Differences in rates of switchbacks after switching from branded to authorized generic and branded to generic drug products: cohort study

Correlation between prescription volumes of generic antiepileptic drugs and the number of clinical epileptologists across prefectural regions in Japan: A descriptive study using a national claims database

PURPOSE

Although generic drugs are essential in reducing medical costs, their use in epilepsy therapy remains a subject of ongoing debate. In this study, we analysed prescription trends of generic drugs using data from the National Database of Health Insurance Claims and Specific Health Checkups (NDB) Open Data Japan.

METHODS

The number of generic drug prescriptions from 2017-2021 was extracted from the NDB Open Data Japan, with data for each medication stratified by prefectural region, sex, and age, allowing for the analysis of the impact of each factor. We analysed the correlation between the prescription volumes of generic antiseizure medications (ASMs) and the number of clinical epileptologists registered with the Japan Epilepsy Society per 100,000 population.

RESULTS

In 2021, the prescription volume of generic ASMs was 49 %, whereas that for other pharmacological agents was between 70-80 %. Notably, for children < 15 years of age, generics made up approximately 20 % of prescriptions, which was significantly less than that in other age groups. Analysis by prefecture revealed a negative correlation between prescription volumes of ASMs and the number of clinical epileptologists across prefectural regions in Japan (R = -0.47, p < 0.01).

CONCLUSION

Our findings indicate that the higher the proportion of clinical epileptologists in each prefecture, the lower the number of prescribed generic ASMs. Clinical epileptologists in Japan therefore prescribe antiseizure agents in accordance with the Japanese epilepsy treatment guidelines that do not recommend the use of generic agents.

Factors influencing drug switching and changes in low-density lipoprotein-cholesterol levels with atorvastatin: a real-world observational study

BACKGROUND

Although generic drugs have been approved with the assurance of interchangeable applications with original drugs, some physicians, and patients still view their efficacy and interchangeability negatively. Using real-world data, we aimed to determine factors that impact switching between drugs that contain the same active ingredient, i.e., atorvastatin, and, in turn, whether this 'switch' could alter clinical outcomes.

METHODS

Using the National Health Insurance Service senior cohort, a retrospective cohort study was conducted to assess patients who had newly started atorvastatin 10 mg and had at least two records of national health examinations from 2010 to 2014. Drug switching, which was defined as a change in the atorvastatin product administered 90 days before the first and second examinations, was assessed. Greedy propensity score matching (1:2) was performed between switchers and non-switchers to control for potential confounders. Factors influencing switching were analyzed using multivariate logistic regression to estimate odds ratios and 95% confidence intervals (CIs). Changes in low-density lipoprotein-cholesterol (LDL-C) levels attributable to drug switching were evaluated using difference-in-differences regression.

RESULTS

A total of 1,588 patients were included, of whom 25.3% switched drugs (1,187 non-switchers and 401 switchers). Compared to patients taking generics before the first examination, those taking the original drugs had a lower odds ratio (0.31; 95% CI [0.21, 0.46]) for subsequent drug switching. A change in medical institution was associated with a significantly higher odds ratio (6.83; 95% CI [4.66, 10.02]). There were no significant differences in LDL-C alterations between switchers and non-switchers (0.42 mg/dL; 95% CI [-2.29, 3.13]).

CONCLUSION

The type of first-time drug administered and changes in medical institution can influence drug switching. No significant changes in LDL-C values were observed in the various switching scenarios between the original and generic drugs, suggesting their interchangeable application in real-world clinical practice.

