H. J. Bos

Antibiotic use during pregnancy and asthma in preschool children: the influence of confounding.

A recent study suggested that early‐life intestinal microbiota may play an important role in the development of childhood asthma, indicating that antibiotics taken during early life or in late pregnancy may be associated with childhood asthma.

Clomiphene citrate utilization in the Netherlands 1998–2007

BACKGROUND Infertility is a growing problem in western societies. Few studies have examined the drug utilization of common treatments for infertility. Clomiphene citrate (CC) is the first-line treatment for normogonadotropic women with absent or irregular ovulation. We examined CC use among women at reproductive age in the northern Netherlands. METHODS Drug dispensing data of CC between 1998 and 2007 were retrieved from the IADB.nl database. Two-year prevalences of CC use per 1000 women covered by the database were calculated and stratified by 5-year age group. The duration of CC use was analyzed using Kaplan-Meier survival analysis. RESULTS From the IADB.nl database, a total of 1854 women aged 20-44 years initiated ovulation induction treatment with CC only in the northern Netherlands during 1998 and 2007. The 2-year prevalence of CC use increased from 6.66 per 1000 women during 1998-1999 to 7.24 per 1000 during 2002-2003, followed by a decrease to 4.82 per 1000 in 2006-2007 (P < 0.05). Median duration of CC use was four cycles for women <30 years of age, three cycles for women aged 30-39 and two cycles for women aged above 40. CONCLUSIONS There is no increase of CC use during 1998-2007, and indeed a decrease of CC use during recent years, among women at reproductive age in northern Netherlands.

Concordance assessment of self-reported medication use in the Netherlands three-generation Lifelines Cohort Study with the pharmacy database IADB.nl: The PharmLines Initiative. Clinical Epidemiology 2018:2010;1-9

Background While self-reported data are commonly used as a source of medication use for pharmaco-epidemiological studies, such information is prone to forms of bias. Several previous studies showed that various factors like age, type of drug and data collection method may influence accuracy. We aimed to assess the concordance of the self-reported medication use that was documented at entry to the Lifelines Cohort Study, a three-generation follow-up study in the Netherlands that started in 2006 and included over 167,000 participants. Materials and methods As part of the PharmLines Initiative, we collected medication data from the Lifelines participants encoded according to the Anatomical Therapeutic Chemical (ATC) coding scheme and linked the data via Statistics Netherlands to the widely used and representative pharmacy prescription database of the University of Groningen, IADB.nl. Analyses were conducted at second level of ATC coding for all recorded medications as well as a top list of most used medications at drug-specific fifth level. Cohen’s kappa statistics were used to measure the concordance for all participants according to sex and age. Results The level of concordance between the two data sources largely differed according to the therapeutic class. Medication used for the cardiovascular system and diabetes, thyroid therapy, bisphosphonates and anti-thrombotic drugs showed a very good agreement (κ>0.75). Medication as needed or prone to stigmatization bias showed a moderate agreement (κ=0.41–0.60), whereas medications used for short periods of time showed a fair agreement (κ=0.0–0.4). Concordance was similar for males and females, but younger adults tended to have lower concordance rates than older adults. Conclusion The self-reported method was valid for capturing prevalent chronic medication use at one moment in time, but invalid for medication used for short periods of time. There is no effect of sex on the agreement, and more studies are needed on the influence of age. Future pharmaco-epidemiological studies should preferably combine the two data sources to achieve the highest accuracy of drug exposure rates.

The limitations of some European healthcare databases for monitoring the effectiveness of pregnancy prevention programmes as risk minimisation measures

PurposePregnancy prevention programmes (PPPs) exist for some medicines known to be highly teratogenic. It is increasingly recognised that the impact of these risk minimisation measures requires periodic evaluation. This study aimed to assess the extent to which some of the data needed to monitor the effectiveness of PPPs may be present in European healthcare databases.MethodsAn inventory was completed for databases contributing to EUROmediCAT capturing pregnancy and prescription data in Denmark, Norway, the Netherlands, Italy (Tuscany/Emilia Romagna), Wales and the rest of the UK, to determine the extent of data collected that could be used to evaluate the impact of PPPs.ResultsData availability varied between databases. All databases could be used to identify the frequency and duration of prescriptions to women of childbearing age from primary care, but there were specific issues with availability of data from secondary care and private care. To estimate the frequency of exposed pregnancies, all databases could be linked to pregnancy data, but the accuracy of timing of the start of pregnancy was variable, and data on pregnancies ending in induced abortions were often not available. Data availability on contraception to estimate compliance with contraception requirements was variable and no data were available on pregnancy tests.ConclusionCurrent electronic healthcare databases do not contain all the data necessary to fully monitor the effectiveness of PPP implementation, and thus, special data collection measures need to be instituted.