patients admitted with severe infection with and without systemic inflammatory response syndrome (SIRS) at arrival, and to ascertain whether the presence of SIRS might affect the timing of antibiotic administration.

METHODS

In this retrospective follow-up study, we included all adult patients (≥15 years) presenting to a medical emergency department in the period between September 2010 and August 2011 with a first-time admission of community-acquired severe infection (infection with evidence of organ dysfunction), with and without SIRS at arrival. The presence of SIRS was defined as two or more of the criteria according to the American College of Chest Physicians/Society of Critical Care Medicine (ACCP/SCCM) definitions. Cases were identified by manual chart review using predefined criteria of infection. Data on vital signs, laboratory values and antibiotic treatment were obtained electronically.

RESULTS

We included 1169 patients with infection and organ dysfunction, treated with antibiotics within 24 h after arrival (median age 76.1 years (IQR 63.1-83.5), 567 (48.5%) men). In all, 886 (75.8%) presented with SIRS, and 283 (24.2%) presented without SIRS. Median time to antibiotics was 4.6 h (IQR 2.9-7.0) in patients with SIRS and 6.7 h (IQR 4.5-10.3) in patients without SIRS (p<0.0001). Thirty-day mortality in patients with and without SIRS was 18.4% (95% CI 15.9% to 21.1%) and 16.6% (95% CI 12.5% to 21.5%), respectively.

CONCLUSIONS

SIRS was absent in one-quarter of patients admitted with severe infection. The 'door-to-antibiotics' time was significantly shorter for patients with SIRS compared with patients without SIRS, but no difference was found in 30-day mortality.

From administrative infrastructure to biomedical resource: Danish population registries, the "Scandinavian laboratory," and the "epidemiologist's dream"

Since the 1970s, Danish population registries were increasingly used for research purposes, in particular in the health sciences. Linked with a large number of disease registries, these data infrastructures became laboratories for the development of both information technology and epidemiological studies. Denmark's system of population registries had been centralized in 1924 and was further automated in the 1960s, with individual identification numbers (CPR-numbers) introduced in 1968. The ubiquitous presence of CPR-numbers in administrative routines and everyday lives created a continually growing data archive of the entire population. The resulting national-level database made possible unprecedented record linkage, a feature epidemiologists and biomedical scientists used as a resource for population health research. The specific assemblages that emerged with their practices of data mining were constitutive of registry-based epidemiology as a style of thought and of a distinct relationship between science, citizens, and the state that emerged as “Scandinavian.”

Prognosis and risk factors for deterioration in patients admitted to a medical emergency department

Objective

Patients that initially appear stable on arrival to the hospital often have less intensive monitoring of their vital signs, possibly leading to excess mortality. The aim was to describe risk factors for deterioration in vital signs and the related prognosis among patients with normal vital signs at arrival to a medical emergency department (MED).

Design and setting

Single-centre, retrospective cohort study of all patients admitted to the MED from September 2010-August 2011.

Subjects

Patients were included when their vital signs (systolic blood pressure, pulse rate, respiratory rate, Glasgow Coma Scale, oxygen saturation and temperature) were within the normal range at arrival. Deterioration was defined as a deviation from the defined normal range 2–24 hours after arrival.

Results

4292 of the 6257 (68.6%) admitted to the MED had a full set of vital signs at first presentation, 1440/4292 (33.6%) had all normal vital signs and were included in study, 44.0% were male, median age 64 years (5th/95th percentile: 21–90 years) and 446/1440 (31.0%) deteriorated within 24 hours. Independent risk factors for deterioration included age 65–84 years odds ratio (OR): 1.79 (95% confidence interval [CI]: 1.27–2.52), 85+ years OR 1.67 (95% CI: 1.10–2.55), Do-not-attempt-to-resuscitate order OR 3.76 (95% CI: 1.37–10.31) and admission from the open general ED OR 1.35 (95% CI: 1.07–1.71). Thirty-day mortality was 7.9% (95% CI: 5.5–10.7%) among deteriorating patients and 1.9% (95% CI: 1.2–3.0%) among the non-deteriorating, hazard ratio 4.11 (95% CI: 2.38–7.10).

Conclusions

Among acutely admitted medical patients who arrive with normal vital signs, 31.0% showed signs of deterioration within 24 hours. Risk factors included old age, Do-not-attempt-to-resuscitate order, admission from the open general ED. Thirty-day mortality among patients with deterioration was four times higher than among non-deteriorating patients. Further research is needed to determine whether intensified monitoring of vital signs can help to prevent deterioration or mortality among medical emergency patients.

The epidemiology of long- and short-term cancer survivors. A population-based cohort study exploring denominators for rehabilitation and palliative care programs

INTRODUCTION

In this study, we present data from a population-based cohort of incident cancer patients separated in long- and short-term survivors. Our aim was to procure denominators for use in the planning of rehabilitation and palliative care programs.

MATERIAL AND METHODS

A registry-linkage cohort study. All cancer patients, diagnosed from 1993 to 2003 from a 470 000 large population, were followed individually from diagnosis to death or until 31 December 2008. Long-term survivors lived five years or more after the time of the cancer diagnosis (TOCD). Short-term survivors died less than five years after TOCD.

