Dispensing epilepsy medication: a method of determining the frequency of symptomatic individuals with seizures

On the Dependence of the Critical Success Index (CSI) on Prevalence

The critical success index (CSI) is an established metric used in meteorology to verify the accuracy of weather forecasts. It is defined as the ratio of hits to the sum of hits, false alarms, and misses. Translationally, CSI has gained popularity as a unitary outcome measure in various clinical situations where large numbers of true negatives may influence the interpretation of other, more traditional, outcome measures, such as specificity (Spec) and negative predictive value (NPV), or when unified interpretation of positive predictive value (PPV) and sensitivity (Sens) is needed. The derivation of CSI from measures including PPV has prompted questions as to whether and how CSI values may vary with disease prevalence (P), just as PPV estimates are dependent on P, and hence whether CSI values are generalizable between studies with differing prevalences. As no detailed study of the relation of CSI to prevalence has been undertaken hitherto, the dataset of a previously published test accuracy study of a cognitive screening instrument was interrogated to address this question. Three different methods were used to examine the change in CSI across a range of prevalences, using both the Bayes formula and equations directly relating CSI to Sens, PPV, P, and the test threshold (Q). These approaches showed that, as expected, CSI does vary with prevalence, but the dependence differs according to the method of calculation that is adopted. Bayesian rescaling of both Sens and PPV generates a concave curve, suggesting that CSI will be maximal at a particular prevalence, which may vary according to the particular dataset.

Prescription patterns of antiepileptic drugs in young women: development of a tool to distinguish between epilepsy and psychiatric disorders

BACKGROUND

Antiepileptic drugs (AEDs) are also prescribed for therapeutic indications other than epilepsy (EPI), namely, psychiatric disorders (PSY). Our aim was to develop an algorithm able to distinguish between EPI and PSY among childbearing age women based on differences in AED exposure in these patient groups.

METHODS

Two groups of women (18-45 years) with EPI or PSY treated with AEDs in the first semester of 2010 or 2011 were extracted from paper or electronic medical charts of specialized centers. Through the prescription database of Bologna Local Health Authority (Italy), AEDs, treatment schedule and co-treatments were collected for each patient. A prescription-based hierarchical classification system was developed. The algorithm obtained was subsequently validated on internal and external data.

RESULTS

Eighty-one EPI and 94 PSY subjects were recruited. AED monotherapy was the most common choice in both groups (69% EPI vs 79% PSY). Some AEDs were used only in EPI, others exclusively in PSY. Co-treatments with antipsychotics (6% vs 67%), lithium (0% vs 9%), and antidepressants (7% vs 70%) were fewer in EPI than in PSY. The hierarchical classification system identified antipsychotics, SSRIs (Selective Serotonin Reuptake Inhibitors), and number of AEDs as variables to discriminate EPI and PSY, with an overall error rate estimate of 9.7% (95%CI: 5.3% to 14.1%).

CONCLUSION

Among the differences between EPI and PSY, prescription data alone allowed an algorithm to be developed to diagnose each childbearing age woman receiving AEDs. This approach will be useful to stratify patients for risk estimates of AED-treated patients based on administrative databases. Copyright © 2016 John Wiley & Sons, Ltd.

Prognostic factors for medically intractable epilepsy: a systematic review

OBJECTIVE

One third of all epilepsy patients have medically intractable epilepsy. Knowledge of prognostic factors that, in an early therapeutic stage of epilepsy, herald intractability could facilitate patient management. In this systematic review, we examined the evidence for independent prognostic factors of intractability in patients with epilepsy.

METHODS

MEDLINE and EMBASE were searched for cohort studies reporting on prognostic factors for medically intractable epilepsy. After selection of abstracts, full-text articles were obtained and their quality was assessed by two reviewers, using the QUIPS checklist. All independent prognostic factors in the individual studies were summarized.

