Generic and therapeutic statin switches and disruptions in therapy

Studies on drug switchability showed heterogeneity in methodological approaches: a scoping review

BACKGROUND AND OBJECTIVE

Several drugs share the same therapeutic indication, including those undergoing patent expiration. Concerns on the interchangeability are frequent in clinical practice, challenging the evaluation of switchability through observational research. The objective of this study was to conduct a scoping review of observational studies on drug switchability to identify methodological strategies adopted to deal with bias and confounding.

METHODS

We searched PubMed, EMBASE, and Web of Science (updated January 31, 2017) to identify studies evaluating switchability in terms of effectiveness/safety outcomes or compliance. Three reviewers independently screened studies extracting all characteristics. Strategies to address confounding, particularly previous drug use and switching reasons, were considered. All findings were summarized in descriptive analyses.

RESULTS

Thirty-two studies, published in the last 10 years, met the inclusion criteria. Epilepsy, cardiovascular, and rheumatology were the most frequently represented clinical areas. Seventy-five percent of the studies reported data on effectiveness/safety outcomes. The most frequent study design was cohort (65.6%) followed by case-control (21.9%) and self-controlled (12.5%). Case-control and case-crossover studies showed homogeneous methodological strategies to deal with bias and confounding. Among cohort studies, the confounding associated with previous drug use was addressed introducing variables in multivariate model (47.3%) or selecting only adherent patients (14.3%). Around 30% of cohort studies did not report reasons for switching. In the remaining 70%, clinical parameters or previous occurrence of outcomes was measured to identify switching connected with lack of effectiveness or adverse events.

CONCLUSION

This study represents a starting point for researchers and administrators who are approaching the investigation and assessment of issues related to interchangeability of drugs.

Therapy discontinuation or substitution in patients with cardiovascular disease, switching among different products of the same off-patent active substance: a 'real-world' retrospective cohort study

OBJECTIVE

The present study investigated the effects of switching to different products of the same off-patent active substance (brand name or generic) on therapy discontinuation or substitution with another molecule of the same class, in patients with cardiovascular disease treated with statins and antihypertensives in a 'real-world' setting.

DESIGN

A retrospective cohort study in a 'real-world' setting.

SETTING

Analysis of data performed by integrating administrative databases that included approximately two million individuals who are assisted by the National Health System from three Local Health Units located in three different regions of Italy.

PARTICIPANTS

All patients aged ≥18 years with at least one prescription of simvastatin, ramipril or amlodipine in the period 1 January to 31 December 2010 were included and followed up for 2 years.

MAIN OUTCOME MEASURES

Prescription refills occurring during follow-up were evaluated. Frequency of discontinuation of therapy or substitution with another molecule of the same class (eg, from simvastatin to a different statin) during follow-up was identified.

RESULTS

During follow-up, therapy discontinuation or substitution was found to be more frequent in patients switching to a different product of the same active substance compared with non-switching patients (11.5% vs 10.8% and 22.2% vs 20.8% (p=0.002), respectively, in the simvastatin group; 4.0% vs 3.5% and 24.6% vs 22.7% (p<0.001), respectively, in the amlodipine group). In the ramipril group, 8% of patients undertook a therapy substitution to another molecule; no trend towards a lower percentage of substitution was observed in the non-switching group, while 18% of patients discontinued treatment, with a significant difference in favour of patients not switching. These findings were partially confirmed by multivariate analysis.

CONCLUSIONS

Switches among products of the same active substance are quite common in patients with cardiovascular disease. Our study suggests that switching may expose patients to a higher risk of therapy discontinuation or substitution.

