Comparative effectiveness and costs of generic and brand-name gabapentin and venlafaxine in patients with neuropathic pain or generalized anxiety disorder in Spain

Abstract

ObjectiveTo explore adherence/persistence with generic gabapentin/venlafaxine versus brand-name gabapentin/venlafaxine (Neurontin®/Vandral®) in peripheral neuropathic pain (pNP) or generalized anxiety disorder (GAD), respectively, and whether it is translated into different costs and patient outcomes in routine medical practice.MethodsA retrospective, new-user cohort study was designed. Electronic medical records (EMR) of patients included in the health plan of Badalona Serveis Assistencials SA, Barcelona, Spain were exhaustively extracted for analysis. Participants were beneficiaries aged 18+ years, followed between 2008 and 2012, with a pNP/GAD International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code, who initiated treatment with generic or brand-name gabapentin or venlafaxine. Assessments included 1-year treatment persistence and adherence (medication possession ratio), health care costs, and reduction in severity of pain and anxiety symptoms.ResultsA total of 2,210 EMR were analyzed; 1,369 on gabapentin (brand 400; generic 969) and 841 on venlafaxine (brand 370 and generic 471). Brand-name gabapentin and venlafaxine were both significantly associated with longer persistence than generic: 7.3 versus 6.3 months, P<0.001; and 8.8 versus 8.1 months, P<0.05, respectively. Brand-name was associated with higher adherence: 86.5% versus 81.3%, P<0.001; and 82.1% versus 79.0%, P<0.05, respectively. Adjusted average costs were higher with generic compared with brand: €1,277 versus €1,057 (difference of €220 per patient; P<0.001) for gabapentin; and €1,110 versus €928 (difference of €182 per patient; P=0.020) for venlafaxine, both because of more use of medical visits and concomitant medication. Compared with generic, brand-name was associated with higher reduction in pain (7.8%; P<0.001) and anxiety (13.2%; P<0.001).ConclusionPatients initiating brand-name gabapentin or venlafaxine were more likely to adhere and persist on treatment of pNP or GAD, have lower health care costs, and show further reduction of pain and anxiety symptoms than with generic drugs in routine medical practice.

Treatment persistence and adherence and their consequences on patient outcomes of generic versus brand-name statins routinely used to treat high cholesterol levels in Spain: a retrospective cost-consequences analysis

“…Gagne et al [ 38 ], in a prospective study, however found that patients who started treatment with brand-name versus generic statins had higher rates of non-adherence and cardiovascular episodes. While these data cannot be generalized, in fact Gagne et al pointed out that such finding could be due to the ample differential acquisition costs of brand-name statins in comparison with generic in the US, these differences are consistent with other published studies [ 33 ]. On the other hand, not only poorer clinical outcomes were showed with generic drugs, but also it was observed a correlates with higher utilization of resources (all-type healthcare costs in particular, but not sick leaves), that was translated into significantly higher costs for the Spanish NHS; on average €1137 per patient (€614 in subjects without previous CVE and €1660 in patients with a previous CVE) in a 5-year follow-up period.…”

“…The temporal relationship between lack of adherence and worst persistence, lower clinical effectiveness and greater use of healthcare resources is beyond doubt, and is consistent with the literature consulted [ 31 – 35 ]. Our research found such poorer persistence for the generic statin; approximately the probability of keeping taken the original therapy was a 14% lower with generics than with brand names, and this was regardless of the occurrence of a previous CVE [ 32 , 33 , 36 ]. Moreover, patients undergoing treatment with generic statins showed lower reduction in their therapeutic goals than those receiving a brand-name statin (approximately 13% chance).…”

Real-life effectiveness and safety of the inhalation suspension budesonide comparator vs the originator product for the treatment of patients with asthma: a historical cohort study using a US health claims database

“…However, this approach has also been used to evaluate patients treated only with either the branded or generic form of a given medication 34. The present study used a hybrid of these two types of designs to examine non-inferiority of effectiveness of budesonide comparator vs budesonide reference and to examine safety through AE rates.…”

“… 32 , 33 However, this approach has also been used to evaluate patients treated only with either the branded or generic form of a given medication. 34 The present study used a hybrid of these two types of designs to examine non-inferiority of effectiveness of budesonide comparator vs budesonide reference and to examine safety through AE rates. A key aspect of the historical analysis design was patient matching, and this method is often used in case-control studies to allow more reliable comparisons between treatments being evaluated.…”

Switching medication products during the treatment of psychiatric illness

“…Adherence (medication possession ratio [MPR: days' supply/days on treatment]) was also significantly higher for reference gabapentin and venlafaxine vs generics (86.5% vs. 81.3%, p < .001; 82.9% vs. 79.0%, p ¼ .045). Reference gabapentin produced a larger adjusted relative reduction in Numeric Rating Scale pain scores than generics (51% vs. 43%, p < .001), and reference venlafaxine was associated with a larger adjusted relative reduction in Hamilton Anxiety Scale score compared with generic products (62% vs. 48%, p < .001) (Sicras-Mainar et al, 2015). Both measures were analysed using a general linear model analysis of covariance with baseline score as a covariate.…”