Compliance after switching from branded to generic statins

Comparison of adherence, persistence, and clinical outcome of generic and brand-name statin users: A retrospective cohort study using the Japanese claims database

BACKGROUND

Non-adherence to statin treatment results in an increased risk of cardiovascular events and all-cause mortality. This study compared adherence, persistence, and clinical outcomes of patients who initiated brand-name and generic statins in the Japanese population.

METHODS

The retrospective cohort study included adult patients who initiated statins between 2014 and 2016. Primary adherence was measured as the proportion of days covered (PDC) within 1 year. Persistence was assessed using the proportion of non-persistent users. Any major adverse cardiac and cerebrovascular event (MACCE) was assessed as a clinical outcome. Propensity score matching was performed to adjust for confounding factors.

RESULTS

Among 47,770 patients who met inclusion criteria in the study, 32,130 (67.3%) initiated generic statins. The median age of the patients was 53 (interquartile range: 46-59) years and 60.2% were male. A higher proportion of patients with PDC ≥80% [60.2% vs. 57.1%; odds ratio, 1.14; 95% confidence interval (CI), 1.09-1.19; p<0.001] and a higher PDC value (median, 90.2% vs. 87.9%; difference, 2.3%; p<0.001) were observed in the generic group. Similarly, fewer patients discontinued statins in the generic group [24.2% vs. 27.7%; hazard ratio (HR), 0.91; 95% CI, 0.87-0.95; p<0.001]. Differences in MACCE occurrence were not significant between the groups (4.3% vs. 4.2%; HR, 1.04; 95% CI, 0.93-1.17; p=0.99).

CONCLUSIONS

Adherence and persistence were higher among generic statin recipients; nevertheless, no significant differences in clinical outcomes were noted between the two groups, suggesting that generic medication did not impair treatment benefits and may improve patient adherence.

Pharmacoepidemiology of statins

The evaluation of the real-life benefits and risks of statins in population is a major pharmacoepidemiological issue, given their widespread use for cardiovascular prevention. The purpose of this review was not to be exhaustive but to show the contributions of pharmacoepidemiology for various aspects of the evaluation of statins such as real-life drug use, effectiveness and risk. Statins are among the most used drugs in the world, but recent data show a slight decrease in use. Actual statin users are older, and have more comorbidities than those studied in clinical trials, but this does not seem to compromise their effectiveness, unlike the compliance issues that are common with these drugs. Beyond the known adverse reactions of statins from the clinical trials, risks of statins can be varied and sometimes difficult to evaluate, considering the ubiquity of cholesterol throughout the body, from drug or endogenous molecule metabolism to the construction of cell membranes or cell activities.

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.

Comparative effectiveness of early versus delayed metformin in the treatment of type 2 diabetes

AIM

The purpose of this study was to evaluate the effectiveness of early versus delayed initiation of metformin in type 2 diabetes.

METHODS

We identified 2925 new users of metformin with type 2 diabetes between 2005 and 2012 in the electronic health records of an integrated health system in Northern California. Patients were matched 1:1 on the propensity for receiving early treatment (defined as ≤6 months from first evidence of diabetes). We evaluated the effectiveness of early versus delayed metformin treatment on intermediate clinical outcomes indicated by changes in hemoglobin A1c (HbA1c) and body mass index (BMI), as well as the incidence of therapy intensification (addition or substitution of a second antihyperglycemic agent).

RESULTS

A total of 2144 propensity-score matched patients were included in the early or delayed treatment group (n=1072, in each). Early treatment was associated with significantly larger decreases in HbA1c (-0.36%; 95% confidence intervals [CI]: -0.44 to -0.27%; P<0.001) and BMI (-0.46 kg/m(2); 95% CI: -0.64 to -0.29 kg/m(2); P<0.001) relative to delayed treatment. Patients receiving early treatment also had a greater likelihood of attaining an HbA1c<7% (<53 mmol/mol) (odds ratio: 2.00; 95% CI: 1.63-2.45; P<0.001) and a reduced risk of therapy intensification (hazard ratio: 0.72; 95% CI: 0.61-0.85; P<0.001).

CONCLUSIONS

Treatment with metformin earlier in the course of type 2 diabetes is associated with better glycemic control, more pronounced weight reduction, and a lower risk for therapy intensification than delayed treatment. Antihyperglycemic therapy should be initiated early after diagnosis to achieve optimal outcomes.

Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study

Background

Several countries have introduced generic substitution, but few studies have assessed its effect on refill adherence. This study aimed to analyse whether generic substitution influences refill adherence to statin treatment.

Methods

Between 1 July 2006 and 30 June 2007, new users of simvastatin (n = 108,806) and atorvastatin (n = 7,464) were identified in the Swedish Prescribed Drug Register . The present study included atorvastatin users as an unexposed control group because atorvastatin was patent-protected and thus not substitutable. We assessed refill adherence using continuous measure of medication acquisition (CMA). To control for potential confounders, we used analysis of covariance (ANCOVA). Differences in CMA associated with generic substitution and generic substitution at first-time statin purchase were analysed.

Results

Nine of ten simvastatin users were exposed to generic substitution during the study period, and their adherence rate was higher than that of patients without substitution [84.6% (95% CI 83.5-85.6) versus 59.9% (95% CI 58.4-61.4), p < 0.001]. CMA was higher with increasing age (60–69 years 16.7%, p < 0.0001 and 70–79 years 17.8%, p < 0.0001, compared to 18–39 years) and secondary prevention (12.8%, p < 0.0001). CMA was lower among patients who were exposed to generic substitution upon initial purchase, compared to those who were exposed to a generic substitution subsequently [80.4% (95% CI 79.4-90.9) versus 89.8% (88.7-90.9), p < 0.001]. This difference decreased when those with only one statin purchase were excluded.

Conclusions

Statin refill adherence was higher among patients who exposed to generic substitution compared to those who were not. Increasing age and previous cardiovascular disease affected refill adherence.

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.