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Reboxetine: competition for 'Prozac'? At the 4th annual meeting of the International

Society for Pharmacoeconomics and Outcomes Research (ISPOR), researchers from Analysis Group/Economics and Pharmacia & Upjohn, US, presented the results of a modelling study comparing the effects of fluoxetine ['Prozac'] and reboxetine - one of the first in a new class of nontricyclic selective norepinephrine [noradrenaline] reuptake inhibitors (NRIs) - on social functioning in patients with depression. I It is hoped that selective NRIs may improve the social functioning of patients with depression through norepinephrine's effect on motivation.

Indeed, the results of the study indicated that, after 4 weeks of therapy, patients with depression who were 'moderately' or 'markedly' ill would have significantly better social functioning if they were receiving reboxetine than if they were taking fluoxetine.

By week 8, it was predicted that the superior effect of reboxetine on social functioning would be evident in all patients with depression (from those classified as 'borderline mentally ill' to 'the most extremely ill'). In contrast, it was predicted that fluoxetine would produce significantly better social functioning than reboxetine only among 'normal, not at all ill' patients during the first 3 weeks of therapy.

The researchers developed the model using a mixed-model analysis of variance approach and used data from two 8-week phase III trials in which 282 patients with major depression were randomised to treatment with either reboxetine (n = 138) or fluoxetine (146). In both trials, social functioning was measured at baseline and at weekly intervals using the Social Adaptation Self-evaluation Scale.

'Prozac'makes California smile In another modelling study, investigators from

California, US, predicted enormous cost savings for California Medicaid ('Medi-Cal') as a result of the 1996 policy decision to include fluoxetine on its formulary.2 They estimated that this decision would generate a net saving of $US 1.025 billion to $US1.760 billion for 'Medi-Cal' over the 8-year period from 1996 to 2004.

These values incorporated fluoxetine's acquisition cost, pharmacy dispensing fees, the manufacturer's rebate, treatment authorisation costs, the cost of the intention to treat with fluoxetine (including medical care associated with both treatment success and failure). An annual discount rate of 5.707% per annum was used.

Fluoxetine also appears to have the added advant­age that patients taking this drug continue receiving it for longer without switching to another agent, compared with other selective serotonin reuptake inhibitors (SSRIS).3

This is the finding of researchers from Ingenix and Eli Lilly and Company, US, who performed a

Inpharma-17 Jul11199 No. 1196

retrospective analysis of the medical and pharmacy claims records of 22 693 patients (aged 18-64 years) with depression from 13 United Health-affiliated health plans. They found that, compared with fluoxetine users, both paroxetine and sertraline users were less likely to achieve stable therapy and to have their SSRI therapy augmented, but were more likely to switch therapy.

Choose a TCA for the first year P Chen from the University of North Carolina, US,

presented a model demonstrating that, from the perspective of a managed-care third-party payer, the first year of medical care for patients with major depressive disorder will be less costly if the tricyclic antidepressant (TCA) imipramine rather than the SSRI paroxetine is used.4

Using a decision-analysis model and data from previous clinical trials, Chen showed that prescribing imipramine to antidepressant-naive patients would cost $US81.39/patient but would save $USI69.25/patient in avoided hospitalisations, physician visits and non-antidepressant drug therapy, generating a net saving of $US87.86/patient in the first year of therapy.

In contrast, paroxetine would cost $US261.33/patient but would only save $US201.811patient in avoided medical costs, resulting in a net cost of $US59.521patient in the first year. These findings were robust to the average wholesale price of imipramine as well as the type of depression (reactive or dysthymic).

Rivastigmine eases Alzheimer's burden? Alzheimer's disease (AD) is a growing concern

for US healthcare payers due to the increasing number of elderly in the general popUlation. In a study by researchers from IMS Health, Pennsylvania, US, analysis of an employer claims database showed that the-average annual direct medical cost (charge) for 265 newly-diagnosed AD patients increased to $USI4 620/patient during the year after diagnosis from an average of $US82921patient the previous year. S Aside from increases in costs related to inpatient and outpatient services and emergency-room (ER) visits, there was a 170% increase in nursing home charges after diagnosis (other costs included in the total were those related to drug acquisition, laboratory tests and other medical resources). Against this background, investigators from Novartis in Switzerland and the US conducted a modelling study to estimate the potential impact of rivastigmine therapy on the cost of AD care.6

Integrating estimates of the probability of insti­tutionalisation with data from a 6-month phase TIl clinical trial of rivastigmine and a hazard model of disease progression, the investigators predicted that 'savings in the overall cost of caring for patients with mild and moderate AD can be as high as $4839.00 [US dollars] per patient after 2 years treatment'.

117~8324J9911196-0008I$01.000 Adlalnternlltlonal Limited 11199. All rights reeerved

PHARMACOECONOMICS

Clozapine drives up cost of schizophrenia Schizophrenia is another psychiatric disorder

that is burdensome in both human and financial terms. In Australia, the average direct medical cost of treating patients with schizophrenia has been calculated at around $All OOO/patient/year.

Researchers from M-TAG, Australia, presented 6-month data from the Schizophrenia Care Assessment Program (SCAP) - a prospective naturalistic non­randomised 3-year follow-up study of 350 patients with schizophrenia, schizoaffective disorder or schizophreniform disorder.7 Six-month data for the first 50 patients indicated that the average direct medical cost was $A5500/patient over that time period. Hospitalisations accounted for 85% of the cost, whereas medications used while patients were in the community accounted for only 2.5% of the cost. The remainder was accounted for by outpatient healthcare services and inpatient medication use.

