Silvana Romio

The incidence of narcolepsy in Europe: Before, during, and after the influenza A(H1N1)pdm09 pandemic and vaccination campaigns

BACKGROUND In August 2010 reports of a possible association between exposure to AS03 adjuvanted pandemic A(H1N1)pdm09 vaccine and occurrence of narcolepsy in children and adolescents emerged in Sweden and Finland. In response to this signal, the background rates of narcolepsy in Europe were assessed to rapidly provide information for signal verification. METHODS We used a dynamic retrospective cohort study to assess the narcolepsy diagnosis rates during the period 2000-2010 using large linked automated health care databases in six countries: Denmark, Finland, Italy, the Netherlands, Sweden and the United Kingdom. RESULTS Overall, 2608 narcolepsy cases were identified in almost 280 million person years (PY) of follow up. The pooled incidence rate was 0.93 (95% CI: 0. 90-0.97) per 100,000 PY. There were peaks between 15 and 30 year of age (women>men) and around 60 years of age. In the age group 5-19 years olds rates were increased after the start of pandemic vaccination compared to the period before the start of campaigns, with rate ratios (RR) of 1.9 (95% CI: 1.1-3.1) in Denmark, 6.4 (95% CI: 4.2-9.7) in Finland and 7.5 (95% CI: 5.2-10.7) in Sweden. Cases verification in the Netherlands had a significant effect on the pattern of incidence over time. CONCLUSIONS The results of this incidence study provided useful information for signal verification on a population level. The safety signal of increased narcolepsy diagnoses following the start of the pandemic vaccination campaign as observed in Sweden and Finland could be observed with this approach. An increase in narcolepsy diagnoses was not observed in other countries, where vaccination coverage was low in the affected age group, or did not follow influenza A(H1N1)pdm09 vaccination. Patient level analyses in these countries are being conducted to verify the signal in more detail.

Guillain-Barré syndrome and adjuvanted pandemic influenza A (H1N1) 2009 vaccine: multinational case-control study in Europe

Objective To assess the association between pandemic influenza A (H1N1) 2009 vaccine and Guillain-Barré syndrome. Design Case-control study. Setting Five European countries. Participants 104 patients with Guillain-Barré syndrome and its variant Miller-Fisher syndrome matched to one or more controls. Case status was classified according to the Brighton Collaboration definition. Controls were matched to cases on age, sex, index date, and country. Main outcome measures Relative risk estimate for Guillain-Barré syndrome after pandemic influenza vaccine. Results Case recruitment and vaccine coverage varied considerably between countries; the most common vaccines used were adjuvanted (Pandemrix and Focetria). The unadjusted pooled risk estimate for all countries was 2.8 (95% confidence interval 1.3 to 6.0). After adjustment for influenza-like illness/upper respiratory tract infection and seasonal influenza vaccination, receipt of pandemic influenza vaccine was not associated with an increased risk of Guillain-Barré syndrome (adjusted odds ratio 1.0, 0.3 to 2.7). The 95% confidence interval shows that the absolute effect of vaccination could range from one avoided case of Guillain-Barré syndrome up to three excess cases within six weeks after vaccination in one million people. Conclusions The risk of occurrence of Guillain-Barré syndrome is not increased after pandemic influenza vaccine, although the upper limit does not exclude a potential increase in risk up to 2.7-fold or three excess cases per one million vaccinated people. When assessing the association between pandemic influenza vaccines and Guillain-Barré syndrome it is important to account for the effects of influenza-like illness/upper respiratory tract infection, seasonal influenza vaccination, and calendar time.

