Publications

2012
Gagne JJ, Fireman B, Ryan PB, Maclure M, Gerhard T, Toh S, Rassen JA, Nelson JC, Schneeweiss S. Design considerations in an active medical product safety monitoring system. Pharmacoepidemiol Drug Saf. 2012;21 Suppl 1 :32-40.Abstract
Active medical product monitoring systems, such as the Sentinel System, will utilize electronic healthcare data captured during routine health care. Safety signals that arise from these data may be spurious because of chance or bias, particularly confounding bias, given the observational nature of the data. Applying appropriate monitoring designs can filter out many false-positive and false-negative associations from the outset. Designs can be classified by whether they produce estimates based on between-person or within-person comparisons. In deciding which approach is more suitable for a given monitoring scenario, stakeholders must consider the characteristics of the monitored product, characteristics of the health outcome of interest (HOI), and characteristics of the potential link between these. Specifically, three factors drive design decisions: (i) strength of within-person and between-person confounding; (ii) whether circumstances exist that may predispose to misclassification of exposure or misclassification of the timing of the HOI; and (iii) whether the exposure of interest is predominantly transient or sustained. Additional design considerations include whether to focus on new users, the availability of appropriate active comparators, the presence of an exposure time trend, and the measure of association of interest. When the key assumptions of self-controlled designs are fulfilled (i.e., lack of within-person, time-varying confounding; abrupt HOI onset; and transient exposure), within-person comparisons are preferred because they inherently avoid confounding by fixed factors. The cohort approach generally is preferred in other situations and particularly when timing of exposure or outcome is uncertain because cohort approaches are less vulnerable to biases resulting from misclassification.
Wahl PM, Gagne JJ, Wasser TE, Eisenberg DF, Rodgers KJ, Daniel GW, Wilson M, Schneeweiss S, Rassen JA, Patrick AR, et al. Early steps in the development of a claims-based targeted healthcare safety monitoring system and application to three empirical examples. Drug Saf. 2012;35 (5) :407-16.Abstract
BACKGROUND: Several efforts are under way to develop and test methods for prospective drug safety monitoring using large, electronic claims databases. Prospective monitoring systems must incorporate signalling algorithms and techniques to mitigate confounding in order to minimize false positive and false negative signals due to chance and bias. OBJECTIVE: The aim of the study was to describe a prototypical targeted active safety monitoring system and apply the framework to three empirical examples. METHODS: We performed sequential, targeted safety monitoring in three known drug/adverse event (AE) pairs: (i) paroxetine/upper gastrointestinal (UGI) bleed; (ii) lisinopril/angioedema; (iii) ciprofloxacin/Achilles tendon rupture (ATR). Data on new users of the drugs of interest were extracted from the HealthCore Integrated Research Database. New users were matched by propensity score to new users of comparator drugs in each example. Analyses were conducted sequentially to emulate prospective monitoring. Two signalling rules--a maximum sequential probability ratio test and an effect estimate-based approach--were applied to sequential, matched cohorts to identify signals within the system. RESULTS: Signals were identified for all three examples: paroxetine/UGI bleed in the seventh monitoring cycle, within 2 calendar years of sequential data; lisinopril/angioedema in the second cycle, within the first monitoring year; ciprofloxacin/ATR in the tenth cycle, within the fifth year. CONCLUSION: In this proof of concept, our targeted, active monitoring system provides an alternative to systems currently in the literature. Our system employs a sequential, propensity score-matched framework and signalling rules for prospective drug safety monitoring and identified signals for all three adverse drug reactions evaluated.
Wang B, Gagne JJ, Choudhry NK. The epidemiology of drug recalls in the United States. Arch Intern Med. 2012;172 (14) :1109-10.