RESULTS

Eleven cohort studies were included, of which ten hospital-based. Younger age at seizure onset, symptomatic etiology, high initial seizure frequency, medical history, epileptic EEG abnormalities, and failure of previous antiepileptic-drugs (AEDs) were documented as independent prognostic factors of intractability in at least 2 of the 11 studies; none of these factors was reported in all 11 studies. None of the studies considered genetic, neurobiological, or immunological factors. The studies were of moderate quality, mostly because they did not provide a conceptual model for the choice of predictors. Heterogeneity in study design, population, candidate prognostic factors, and outcome definitions precluded statistical pooling.

CONCLUSIONS

While potentially relevant prognosticators of medically intractable epilepsy have been identified, the evidence for these factors is not consistent. There is a need for well-designed prognostic population-based cohort studies that also include pharmacological, genetic, neurobiological, and immunological factors. A valid model for the early prediction of medically intractable epilepsy could improve patient management.

Surveillance of contact allergies: methods and results of the Information Network of Departments of Dermatology (IVDK)

Contact allergy (CA) surveillance networks provide information to a multitude of stakeholders, which is indispensable for evidence-based decision-making in the field of prevention. Methods and results of the German surveillance system on CA are reviewed and discussed with reference to other systems. The German network structure comprises 56 departments of dermatology and includes all patients who are patch-tested for suspected CA. Data analysis considers the results of patch testing and further pertinent information for each patient. Following aspects are addressed: (i) the description of the clinical population, (ii) evaluation of patch test reactions, (iii) relationship between patch test results and population characteristics. Trend analyses on chromate (decreasing), epoxy resin (increasing) and nickel (heterogeneous) served as examples for surveillance system analyses, with the identification of sentinel events, as well as proof of success or failure of prevention. In addition, external data sources can be used such as sales data of patch test preparations to estimate frequencies of sensitization on a population level. National prescription data of drugs and statistics of labelling of preservatives on cosmetics can be included, the latter two approaches allowing for risk estimates conferred by specific allergens.

The incidence rate of seizures in relation to BMI in UK adults

A retrospective cohort study using the data from The Health Improvement Network (THIN) database in the United Kingdom was conducted to examine the incidence rates of seizures across different BMI levels in the adult population aged > or = 18 years. Poisson regression was used to examine the relationship between BMI and seizures. The overall incidence rate of seizures was found to be 31.2 cases per 100,000 person-years. The incidence rate of seizures (cases per 100,000 person-years) in obese patients (BMI > or = 30 kg/m2) was 34.8 (95% confidence interval (CI), 23.1, 46.4), comparable to that in patients with normal weight (BMI between 18.5 and 24.9 kg/m2) (35.8, 95% CI (26.6, 44.9)). In contrast, underweight patients (< 18.5 kg/m2) or extremely obese (> or = 40 kg/m2) patients tended to have higher incidence rates than those with normal weight. After adjustment for age, gender, and smoking status, compared to patients with normal weight, those who were underweight or extremely obese had a rate ratio (RR) for seizures of 1.6 (95% CI (0.7, 3.8)) and 1.7 (95% CI (0.7, 3.9)), respectively. To date, we have not found any study that examines the associations between BMI or obesity and seizures. In this study, the incidence rates of seizures in the extremely obese and underweight patients tended to be higher than that in the normal-weight patients.

10-year prevalence of contact allergy in the general population in Denmark estimated through the CE-DUR method

The prevalence of contact allergy in the general population has traditionally been investigated through population-based epidemiological studies. A different approach is the combination of clinical epidemiological (CE) data and the World Health Organization-defined drug utilization research (DUR) method. The CE-DUR method was applied in Denmark to estimate the prevalence of contact allergy in the general population and compare it with the prevalence estimates from the Glostrup allergy studies. Contact allergy prevalence estimates ranging from very liberal ('worst case') to conservative ('best case') assumptions were based on patch test reading data in combination with an estimate of the number of persons eligible for patch testing each year based on sales data of the 'standard series'. The estimated 10-year prevalence of contact allergy ranged between 7.3% and 12.9% for adult Danes older than 18 years. The 10-year prevalence of contact allergy measured by CE-DUR was slightly lower than previous prevalence estimates from the Glostrup allergy studies. This could probably be explained by a decrease in nickel allergy. The CE-DUR approach holds the potential of being an efficient and easy monitoring method of contact allergy prevalence.

