Aims: We aimed to assess and characterize sex differences in adverse drug reactions (ADRs) reported to the national pharmacovigilance centre in the Netherlands while considering differences in drug use.Methods: ADRs spontaneously reported by healthcare professionals and patients to the Netherlands pharmacovigilance centre Lareb were used. Drug–ADR combinations reported at least 10 times between 2003–2016 for drugs used by ≥10,000 persons in that period were included. Data about the number of drug users was obtained from the National Health Care Institute. Sex‐specific ADRs, like gynaecological problems, were excluded. Sex differences in specific drug–ADR combinations were tested using bivariate logistic regression analyses in which the number of drug users per sex was taken into account.Results: In total, 2483 drug–ADR combinations were analysed. Possibly relevant sex differences were shown in 363 combinations (15%). Most of these drug–ADR combinations were reported more often for women (322 combinations). Drugs with the highest number of ADRs that were more often reported for women included thyroid hormones (32 combinations) and antidepressants (16 combinations for the centrally acting sympathomimetics; 14 combinations for other antidepressants). Some ADRs were predominantly reported for women across a range of drugs such as headache and dizziness whereas other ADRs such as tendon ruptures and aggression were reported more often for men.Conclusions: Identified sex differences in reported ADRs often referred to women. These differences may have various causes, including pharmacological and behavioural causes, which need to be further assessed. The results may ultimately lead to sex‐specific prescribing or monitoring recommendations.

Polypharmacy is becoming increasingly common owing to the ageing population, which can pose problems for patients and society. We investigated the trends in polypharmacy and underlying drug groups among adults in the Netherlands from 1999 to 2014 stratified by age, and compared these with findings from the United States (US). We conducted a repeated cross-sectional study using the Dutch IADB.nl prescription database. All patients aged 20 years and older in the period 1999 to 2014 were included. Polypharmacy was defined as the dispensing of five or more chronic drugs at the pharmacological subgroup level. Chi-square tests were applied to calculate the p-value for trends. Changes in prevalences were compared between the Netherlands and the US. The prevalence of polypharmacy increased from 3.1% to 8.0% (p-value for trend <0.001) over 15 years, and increased in all age groups. The highest rates were observed in patients aged ≥65 years, but the relative increase over time was higher in the younger age groups. Overall, large increases were observed for angiotensin-II inhibitors, statins and proton-pump inhibitors. The relative increase in polypharmacy was larger in the Netherlands than in the US (ratio of polypharmacy prevalence 2.4 versus 1.8). The Netherlands showed larger relative increases for angiotensin-II inhibitors, statins, proton-pump inhibitors, biguanides and smaller relative increases for antidepressants, benzodiazepines and insulins. Polypharmacy more than doubled from 1999 to 2014, and this increase was not limited to the elderly. The relative increase was larger in the Netherlands compared to the US, which was partly due to larger increases in several guideline-recommended preventive drugs.

Introduction In general, women more often experience metformin-associated adverse drug reactions (ADRs) than men. Objectives We aimed to assess whether sex differences in reported ADRs for metformin are observed at different times after initiation, and to explore their concurrence with sex differences in the dose of metformin over time. This may guide future studies in assessing the involved mechanisms of sex differences in metformin-associated ADRs and may guide sex-specific management of ADRs in clinical practice. Methods This study has a longitudinal design using data about patients initiating metformin collected by the Dutch National Pharmacovigilance Center Lareb through their Intensive Monitoring program. Patients were asked to complete a web-based questionnaire six times after initiation (i.e., at 2 weeks, 6 weeks and at 3, 6, 9, and 12 months). The outcome variables were the proportion of patients reporting any ADR (primary) and the dose of metformin (secondary). Sex differences in the proportions of ADRs and in the dose were tested at each assessment using Pearson Chi-Squared tests and Wilcoxon rank-sum tests, respectively. Using Bonferroni adjustment for multiple testing, a p value < 0.01 was considered statistically significant. Results The number of included patients was 1712 (40.9% women). Women reported an ADR more often than men, which was statistically significant at the assessment at 2 weeks (34% vs 25%, p < 0.001), and 6 weeks (37% vs 28%, p = 0.001) after initiation. In general, women were reported to be prescribed a lower dose than men, which became statistically significant at the 9-month assessment (p < 0.01). Conclusions Sex differences in reported ADRs were seen in the first weeks after metformin initiation, whereas statistically significant differences in self-reported prescribed dosing were observed after several months. Patients, in particular women, might benefit from being prescribed lower metformin doses at treatment initiation.