A US Claims-Based Analysis of Real-World Lipid-Lowering Treatment Patterns in Patients With High Cardiovascular Disease Risk or a Previous Coronary Event

The objective was to examine real-world treatment patterns of lipid-lowering therapies and their possible associated intolerance and/or ineffectiveness in patients with high cardiovascular disease (CVD) risk initiating statins and/or ezetimibe. Patients aged ≥18 years who initiated statins and/or ezetimibe from January 01, 2007, to June 30, 2011, were retrospectively identified from the IMS LifeLink PharMetrics Plus commercial claims database. Patients were further classified into 2 cohorts: (1) history of cardiovascular event (CVE) and (2) history of coronary heart disease risk equivalent (CHD RE). Patients had continuous health plan enrollment ≥1 year pre- and post-index date (statin and/or ezetimibe initiation date). Primary outcomes were index statin intensity, treatment modifications, possible associated statin/nonstatin intolerance and/or ineffectiveness issues (based on treatment modification), and time-to-treatment modifications. Analyses for each cohort were stratified by age group (<65 and ≥65 years). A total of 41,934 (history of CVE) and 170,344 patients (history of CHD RE) were included. On the index date, 8.8% to 25.1% of patients were initiated on high-intensity statin. Among patients aged <65, 79.2% and 48.8% of those with history of CVE and 78.6% and 47.3% of those with a history of CHD RE had ≥1 and 2 treatment modifications, respectively. Among all patients, 24.6% to 25.6% had possible statin intolerance and/or ineffectiveness issues after accounting for second treatment modification (if any). In conclusion, in patients with high CVD risk, index statin treatment modifications that imply possible statin intolerance and/or ineffectiveness were frequent; low use of high-intensity statins indicates unmet need in the management of hyperlipidemia and possible remaining unaccounted CVD residual risk.

Adherence to changing from brand-name to generic atorvastatin in newly treated patients: a retrospective cohort study using health insurance claims

BACKGROUND

Effect of statin therapy has been reported to be associated with patient's adherence. Atorvastatin was available in Japan as a brand-name product beginning in 2000. The first atorvastatin generics were introduced in Japan in November 2011. The objective of this study was to analyze whether changing from a brand-name atorvastatin to a generic product would affect patient adherence.

METHODS

We conducted a retrospective cohort study that included adult patients who received newly prescribed brand-name atorvastatin between June 1, 2011 and May 31, 2012, using a health insurance claims database in Japan. Patients were classified by the presence or absence of changing to a generic during the 6 months from December 1, 2011 to May 31, 2012 (the index period). The first prescription date for the generic or brand product during the index period was defined as the index date. Adherence to therapy was assessed by the proportion of days covered (PDC) and persistence of treatment by time to discontinuation.

RESULTS

There were 135 patients changing to generic atorvastatin and 147 continuing with the brand-name product. There was no significant difference in decrease of PDC from pre- to post-index date between the changed cohort and continued cohort (-8.6% vs -10.3%, respectively; P = 0.443). After adjusting for baseline covariates, including adherence in pre-index date, no statistically significant differences were observed in the adjusted odds of adherence between the cohorts (adjusted odds ratio = 0.83, 95% confidence interval (CI) = 0.46-1.53). There was also no significant difference in persistence between two cohorts in the 180-day after post-index date. After analysis of a Cox proportional hazard regression model controlling for baseline covariates, including adherence in pre-index date, no statistically significant differences were observed for the hazard of non-persistence between the cohorts (adjusted hazard ratio = 0.96, 95% CI = 0.60-1.53).

CONCLUSIONS

Changing from a brand-name atorvastatin to generic product did not affect adherence for patients newly treated with atorvastatin.

Lipid-lowering treatment patterns among patients with type 2 diabetes mellitus with high cardiovascular disease risk

OBJECTIVE

To examine real-world treatment patterns of lipid-lowering treatment and their possible associated intolerance and/or ineffectiveness among patients with type 2 diabetes mellitus initiating statins and/or ezetimibe.

RESEARCH DESIGN AND METHODS

Adult (aged ≥18 years) patients diagnosed with type 2 diabetes who initiated statins and/or ezetimibe from January 1, 2007 to June 30, 2011 were retrospectively identified from the IMS LifeLink Pharmetrics Plus commercial claims database. Patients were further classified into 3 high-risk cohorts: (1) history of cardiovascular event (CVE); (2) two risk factors (age and hypertension); (3) aged ≥40 years. Patients had continuous health plan enrolment ≥1 year preindex and postindex date (statin and/or ezetimibe initiation date). Primary outcomes were index statin intensity, treatment modification(s), possible associated statin/non-statin intolerance and/or ineffectiveness issues (based on treatment modification type), and time-to-treatment modification(s). Analyses for each cohort were stratified by age groups (<65 and ≥65 years).