Gagne JJ, Walker AM, Glynn RJ, Rassen JA, Schneeweiss S. An event-based approach for comparing the performance of methods for prospective medical product monitoring. Pharmacoepidemiol Drug Saf. 2012;21 (6) :631-9.Abstract
BACKGROUND: Prospective medical product monitoring is intended to alert stakeholders about whether and when safety problems are identifiable in longitudinal electronic healthcare data. Little attention has been given to how to compare methods in this setting. PURPOSE: To explore aspects of prospective monitoring that should be considered when comparing method performance and to develop a metric that explicitly accounts for these considerations. METHODS: We reviewed existing metrics and propose an event-based approach that classifies exposed outcomes according to whether a prior alert was generated. RESULTS: In comparing performance of methods for prospective monitoring, three factors must be considered: (1) accuracy in alerting; (2) timeliness of alerting; and (3) the trade-offs between the costs of false negative and false positive alerting. Traditional scenario-based measures of accuracy, such as sensitivity and specificity, which classify only at the end of monitoring, fail to appreciate timeliness of alerting and impose fixed tradeoffs between false positive versus false negative consequences. We provide an expression that summarizes event-based sensitivity (the proportion of exposed events that occur after alerting among all exposed events in scenarios with true safety issues) and event-based specificity (the proportion of exposed events that occur in the absence of alerting among all exposed events in scenarios with no true safety issues) by taking an average weighted by relative costs of false positive and false negative alerting. CONCLUSIONS: The proposed approach explicitly accounts for accuracy in alerting, timeliness in alerting, and the trade-offs between the costs of false negative and false positive alerting.
Glynn RJ, Gagne JJ, Schneeweiss S. Role of disease risk scores in comparative effectiveness research with emerging therapies. Pharmacoepidemiol Drug Saf. 2012;21 Suppl 2 :138-47.Abstract
BACKGROUND: Usefulness of propensity scores and regression models to balance potential confounders at treatment initiation may be limited for newly introduced therapies with evolving use patterns. OBJECTIVES: To consider settings in which the disease risk score has theoretical advantages as a balancing score in comparative effectiveness research because of stability of disease risk and the availability of ample historical data on outcomes in people treated before introduction of the new therapy. METHODS: We review the indications for and balancing properties of disease risk scores in the setting of evolving therapies and discuss alternative approaches for estimation. We illustrate development of a disease risk score in the context of the introduction of atorvastatin and the use of high-dose statin therapy beginning in 1997, based on data from 5668 older survivors of myocardial infarction who filled a statin prescription within 30 days after discharge from 1995 until 2004. Theoretical considerations suggested development of a disease risk score among nonusers of atorvastatin and high-dose statins during the period 1995-1997. RESULTS: Observed risk of events increased from 11% to 35% across quintiles of the disease risk score, which had a C-statistic of 0.71. The score allowed control of many potential confounders even during early follow-up with few study endpoints. CONCLUSIONS: Balancing on a disease risk score offers an attractive alternative to a propensity score in some settings such as newly marketed drugs and provides an important axis for evaluation of potential effect modification. Joint consideration of propensity and disease risk scores may be valuable.
2011
Gagne JJ, Patrick AR, Mogun H, Solomon DH. Antidepressants and fracture risk in older adults: a comparative safety analysis. Clin Pharmacol Ther. 2011;89 (6) :880-7.Abstract
We examined variations in fracture rates among patients initiated on antidepressant drug treatment as identified from Medicare data in two US states and assessed whether the observed variation could be explained by affinity for serotonin transport receptors. We used Cox proportional hazards models to compare fracture rates of the hip, humerus, pelvis, wrist, and a composite of these, among propensity score-matched cohorts of users of secondary amine tricyclics, tertiary amine tricyclics, selective serotonin reuptake inhibitors (SSRIs), and atypical antidepressants. As compared with secondary amine tricyclics, SSRIs showed the highest association with composite fracture rate (hazard ratio 1.30; 95% confidence interval (CI) 1.12-1.52), followed by atypical antidepressants (hazard ratio 1.12; 95% CI 0.96-1.31) and tertiary amine tricyclics (hazard ratio 1.01; 95% CI 0.87-1.18). The results were robust to sensitivity analyses. Although SSRI use was associated with the highest rate of fractures, variation in fracture risk across specific antidepressant medications did not depend on affinity for serotonin transport receptors.