Authorized Generics In The US: Prevalence, Characteristics, And Timing, 2010-19

Authorized generics are approved brand-name drugs that are sold by brand-name manufacturers or licensees without brands on their labeling. Despite their prevalence in prescription drug markets in the US, little is known about trends in their launches, their timing relative to traditional generics, and the characteristics of their respective brand-name drugs. We linked Food and Drug Administration and IQVIA data to investigate newly launched authorized generics during the period 2010-19. We found 854 launches over this period, with launches peaking in 2014. Marketing appears strategic: In markets with traditional generics, three-fourths of authorized generics launched after the respective generic competition started. When we focused on markets where generics were eligible for the 180-day exclusivity, about 70 percent of authorized generics launched before or during the exclusivity period. These findings provide insights for future research on the effect of authorized generics on competition, prices, and access to generics.

Meta-analysis of placebo-arm dropouts in osteoporosis randomized-controlled trials and implications for nocebo-associated discontinuation of anti-osteoporotic drugs in clinical practice

Dropout from placebo arms in randomized-controlled trials is a surrogate for nocebo responses, resulting from patients' negative expectations to treatment. Among 16,460 placebo-treated patients in oral anti-osteoporotic drug trials, nocebo dropouts were 8% on average, being higher in older patients. This implies that nocebo may contribute to the osteoporosis treatment gap in clinical practice.

PURPOSE

Osteoporosis is a common disease requiring long-term treatment. Despite the availability of effective anti-osteoporotic drugs, adherence to treatment is low. Nocebo, a behavior mostly related to the negative expectations to a certain treatment, decreases adherence and negatively affects treatment outcomes and health-related care costs in chronic diseases. Since in double-blind placebo-controlled randomized trials any unfavorable outcome leading to discontinuation in placebo arms is considered as nocebo, we aimed to investigate the size of nocebo response in patients participating in osteoporosis trials.

METHODS

We searched MEDLINE, EMBASE, SCOPUS, and Cochrane databases for dropouts due to reported adverse events in the placebo arms (nocebo dropouts) in all double-blind trials investigating anti-osteoporotic drugs published between January 1993 and March 2022. Only data on bisphosphonates and selective estrogen receptor modulators (SERMs) were analyzed (Prospero registration number CRD42020212843).

RESULTS

Data from 44 trials were extracted. In 16,460 placebo-treated patients, the pooled nocebo-dropout was 8% both for bisphosphonates (average: 0.08; range 0.01-0.27; 95%CI 0.06-0.10) and SERMs (average: 0.08; range 0.03-0.15; 95%CI 0.05-0.13). Nocebo-dropouts were higher in bisphosphonate trials enrolling individuals ≥ 65 years (11%) (n = 18) compared to trials enrolling younger individuals (6%) (n = 18) (average: 0.11; 95%CI 0.08-0.13 vs. average: 0.06; 95%CI 0.05-0.08, respectively, p = 0.001). Participants' sex, dosing-intervals, publication year, or severity of osteoporosis had no impact on the nocebo-dropouts.

CONCLUSION

Almost 1 in 10 osteoporosis patients receiving placebo in trials of bisphosphonates and SERMs experiences AEs leading to dropout, implying that nocebo contributes to treatment-discontinuation in clinical practice. Efforts to identify and minimize nocebo, especially in older patients, are warranted.

Understanding treatment patterns and patient-reported outcomes associated with the use of authorized generics and corresponding independent generics across multiple therapeutic areas

OBJECTIVES

To assess patient characteristics, treatment patterns, and patient-reported outcomes (PROs) associated with authorized generics (AGs) and independent generics (IGs) use.

METHODS

Prescription claims and National Health and Wellness Survey (NHWS) data were linked. Adults with billable national drug code (AG or IG), NHWS completion from June 2015 to July 2019, AG or IG on-hand at NHWS completion, and continuous insurance eligibility in 12 months pre- and post-NHWS completion were included. To be included, all unique medication formulations had to have at least one AG and one IG observation. PRO index date was NHWS completion; claims index date was defined as the first prescription claim identified during the 180-day period prior to NHWS completion for the same active ingredient and formulation type that was on-hand at NHWS completion.