RESULTS

The cohort comprised 24 162 incident cancer patients with 41% long-term survivors (N = 9813). Seventy percent of the cohort was 60 + years at TOCD. The 14 349 short-term survivors' median survival was 0.6 year, and 78% died less than two years after TOCD. A 12 years' difference in age at TOCD was seen between long- and short-term survivors, with median ages of 60 versus 72 years, respectively. Females comprised 64% of long-term, and 46% of short-term survivors. The proportion of breast and lung cancers differed between the groups: Long-term survivors: 31% breast cancer, 2.4% lung cancer. Short-term survivors: 21% lung cancer, 7.2% breast cancer. Chemotherapy was provided to 15% of all patients, and to 10% of the 60 + year olds.

DISCUSSION

The epidemiology of long- and short-term survivors shows significant differences with regard to age at TOCD, cancer types and sex. Two-year crude cancer survival seems as a clinically relevant cut point for characterizing potential "denominators" for rehabilitation or palliative care programs. From this cohort of incident cancer patients, and using two-year survival as a cut point, it could be estimated that 54% would candidate to a "care trajectory" focusing on rehabilitation and 46% a "care trajectory" focusing on palliative care at TOCD.

How well do discharge diagnoses identify hospitalised patients with community-acquired infections?--a validation study

Background

Credible measures of disease incidence, trends and mortality can be obtained through surveillance using manual chart review, but this is both time-consuming and expensive. ICD-10 discharge diagnoses are used as surrogate markers of infection, but knowledge on the validity of infections in general is sparse. The aim of the study was to determine how well ICD-10 discharge diagnoses identify patients with community-acquired infections in a medical emergency department (ED), overall and related to sites of infection and patient characteristics.

Methods

We manually reviewed 5977 patients admitted to a medical ED in a one-year period (September 2010-August 2011), to establish if they were hospitalised with community-acquired infection. Using the manual review as gold standard, we calculated the sensitivity, specificity, predictive values, and likelihood ratios of discharge diagnoses indicating infection.

Results

Two thousand five hundred eleven patients were identified with community-acquired infection according to chart review (42.0%, 95% confidence interval [95%CI]: 40.8–43.3%) compared to 2550 patients identified by ICD-10 diagnoses (42.8%, 95%CI: 41.6–44.1%). Sensitivity of the ICD-10 diagnoses was 79.9% (95%CI: 78.1–81.3%), specificity 83.9% (95%CI: 82.6–85.1%), positive likelihood ratio 4.95 (95%CI: 4.58–5.36) and negative likelihood ratio 0.24 (95%CI: 0.22–0.26). The two most common sites of infection, the lower respiratory tract and urinary tract, had positive likelihood ratios of 8.3 (95%CI: 7.5–9.2) and 11.3 (95%CI: 10.2–12.9) respectively. We identified significant variation in diagnostic validity related to age, comorbidity and disease severity.

Conclusion

ICD-10 discharge diagnoses identify specific sites of infection with a high degree of validity, but only a moderate degree when identifying infections in general.

Congenital cerebral palsy, child sex and parent cardiovascular risk

Objective

Genes associated with cardiovascular disease may also be risk factors for congenital cerebral palsy (CP) and these associations may be modified by sex, since there is an increased risk of CP in male children. We investigated the association between CP of the child with cardiovascular disease in parents, taking sex of the child into consideration.

Methods

All parents of non-adopted singletons born in Denmark between 1973 and 2003 were included. Parents of a child with CP, confirmed by the Danish National CP registry, were considered exposed. Cox proportional hazards regressions were used to model risk of cardiovascular outcomes for exposed parents compared to all other parents beginning at the child’s 10^th birthday.

Results

We identified 733,730 mothers and 666,652 fathers among whom 1,592 and 1,484, respectively, had a child with CP. The mean age for mothers at end of follow up was 50±8 years. After adjustment for maternal age, parental education, child’s sex, child’s residence, child being small for gestational age and maternal hypertensive disorder during pregnancy, mothers of CP male children had an excess risk of cardiovascular disease (HR: 1.52, 95% CI: 1.16-2.00), attributable mostly to an increased incidence of hypertension and cerebrovascular disease. After additional adjustment for preterm birth, the association was markedly attenuated for cardiovascular disease (1.34, 95%CI: 1.02 - 1.76), became nonsignificant for hypertension, but remained significant for cerebrovascular disease (HR: 2.73, 95% CI: 1.45- 5.12). There was no increased risk of cardiovascular events in mothers of female CP children, or fathers of CP children of any sex.

Conclusions

Women that have a male child with CP are at increased risk for premature cardiovascular disease. Part of this association may be related to risk factors for preterm births.

Maternal infections during pregnancy and cerebral palsy: a population-based cohort study

BACKGROUND

Cerebral palsy (CP) is a common motor disability in childhood. We examined the association between maternal infections during pregnancy and the risk of congenital CP in the child.

METHODS

Liveborn singletons in Denmark between 1997 and 2003 were identified from the Danish National Birth Registry and followed from 1 year of life until 2008. Redemption of antibiotics from the National Register of Medicinal Product Statistics and maternal infections reported by the National Hospital Register were used as markers of maternal infection during pregnancy. CP diagnoses were obtained from the Danish Cerebral Palsy Registry. Adjusted hazard ratio (HR) and 95% confidence interval (CI) were estimated by Cox proportional hazard models.