Use of tiotropium Respimat Soft Mist Inhaler versus HandiHaler and mortality in patients with COPD

Tiotropium, a long-acting anticholinergic, is delivered via HandiHaler or via Respimat. Randomised controlled trials suggest that use of tiotropium Respimat increases the risk of dying. We compared the risk of mortality between tiotropium Respimat versus HandiHaler. Within the Integrated Primary Care Information database, we defined a source population of patients, aged ≥40 years, with ≥1 year of follow-up. Based on prescription data, we defined episodes of tiotropium use (Respimat or HandiHaler). The risk of mortality, within these episodes, was calculated using a Cox proportional hazard regression analysis. From the source population, 11 287 patients provided 24 522 episodes of tiotropium use. 496 patients died while being exposed to HandiHaler or Respimat. Use of Respimat was associated with almost 30% increased risk of dying (adjusted HR 1.27, 95% CI 1.03–1.57) with the highest risk for cardiovascular/cerebrovascular death (adjusted HR 1.56, 95% CI 1.08–2.25). The risk was higher in patients with co-existing cardiovascular disease (adjusted HR 1.36, 95% CI 1.07–1.73) than in patients without (adjusted HR 1.02, 95% CI 0.61–1.71). Use of tiotropium Respimat was associated with an almost 30% increase of mortality compared with HandiHaler and the association was the strongest for cardiovascular/cerebrovascular death. It is unclear whether this association is causal or due to residual confounding by chronic obstructive pulmonary disease severity. Tiotropium Respimat was associated with a 30% increase in mortality compared with HandiHaler in COPD http://ow.ly/mpmhp

Risk of Upper Gastrointestinal Bleeding From Different Drug Combinations

BACKGROUND & AIMS Concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs) and low-dose aspirin increases the risk of upper gastrointestinal bleeding (UGIB). Guidelines suggest avoiding certain drug combinations, yet little is known about the magnitude of their interactions. We estimated the risk of UGIB during concomitant use of nonselective (ns)NSAIDs, cyclooxygenase -2 selective inhibitors (COX-2 inhibitors), and low-dose aspirin with other drugs. METHODS We performed a case series analysis of data from 114,835 patients with UGIB (930,888 person-years of follow-up) identified from 7 population-based health care databases (approximately 20 million subjects). Each patient served as his or her own control. Drug exposure was determined based on prescriptions of nsNSAIDs, COX-2 inhibitors, or low-dose aspirin, alone and in combination with other drugs that affect the risk of UGIB. We measured relative risk (incidence rate ratio [IRR] during drug exposure vs nonexposure) and excess risk due to concomitant drug exposure (relative excess risk due to interaction [RERI]). RESULTS Monotherapy with nsNSAIDs increased the risk of diagnosis of UGIB (IRR, 4.3) to a greater extent than monotherapy with COX-2 inhibitors (IRR, 2.9) or low-dose aspirin (IRR, 3.1). Combination therapy generally increased the risk of UGIB; concomitant nsNSAID and corticosteroid therapies increased the IRR to the greatest extent (12.8) and also produced the greatest excess risk (RERI, 5.5). Concomitant use of nsNSAIDs and aldosterone antagonists produced an IRR for UGIB of 11.0 (RERI, 4.5). Excess risk from concomitant use of nsNSAIDs with selective serotonin reuptake inhibitors (SSRIs) was 1.6, whereas that from use of COX-2 inhibitors with SSRIs was 1.9 and that for use of low-dose aspirin with SSRIs was 0.5. Excess risk of concomitant use of nsNSAIDs with anticoagulants was 2.4, of COX-2 inhibitors with anticoagulants was 0.1, and of low-dose aspirin with anticoagulants was 1.9. CONCLUSIONS Based on a case series analysis, concomitant use of nsNSAIDs, COX-2 inhibitors, or low-dose aspirin with SSRIs significantly increases the risk of UGIB. Concomitant use of nsNSAIDs or low-dose aspirin, but not COX-2 inhibitors, with corticosteroids, aldosterone antagonists, or anticoagulants produces significant excess risk of UGIB.