Contact allergy to topical drugs: prevalence in a clinical setting and estimation of frequency at the population level

OBJECTIVES

To estimate the prevalence of contact allergy (CA) to a set of topical drugs patch tested in the research network IVDK (Information Network of Departments of Dermatology; www.ivdk.org) between 1995 and 2004, and to extrapolate these clinical data to the German population.

METHODS

Clinical data comprised results of allergy patch tests with topical drugs in patients with suspected CA. Clinical epidemiology and drug utilization research (CE-DUR) methods were employed to grossly estimate the incidence of CA to these topical drugs during two 5-year periods (1995-1999 and 2000-2005) in the German general population. To estimate the number of persons eligible for patch testing (with the topical drugs) on a general population level, sales data of patch test material were obtained. By relating this denominator to the CA frequency observed in the IVDK, the incidence of CA to selected topical drugs in the German general population was crudely estimated.

RESULTS

In general, topical aminoglycosides showed the highest CA frequencies and, except for gentamicin sulfate, frequencies of CA to all other allergens tested were lower in the 2nd period of analysis. According to the medium model, 1-year incidence rates ranged from 1 (hydrocortisone-17-butyrate) to 29 persons/100,000 (neomycin sulfate) in the general population (1995-1999).

CONCLUSION

The CE-DUR approach yielded incidence estimates of CA to relevant topical drugs in the German general population, which, despite their limited precision in absolute terms, illustrate the relative frequency of this particular adverse effect. However, comparative risk assessment should preferably take exposure information into account.

The Use of TDM Data to Assess the Validity of Defined Daily Doses of Antiepileptics: A Comparison Between a Czech and Swedish University Hospital

Prescribed daily doses (PDDs) of antiepileptic drugs (AED) (N03A ATC group) were recorded for drugs used in monotherapy or in combination therapy in the University Hospitals in Ostrava, Czech Republic and Huddinge, Sweden. Plasma concentrations were used as an indicator of the quality of treatment. PDDs were compared with the defined daily doses (DDDs) suggested by WHO in the ATC/DDD index 2005. Request and reply forms for therapeutic drug monitoring (TDM) were used as a source of mean PDDs. The study included 2,824 adult out- and in-patients in Huddinge treated from 1995 to 1999 and 1,268 out-patients treated in Ostrava from 1993 to 2004. The differences in PDD were tested by Student's t-test. Mean values of PDD were used when patients were examined more than once. Doses given in mono- and polytherapy were compared. Mean PDDs (in mg) in mono-/polytherapy in Huddinge and Ostrava were as follows (DDDs in parenthesis): carbamazepine 588/842 and 618/770 (1,000), clonazepam 3.0/2.5 and 3.4/2.4 (8), phenytoin 278/314 and 291/288 (300), gabapentin -/1,533 and -/921 (1,800), lamotrigine 228/228 and 216/195 (300), phenobarbital 90/75 and 183/117 (100), vigabatrin -/1,794 and -/1,259 (2,000), valproic acid 1,139/1,476 and 814/950 (1,500). The PDDs of most of the AEDs were lower than the DDDs with the exceptions for valproic acid (Huddinge, in polytherapy only), phenytoin, for which PDDs and DDDs were very close, and phenobarbital for which they were similar in Huddinge but higher in Ostrava. PDDs in monotherapy were only slightly lower than in combination therapy. Patients with plasma concentrations within the therapeutic range were usually treated with slightly higher doses than the remainder. In general, plasma concentrations tended to be in the low therapeutic range. The differences in PDDs between hospitals were significant in the case of valproic acid (P < 0.001), phenobarbital (except monotherapy within), vigabatrin, and gabapentin (P < 0.01), and carbamazepine (in monotherapy P < 0.05, polytherapy P < 0.01). Our data suggest that the DDDs of AEDs should be reconsidered as, in the majority of cases, they appear to be too high.

Trends in utilization of antiepileptic drugs in Denmark

OBJECTIVES

To describe utilization of antiepileptic drugs (AEDs) in Denmark during 1993-2002, with special emphasis on oxcarbazepine, and to assess probable indications for AED use.