RESULTS

Of the 440 564 singletons with follow-up data, 840 were diagnosed with congenital CP. Maternal genito-urinary tract infections (HR 2.1, 95% CI 1.4, 3.2) were associated with CP in all births, in term births (HR 1.9, 95% CI 1.1, 3.2), in children with spastic CP (HR 2.1, 95% CI 1.4, 3.3), and among first-born children (HR 1.9, 95% CI 1.4, 3.3). Overall, we found associations between redeemed nitrofurantoin (HR 1.7, 95% CI 1.1, 2.8) and CP. Among trimester-specific exposures, CP risk was associated with prescriptions redeemed in the first trimester for any antibacterials, beta-lactam antibacterials, and nitrofurantoin, an antibiotic commonly used to treat lower urinary tract infection, and genito-urinary tract infections in the third trimester.

CONCLUSION

Genito-urinary tract infections and antibiotic use during pregnancy were associated with increased risks of CP, indicating that some maternal infections or causes of maternal infections present in prenatal life may be part of a causal pathway leading to CP.

Risk of death associated with the use of conventional vs. atypical antipsychotic medications: evaluating the use of the Emilia-Romagna Region database for pharmacoepidemiological studies

WHAT IS KNOWN AND OBJECTIVE

Since 2005, a mounting base of evidence has identified that conventional antipsychotic medications are associated with an increased risk of mortality among elderly patients when compared to atypical antipsychotics. This study sought to explore the feasibility of using the Emilia-Romagna Region (RER) database for comparative safety analyses by replicating and refining risk estimates of this well-known drug safety example through meta-analysis.

METHODS

We identified a cohort of 23 681 Italian RER patients (aged ≥65) who initiated treatment with a conventional or atypical antipsychotic between 1 July 2009 and 30 June 2011. We compared 180-day mortality using Cox proportional hazards models adjusted for risk factors for death, use of other medications and measures of health services utilization intensity, all measured before antipsychotic initiation. We conducted a meta-analysis of studies with similar methods against which to compare our results.

RESULTS

Among 14 462 and 9219 patients prescribed conventional and atypical antipsychotics, respectively, we observed 2402 (16·6%) and 821 (8·9%) deaths during follow-up. Conventional antipsychotic initiators were older and generally had higher prevalence of outcome risk factors and higher baseline health service use intensity. The crude hazard ratio (HR) was 1·95 [95% confidence interval (CI), 1·80-2·11], which decreased to 1·47 (95% CI, 1·35-1·60) after full adjustment. We identified seven published studies that examined this association using similar methods. The pooled HR from these studies was 1·34 (95% CI, 1·28-1·39). Including our study, the meta-analysis yielded a summary estimate of 1·35 (95% CI, 1·31-1·40) and did not introduce any heterogeneity (I(2)  = 0%; P = 0·455).

WHAT IS NEW AND CONCLUSIONS

Our results support the use of the RER database for pharmacoepidemiological studies and provide an up-to-date and pooled estimate of the magnitude of the association between mortality and conventional vs. atypical antipsychotics.

The Nordic prescription databases as a resource for pharmacoepidemiological research--a literature review

PURPOSE

All five Nordic countries have nationwide prescription databases covering all dispensed drugs, with potential for linkage to outcomes. The aim of this review is to present an overview of therapeutic areas studied and methods applied in pharmacoepidemiologic studies using data from these databases.

METHODS

The study consists of a Medline-based structured literature review of scientific papers published during 2005-2010 using data from the prescription databases in Denmark, Finland, Iceland, Norway, and Sweden, covering 25 million inhabitants. Relevant studies were analyzed in terms of pharmacological group, study population, outcomes examined, type of study (drug utilization vs. effect of drug therapy), country of origin, and extent of cross-national collaboration.

RESULTS

A total of 515 studies were identified. Of these, 262 were conducted in Denmark, 97 in Finland, 4 in Iceland, 87 in Norway, and 61 in Sweden. Four studies used data from more than one Nordic country. The most commonly studied drugs were those acting on the nervous system, followed by cardiovascular drugs and gastrointestinal/endocrine drugs. A total of 228 studies examined drug utilization and 263 focused on the effects and safety of drug therapy. Pregnant women were the most commonly studied population in safety studies, whereas prescribers' adherence to guidelines was the most frequent topic of drug utilization studies.

CONCLUSIONS

The Nordic prescription databases, with their possibility of record-linkage, represent an outstanding resource for assessing the beneficial and adverse effects of drug use in large populations, under routine care conditions, and with the potential for long-term follow-up.

Maternal use of antibiotics and the risk of childhood febrile seizures: a Danish population-based cohort

Objective

In a large population-based cohort in Denmark to examine if maternal use of antibiotics during pregnancy, as a marker of infection, increases the risk of febrile seizures in childhood in a large population-based cohort in Denmark.

Methods

All live-born singletons born in Denmark between January 1, 1996 and September 25, 2004 and who were alive on the 90^th day of life were identified from the Danish National Birth Registry. Diagnoses of febrile seizures were obtained from the Danish National Hospital Register and maternal use of antibiotics was obtained from the National Register of Medicinal Product Statistics. Hazard ratios (HR) and 95% confidence intervals (95% CI) were estimated by Cox proportional hazard regression models.