Schneeweiss S, Gagne JJ, Glynn RJ, Ruhl M, Rassen JA. Assessing the comparative effectiveness of newly marketed medications: methodological challenges and implications for drug development. Clin Pharmacol Ther. 2011;90 (6) :777-90.Abstract
Comparative-effectiveness research (CER) aims to produce actionable evidence regarding the effectiveness and safety of medical products and interventions as they are used outside of controlled research settings. Although CER evidence regarding medications is particularly needed shortly after market approval, key methodological challenges include (i) potential bias due to channeling of patients to the newly marketed medication because of various patient-, physician-, and system-related factors; (ii) rapid changes in the characteristics of the user population during the early phase of marketing; and (iii) lack of timely data and the often small number of users in the first few months of marketing. We propose a mix of approaches to generate comparative-effectiveness data in the early marketing period, including sequential cohort monitoring with secondary health-care data and propensity score (PS) balancing, as well as extended follow-up of phase III and phase IV trials, indirect comparisons of placebo-controlled trials, and modeling and simulation of virtual trials.
Power MC, Weuve J, Gagne JJ, McQueen MB, Viswanathan A, Blacker D. The association between blood pressure and incident Alzheimer disease: a systematic review and meta-analysis. Epidemiology. 2011;22 (5) :646-59.Abstract
BACKGROUND: Many epidemiologic studies have considered the association between blood pressure (BP) and Alzheimer disease, yet the relationship remains poorly understood. METHODS: In parallel with work on the AlzRisk online database (www.alzrisk.org), we conducted a systematic review to identify all epidemiologic studies meeting prespecified criteria reporting on the association between hypertension, systolic BP, or diastolic BP and incident Alzheimer disease. When possible, we computed summary measures using random-effects models and explored potential heterogeneity related to age at BP assessment. RESULTS: Eighteen studies reporting on 19 populations met the eligibility criteria. We computed summary relative risks (RR(Σ)) for 3 measures of BP: hypertension (RR(Σ) = 0.97 [95% confidence interval = 0.80-1.16]); a 10-mm Hg increase in systolic BP (RR(Σ) = 0.95 [0.91-1.00]); and a 10-mm Hg increase in diastolic BP (RR(Σ) = 0.94 [0.85-1.04]). We were unable to compute summary estimates for the association between categories of systolic or diastolic BP and Alzheimer disease; however, there did not appear to be a consistent pattern across studies. After stratifying on age at BP assessment, we found a suggestion of an inverse association between late-life hypertension and Alzheimer disease and a suggestion of an adverse association between midlife diastolic hypertension and Alzheimer disease. CONCLUSIONS: Based on existing epidemiologic research, we cannot determine whether there is a causal association between BP and Alzheimer disease. Selection bias and reverse causation may account for the suggested inverse association between late-life hypertension on Alzheimer disease, but, given the expected direction of these biases, they are less likely to account for the suggestion that midlife hypertension increases risk. We advocate continuing systematic review; the AlzRisk database entry on this topic (www.alzrisk.org), which was completed in parallel with this work, will be updated as new studies are published.
Goldberg NH, Schneeweiss S, Kowal MK, Gagne JJ. Availability of comparative efficacy data at the time of drug approval in the United States. JAMA. 2011;305 (17) :1786-9.Abstract
CONTEXT: Comparative effectiveness is taking on an increasingly important role in US health care, yet little is known about the availability of comparative efficacy data for drugs at the time of their approval in the United States. OBJECTIVE: To quantify the availability of comparative efficacy data for new molecular entities (NMEs) approved in the United States. DATA SOURCES: Approval packages publicly available through the online database of drug products approved by the US Food and Drug Administration (FDA). STUDY SELECTION: Identification of efficacy studies that supported approval of each NME approved by FDA between 2000 and 2010. DATA EXTRACTION: We determined whether eligible studies were head-to-head active controlled trials and whether the results of such studies were available in the approval packages. We recorded the approved indication, whether the NME was an orphan product, whether the NME had undergone priority review, and whether the control group was a specific active comparator or standard care. RESULTS: Of 197 NMEs identified that met eligibility criteria, 100 (51% [95% confidence interval {CI}, 44%-58%]) met criteria for having comparative efficacy data available at the time of market authorization. After excluding NMEs designated as orphan products (n = 37) and those approved for indications for which no alternative treatments existed (n = 17), this proportion increased to 70% (95% CI, 62%-77%). The proportions of NMEs with available comparative efficacy data varied widely by therapeutic area, from 33% (95% CI, 9%-67%) for hormones and contraceptives to 89% (95% CI, 56%-99%) for diabetes medications. CONCLUSION: Publicly available FDA approval packages contain comparative efficacy data for about half of NMEs recently approved in the United States and for more than two-thirds of NMEs for which alternative treatment options exist. We did not investigate the extent to which available comparative efficacy information is useful for clinical guidance.