MATERIALS AND METHODS

We retrieved prescription data from Odense University Pharmacoepidemiological Database, in Funen County, Denmark (population in 2002: 472,869). Within each calendar year we estimated period prevalence, incidence rate and monotherapy rate. Based on co-medication we defined 'epilepsy' when only AEDs were prescribed, 'pain' with co-prescription of opioids, and 'mood disorder' with co-prescription of antipsychotics or antidepressants.

RESULTS

We identified 15,604 AED users. The prevalence of using AED increased from 9.3 (95% CI, 9-9.5) to 12.1 (11.8-12.4)/1000 persons. The incidence rate increased from 1.4 (1.3-1.6) to 1.7 (1.6-1.9)/1000 personyears. The monotherapy rate was 79-82%. AED use for 'epilepsy' declined by 19.7%, whereas the proportion of 'pain' and 'mood disorder' treatment increased by 11.2% and 8.4% respectively.

CONCLUSIONS

Antiepileptic drug utilization increased during the study period, the increase probably caused by expanding use in areas other than epilepsy.

Psychiatric comorbidity in epilepsy

Many studies on psychiatric comorbidity in epilepsy have been performed using many different patient groups and diagnostic instruments. This methodological heterogeneity complicates comparison of the findings. In this article, psychiatric disorders in epilepsy are reviewed from the perspective of the DSM classification system. The empirical findings of axis I clinical disorders and axis II personality disorders are described separately. Furthermore, the existence and specificity of conditions such as interictal dysphoric disorder, interictal behavior syndrome, and psychosis of epilepsy are discussed. From the many studies that have been performed on this topic it can be learned that there is a need for well-controlled studies using representative patient groups and valid and standardized diagnostic instruments. So far, the majority of the studies have concerned axis I disorders; relatively little research has been performed on axis II personality disorders. More research on personality disorders, as well as on the relative contributions of the different (brain- and non-brain-related) factors to the relationship between epilepsy and psychiatric disorders, is recommended.

Volume and market share of anti-epileptic drugs in the Netherlands: impact of new drugs

OBJECTIVE

In the past decade, several new anti-epileptic drugs (AEDs) were introduced in The Netherlands. These new drugs, one of which is lamotrigine, are 6 to 10 times more expensive than conventional anti-convulsants. In 1997, the high cost of lamotrigine, together with a lack of clinical data supporting its superiority over conventional drugs, prompted the Dutch Health Insurance Board to release a guideline in which the use of lamotrigine was restricted to difficult-to-treat patients. Other new drugs that were marketed after 1997 also became subject to this guideline. The utilisation of new AEDs and the cost consequences are the subject of this paper.

METHODS

Data from extramurally prescribed AEDs was obtained from the Dutch Drug Information Project, which is a database containing prescriptions for about 5.5 million inhabitants of the Netherlands. This data was used to study the impact of new AEDs on volume and market share of AEDs in the period from 1995 to 2001 in The Netherlands.

RESULTS

Between 1995 and 2001, the total volume of AEDs increased by 130%, 60% of which consisted of new AEDs. Gabapentin, lamotrigine and oxcarbazepine were the most frequently prescribed new compounds. The volume share of new AEDs increased from 5% in 1995 to 18% in 2001. The market share amounted to 21.5 million euros in 1995 and rose to 47 million euros in 2001; 80% of this increase was due to the introduction of new AEDs.

DISCUSSION

Although in 2001 the volume share of new AEDs was still modest, their introduction has led to a strong increase in the cost. New data is emerging on the effectiveness and cost-benefit sum of the new AEDs; this may change the place in therapy of these drugs. Because of their strong potential to force up cost, the positioning of new AEDs requires further attention.

Subjective sleep disturbance in patients with partial epilepsy: a questionnaire-based study on prevalence and impact on quality of life

PURPOSE

This study was designed to assess whether sleep disturbance is more frequent among patients with partial seizures and what impact on quality of life (QoL) sleep disturbance may have on patients with partial seizures.