Results

We followed 551,518 singletons for up to 5 years and identified a total of 21,779 children with a diagnosis of febrile seizures. Slightly increased hazard ratios were observed among most exposure groups when compared to the unexposed group, ex. HR 1.08 95% CI: 1.05–1.11 for use of any systemic antibiotic during pregnancy.

Conclusion

We found weak associations between the use of pharmacologically different antibiotics during pregnancy and febrile seizures in early childhood which may indicate that some infections, or causes or effects of infections, during pregnancy could affect the fetal brain and induce susceptibility to febrile seizures.

Does C-reactive protein independently predict mortality in adult community-acquired bacteremia patients with known sepsis severity?

We evaluated whether sepsis severity and C-reactive protein (CRP) level on admission prognostically corroborated or annulled each other in adult patients with incident community-acquired bacteremia (Funen, Denmark, 2000-2008). We used logistic regression and area under the receiver operating characteristic curve (AUC) to evaluate 30-day mortality in four models: (i) age, gender, comorbidity, bacteria, and ward. (ii) Model 1 and sepsis severity. (iii) Model 1 and CRP. (iv) Model 1, sepsis severity, and CRP. Altogether, 416 of 1999 patients died within 30 days. CRP independently predicted 30-day mortality [Model 4, odds ratio (95% CIs) for 100 mg/L: 1.16 (1.06-1.27)], but it did not contribute to the AUC (Model 2 vs Model 4: p = 0.31). In the 963 non-severe sepsis patients, CRP independently predicted 30-day mortality [Model 4: 1.42 (1.20-1.69)] and it increased the AUC (Model 2 vs Model 4: p = 0.06), thus CRP contributed as much as sepsis severity to prognosis.

Maternal use of cystitis medication and childhood epilepsy in a danish population-based cohort

BACKGROUND

Maternal infections during pregnancy have been associated with an increased risk for neurological outcomes in the child, including epilepsy. We examined cystitis antibiotics commonly used during pregnancy, as a marker of cystitis, and the risk of childhood epilepsy in a population-based cohort in Denmark.

METHODS

We examined all liveborn singletons born in Denmark between January 1996 and September 2004, identified from the Danish National Birth Registry. Epilepsy diagnoses were obtained from the Danish National Hospital Register and maternal antibiotic use from the National Register of Medicinal Product Statistics. Cystitis antibiotics consisted of pivmecillinam, sulphamethizole and nitrofurantoin. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated with Cox proportional hazard regression models.

RESULTS

The study followed 447629 singletons for up to 9.9 years and identified 2848 children diagnosed with epilepsy. We found slightly increased risks of epilepsy in children whose mothers had redeemed prescriptions during pregnancy for pivmecillinam HR=1.2 [95% CI 1.0, 1.4], sulphamethizole HR=1.2 [95% CI 1.1, 1.4] or nitrofurantoin HR=1.1 [95% CI 0.8, 1.5], compared with those unexposed. Among mothers with multiple redeemed prescriptions during pregnancy, adjusted HR were for pivmecillinam HR=1.3 [95% CI 1.1, 1.5], sulphamethizole HR=1.3 [95% CI 1.1, 1.5] and nitrofurantoin HR=1.3 [95% CI 1.0, 1.8].

CONCLUSIONS

Similar magnitudes of associations between chemically different drugs, used almost exclusively to treat cystitis, may suggest an impact of maternal infection on the fetal brain. However, direct drug effects or confounding factors are also possible explanations.

Comorbidity in elderly cancer patients in relation to overall and cancer-specific mortality

BACKGROUND

Aims of this study were to describe the prevalence of comorbidity in newly diagnosed elderly cancer cases compared with the background population and to describe its influence on overall and cancer mortality.

METHODS

Population-based study of all 70+ year-olds in a Danish province diagnosed with breast, lung, colorectal, prostate, or ovarian cancer from 1 January 1996 to 31 December 2006. Comorbidity was measured according to Charlson's comorbidity index (CCI). Prevalence of comorbidity in newly diagnosed cancer patients was compared with a control group by conditional logistic regression, and influence of comorbidity on mortality was analysed by Cox proportional hazards method.

RESULTS

A total of 6325 incident cancer cases were identified. Elderly lung and colorectal cancer patients had significantly more comorbidity than the background population. Severe comorbidity was associated with higher overall mortality in the lung, colorectal, and prostate cancer patients, hazard ratios 1.51 (95% CI 1.24-1.83), 1.41 (95% CI 1.14-1.73), and 2.14 (95% CI 1.65-2.77), respectively. Comorbidity did not affect cancer-specific mortality in general.

CONCLUSION

Colorectal and lung cancer was associated with increased comorbidity burden in the elderly compared with the background population. Comorbidity was associated with increased overall mortality in elderly cancer patients but not consistently with cancer-specific mortality.

The Danish National Prescription Registry

INTRODUCTION

Individual-level data on all prescription drugs sold in Danish community pharmacies has since 1994 been recorded in the Register of Medicinal Products Statistics of the Danish Medicines Agency.