Maio V, Marino M, Robeson M, Gagne JJ. Beta-blocker initiation and adherence after hospitalization for acute myocardial infarction. Eur J Cardiovasc Prev Rehabil. 2011;18 (3) :438-45.Abstract
AIMS: We sought to: (1) estimate the proportion of patients who initiated beta-blocker therapy after acute myocardial infarction (AMI) in Regione Emilia-Romagna (RER); (2) examine predictors of post-AMI beta-blocker initiation; and (3) assess adherence to such therapy. METHODS AND RESULTS: Using healthcare claims data covering all of RER, we identified a cohort of 24,367 patients with a hospitalization for AMI between 2004 and 2007, who were discharged from the hospital alive and without contraindications to beta-blocker therapy. We estimated the proportion of eligible patients with at least one prescription for a beta-blocker following discharge and performed a multivariable logistic regression analysis to identify independent predictors of post-AMI beta-blocker initiation. We computed the proportion of days covered (PCD) as a measure of medication adherence at 6 and 12 months post-discharge. Following discharge, 16,383 (67%) cohort members initiated beta-blocker therapy. Independent predictors of beta-blocker initiation included age and receipt of invasive procedures during hospitalization, such as coronary artery bypass graft surgery (odds ratio [OR], 2.37; 95% confidence interval [CI], 2.00-2.81), percutaneous transluminal coronary angioplasty (OR, 1.42; 95% CI, 1.31-1.54), and cardiac catheterization (OR, 1.21; 95% CI, 1.11-1.32). Among initiators, adherence to beta-blocker treatment at 6 and 12 months was low and decreased in each study year. CONCLUSION: Overall, use of and adherence to post-AMI beta-blocker therapy was suboptimal in RER between 2004 and 2007. Older patients and those with indicators of frailty were less likely to initiate therapy. The proportion of patients adherent at 6 and 12 months decreased over time.
Gagne JJ, Glynn RJ, Avorn J, Levin R, Schneeweiss S. A combined comorbidity score predicted mortality in elderly patients better than existing scores. J Clin Epidemiol. 2011;64 (7) :749-59.Abstract
OBJECTIVE: To develop and validate a single numerical comorbidity score for predicting short- and long-term mortality, by combining conditions in the Charlson and Elixhauser measures. STUDY DESIGN AND SETTING: In a cohort of 120,679 Pennsylvania Medicare enrollees with drug coverage through a pharmacy assistance program, we developed a single numerical comorbidity score for predicting 1-year mortality, by combining the conditions in the Charlson and Elixhauser measures. We externally validated the combined score in a cohort of New Jersey Medicare enrollees, by comparing its performance to that of both component scores in predicting 1-year mortality, as well as 180-, 90-, and 30-day mortality. RESULTS: C-statistics from logistic regression models including the combined score were higher than corresponding c-statistics from models including either the Romano implementation of the Charlson Index or the single numerical version of the Elixhauser system; c-statistics were 0.860 (95% confidence interval [CI]: 0.854, 0.866), 0.839 (95% CI: 0.836, 0.849), and 0.836 (95% CI: 0.834, 0.847), respectively, for the 30-day mortality outcome. The combined comorbidity score also yielded positive values for two recently proposed measures of reclassification. CONCLUSION: In similar populations and data settings, the combined score may offer improvements in comorbidity summarization over existing scores.