RESULTS

A total of 9823 (history of CVE), 62 049 (2 risk factors), and 128 691 (aged ≥40 years) patients were included. Among patients aged <65 years, 81.4% and 51.8% of those with history of CVE, 75.6% and 44.4% of those with 2 risk factors, and 77.9% and 47.1% of those aged ≥40 years had ≥1 and 2 treatment modification(s), respectively. Among all patients, 23.2-28.4% had possible statin intolerance and/or ineffectiveness issues after accounting for second treatment modification (if any).

CONCLUSIONS

Among patients with type 2 diabetes with high cardiovascular disease risk, index statin treatment modifications that potentially imply possible statin intolerance and/or ineffectiveness were frequent.

Predictors of statin compliance after switching from branded to generic agents among managed-care beneficiaries

OBJECTIVES

To identify patient demographics and characteristics associated with compliance to statin therapy after switching from branded to generic agents

DESIGN

Retrospective cohort study using electronic health records and pharmacy claims data from Sutter Health's ambulatory-care medical network

PATIENTS

Managed-care beneficiaries, ≥ 18 years of age, who were switched from branded to generic statins between 1 January 2003 and 31 December 2012 MAIN MEASURES: Compliance was calculated as days of therapy dispensed divided by days from first to last generic prescription fill over 6 months, and was defined as a medication possession ratio ≥ 0.80. We used multivariable logistic regression to assess factors associated with compliance. Adjusted ORs and 95% CI were generated.

KEY RESULTS

We identified 5,156 patients who were switched from branded to generic statins; 73% of patients were compliant in the 6 months after switching. After statistical adjustment, higher compliance was associated with each 10-year increase in age (OR: 1.13; 95% CI: 1.07, 1.19; p < 0.001), receipt of a generic statin equivalent in potency to the prior branded statin (OR: 1.41; 95% CI: 1.16, 1.70; p < 0.001), and compliance with prior branded statin (OR: 4.68; 95% CI: 4.07, 5.39; p < 0.001). Lower compliance was seen among Hispanic patients compared to non-Hispanic white patients (OR: 0.68; 95% CI: 0.52, 0.91; p = 0.009). Also, a switch to a higher potency generic statin, regardless of prior dose/potency, was negatively associated with compliance after switching (OR: 0.87; 95% CI: 0.80, 0.94; p = 0.001).

CONCLUSIONS

The majority of patients switched from branded to generic agents were compliant with therapy in the first 6 months after switching. The potential for non-compliance to generic statin therapy, particularly among younger or Hispanic patients or when dose/potency changes are made, should be considered prior to switching. For these patients, counseling or close monitoring may be required to optimize generic interchange.

Cardiovascular event rates in atorvastatin patients versus patients switching from atorvastatin to simvastatin

OBJECTIVE

Statin dose, adherence, and cardiovascular (CV) outcomes are important factors when considering switching statin therapies. The objective of the study was to compare CV event rates and risk in managed care patients receiving atorvastatin versus those switched to simvastatin from atorvastatin.

METHODS

Patients 18-64 years, with ≥3 continuous pharmacy claims for atorvastatin between 1/1/05-11/30/07 and ≥12 months pre- and ≥3 months post-index continuous eligibility were identified using HealthCore Integrated Research Database (HIRD). Patients were stratified into two cohorts: one continued atorvastatin without interruption and the other switched to simvastatin. Patients were matched 1:10 (continue atorvastatin/switch simvastatin) on five variables, excluding lipid parameters due to limited data availability. Descriptive statistics were reported for sample characteristics. A multivariate Cox proportional hazards model was developed to evaluate adjusted CV risk.

RESULTS

In total 73,960 atorvastatin patients and 7396 simvastatin-switch patients were analyzed. The mean age was 54 ± 7 years (both cohorts). Mean follow-up was 440 days for atorvastatin patients and 237 days for simvastatin-switch patients. Mean dose and therapy duration for atorvastatin was 20 mg and 321 days compared with 33 mg and 195 days for simvastatin-switch, respectively. Of the simvastatin-switch patients, 32% were switched to a less potent simvastatin dose (<2× prior atorvastatin dose). After adjusting for demographic/clinical characteristics, no significant differences were found in CV risk between cohorts.