CONTENT

The register subset, termed the Danish National Prescription Registry (DNPR), contains information on dispensed prescriptions, including variables at the level of the drug user, the prescriber, and the pharmacy.

VALIDITY AND COVERAGE

Reimbursement-driven record keeping, with automated bar-code-based data entry provides data of high quality, including detailed information on the dispensed drug.

CONCLUSION

The possibility of linkage with many other nationwide individual-level data sources renders the DNPR a very powerful pharmacoepidemiological tool.

Record linkage for pharmacoepidemiological studies in cancer patients

BACKGROUND

An increasing need has developed for the post-approval surveillance of (new) anti-cancer drugs by means of pharmacoepidemiology and outcomes research in the area of oncology.

OBJECTIVES

To create an overview that makes researchers aware of the available database linkages in Northern America and Europe which facilitate pharmacoepidemiology and outcomes research in cancer patients.

METHODS

In addition to our own database, i.e. the Eindhoven Cancer Registry (ECR) linked to the PHARMO Record Linkage System, we considered database linkages between a population-based cancer registry and an administrative healthcare database that at least contains information on drug use and offers a longitudinal perspective on healthcare utilization. Eligible database linkages were limited to those that had been used in multiple published articles in English language included in Pubmed. The HMO Cancer Research Network (CRN) in the US was excluded from this review, as an overview of the linked databases participating in the CRN is already provided elsewhere. Researchers who had worked with the data resources included in our review were contacted for additional information and verification of the data presented in the overview.

RESULTS

The following database linkages were included: the Surveillance, Epidemiology, and End-Results-Medicare; cancer registry data linked to Medicaid; Canadian cancer registries linked to population-based drug databases; the Scottish cancer registry linked to the Tayside drug dispensing data; linked databases in the Nordic Countries of Europe: Norway, Sweden, Finland and Denmark; and the ECR-PHARMO linkage in the Netherlands. Descriptives of the included database linkages comprise population size, generalizability of the population, year of first data availability, contents of the cancer registry, contents of the administrative healthcare database, the possibility to select a cancer-free control cohort, and linkage to other healthcare databases.

CONCLUSIONS

The linked databases offer a longitudinal perspective, allowing for observations of health care utilization before, during, and after cancer diagnosis. They create new powerful data resources for the monitoring of post-approval drug utilization, as well as a framework to explore the (cost-)effectiveness of new, often expensive, anti-cancer drugs as used in everyday practice.

What you see is not what you get in the PDF document format

The sharing and storage of scientific knowledge, information and data are today mainly in digitized form, which will become the predominant means of communicating scientific work in the future. One of the best-established formats is the open standard of PDF (Portable Document Format), which is renowned for its flexibility and stability. In this article, we expose a major flaw in the format with respect to the security of confidential information, such that even organizations responsible for safeguarding and setting the standards for data management were unintentionally revealing confidential patient data. By collecting and analysing a random sample of files from a health informatics organization, we demonstrate the extent of the problem and determine its cause by code analysis of an example. In conclusion, we suggest the development of a knowledge-sharing format that does not demand expert skills for safe usage: WYSIWYS (What You See Is What You Store).

Temporal data mining for adverse events following immunization in nationwide Danish healthcare databases

BACKGROUND

A rarely used opportunity in pharmacovigilance is data mining for adverse drug reactions (ADRs) in population-based healthcare databases.

OBJECTIVE

To evaluate the potential of data mining for ADRs in the nationwide Danish healthcare databases. We specifically considered hospital contacts following measles, mumps and rubella (MMR) immunization.

METHODS

We constructed a cohort consisting of all children born in Denmark from 1995 to 2007 (n = 918,831) with individual-level linked data on childhood vaccinations and hospital contacts from the nationwide Danish healthcare databases. We applied a cohort-based data mining methodology to compare the observed versus the expected incidence of adverse event in different time periods relative to immunization. With this approach we evaluated temporal associations between MMR immunization and 5915 different diagnoses occurring in the cohort. In order to evaluate the ability of our approach to detect signals, we singled out a set of four adverse events previously recognized as being associated with the MMR vaccine.

RESULTS

We were able to link a total of 3,162,251 hospital contacts and 5915 different diagnoses to the children in the cohort. Previously recognized temporal associations between adverse events (febrile convulsions, idiopathic thrombocytopenic purpura, lymphadenopathy and rash) and MMR immunization were identified in the Danish databases by our method.

CONCLUSIONS

Data mining in the Danish population-based healthcare databases provides adequate ability to detect adverse events. Pharmacovigilance using electronic healthcare databases holds potential as an important supplement to traditional pharmacovigilance.

Existing data sources for clinical epidemiology: Aarhus University Prescription Database

Population-based prescription databases in Nordic countries have become a mainstay of epidemiologic research. Denmark has both national and regional population-based prescription databases. Aarhus University Prescription Database collects data on reimbursed medications dispensed at all community pharmacies of the North Denmark Region and the Central Denmark Region. The regions have a combined population of 1.8 million inhabitants, or one-third of the Danish population. Denmark’s primary health care sector, which includes general practitioners, specialists, and dentists, generates about 96% of the prescription sales, most of which are reimbursable and are dispensed by the community pharmacies. The Aarhus University Prescription Database combines the region’s pharmacy records in a single database, maintained and updated for research purposes. Each dispensation record contains patient-, drug-, and prescriber-related data. Dispensation records retain patients’ universal personal identifier, which allows for individual-level linkage to all Danish registries and medical databases. The linked data have many applications in clinical epidemiology, including drug utilization studies, safety monitoring, etiologic research, and validation studies.