METHODS

Questionnaire booklets were mailed to 1,183 patients from four Dutch clinics. Each patient was asked to find two age- and gender-matched controls to complete the same set of questionnaires [Sleep Diagnosis List (SDL), Medical Outcomes Study (MOS)-Sleep Scale, Groningen Sleep Questionnaire, Epworth Sleepiness Scale, and the SF-36 Health Survey]. The prevalence of sleep disturbance, based on the SDL, was compared between those with partial epilepsy and controls. Mean scores on sleep and the SF-36 Physical (PCS) and Mental (MCS) Component Summary scales were compared.

RESULTS

Responses from 486 patients and 492 controls were analyzed. Respondents with partial epilepsy had a highly significant, twofold higher prevalence of sleep disturbance compared with controls (38.6 vs. 18.0%; p < 0.0001). Most sleep-disorder subscales showed significant abnormalities in respondents with epilepsy, compared with controls. Mean SF-36 MCS and PCS scores were significantly lower in respondents with epilepsy compared with controls in both the strata with sleep disturbance and without (all p values <0.05). The presence of a sleep disturbance in respondents with epilepsy was associated with the greatest impairment in QoL.

CONCLUSIONS

Sleep disturbance is more than twice as prevalent in persons with partial epilepsy compared with controls, and most domains of sleep are significantly disturbed. Persons with partial epilepsy have significant QoL impairment, and sleep disturbance further compounds this.

Diffusion of the new antiepileptic drug lamotrigine in Dutch clinical practice

INTRODUCTION

Lamotrigine is one of the recently introduced antiepileptic drugs (AEDs) licensed in the Netherlands in 1995. The objective of this study was to examine the diffusion of lamotrigine into clinical practice. Three different aspects of this diffusion process were examined: incidence of use, patient characteristics and changes in prescription patterns in the first 5 years following its introduction.

METHODS

A retrospective follow-up study has been conducted using drug prescription data from the database of the Dutch Drug Information Project (GIP database). Patients were included who started with lamotrigine, carbamazepine, phenytoin or valproate in the period between January 1996 and December 2000. Incidence of use was calculated for the four drugs. Multiple logistic regression analysis was used to determine differences in baseline characteristics. The Chi-square test was used to analyse changes in the usage patterns of lamotrigine.

RESULTS

The study population consisted of a total of 29,718 patients who were prescribed carbamazepine, phenytoin, valproate or lamotrigine for the first time in the study period. Carbamazepine and valproate accounted for the majority of all new prescriptions; the incidence of lamotrigine use remained stable with 4.4 patients per 100,000 per year. Baseline characteristics of lamotrigine differed depending on the patient's age and gender (OR 3.7, 95% CI 3.3-4.2; OR 1.4, 95% CI 1.3-1.5) relative to the conventional AEDs. In a large majority of cases, lamotrigine was used as a second-line or third-line AED. Physicians prescribing lamotrigine were predominantly neurologists, in contrast to prescribers of conventional AEDs. The prevalence of psychotropic medication and migraine-abortive drugs was significantly lower in users of lamotrigine than in users of conventional AEDs. During follow-up, several significant trends were noticed in the prescribing of lamotrigine with regard to age groups, gender, antiepileptic history and off-label use.

DISCUSSION

Lamotrigine is prescribed to a population different from that using conventional AEDs. The uptake of lamotrigine in clinical practice is slow, for reasons probably related to characteristics of the drug itself and the prescribers. During the observation period, lamotrigine diffused gradually towards more first-line use as an AED and more off-label use.

How to estimate the population that is covered by community pharmacies? An evaluation of two methods using drug utilisation information

PURPOSE

Pharmacy-dispensing data are valuable sources of drug information, but the population that is covered by the pharmacies is often difficult to determine. We evaluated two methods using drug utilisation information to estimate the population size: a drug-use-based extrapolation of a known part of the population and a capture-recapture estimation without any prior knowledge of the population.

METHODS

Using pharmacy-dispensing data of three towns with known populations in the Netherlands, we estimated age-and-sex specific population sizes by extrapolating the proportion of drug-using inhabitants. In addition, we applied two-source and three-source capture-recapture models with all combinations of the following drug groups as different sources: anti-asthmatics, analgesics, antibiotics and anti-histamines.