International collaboration to assess the risk of Guillain Barre Syndrome following Influenza A (H1N1) 2009 monovalent vaccines

BACKGROUND The global spread of the 2009 novel pandemic influenza A (H1N1) virus led to the accelerated production and distribution of monovalent 2009 Influenza A (H1N1) vaccines (pH1N1). This pandemic provided the opportunity to evaluate the risk of Guillain-Barré syndrome (GBS), which has been an influenza vaccine safety concern since the swine flu pandemic of 1976, using a common protocol among high and middle-income countries. The primary objective of this project was to demonstrate the feasibility and utility of global collaboration in the assessment of vaccine safety, including countries both with and without an established infrastructure for vaccine active safety surveillance. A second objective, included a priori, was to assess the risk of GBS following pH1N1 vaccination. METHODS The primary analysis used the self-controlled case series (SCCS) design to estimate the relative incidence (RI) of GBS in the 42 days following vaccination with pH1N1 vaccine in a pooled analysis across databases and in analysis using a meta-analytic approach. RESULTS We found a relative incidence of GBS of 2.42 (95% CI 1.58-3.72) in the 42 days following exposure to pH1N1 vaccine in analysis of pooled data and 2.09 (95% CI 1.28-3.42) using the meta-analytic approach. CONCLUSIONS This study demonstrates that international collaboration to evaluate serious outcomes using a common protocol is feasible. The significance and consistency of our findings support a conclusion of an association between 2009 H1N1 vaccination and GBS. Given the rarity of the event the relative incidence found does not provide evidence in contradiction to international recommendations for the continued use of influenza vaccines.

Prescribing pattern of glucose lowering drugs in the United Kingdom in the last decade: a focus on the effects of safety warnings about rosiglitazone.

AIM In the last decade, new glucose lowering drugs (GLDs) have been launched, and also several warnings regarding their safety. The cardiovascular safety of thiazolidinediones (TZD) has been questioned. We analyzed the prescription pattern of GLDs from 2000 to November 2009 in the United Kingdom (UK) using the THIN database with special focus on the effects of the safety warnings about rosiglitazone issued in May 2007 and January 2008. METHODS Annual prevalence and incidence of GLD prescriptions were measured. For TZD, the monthly prevalence and incidence of prescription were calculated from May 2006 to January 2009. The switching pattern around the FDA alert and the characteristics of subjects starting treatment with TZD before and after the alerts were observed. RESULTS The prevalence of prescriptions of GLDs increased during the 10 year period, metformin increasing more than three times. Rosiglitazone prevalence showed an increased trend until May 2007, (2.3/1000 person-years) and decreased thereafter (January 2009: 1.1/1000 person-years). The use of pioglitazone increased surpassing rosiglitazone from April 2008 onwards. The incidence of rosiglitazone use decreased sharply after May 2007 (0.8/1000 person-years). The prevalence of use of other therapies remained rather stable from 2000 to 2007 but increased afterwards. After May 2007, rosiglitazone users were increasingly switched to pioglitazone. There was an increased proportion of new users of pioglitazone with cardiovascular risk after the alerts. CONCLUSIONS The prescription of GLDs in the UK has increased in the last decade. For TZDs, it changed after May 2007 as well as the characteristics of the subjects treated with them.

Prescribing of Rosiglitazone and Pioglitazone Following Safety Signals Analysis of Trends in Dispensing Patterns in the Netherlands from 1998 to 2008

I read with interest the article by Ruiter et al. [1]. I must say that I found it odd that the results of this study differ from those of other studies in European regions in terms of the use of glitazones [2]. Other European studies have found that rosiglitazone was still used more than pioglitazone in early 2008, despite cardiovascular safety warnings, while this study results were shown differently. In figure 2 of the study by Ruiter et al. [1], a sharp drop in the data series in mid 2007 caught my attention. At that point, a strong diminution in the use of all glitazones can be seen, especially for rosiglitazone, which falls more than 50 %. Before that point, rosiglitazone was being used more than pioglitazone; afterwards, it was the opposite. That led me to suspect that, on that date, an intervention other than the safety warning may have occurred, perhaps some kind of administrative measure regarding the prescription of glitazones. For example, Carracedo-Martı́nez et al. [3] found that no decrease in the use of piroxicam was observed after a health safety warning; however, the month after mandatory prior authorization for piroxicam was introduced (6 months after the safety warning), its use declined sharply (more than 95 %). According to prior authorization rules, the medicine would not be reimbursed for a certain patient if it was not authorized by a health authority, which would only authorize treatment with such medicine if certain prerequisites were met. Indeed, after searching, I found that, in the Netherlands, from 1 July 2007, a measure similar to prior authorization was implemented regarding the prescription of glitazones, and health insurers would be more stringent [4]. The use of glitazones by patients with diabetes who do not meet certain conditions according to health insurance regulations would no longer be reimbursed [4]. Ruiter et al. [1] make no mention of this change in the administrative status of glitazone prescriptions that took place in July 2007. It is neither included in the study design nor mentioned in the discussion. In particular, some safety warnings that were released near July 2007 have proved statistically significant in the study. Ruiter et al. [1] conclude that, in their study, it was difficult to disentangle the effect of Direct Healthcare Professional Communications and European Medicines Agency press releases from the effect of reports published in the literature. I believe that not only that, but also changes in the administrative status of medicines (for instance, if a medicine goes from normal prescription to prescription requiring prior authorization, or if health insurance for a particular medicine changes) should also be taken into account. The fact that, according to figure 2, the strongest diminution by far in the use of glitazones takes place just after such a change in their administrative status in July 2007 [4] is very suggestive.