RESULTS

Patients (N = 20,229; 17.2% AG users) in six therapeutic areas (attention deficit-hyperactivity disorder [ADHD], antidepressants, beta blockers [BBs], calcium channel blockers [CCBs], statins, and thyroid) were included. Generally, AG (vs. IG) users were younger and differed in regional access and insurance type (all, p < .05). In multivariable analysis, significant differences were observed for presenteeism and overall work impairment (BBs), healthcare provider visits (BBs), and indirect costs (thyroid) (all, p < .05). AG and IG users differed in persistence (ADHD and statins; both, p < .05) and switch (BBs and CCBs; both, p < .01) rates.

CONCLUSIONS

PRO differences were often small in magnitude and varied by therapeutic area. The impact of switching should consider observed PRO differences, patient preferences, and market availability of AG and IG alternatives.

Retrospective Database Analysis to Explore Patterns and Economic Burden of Switchback to Brand After Generic or Authorized Generic Utilization

Background

Despite demonstration of bioequivalence of generics to brands and the potential for reduced costs, some patients switch back from a generic to the brand. A prior retrospective analysis suggested that this switchback rate may be lower among patients that had initially switched to authorized generics (AG), often both produced and marketed by the brand company, compared to those initially switched to another generic.

Objective

Explore switching patterns of brands, AGs, and generics, switchback rates, and the potential impact of switchbacks on healthcare costs.

Methods

An analysis of the Pharmetrics Plus™ database (2007–2019), a United States (US) payer administrative database, was conducted to examine the use of Upjohn medications available as AGs across multiple therapeutic areas. Patients initiating treatment with brand medication in the 6 months prior to generic market entry were identified and switch rates to generics and AGs, as well as switchback rates, were evaluated. Costs were descriptively compared between patients who switched back to brand and those who remained on any generic.

Results

Across 14 brand medications, more than half of the patients initiating treatment with the brand medication were switched to a generic. Generally, switching to AG, which ranged from 0.5 to 39.6%, was lower than switching to non-AG generics (16.7–79.9%). The comparison of switchback rates from AGs to brand and non-AGs to brand showed similar results (AG:1.3–7.5%; non-AG:1.4–12.9%); however, the most substantial differences were observed where non-AG switchbacks were higher. Patients that switched back to brand remained on AG or generic for an average of 1–3 months (32–88 days). The analysis showed a tendency towards increased medical costs in the period immediately preceding switchback for all medications except sildenafil in both indications (erectile dysfunction and pulmonary arterial hypertension). For the remaining medications, medical costs ranged from $63 to $1544 higher for the switchback population. Pharmacy costs similarly tended to be higher for patients who had a switchback, with the exception of sildenafil for pulmonary arterial hypertension and sirolimus.

Conclusion

Patients receiving a brand medication are likely to be switched to a generic upon market availability. Some patients switch back to the brand medication, usually within 1–3 months; this may be associated with increased medical costs. Additional research is needed to understand switching, its potential disruption to patients, and the role of brands, generics, and AGs.

Clinical equivalence of generic and brand-name drugs used in cardiology: what do we know?