Antipsychotics and risk of venous thromboembolism: A population-based case-control study

During the last decade, the risk of venous thromboembolism (VTE) has been reported in users of antipsychotic drugs. However, the reports have been inconclusive. This study aimed to determine the relative risk of VTE in antipsychotic drug users. Using data from medical databases in North Jutland and Aarhus Counties, Denmark, and the Danish Civil Registration System, we identified 5,999 cases with a first-time diagnosis of VTE and, based on risk set sampling, 59,990 sex- and age-matched population controls during 1997–2005. Users of antipsychotic drugs were identified from population-based prescription databases and categorized based on filled prescriptions prior to admission date for VTE or index date for controls as current (at least one prescription within 90 days), recent (at least one prescription within 91–180 days), former (at least one prescription within 181–365 days) or nonusers (no recorded prescription within 365 days). Compared with nonusers, current users of any antipsychotic drugs had an increased risk of VTE (adjusted relative risk [ARR]: 1.99, 95% confidence interval [CI]: 1.69–2.34). Former users of any antipsychotic drugs had a nonsignificant elevated risk of VTE compared with nonusers (ARR: 1.54, 95% CI: 0.99–2.40, p-value: 0.056). In conclusion, users of antipsychotic drugs have an increased risk of VTE, compared with nonusers, which might be due to the treatment itself, to lifestyle factors, to the underlying disease, or to residual confounding.

Databases for pediatric medicine research in Europe--assessment and critical appraisal

PURPOSE

To identify and describe European health care databases that can be used for pediatric pharmacoepidemiological research.

METHODS

A web-based survey was conducted among all European databases that were listed on the website of the International Society of Pharmacoepidemiology (ISPE) and/or known by an expert group. The survey comprised of questions regarding (a) the nature of the database, (b) database size, (c) demographic, clinical and drug related data provided, (d) cost, and (e) accessibility of the database.

RESULTS

A total of 25 data sources from 12 European countries were identified and invited to participate in the survey. Responses were obtained from 21 (84%) databases located in 10 different European countries. Seventeen databases were included in the assessment comprising a total of at least 9 million children aged 0-18 years. The majority of databases are based on outpatient data and all keep either prescription or drug dispensing data. Ten databases are based on electronic patient records from primary care physicians and five databases are predominantly claims oriented. Three databases do not belong to either of the above mentioned categories. Almost all of the databases can be used for pediatric drug utilization studies. For drug safety studies it is more appropriate to use electronic patient record databases because of the available clinical information and the potential to obtain additional information.

CONCLUSIONS

There are many European healthcare databases providing an enormous potential for pediatric pharmacoepidemiological research. Future research should focus on methods to bring data from different databases together to use the full capacity effectively.

Health care costs, work productivity and activity impairment in non-malignant chronic pain patients

This study explores the costs of non-malignant chronic pain in patients awaiting treatment in a multidisciplinary pain clinic in a hospital setting. Health care costs due to chronic pain are particular high during the first year after pain onset, and remain high compared with health care costs before pain onset. The majority of chronic pain patients incur the costs of alternative treatments. Chronic pain causes production losses at work, as well as impairment of non-work activities.

Variable access to clopidogrel in a harmonized EU market

OBJECTIVES

This study focuses on the different national coverage and reimbursement strategies and their consequences for access to clopidogrel, a drug with a central European Union (EU) registration. Our objectives are 1) to assess whether changes in reimbursement policies in EU member states influenced clopidogrel prescribing; and 2) to determine whether clopidogrel-specific policy characteristics, general characteristics of the health system, or indicators for the amount of cardiovascular care delivered were associated with the level of clopidogrel prescribing.

METHODS

Data were collected in Austria, Belgium, Denmark, Germany, Hungary, Portugal, Slovenia, The Netherlands, and the United Kingdom (England). Utilization rates were expressed as defined daily doses (DDDs)/1000 persons/day. To determine whether changes in reimbursement policies influenced clopidogrel utilization, a segmented linear regression approach was used.

RESULTS

Clopidogrel prescribing varied widely in the studied countries, from 2.76 (The Netherlands) to 6.83 (Belgium) DDDs/1000 persons/day (March 2005). Six countries had therapeutic indication restrictions to clopidogrel use. Health system characteristics did not explain variation in clopidogrel prescribing.

CONCLUSION

A disconnect will be indicated in this study between the concept of a harmonized EU pharmaceuticals market and the reality in an individual member state. Although clopidogrel was centrally registered in the EU, policy measures at the national level result in different roles in clinical practice for this drug.

Early discontinuation: more frequent among general practitioners with high levels of prescribing

INTRODUCTION

Discontinuation of medical drug treatment is a serious problem in primary care. The need for a better understanding of the processes, including physician-specific mechanisms, is apparent. The aim of this study was to analyse the association between general practitioners' prescribing prevalence and rate of early discontinuation of different drugs consisting of, in this study, lipid-lowering drugs, antihypertensive drugs, antidepressants, antidiabetics and drugs against osteoporosis.