Myers JA, Rassen JA, Gagne JJ, Huybrechts KF, Schneeweiss S, Rothman KJ, Joffe MM, Glynn RJ. Effects of adjusting for instrumental variables on bias and precision of effect estimates. Am J Epidemiol. 2011;174 (11) :1213-22.Abstract
Recent theoretical studies have shown that conditioning on an instrumental variable (IV), a variable that is associated with exposure but not associated with outcome except through exposure, can increase both bias and variance of exposure effect estimates. Although these findings have obvious implications in cases of known IVs, their meaning remains unclear in the more common scenario where investigators are uncertain whether a measured covariate meets the criteria for an IV or rather a confounder. The authors present results from two simulation studies designed to provide insight into the problem of conditioning on potential IVs in routine epidemiologic practice. The simulations explored the effects of conditioning on IVs, near-IVs (predictors of exposure that are weakly associated with outcome), and confounders on the bias and variance of a binary exposure effect estimate. The results indicate that effect estimates which are conditional on a perfect IV or near-IV may have larger bias and variance than the unconditional estimate. However, in most scenarios considered, the increases in error due to conditioning were small compared with the total estimation error. In these cases, minimizing unmeasured confounding should be the priority when selecting variables for adjustment, even at the risk of conditioning on IVs.
Gagne JJ, Choudhry NK. How many "me-too" drugs is too many?. JAMA. 2011;305 (7) :711-2.
2010
Gagne JJ, Power MC. Anti-inflammatory drugs and risk of Parkinson disease: a meta-analysis. Neurology. 2010;74 (12) :995-1002.Abstract
BACKGROUND/OBJECTIVE: Anti-inflammatory drugs may prevent Parkinson disease (PD) by inhibiting a putative underlying neuroinflammatory process. We tested the hypothesis that anti-inflammatory drugs reduce PD incidence and that there are differential effects by type of anti-inflammatory, duration of use, or intensity of use. METHODS: MEDLINE and EMBASE were searched for studies that reported risk of PD associated with anti-inflammatory medications. Random-effects meta-analyses were used to pool results across studies for each type of anti-inflammatory drug. Stratified meta-analyses were used to assess duration- and intensity-response. RESULTS: Seven studies were identified that met the inclusion criteria, all of which reported associations between nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) and PD, 6 of which reported on aspirin, and 2 of which reported on acetaminophen. Overall, a 15% reduction in PD incidence was observed among users of nonaspirin NSAIDS (relative risk [RR] 0.85, 95% confidence interval [CI] 0.77-0.94), with a similar effect observed for ibuprofen use. The protective effect of nonaspirin NSAIDs was more pronounced among regular users (RR 0.71, 95% CI 0.58-0.89) and long-term users (RR 0.79, 95% CI 0.59-1.07). No protective effect was observed for aspirin (RR 1.08, 95% CI 0.92-1.27) or acetaminophen (RR 1.06, 95% CI 0.87-1.30). Sensitivity analyses found results to be robust. CONCLUSIONS: There may be a protective effect of nonaspirin nonsteroidal anti-inflammatory drug use on risk of Parkinson disease (PD) consistent with a possible neuroinflammatory pathway in PD pathogenesis.