The problem of using generics in the treatment of patients with cardiovascular diseases remains relevant for more than a decade. The concern of doctors, pharmacists and patients is not diminishing with the constant rise in cardiovascular morbidity and mortality worldwide. Based on a systematic review of 186 publications, physicians identified concerns about the quality, reliability and replaceability of original drugs; pharmacists have shown the highest level of generic approval. Patients distrust of generics was revealed, caused by a lack of information, concerns about packaging, and negative experience of replacing the original drug. Three meta-analyzes compared generic and original drugs of cardiovascular groups in terms of efficacy and safety. A 2008 meta-analysis (47 studies, 9 classes of cardiovascular drugs) assessed the effect on mild outcomes, a 2016 meta-analysis (74 studies, 7 classes of drugs) also assessed side effects. The cumulative effect revealed a small and nonsignificant difference, which indicated that there was no superiority of original drugs over generics; there were no differences in the frequency and severity of side effects between generics and original drugs. A 2020 meta-analysis (72 studies, 9 drug classes) assessed the frequency of hospital admissions (including emergency department consultations, hospitalizations) and found a significant increase in the risk for generics for any reason (14%), but not for cardiac vascular diseases. A review of 8 cohort studies evaluating antihypertensive drugs for long-term cardiovascular outcomes, duration of retention, and substitution effect did not find significant differences between generics and brands. In a systematic review of studies comparing warfarin and generics, there were no significant differences in international normalized ratio and the incidence of thromboembolic and hemorrhagic complications; however, in one study, the frequency of hospital visits was 10% higher for generics. A systematic review of studies comparing clopidogrel versus generics shows drug comparability for major cardiovascular events and mortality. A review of 5 cohort studies evaluating originator statins and generics showed comparable rates of all-cause mortality and major cardiovascular events, except for one study with conflicting results. Meta-analyzes and large observational studies indicate that generics are not the worst efficacy, sometimes even surpass that of original drugs and can be justifiably used in clinical practice.

Attitude and Purchase Intention to Generic Drugs

Generic drugs were instituted in 1984 in the United States. Since that time, many studies have been conducted in several countries into consumer attitude and behavior when purchasing generic drugs. Understanding the factors that can influence attitude and purchasing intention in this segment has been a challenge. Thus, this paper aims to present a mapping of the literature on the attitude toward and intention to purchase generic drugs and capture insights that can help define and improve promotional strategies for the use of these products. To identify articles related to the theme, we selected the Web of Science, Science Direct, Scopus, Lilacs, Pubmed Central, Springer, and Embase databases time limited to June 2020, using the keywords “generic drug”, “purchase intention”, and “attitude”. The results indicate that this topic is relatively new, with publications in the leading journals in the area demonstrating its importance. Analysis revealed five strategic insights and showed that the research theme could be grouped into three clusters: (i) consumer attitude and behavior, (ii) perspective of patients and health professionals, and (iii) assessment of the risks associated with generic medications to determine which factors can influence purchase intention, providing decision makers with a broader view with regard to directing public policy strategies in healthcare.

Understanding authorized generics-A review of the published clinical data

WHAT IS KNOWN AND OBJECTIVES

Despite the large body of evidence demonstrating equivalent efficacy and safety for branded drugs and their generic counterparts, some patients and providers have the perception that generics may be less safe and effective than branded agents. Authorized generics (AGs) are a category of generic drugs defined by the United States Food and Drug Administration (FDA) as being the same as the brand-name drug without the brand's name on the label and which may have minor differences, such as tablet or capsule markings for identification. Studies in which AGs are considered along with other generics may increase our understanding of factors that may influence perceptions about generics and shed light on areas where education may be impactful. The objectives of this paper are to provide information about AGs, review studies in which they have been evaluated and explore the role that AGs may fill in the individualized treatment of patients.

METHODS

A literature review was conducted on 30 September 2019 with follow-up search on 4 March 2020. The search was focussed on published papers and meeting abstracts that provided information on AGs with respect to medical and health outcomes of therapy as well as switching in individuals receiving branded, AG, or other generic agents. Information about patients' perceptions of generic medications and adherence to therapy was also included. Additional information, including relevant government sources, such as the FDA website and the Federal Trade Commission Report, was included as appropriate.

RESULTS

The literature specific to AGs is limited, but available data clearly highlight the importance of patient perception of generics as well as medication appearance as factors that may affect adherence and potentially more frequent switchbacks to branded agents from generics or AGs.

WHAT IS NEW AND CONCLUSION

To our knowledge, this is the first narrative review to provide a summary of the published evidence about AGs with respect to clinical and health outcomes and switching. There is a need for more research and education regarding the use of AGs in clinical practice if they are to become more recognized as a potential treatment choice for patients. Generic medications play an important role in the healthcare system, and AGs may be able to provide an option to meet the specific needs of individual patients.