RESULTS

Drug-use-based extrapolation resulted in the best estimates with the least variability. All capture-recapture models provided underestimations of the true population. Three-source capture-recapture resulted in better average estimates than two-source capture-recapture, but also had more variability.

CONCLUSIONS

If a part of the population is known, and if there is reason to assume that drug utilisation patterns do not vary within the region, it is best to use drug-use-based extrapolation. In all other situations capture-recapture may be considered, with as main limitation that we found all models to underestimate the population considerably.

Patterns of lamotrigine use in daily clinical practice during the first 5 years after introduction in the Netherlands

OBJECTIVE

Follow-up data on the long-term effectiveness (efficacy and tolerability) of lamotrigine are limited. A useful though crude measure for effectiveness in daily clinical practice is the treatment retention rate determined from drug dispensing data. This study describes the baseline characteristics, the usage patterns and the retention rate of this antiepileptic drug (AED) in a population-based cohort of lamotrigine users in the Netherlands during the first 5 years after its registration in 1995. Data from this cohort are compared with those from the initial randomized clinical trials (RCTs) in patients with refractory epilepsy.

METHODS

This retrospective cohort study used dispensing data from community pharmacies. Baseline characteristics and usage patterns were evaluated for first time users of lamotrigine in this study. Usage patterns were characterized as continued, add-on or discontinued use during the patient observation time window. Cox regression analysis was used to explore possible relationships between baseline characteristics and specific usage patterns defined. The baseline characteristics and discontinuation rates in this cohort study were compared with RCT data reported in medical literature.

RESULTS

A total of 3598 lamotrigine users were identified. The mean age of the population was 39 years and 54% were female. On average, patients used two other AEDs at the start of lamotrigine therapy and approximately 6% of the patients had no history of prior AED use. The discontinuation rate was 25% after 1 year, and approximately 32% at the end of the 5-year study. Addition of another drug or discontinuation was seen in more than half of the population 3 years after the start of therapy. Concurrent use of valproic acid was associated with a better retention rate. Absence of AED history, use of antidepressants, or use of migraine abortive drugs resulted in an increased likelihood of discontinuing lamotrigine. The population from RCTs differed from the study cohort with respect to age, concurrent use of AEDs and length of follow-up.

CONCLUSION

Data from RCTs cannot easily be extrapolated to daily clinical practice. In this large, observational study, lamotrigine therapy failed in a considerable number of patients, although the mean retention rate was better than previously reported by others. Population-based linkage of health care records can be used to further clarify the effectiveness of lamotrigine.

The effectiveness of psychological interventions for patients with relatively well-controlled epilepsy

Previous reviews about psychological interventions focused on refractory epilepsy patients and were inconclusive; this review investigates what the contribution of the psychologist can be for the large group of patients with relatively well-controlled epilepsy. This review was restricted to the literature reporting on adult patients with relatively well-controlled epilepsy. A literature search on the effect of psychological interventions was conducted using Medline and PsychInfo, including those studies published through March 2002. Applying strict inclusion criteria, a total of seven studies were identified. Four studies incorporated a waiting-list control group. Of these, one study addressing cognitive rehabilitation reported positive results on psychological outcome and one intervention based on comprehensive care led to seizure reduction, whereas all other studies were plagued too much by methodological inadequacies to allow firm conclusions to be drawn. Recommendations for future intervention studies, such as standardized interventions, controlling for positive attention, outcome measures without overlap with the intervention, and a follow-up measurement, are given. It is concluded that a concerted effort to assemble larger patient groups in randomized-controlled studies is a prerequisite to acquiring well-founded knowledge about psychological interventions in patients with relatively well-controlled epilepsy.