Cadarette SM, Gagne JJ, Solomon DH, Katz JN, Stürmer T. Confounder summary scores when comparing the effects of multiple drug exposures. Pharmacoepidemiol Drug Saf. 2010;19 (1) :2-9.Abstract
PURPOSE: Little information is available comparing methods to adjust for confounding when considering multiple drug exposures. We compared three analytic strategies to control for confounding based on measured variables: conventional multivariable, exposure propensity score (EPS), and disease risk score (DRS). METHODS: Each method was applied to a dataset (2000-2006) recently used to examine the comparative effectiveness of four drugs. The relative effectiveness of risedronate, nasal calcitonin, and raloxifene in preventing non-vertebral fracture, were each compared to alendronate. EPSs were derived both by using multinomial logistic regression (single model EPS) and by three separate logistic regression models (separate model EPS). DRSs were derived and event rates compared using Cox proportional hazard models. DRSs derived among the entire cohort (full cohort DRS) was compared to DRSs derived only among the referent alendronate (unexposed cohort DRS). RESULTS: Less than 8% deviation from the base estimate (conventional multivariable) was observed applying single model EPS, separate model EPS or full cohort DRS. Applying the unexposed cohort DRS when background risk for fracture differed between comparison drug exposure cohorts resulted in -7 to + 13% deviation from our base estimate. CONCLUSIONS: With sufficient numbers of exposed and outcomes, either conventional multivariable, EPS or full cohort DRS may be used to adjust for confounding to compare the effects of multiple drug exposures. However, our data also suggest that unexposed cohort DRS may be problematic when background risks differ between referent and exposed groups. Further empirical and simulation studies will help to clarify the generalizability of our findings.
Maio V, Gagne JJ. Impact of ALLHAT publication on antihypertensive prescribing patterns in Regione Emilia-Romagna, Italy. J Clin Pharm Ther. 2010;35 (1) :55-61.Abstract
BACKGROUND AND OBJECTIVE: Studies from the US and Canada observed changes in antihypertensive prescribing patterns in accordance with Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) study findings immediately after the study's publication, but little is known about the impact of ALLHAT in Italy. The objective of this study was to examine antihypertensive prescribing patterns in Regione Emilia-Romagna (RER), Italy, following the publication of the ALLHAT main results. METHODS: We conducted a time series analysis using automated pharmacy data of approximately 4 million RER residents between 1 January 2000 and 31 December 2003. We computed monthly relative percentages of prescriptions for all antihypertensive medications and separately for all new antihypertensives defined as no recorded antihypertensive use in the previous year. A stepwise auto-regressive forecasting model based on data prior to the ALLHAT publication was used to estimate predicted relative percentages for the 12 months following the ALLHAT publication. Observed and predicted values were compared. RESULTS AND DISCUSSION: Use of thiazide-type diuretics showed a general increasing trend over the study period, but the difference between the observed and predicted values reached statistical significance only for new prescriptions in October 2003 (3.71% vs. 2.32%; P = 0.0170). The relative percentage of new angiotensin-converting enzyme inhibitor and angiotensin receptor blocker (ACE/ARB) prescriptions was higher than predicted for the months May to August 2003 (P < 0.05), but no significant differences were observed for total ACE/ARB prescriptions. Modest changes in patterns of prescribing of calcium channel blockers and alpha-blockers were observed. CONCLUSION: We found little evidence that the ALLHAT study had an impact on antihypertensive prescribing patterns in RER in the year following their publication.
Gagne JJ, Avorn J, Shrank WH, Schneeweiss S. Refilling and switching of antiepileptic drugs and seizure-related events. Clin Pharmacol Ther. 2010;88 (3) :347-53.Abstract
We sought to estimate the risk of seizure-related events associated with refilling prescriptions for antiepileptic drugs (AEDs) and to estimate the effect of switching between brand-name and generic drugs or between two generic versions of the same drug. We conducted a case-crossover study using health-care databases from British Columbia, Canada, among AED users who had an emergency room visit or hospitalization for seizure (index seizure-related event), defined using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9) codes 345.xx (epilepsy and recurrent seizures) and 780.3x (convulsions), between 1997 and 2005. AED prescription refilling itself was associated with 2.3-fold elevated odds of seizure-related events when the refill occurred within 21 days before the index event (odds ratio (OR) 2.31; 95% confidence interval (CI) 1.56-3.44). The OR was 2.75 (95% CI 0.88-8.64) for refills that involved switching, yielding a refill-adjusted OR for switching of 1.19 (95% CI 0.35-3.99). Refilling the same AED prescription was associated with an elevated risk of seizure-related events whether or not the refill involved switching from a brand-name to a generic product.