Acceptability of generic versus innovator oral medicines: not only a matter of taste

Optimum use of generic products would require equivalence, not only in terms of quality, safety, and efficacy in clinical studies, but also patient acceptability to not jeopardize treatment success because of non-adherence which would de facto limit the potential cost saving anticipated by their use. Although acceptability is a requirement for the authorization of pediatric innovator products, a survey of European Union (EU) regulatory authorities showed that few have a formal process for assessing patient acceptability of generic products during the registration processes. The current International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) focus on unifying guidance for the development and scrutiny of generics but should include acceptability alongside the other factors being considered for harmonization.

Multiple sclerosis relapse rates and healthcare costs of two versions of glatiramer acetate

Objective: To compare relapse rates and healthcare costs in MS patients treated with Glatopa 20 mg (generic glatiramer acetate) versus Copaxone 20 mg in a US managed care population.Methods: A retrospective claims study was conducted using the HealthCore Integrated Research Database. Patients with ≥1 Glatopa or Copaxone claim between 01 April 2015 (Glatopa) or 01 January 2013 (Copaxone) and 30 April 2018 were included. Patients with prior Copaxone 40 mg use or <1 year continuous health plan enrollment were excluded. Patients who switched from Glatopa to Copaxone were censored. Glatopa users were matched to Copaxone users, and outcomes measured at 6-12 months follow-up.Results: A total of 357 Glatopa and 2291 Copaxone patients qualified for inclusion; 158 per cohort were retained after matching. Baseline characteristics were well-balanced (mean age 49.9 years, 75% female, mean 3.8 Copaxone fills). At baseline, 8% of patients had ≥1 relapse with mean annualized relapse rates (ARR) of 0.18; at follow-up, the relapse rates were 8% versus 15% (Glatopa versus Copaxone; p = .05), and ARRs were 0.12 versus 0.30 (p = .05). 45% of Glatopa patients switched (back) to Copaxone 20/40 mg and were censored at that point. Mean (SD) all-cause medical and pharmacy costs were $51,507 ($28,494) versus $55,085 ($37,061; p = .50). Mean MS-related costs were $45,379 ($24,732) versus $47,949 ($32,615; p = .67), of which mean disease modifying therapy costs were $42,926 ($23,196) versus $44,932 ($28,554; p = .59). Results were similar in sensitivity analyses.Conclusions: In this real-world study, MS patients treated with Glatopa experienced similar health outcomes and costs compared to those treated with Copaxone, with a trend towards lower relapse rates (borderline statistically significant) and cost savings (not statistically significant).

Quantification of Adverse Drug Reactions Related to Drug Switches in The Netherlands

We performed a retrospective cohort study in the Dutch patient population to identify active substances with a relatively high number of adverse drug reactions (ADRs) potentially related to drug switching. For this, we analyzed drug switches and reported ADRs related to switching between June 1, 2009, and December 31, 2016, for a selection of 20 active substances. We also compared pharmacovigilance analyses based on the absolute, switch-corrected, and user-corrected numbers of ADRs. In total, 1,348 reported ADRs and over 23.8 million drug switches were obtained from the National Health Care Institute in The Netherlands and from Lareb, which is The Netherlands Pharmacovigilance Centre. There was no correlation between the number of ADRs and the number of switches, but, on average, we found 5.7 reported ADRs per 100,000 switches. The number was relatively high for rivastigmine, levothyroxine, methylphenidate, and salbutamol, with 74.9, 50.9, 47.6, and 26.1 ADRs per 100,000 switches, respectively. When comparing analyses using the absolute number and the switch-corrected number of ADRs, we demonstrate that different active substances would be identified as having a relatively high number of ADRs, and different time periods of increased numbers of ADRs would be observed. We also demonstrate similar results when using the user-corrected number of ADRs instead of the switch-corrected number of ADRs, allowing for a more feasible approach in pharmacovigilance practice. This study demonstrates that pharmacovigilance analyses of switch-related ADRs leads to different results when the number of reported ADRs is corrected for the actual number of drug switches.