MATERIAL AND METHODS

This was a register study based on prescription data covering a 4-year period and consisting of 470,000 citizens. For each practice and group of drug, a 1-year prevalence for 2002 and the rate of early discontinuation among new users in 2002-2003 were estimated. Early discontinuation was defined as no prescriptions during the second half-year following the first prescription, with the exception of new users of antidepressants for whom it was the first half-year. Correlations were analysed using the SAS ver. 9.1PROC MIXED procedure. The association with the total prescribing prevalence (all drugs) was also analysed.

RESULTS

A total of 141 general practices were included in the study. There was a positive association between the prevalence of prescribing for the specific drugs studied (antidepressants, antidiabetics, drugs against osteoporosis and lipid-lowering drugs) and early discontinuation (r = 0.29 -0.44), but not for anti-hypertensive drugs. The analysis of the association between prevalence of all drugs and drug-specific early discontinuation showed some degree of positive association - strongest for anti-hypertensive drugs (r = 0.62) and antidepressants (r = 0.43).

CONCLUSION

This study confirmed our hypothesis that general practitioners with high levels of prescribing attain higher rates of early discontinuation compared with colleagues with low levels of prescribing, not only with respect to antidepressants but also for various groups of drugs. A common underlying mechanism is suggested but has to be verified in future studies.

Identification of asthmatic children using prescription data and diagnosis

OBJECTIVE

The aim of the study was to develop and validate a method for identifying asthmatic children between 6 and 14 years of age based on prescription data on anti-asthmatic drugs and diagnostic data.

METHODS

A register-based study of 125,907 Danish children aged 6-14 years identified 9695 children who had redeemed at least one anti-asthmatic drug prescription in 2002. The asthma diagnosis in these children was validated by discharge information and by a questionnaire completed by general practitioners. Models based on combinations of different types of drugs were tested to find the best model that would include as many children as possible with a validated diagnosis and exclude as many false positives as possible. Different time windows were tested in terms of detecting the children and the observation period of refilling prescriptions.

RESULTS

The highest specificity of 0.86 [95% confidence interval (95% CI): 0.84-0.87] together with a sensitivity of 0.63 (95% CI: 0.62-0.65) were found in the model that included children who had redeemed a prescription for any anti-asthmatic drug - with the exception of prescriptions for beta2-agonists as liquid, one prescription only of inhaled beta2-agonist or an inhaled steroid - during a 12-month period. Lengthening the observation time by 6 months did not significantly improve the specificity (0.87; 95% CI: 0.85-0.88), but it did result in a statistically significantly lower sensitivity (0.59; 95% CI: 0.58-0.60).

CONCLUSION

Register-based data on redeemed prescriptions can be utilised to identify asthmatic school children. This method will be useful in health services research and in the proactive care of asthmatic children.

Cost effectiveness of preventive home visits to the elderly: economic evaluation alongside randomized controlled study

We evaluated the cost effectiveness of preventive home visits to elderly persons in Denmark alongside a 3-year randomized controlled study. The main outcome measure was incremental costs per active life-year gained. The number of active life-years was defined as those during which the person is able independently to transfer, walk indoors, go outdoors, walk outdoors in both pleasant and poor weather, and climb stairs. In 17 of 34 municipalities health visitors and general practitioners were offered geriatric training, which focused on early signs of disability, physical activity, and interdisciplinary follow-up. The remaining 17 municipalities offered preventive home visits as usual. Outcomes were measured in 4,034 persons aged 75 or 80 years old and dwelling at home. The difference in mean total costs between the intervention and the control group discounted at 3% was -856 euro (95% CI -2,455 to 744) in 75-year-olds and 694 euro (-2,684 to 4,071) in 80-year-olds. The discounted difference in mean active life-years was 0.034 (-0.058 to 0.125) and 0.197 (0.013 to 0.380), respectively. The study did not provide conclusive evidence on the cost effectiveness of the programs under consideration.

Income-related inequality in utilization of health services in Denmark: evidence from Funen County

AIMS

To examine income-related inequity in utilization of healthcare services in Denmark.

METHODS

A health survey of 2,915 respondents in Funen County interviewed in 2000 and 2001 on health status and socioeconomic and sociodemographic characteristics was merged with various computerized registers including inpatient stays, ambulatory visits, contacts in the primary healthcare sector, and prescription medicine. The index of horizontal inequity was used to estimate the degree of horizontal inequity in utilization of healthcare services across income groups, using the indirect method of standardization to control for age, gender, and self-assessed health as a proxy for need. The standardization method rests on the assumption of equal response behaviour across income groups.

RESULTS

The least advantaged with respect to income consume a bigger share of the health services than the most advantaged with the exception of dental treatments where the opposite is true. After standardization for age, gender, and health status there is no significant inequity in use of all healthcare services. However, when it comes to specific healthcare services the least advantaged have a significantly lower share of the medicine consumption and dental treatments than expected.

CONCLUSION

The index of horizontal inequity suggests that the Danish healthcare system is in general equitable. In sectors with a high degree of co-payment some horizontal inequity disfavouring the lower income groups appears to be present.