Epidemiology of contact allergy: an estimation of morbidity employing the clinical epidemiology and drug-utilization research (CE-DUR) approach

Clinical epidemiology (CE) is considered unable to estimate morbidity concerning either contact sensitization (CS) or allergic contact dermatitis (ACD) at the population level. Drug-utilization research (DUR) methods estimate the morbidity of suitable diseases based on prescription data for disease-specific drugs. Our objective was to estimate population figures for incidence and prevalence of ACD and CS based on sales data for patch test material in Germany and on patient data from the Information Network of Departments of Dermatology (IVDK). Approximately 600000 standard series are sold per year in Germany, according to the 2 main manufacturers. This raw sales figure was corrected for certain effects (discarded preparations, proportion of formerly patch-tested patients, proportion of patients with ACD seeking medical advice) to obtain an estimate of the denominator of patients eligible for patch testing annually, and combined with patch test results from the Information Network of Departments of Dermatology (IVDK). In 17.8% (of 9266 IVDK patients) ACD was established. Extrapolated to the general population, an incidence of ACD of between 1.7 and 7 per 1000 per year was estimated, depending on whether conservative or more liberal assumptions concerning the above effects were made. Of 78067 IVDK patients tested between 1992 and 2000, 46.8% had at least 1 positive reaction (+ to + + +), and 22.7% had at least 1 stronger positive reaction (+ + or + + +). The 9-year prevalence of CS was estimated to lie between 4.0% and 16.6% for the first outcome, and between 2.0% and 8.1% for the second. Concerning single allergens, 1.9-4.5 million individuals are probably sensitized to nickel, and 1.4-3.4 million to fragrance mix among the German population of 82 million inhabitants. The morbidity data found in this study are in good accordance with data from population-based epidemiological studies. In comparison to these, the CE-DUR approach seems to be an economically feasible method to estimate continuously the population impact of ACD and CS.

Comparison of different methods to estimate prevalence of drug use by using pharmacy records

Several methods to estimate prevalence of drug use are available, which may complicate a valid comparison of these estimates. Standardization may contribute to more valid comparisons. We compared different methods to estimate prevalence of drug use by using pharmacy records. Data were obtained from the Dutch population-based PHARMO-database comprising medication histories of 300,000 subjects. Five point prevalences and a 1-year prevalence of cholesterol-lowering drug use were estimated in 1995. Four point prevalences differed in data handling before estimating prevalence (e.g., correction for irregular drug use or construction of episodes of drug use). The numerator of the fifth point prevalence estimate represented the number of defined daily doses (DDDs) instead of the number of patients filling a prescription. The first four point prevalences ranged from 11.0-12.1 per thousand. Prevalence ratio (male:female) was 1.2 for these methods. The fifth method resulted in an estimate similar to the other point prevalences (11.9 DDDs/1000 inhabitants). However, the prevalence ratio was 1.4 due to larger average number of DDDs prescribed to men. One year-prevalence was 4-5 per thousand higher than point prevalences. The comparison of these methods indicated that the choice of prevalence measure (point versus period prevalence) substantially influenced the prevalence estimate, whereas the influence of data handling was negligible. For standardization purposes in drug utilization research, we recommend estimating point prevalence instead of period prevalence. The various methods of data handling before estimating point prevalence yielded similar results and therefore we cannot recommend one specific method. However, defined daily doses should not be used to estimate (point) prevalences of drug use because this measure is significantly influenced by prescribed dosage regimens.

Antiepileptic drug utilization: a Danish prescription database analysis

OBJECTIVES

The purpose of the study was to use prescription data from a Danish database to analyse and evaluate antiepileptic drug (AED) utilization, and compare with other prevalence studies.

METHODS

A Danish research database covering outpatient prescription data from a population of 471,873 persons was used. Prescription records on all patients prescribed AEDs during 1998 were retrieved. A cohort was extracted from the group of AED users.

RESULTS

We identified 5426 AED users. A total of 3756 of the 5426 AED users were included in our cohort. Of the subjects in the cohort 74% were on monotherapy, 19% used two AEDs and only 7% used three or more AEDs. The eight most frequent regimens were all monotherapy: carbamazepine, oxcarbazepine, phenobarbital, valproic acid, lamotrigine, clonazepam, phenytoin and primidon in that order. The estimated crude 1-year prevalence of AED use was 0.77% for women and 0.83% for men (P<0.001), and it increased with age for both genders.

CONCLUSIONS

The prescription pattern reported here is in accordance with the general guidelines for the treatment of epilepsy in Denmark, except for a surprisingly extensive use of phenobarbital. With specific reservations the figures appear to be reasonable estimates of the prevalence of epilepsy.