Nocebos in rheumatology: emerging concepts and their implications for clinical practice

Nocebo effects are noxious reactions to therapeutic interventions that occur because of negative expectations of the patient. In the past decade, neurobiological data have revealed specific neural pathways induced by nocebos (that is, interventions that cause nocebo effects), as well as the associated mechanisms and predisposing factors of nocebo effects. Epidemiological data suggest that nocebos can have a notable effect on medication adherence, clinical outcomes and health-care policy. Meta-analyses of randomized controlled trials (RCTs) of patients with rheumatic and musculoskeletal diseases (RMDs) indicate that withdrawal of treatment by placebo-arm participants owing to adverse events is common; a proportion of these events could be nocebo effects. Moreover, in large-scale, open-label studies of patients with RMDs who transition from bio-originator to biosimilar therapeutics, biosimilar retention rates were much lower than in previous double-blind switch RCTs. This discrepancy suggests that in addition to the lack of response in some patients because of intrinsic differences between the drugs, nocebos might have an important role in low biosimilar retention, thus increasing the need for awareness and early identification of nocebo effects by rheumatologists and allied health-care professionals.

Cost saving of switching to equivalent inhalers and its effect on health outcomes

BACKGROUND

Switching inhalers to cheaper equivalent products is often advocated as a necessary cost saving measure, yet the impact on patient's health and healthcare utilisation has not been measured.

METHODS

We identified asthma and chronic obstructive pulmonary disease (COPD) patients from UK primary care electronic healthcare records between 2000 and 2016. A self-controlled case series was used to estimate incidence rate ratios (IRR); comparing outcome rates during the risk period, 3 months after the exposure (financially motivated switch), and control periods (preswitch and postrisk period). Four outcomes were assessed: disease exacerbation, general practitioner consultation, non-specific respiratory events and adverse-medication events. Medication possession ratio (MPR) was calculated to assess adherence. 2017 National Health Service indicative prices were used to estimate cost differences per equivalent dose.

RESULTS

We identified a cohort of 569 901 asthma and 171 231 COPD regular inhaler users, 2% and 6% had been switched, respectively. Inhaler switches between a brand-to-generic inhaler, and all other switches (brand-to-brand, generic-to-generic, generic-to-brand), were associated with reduced exacerbations (brand-to-generic: IRR=0.75, 95% CI 0.64 to 0.88; all other: IRR=0.79, 95% CI 0.71 to 0.88). Gender, age, therapeutic class, inhaler device and inhaler-technique checks did not significantly modify this association (p<0.05). The rate of consultations, respiratory-events and adverse-medication events did not change significantly (consultations: IRR=1.00, 95% CI 0.99 to 1.01; respiratory-events: IRR=0.96, 95% CI 0.95 to 0.97; adverse-medication-events: IRR=1.05, 95% CI 0.96 to 1.15). Adherence significantly increased post-switch (median MPR: pre-switch=54%, post-switch=62%; p<0.001). Switching patients, in the cohort of regular inhaler users, to the cheapest equivalent inhaler, could have saved around £6 million annually.

CONCLUSION

Switching to an equivalent inhaler in patients with asthma or COPD appeared safe and did not negatively affect patient's health or healthcare utilisation.

Methodologic considerations for noninterventional studies of switching from reference biologic to biosimilars

PURPOSE

As more biosimilars become available in the United States, postapproval noninterventional studies describing biosimilar switching and comparing effectiveness and/or safety between switchers and nonswitchers will play a key role in generating real-world evidence to inform clinical practices and policy decisions. Ensuring sound methodology is critical for making valid inferences from these studies.