Kesselheim AS, Stedman MR, Bubrick EJ, Gagne JJ, Misono AS, Lee JL, Brookhart AM, Avorn J, Shrank WH. Seizure outcomes following the use of generic versus brand-name antiepileptic drugs: a systematic review and meta-analysis. Drugs. 2010;70 (5) :605-21.Abstract
The automatic substitution of bioequivalent generics for brand-name antiepileptic drugs (AEDs) has been linked by anecdotal reports to loss of seizure control. To evaluate studies comparing brand-name and generic AEDs, and determine whether evidence exists of superiority of the brand-name version in maintaining seizure control. English-language human studies identified in searches of MEDLINE, EMBASE and International Pharmaceutical Abstracts (1984 to 2009). Randomized controlled trials (RCTs) and observational studies comparing seizure events or seizure-related outcomes between one brand-name AED and at least one alternative version produced by a distinct manufacturer. We identified 16 articles (9 RCTs, 1 prospective nonrandomized trial, 6 observational studies). We assessed characteristics of the studies and, for RCTs, extracted counts for patients whose seizures were characterized as 'controlled' and 'uncontrolled'. Seven RCTs were included in the meta-analysis. The aggregate odds ratio (n = 204) was 1.1 (95% CI 0.9, 1.2), indicating no difference in the odds of uncontrolled seizure for patients on generic medications compared with patients on brand-name medications. In contrast, the observational studies identified trends in drug or health services utilization that the authors attributed to changes in seizure control. Although most RCTs were short-term evaluations, the available evidence does not suggest an association between loss of seizure control and generic substitution of at least three types of AEDs. The observational study data may be explained by factors such as undue concern from patients or physicians about the effectiveness of generic AEDs after a recent switch. In the absence of better data, physicians may want to consider more intensive monitoring of high-risk patients taking AEDs when any switch occurs.
2009
Gagne JJ, Griesdale DEG, Schneeweiss S. Aprotinin and the risk of death and renal dysfunction in patients undergoing cardiac surgery: a meta-analysis of epidemiologic studies. Pharmacoepidemiol Drug Saf. 2009;18 (4) :259-68.Abstract
PURPOSE: Observational studies have reported conflicting results regarding aprotinin's risk of renal dysfunction and death. A meta-analysis was conducted to summarize results and explain variation of published epidemiologic studies on risks of renal dysfunction and death associated with aprotinin. METHODS: MEDLINE and EMBASE were systematically searched for non-experimental studies that reported risk of renal dysfunction or death with aprotinin use during cardiac surgery in adults. Random-effects meta-analyses were used to pool results across studies for each outcome. Stratified and meta-regression analyses were used to identify sources of heterogeneity. RESULTS: Eleven relevant studies were identified and included in the analysis, including 10 that reported renal dysfunction and seven that reported death. Aprotinin was associated with renal dysfunction (risk ratio (RR), 1.42; 95%CI 1.13-1.79) and long-term mortality (hazard ratio (HR) 1.22; 95%CI 1.08-1.39). Pooled estimates were lower for short-term mortality (RR 1.16; 95%CI 0.84-1.58) and renal failure requiring dialysis (RR 1.17; 95%CI 0.99-1.38). Cardiopulmonary bypass (CPB) time, which may be on the causal pathway, was a significant source of heterogeneity, with a 29% increased risk of renal dysfunction for every 10 minute increase in CPB time (p = 0.03). CONCLUSIONS: Despite some studies that reported no association between aprotinin and renal outcomes during cardiac surgery, the totality of epidemiologic evidence indicates an increased risk that cannot be fully explained by need for transfused red blood cells (RBCs). Epidemiologic studies also suggest an increased risk of long-term mortality associated with aprotinin as compared to various comparators used in these studies, although residual confounding cannot be ruled out.
Gagne JJ, Maio V. Comment: pharmaceutical care for migraine and headache patients: a community-based, randomized intervention. Ann Pharmacother. 2009;43 (3) :550-1; author reply 551.

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