Prescribing of Rosiglitazone and Pioglitazone Following Safety Signals

AbstractBackground: Relevant safety signals in the EU are regularly communicated in so-called ‘Direct Healthcare Professional Communications’ (DHPCs) or European Medicines Agency (EMA) press releases. Trends of a decrease in the use of rosiglitazone following regulatory safety warnings have been described in the US. In the EU, however, relatively little is known about dispensing patterns following DHPCs or other safety signals such as EMA press releases. Objective: The objective of this study was to analyse trends in dispensing patterns of rosiglitazone and pioglitazone following DHPCs and EMA press releases in the EU member state, the Netherlands. Methods: Data for this study were obtained from the PHARMO Record Linking System, which includes drug dispensing records from community pharmacies of approximately 2.5 million individuals in the Netherlands. Over the period 1998–2008 an auto-regressive, integrated, moving average model (ARIMA) was fitted. The DHPC letters or EMA press releases were used as determinants. Adjustments were made for publication of certain literature. Stratification was performed for dispensings prescribed by general practitioners (GPs) and those prescribed by specialists. Results: for rosiglitazone, four EMA press releases and two DHPCs were issued; for pioglitazone, one DHPC was issued. The number of rosiglitazone dispensings prescribed by GPs decreased significantly after publication of DHPCs and EMA press releases concerning the risk of macular oedema and risk of fractures (both p-values 0.001). The number of rosiglitazone dispensings decreased statistically significantly after publication of EMA press releases 2 and 3 concerning cardiovascular risks but not for EMA press release 4. Adjustment for certain publications in the literature reduced the effect of communicated safety issues on the proportion of dispensings. Conclusions: Although it is difficult to disentangle the effect of DHPCs and EMA press releases from the effect of reports published in the literature, our results suggest that prescribers may react to such safety communications.

A simulation study to compare three self-controlled case series approaches: correction for violation of assumption and evaluation of bias.

The assumption that the occurrence of outcome event must not alter subsequent exposure probability is critical for preserving the validity of the self‐controlled case series (SCCS) method. This assumption is violated in scenarios in which the event constitutes a contraindication for exposure. In this simulation study, we compared the performance of the standard SCCS approach and two alternative approaches when the event‐independent exposure assumption was violated.

Pandemic influenza vaccine & narcolepsy: simulations on the potential impact of bias

ABSTRACT Several studies have identified an association between PandemrixTM, an AS03 adjuvanted pandemic influenza A(H1N1) vaccine, and narcolepsy, a rare and under-diagnosed sleep disorder with a median onset-to-diagnosis interval of ten years. This paper reviews potential sources of bias in published studies and aims to provide, through simulation, methodological recommendations for assessment of vaccine safety signals. Our simulation study showed that in the absence of an association between the vaccine and the outcome, presence of detection bias and differential exposure misclassification could account for elevated risk estimates. These may play a major role, particularly in alert situations when observation times are limited and the disease has a long latency period. Estimates from the case-control design were less inflated than those from the cohort design when these biases were present. Overall, these simulations provide useful insights for the design and interpretation of future studies.