METHODS

The Biologics and Biosimilars Collective Intelligence Consortium (BBCIC) convened a workgroup consisting of academic researchers, industry scientists, and practicing clinicians to establish best practice recommendations for the conduct of noninterventional studies of biosimilar and reference biologic switching. The workgroup members participated in eight teleconferences between August 2017 and February 2018 to discuss specific topics and build consensus.

RESULTS

This report provides workgroup recommendations covering five main considerations relating to noninterventional studies describing reference biologic to biosimilar switching and comparing reference biologic to biosimilars for safety and effectiveness in the presence of switching at treatment initiation and during follow-up: (a) selecting appropriate data sources from a range of available options including insurance claims, electronic health records, and registries; (b) study designs; (c) outcomes of interest including health care utilization and clinical endpoints; (d) analytic approaches including propensity scores, disease risk scores, and instrumental variables; and (e) special considerations including avoiding designs that ignore history of biologic use, avoiding immortal time bias, exposure misclassification, and accounting for postindex switching.

CONCLUSION

Recommendations provided in this report provide a framework that may be helpful in designing and critically evaluating postapproval noninterventional studies involving reference biologic to biosimilar switching.

Evaluation of Switching Patterns in FDA's Sentinel System: A New Tool to Assess Generic Drugs

INTRODUCTION

Nearly 90% of drugs dispensed in the US are generic products.

OBJECTIVE

The aim of this study was to develop and implement a tool for analyzing manufacturer-level drug utilization and switching patterns within the US Food and Drug Administration's Sentinel system.

METHODS

A descriptive tool was designed to analyze data in the Sentinel common data model and was tested with two case studies-metoprolol extended release (ER) and lamotrigine ER-using claims data from four Sentinel data partners. We plotted initiators of each brand and generic product over time. For metoprolol ER, we evaluated rates of switching from generics around the time of manufacturing issues. For lamotrigine ER, we examined rates of switching back to the brand among those who switched from brand to generic.

RESULTS

We identified 1,651,285 initiators of metoprolol ER products between July 2008 and September 2015. We observed a large decrease in monthly metoprolol ER initiators (from 25,465 in December 2008 to 13,128 in February 2009), corresponding to recalls by generic manufacturers. We observed simultaneous increases in utilization of the authorized generic and brand products. We identified 4266 initiators of lamotrigine ER with an epilepsy diagnosis between January 2012 and September 2015. Among those who switched from brand to generic, the cumulative incidence of switching back was close to 20% at 2 years. Switchback rates were higher for the first available generic products.

CONCLUSIONS

This developed tool was able to elucidate novel utilization and switching patterns in two case studies. Such information can be used to support surveillance of generic drugs and biosimilars.

Comparative effectiveness of generic and brand-name medication use: A database study of US health insurance claims

BACKGROUND

To the extent that outcomes are mediated through negative perceptions of generics (the nocebo effect), observational studies comparing brand-name and generic drugs are susceptible to bias favoring the brand-name drugs. We used authorized generic (AG) products, which are identical in composition and appearance to brand-name products but are marketed as generics, as a control group to address this bias in an evaluation aiming to compare the effectiveness of generic versus brand medications.