Cancer patients’ first treatment episode with opioids: a pharmaco-epidemiological perspective

GOAL

The factors underlying the choice of opioids for cancer patients in primary care are largely unknown. Our aim was to describe cancer patients' first treatment episode with opioids in relation to disease characteristics and clinical course.

PATIENTS AND METHODS

During 1997 and 1998, a population-based cohort of 4,006 incident cancer patients from a Danish county was identified. The patients were followed up from diagnosis to death or until 31 December 2003, and data on their use of opioids were obtained from a prescription database.

MAIN RESULTS

Eventually, 54% of the cancer patients became incident users of opioids. Opioid treatment was initiated close to the diagnosis date in 20% of the patients. Most incident users (57%) were not terminal when they began using opioids, and 44% survived the first treatment episode. Of those who died, 70% received opioids in their terminal phase. The incidence rates of new opioid users were inversely related to the 5-year cancer survival period. A weak opioid was the first choice in 64% of the non-terminal users and in 43% of the terminal ones. No statistically significant differences in opioid use were found between men and women.

CONCLUSIONS

Opioid use in cancer patients was not confined to the terminal course. Treatment with opioids should be viewed as a dynamic condition, with patients shifting between periods of use and non-use. The aggressiveness of the cancer and the presence of metastases were characteristics found to be strong determinants of opioid use.

Use of six main drug therapeutic groups across educational groups: self-reported survey and prescription records

OBJECTIVES

To assess whether the use of six main therapeutic groups was congruent with the occurrence of related diseases across educational groups.

METHODS

Two data sources were analysed: (i) Interview data from The Danish Health and Morbidity Survey 2000 on a representative sample of the Danish population ages 16 years and above (n = 16,690); (ii) Prescription records linked to a health survey on a representative sample of the population of Funen County 2000-2001 (n = 3,422). The use of six therapeutic main groups (ATC groups A, B, C, M, N and R) and related diseases in educational groups was analysed by indirect standardization. Age and gender standardized prevalence ratios (SPRs) and 95% confidence intervals were calculated on the basis of the total study population.

RESULTS

In general, respondents in the two least educated groups used medicines more frequently and a higher proportion of them reported the related disease than could be expected from indirect standardization. The opposite picture appeared for respondents in the two highest educational groups (SPR < 100). The overall patterns were similar for the six medicine groups, although some of the SPRs were not significant.

CONCLUSION

The results show the uneven distribution of disease in the general population. The distribution of medicine use generally followed this pattern, which means that those in the greatest medical need used the most medicine. Hence, individual co-payment for medicine did not seem to be a barrier to access to medicine in any of the educational groups.

Income related inequality in prescription drugs in Denmark

PURPOSE

To examine income-related inequity in utilisation of prescription drugs in Funen County, Denmark after a new reimbursement system was implemented.

METHODS

An individual level prescription database was merged with a health survey of 2927 respondents interviewed in 2000 and 2001 about their health status and socio-economic and socio-demographic characteristics. An index of horizontal inequity was used to estimate the degree of inequity in drug utilisation across income groups, using the indirect method of standardisation to control for age, gender and health status as a proxy for need. The results were compared to estimates from a traditional regression analysis.

RESULTS

The least advantaged with respect to income consume a bigger share of the prescription drugs than the most advantaged. After standardisation for age, gender and health status the least advantaged have a lower share of the drug consumption than expected. However, traditional regression analysis showed no signs of an income effect on the level of consumption of prescription drugs.

CONCLUSIONS

The index of horizontal inequity suggests that some horizontal inequity favouring the better off is present. However, the results deviate from what can be found by traditional regression analysis.

A review of uses of health care utilization databases for epidemiologic research on therapeutics

OBJECTIVE

Large health care utilization databases are frequently used in variety of settings to study the use and outcomes of therapeutics. Their size allows the study of infrequent events, their representativeness of routine clinical care makes it possible to study real-world effectiveness and utilization patterns, and their availability at relatively low cost without long delays makes them accessible to many researchers. However, concerns about database studies include data validity, lack of detailed clinical information, and a limited ability to control confounding.

STUDY DESIGN AND SETTING

We consider the strengths, limitations, and appropriate applications of health care utilization databases in epidemiology and health services research, with particular reference to the study of medications.

CONCLUSION

Progress has been made on many methodologic issues related to the use of health care utilization databases in recent years, but important areas persist and merit scrutiny.

Use of opioids in a Danish population-based cohort of cancer patients

Until recently, Denmark has had the highest use of strong opioids per capita in the world. Our aim was to analyze cancer patients' use of opioids in this population by linkage between the Danish Cancer Register and a prescription database. The changes in opioid use from 1994 to 1998 in the entire cohort of cancer patients (n=24,190) in a Danish county (n approximately 470,000) were analyzed. The overall consumption of opioids increased from 20 kg to 37 kg oral morphine equivalents (omeq) per year. The average consumption increased from 7.6 to 10.7 g omeq/opioid user/year. The annual proportion of users increased from 17% to 20%. The proportion of patients who were alive 2 years after their first opioid prescription increased from 38% to 55%. Increased awareness towards pain treatment, with earlier initiation of opioid treatment and higher doses to the cancer patients, could be major explanations for the increase in the cancer patients' use of opioids.