LIMITATIONS

Limitations include use of administrative claims data without lipid level laboratory results data and the length of follow-up which may not have been sufficient to demonstrate significant differences in event rates between groups.

CONCLUSION

In this managed care population, no significant differences were found in risk of CV events among patients switching to simvastatin compared to patients continuing atorvastatin. Switched patients may differ from controls for reasons not captured in the database.

Changes to the statin prescribing policy in Belgium: potential impact in clinical and economic terms

BACKGROUND AND OBJECTIVE

New policies in Belgium encourage prescribing of generic HMG-CoA reductase inhibitors (statins), but may lead to non-equivalent switching of patients from more potent second generation statins, as has occurred elsewhere. We sought to assess the potential health economic impact of the new policies.

DESIGN

This was a cost-effectiveness analysis.

METHODS

A Markov model was constructed to simulate the onset of cardiovascular disease (CVD) and death among a representative cohort of 80 Belgian patients initially free of CVD and taking atorvastatin. Cardiovascular risks were estimated from calibrated Framingham equations, and utilities and costs from published data. Decision analysis assessed the potential impact of switching all 80 patients to simvastatin. Changes in lipid levels expected to arise from switching were based on a published meta-analysis.

RESULTS

If the 80 patients remained on atorvastatin, the model predicted that 23 (29%) would develop CVD over 20 years. If they were switched to simvastatin, the predicted number was 25 (31%), equating to a 'number needed to harm' of 52. Switching would lead to a net cost saving of €131 (2012) per subject, but also a loss of 0.03 quality-adjusted life-years (QALYs) per subject. These equated to a decremental cost-effectiveness ratio of €4777 per QALY lost. Sensitivity analyses indicated this result to be robust.

CONCLUSION

Recently introduced statin prescribing policies in Belgium are likely, as intended, to reduce statin costs, but also increase the burden of CVD due to non-equivalent switching. It would be cost effective to maintain patients on atorvastatin for primary prevention rather than switch them to simvastatin.

Potential cardiovascular consequences of switching from atorvastatin to generic simvastatin in the Netherlands

BACKGROUND

The statin authorisation form implemented in the Netherlands in January 2009 has led to significant switching of patients from atorvastatin to generic simvastatin, but often to less than equipotent doses. We sought to assess the potential consequences of this.

METHODS

A modelling analysis was undertaken using data from a pharmacy database covering the majority of drug prescriptions in the Netherlands. Recent meta-analyses provided data on the dose-specific, lipid-modifying potencies of atorvastatin and simvastatin, and the relationship between reduction in low-density lipoprotein cholesterol (LDL-C) achieved by statin therapy and relative reduction in risk of cardiovascular disease (CVD).

RESULTS

In the first quarter of 2009, 33.7%, 47.2% and 19.1% of Dutch patients initially on atorvastatin were switched to less potent, equipotent and more potent doses of simvastatin, respectively. The net effect was estimated to be a 6.8% increase in LDL-C. Assuming a pre-switch LDL-C of 2 mmol/L, the predicted relative increases (95%CI) in the risks of all-cause mortality and major cardiovascular events were 1.7% (0.9%-2.6%) and 2.8% (1.6%-4.1%), respectively.

CONCLUSIONS

In the Netherlands, policy-driven switching from atorvastatin to generic simvastatin led overall to less potent doses being used, with possible significant clinical implications.

Polypharmacy and food-drug interactions among older persons: a review

Polypharmacy is generally defined as the use of 5 or more prescription medications on a regular basis. The average number of prescribed and over-the-counter medications used by community-dwelling older adults per day in the United States is 6 medications, and the number used by institutionalized older persons is 9 medications. Almost all medications affect nutriture, either directly or indirectly, and nutriture affects drug disposition and effect. This review will highlight the issues surrounding polypharmacy, food-drug interactions, and the consequences of these interactions for the older adult.