METHODS AND FINDINGS

For commercial health insurance enrollees from the US, administrative claims data were derived from 2 databases: (1) Optum Clinformatics Data Mart (years: 2004-2013) and (2) Truven MarketScan (years: 2003-2015). For a total of 8 drug products, the following groups were compared using a cohort study design: (1) patients switching from brand-name products to AGs versus generics, and patients initiating treatment with AGs versus generics, where AG use proxied brand-name use, addressing negative perception bias, and (2) patients initiating generic versus brand-name products (bias-prone direct comparison) and patients initiating AG versus brand-name products (negative control). Using Cox proportional hazards regression after 1:1 propensity-score matching, we compared a composite cardiovascular endpoint (for amlodipine, amlodipine-benazepril, and quinapril), non-vertebral fracture (for alendronate and calcitonin), psychiatric hospitalization rate (for sertraline and escitalopram), and insulin initiation (for glipizide) between the groups. Inverse variance meta-analytic methods were used to pool adjusted hazard ratios (HRs) for each comparison between the 2 databases. Across 8 products, 2,264,774 matched pairs of patients were included in the comparisons of AGs versus generics. A majority (12 out of 16) of the clinical endpoint estimates showed similar outcomes between AGs and generics. Among the other 4 estimates that did have significantly different outcomes, 3 suggested improved outcomes with generics and 1 favored AGs (patients switching from amlodipine brand-name: HR [95% CI] 0.92 [0.88-0.97]). The comparison between generic and brand-name initiators involved 1,313,161 matched pairs, and no differences in outcomes were noted for alendronate, calcitonin, glipizide, or quinapril. We observed a lower risk of the composite cardiovascular endpoint with generics versus brand-name products for amlodipine and amlodipine-benazepril (HR [95% CI]: 0.91 [0.84-0.99] and 0.84 [0.76-0.94], respectively). For escitalopram and sertraline, we observed higher rates of psychiatric hospitalizations with generics (HR [95% CI]: 1.05 [1.01-1.10] and 1.07 [1.01-1.14], respectively). The negative control comparisons also indicated potentially higher rates of similar magnitude with AG compared to brand-name initiation for escitalopram and sertraline (HR [95% CI]: 1.06 [0.98-1.13] and 1.11 [1.05-1.18], respectively), suggesting that the differences observed between brand and generic users in these outcomes are likely explained by either residual confounding or generic perception bias. Limitations of this study include potential residual confounding due to the unavailability of certain clinical parameters in administrative claims data and the inability to evaluate surrogate outcomes, such as immediate changes in blood pressure, upon switching from brand products to generics.

CONCLUSIONS

In this study, we observed that use of generics was associated with comparable clinical outcomes to use of brand-name products. These results could help in promoting educational interventions aimed at increasing patient and provider confidence in the ability of generic medicines to manage chronic diseases.

What is associated with increased side effects and lower perceived efficacy following switching to a generic medicine? A New Zealand cross-sectional patient survey

OBJECTIVE

Following a switch from either a generic or branded antidepressant (venlafaxine) to a new generic, we investigated the factors associated with a preference for branded medicines, side effects reported following switching and efficacy ratings of the new generic drug.

DESIGN

A cross-sectional survey of patients switched to a new generic.

SETTING

Patients accessing venlafaxine information online from the New Zealand government pharmaceuticals funding website.

PARTICIPANTS

310 patients, comprising 205 originally on branded venlafaxine and 105 previously taking a generic version.

MAIN OUTCOME MEASURES

An online questionnaire assessing demographic factors, perceived sensitivity to medicines, trust in pharmaceutical agencies, sources of switch information, preference for branded medicine, new medicine perceptions, side effects and efficacy ratings.

RESULTS

Preference for branded medicine was significantly stronger in older patients (OR=1.04, 95% CI 1.01 to 1.05), those taking branded venlafaxine (OR=2.02, 95% CI 1.13 to 3.64) and patients with a higher perceived sensitivity to medicine (OR=1.23, 95% CI 1.06 to 1.19). Different factors predicted side effects in those switching from the branded and those switching from the generic venlafaxine. Trust in pharmaceutical agencies and the number of side effects were significant predictors of efficacy ratings of the new generic in both patients switching from a branded and those switching from a generic version of venlafaxine.

CONCLUSIONS

In patients switching from a branded medicine and those already taking a generic, different demographic and psychological factors are associated with preference for branded medicine, side effect reporting and perceived efficacy of the new drug. When switching to new generic, there appears to be a close bidirectional relationship between the experience of side effects and perceived drug efficacy. Trust in pharmaceutical agencies impacts directly on perceived efficacy and increasing such trust could reduce the nocebo response following a generic switch.