Interestingly, the results of a retrospective study presented by D Christensen from the University of North Carolina, US, suggest that medical resource use by patients with schizophrenia varies substantially depending on the choice of antipsychotic therapy.s

Using claims data for 3997 Medicaid patients (aged 18-65 years) with schizophrenia, Christensen found that patients prescribed clozapine (n = 787) had a per-patient direct cost for the first 6 months of all medical care of $US9300; this value was higher than that for patients prescribed risperidone (960; $US6400) and> 2-fold that for those prescribed haloperidol or other antipsychotics (2250; $US4200). Costs for schizophrenia-related care, and total costs at 12 months, showed a similar pattern. Compared with the other treatment groups, clozapine recipients had higher drug-acquisition, physician-visit and laboratory costs, but lower hospitalisation and ER costs.

Multiple regression analysis indicated that total and schizophrenia-related costs were associated with the cost of care during baseline, clozapine use, risperidone use, the duration of antipsychotic drug use, and comorbidities.

Focus on epilepsy, Parkinson's, ADHD Investigators from Covance Health Economics

and Outcomes Services, US, have estimated that, from the US payer perspective, the annual cost of inpatient and outpatient care reaches $US4.8 billion for patients with a primary diagnosis of epilepsy or convulsions and $US22 billion for patients with any diagnosis code for epilepsy or convulsions [see table ].9

These costs exclude those for anticonvulsant medications, and 'appear higher than previously estimated' , say the investigators. They used 1992-1996 national survey data from 3 sources: the Healthcare Cost and Utilization Project Nationwide Inpatient Sample; the National Ambulatory Medical Care Survey; and the National Hospital Ambulatory Medical Care Survey.

Another retrospective study conducted by D Doshi and Dr M Chatterton from Thomas Jefferson University, Philadelphia, US, showed that nursing care was the major driver of inpatient costs for patients with Parkinson's disease admitted to a large academic medical centre between July 1994 and June 1997.10

1173-832419911196-00091$01 .O<f Adl.lntematlonel Umited 1999. All right. rneMKI

The total inpatient cost was $US8145 and $US 18 617 per patient per hospitalisation among patients with a primary (n = 16) and secondary (54) diagnosis of Parkinson's disease, respectively. Nursing care accounted for most of this cost (73% in the primary-diagnosis group vs 58% in the secondary-diagnosis group), followed by surgical care and cast room services (20 vs 5%), diagnostic, laboratory and pharmacy services (19 vs 14%) and rehabilitation (8 vs 3%).

Attention deficit hyperactivity disorder (ADHD) is thought to be one of the most prevalent psychiatric disorders of childhood, yet the cost of ADHD is not well understood. In 1997, US-based researchers conducted a survey of 154 primary caregivers of children with ADHD to identify direct and indirect healthcare resource use during the year prior to the survey. 11

35% of children were being treated with methylphenidate and 33% were receiving some other ADHD medication. Over the 12 months prior to the survey, there were 'very few' hospitalisations or ER visits, but patients visited paediatricians (mean 2 visits/patient), psychiatrists (3.7), other physicians (1.3), psychologists (2.9) and counsellors (6.6).

In addition, the researchers found that 61 % of caregivers had changed their work status since the initial ADHD diagnosis of the child in their care. During the month prior to the survey, caregivers lost an average of 0.8 work-days each and incurred 2.4 days on which they were 25% less productive due to a child's ADHD. From these data, the researchers estimated that ADHD would result in 39 days of reduced caregiver productivity per year. 1. Venditti LN, et al. Antidepressant impact on social functioning: reboxetine venus fluoxetine. Value in Health 2: 171·172, May·Jun 1999 2. FieldJ, et al. Cost·benefit analysis of fluoxetine inclusion in the Medi-Cal formulary. Value in Health 2: 172, May·Jun 1999 3. Brondum J, et al. Selective serotonin reuptakc inhibitor utilization pattc:ms in patients with or without a depression diagnosis. Value in Health 2: 170-171, May.Jun 1999 4. Olen P. Cost·benefit analysis of oral antidepressants in the maDlI8ement of major depressive disorder: a maDlI8ed care perspective. Value in Health 2: 170, May·Jun 1999 5. Morris LS. et al. Evaluation of medical resource utilization in Alzbeimcr's disease. Value in Health 2: 143, May·Jun 1999 6. Hauber AB, et al. Potential savings in the cost of treating Alzbeimcr'I disease: patient treatment with rivastigmine. Value in Health 2: 131, May·Jun 1999 7. Gibson J, et al. Schizophrenia Care Assessment Program: initial findings on bea1thcare resource utilization in Australia. Value in Health 2: 143, May·Jun 1999 8. OnistenSCII D, et al. Cost and utilization outcomes of patients treated for schizophrenia in a Medicaid population. Value in Health 2: 173-174, May·Jun 1999 9. Griffiths RI, et al. Medical resource use and payer costs of inpatient and outpatient care related to epilepsy. Value in Health 2: 144, May·Jun 1999 10. Doshi DP, et al.lnpatient cost and resource utilization for Parkinson's disease. Value in Health 2: 130-131. May·Jun 199911. Jackson SE, et al. Impact of attention deficit and hyperactivity disorder: a survey of primary caregiven. Value in Health 2: 161, May·Jun 1999 100762113

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