A retrospective cohort study of the potency of lipid-lowering therapy and race-gender differences in LDL cholesterol control

BACKGROUND

Reasons for race and gender differences in controlling elevated low density lipoprotein (LDL) cholesterol may be related to variations in prescribed lipid-lowering therapy. We examined the effect of lipid-lowering drug treatment and potency on time until LDL control for black and white women and men with a baseline elevated LDL.

METHODS

We studied 3,484 older hypertensive patients with dyslipidemia in 6 primary care practices over a 4-year timeframe. Potency of lipid-lowering drugs calculated for each treated day and summed to assess total potency for at least 6 and up to 24 months. Cox models of time to LDL control within two years and logistic regression models of control within 6 months by race-gender adjust for: demographics, clinical, health care delivery, primary/specialty care, LDL measurement, and drug potency.

RESULTS

Time to LDL control decreased as lipid-lowering drug potency increased (P < 0.001). Black women (N = 1,440) received the highest potency therapy (P < 0.001) yet were less likely to achieve LDL control than white men (N = 717) (fully adjusted hazard ratio [HR] 0.66 [95% CI 0.56-0.78]). Black men (N = 666) and white women (N = 661) also had lower adjusted HRs of LDL control (0.82 [95% CI 0.69, 0.98] and 0.75 [95% CI 0.64-0.88], respectively) than white men. Logistic regression models of LDL control by 6 months and other sensitivity models affirmed these results.

CONCLUSIONS

Black women and, to a lesser extent, black men and white women were less likely to achieve LDL control than white men after accounting for lipid-lowering drug potency as well as diverse patient and provider factors. Future work should focus on the contributions of medication adherence and response to treatment to these clinically important differences.

Cost effectiveness of letrozole versus anastrozole in postmenopausal women with HR+ early-stage breast cancer

BACKGROUND

The Breast International Group (BIG) 1-98 and Arimidex, Tamoxifen Alone or in Combination (ATAC) trials demonstrated that, in postmenopausal women with hormone receptor positive (HR+) early-stage breast cancer, 5 years of initial adjuvant endocrine therapy with letrozole or anastrozole is superior to tamoxifen. With expected generic availability of anastrozole in July 2010 and letrozole in June 2011, there may be financial pressures prior to letrozole's generic availability to start treatment-naïve patients on anastrozole vs. letrozole or to switch patients already receiving letrozole to anastrozole.

METHODS

A Markov model was used to estimate cost per quality-adjusted life-year (QALY) gained with letrozole vs. anastrozole from the US healthcare system perspective. Cost effectiveness was examined separately in treatment-naïve patients and in patients already receiving letrozole. For the latter, cost effectiveness of continued letrozole vs. therapeutic substitution (TS) to generic anastrozole was evaluated separately in cohorts defined on years of endocrine therapy remaining. TS to generic anastrozole was assumed to result in an additional 5% of patients discontinuing endocrine therapy. Probabilities of distant recurrence and death were taken from reports of BIG 1-98, ATAC, the Early Breast Cancer Trialists' Collaborative Group meta-analysis of tamoxifen, and other published sources. Carry-over effects of aromatase inhibitors were assumed to be proportional to treatment duration. Costs of aromatase inhibitors were assumed to decline by 75% with generic availability.

RESULTS

In treatment-naïve patients, total expected lifetime costs are $3916 greater with letrozole vs. anastrozole. However, initiation of treatment with letrozole results in a gain of 0.15 QALYs. Cost per QALY gained with letrozole vs. anastrozole is $25,846. In patients already receiving letrozole, the increase in total expected lifetime costs with continued letrozole vs. TS to anastrozole is between $4200 and $4500 in all cohorts. QALYs gained with letrozole range from 0.21 in those with 4 years of endocrine therapy remaining to 0.13 in those with 1 year of therapy remaining. Cost per QALY gained ranges from $20,276 to $34,356.

CONCLUSION

For postmenopausal women with HR+ early-stage breast cancer, letrozole is more likely to be cost effective vs. anastrozole in treatment-naïve patients and in patients already receiving letrozole. Limitations of the study include a lack of direct evidence comparing letrozole and anastrozole and lack of data on rates of discontinuation due to therapeutic substitution with aromatase inhibitors.