• 2
    Jul
  • Postmenopausal Osteoporotic Women at High Risk of Fracture: RESULTS

Over the three-year period, risedronate produced greater reductions in fractures compared to alendronate. Patients treated with risedronate experienced 23 hip and 111 vertebral fractures (134 total fractures) per 1,000 patients (Table 3). In contrast, a total of 28 hip fractures and 115 vertebral fractures per 1,000 patients (for a total of 143 fractures) were experienced. Among the 1,000 patients in the untreated cohort, there were 58 hip fractures (three-year risk of 5.8%) and 217 vertebral fractures (three-year risk of 21.7%). Treatment with risedronate also resulted in higher QALYs than alendronate (2,359 versus 2,356 per 1,000 patients, respectively) and placebo (2,321 per 1,000 patients). The total costs were lowest for the untreated cohort, followed by risedronate and alen-dronate.

Cost-Effectiveness Analysis

When risedronate was compared to the least expensive option (no therapy), the incremental cost per hip fracture avoided was $16,158, whereas the incremental cost per QALY gained was $17,649. Prior to the availability of risedronate, a comparison of alendronate to no therapy would have been appropriate and would have resulted in an incremental cost per hip fracture averted of nearly $36,000, whereas the incremental cost per QALY gained was over $30,000. The use of risedronate instead of alendronate was found to produce a “dominant” situation in which risedronate resulted in lower overall costs and better outcomes. In this situation, a cost-effectiveness ratio comparing to alendronate was not calculated because alendronate is considered to be dominated by risedronate (Table 3).

Table 3 Costs, Outcomes, and Incremental Cost-Effectiveness from the Base Case Analysis

No. of Fractures

Incremental Cost

Cost

QALYs

per 1000 Patients

Per Hip

Therapy

(per Patient)

(per Patient)

Vertebral

Hip

Versus

Per QALY Gained

Fracture Averted

None

$2,720

2.32l

2l7

58

Risedronate

$3,33l

2.359

lll

23

None

$l6,l58

$l7,649

Alendronate

$3,773

2.356

ll5

28

Risedronate

Dominated

Dominated

Budget Impact Analysis

Table 4 presents the budget impact analysis for the base case scenario over three years. In contrast to an untreated group, treating patients with either risedronate or alendronate led to lower inpatient care, long-term care, and outpatient care costs. Drug acquisition costs of approximately $2,400 for alendronate and $2,200 for rise-dronate led to an increase in overall budget per patient compared to no therapy, which was partially offset by cost savings related to averted fractures. The use of risedronate instead of alendronate resulted in total cost savings of $442 per patient, primarily as a result of lower acquisition costs ($226 per patient) and lower inpatient costs ($121 per patient) related to fracture care.

Table 4 Budget Impact (in Thousands) by Type of Care from the Base Case Analysis

Type of Care No Therapy Risedronate Risedronate ® versus Alendronate No Therapy    Alendronate
Inpatient Care

$l,568

$659

$780

($909)

($l2l)
Long-Term Care

$84l

$345

$4l8

($495)

($72)
Outpatient

$3ll

$l36

$l58

($l75)

($22)
Drug

$2,l90

$2,4l6

$2,l90

($226)
Total

$2,720

$3,33l

$3,773

$6ll

($442)

Sensitivity Analysis

Alternative parameter values were used to assess the sensitivity of the base case cost-effectiveness results. In most scenarios, risedronate remained the dominant therapy, producing cost savings and better efficacy than alendronate. Alendronate was dominant over risedronate in two scenarios: (1) when the low efficacy value was applied to risedronate and the base case efficacy was used for alen-dronate or (2) when the high efficacy value was used for alen-dronate and the base case efficacy was applied to risedronate. Cost-effectiveness of risedronate compared to an untreated cohort was most sensitive to changes in fracture efficacy rates, RR of fracture, therapy discontinuation, observation follow-up time, and starting age of therapy (Tables 5 and 6). With low fracture efficacy values, the cost per QALY gained and cost per hip fracture averted, in contrast to no therapy, increased dramatically to approximately $90,000 and $140,000 (data not shown), respectively. Starting ages below 65 years resulted in higher ratios because of lower fracture rates at those ages, whereas the treatment of older cohorts resulted in lower ratios (Table 6).

Table 5 Cost-Effectiveness of Risedronate Compared to No Therapy from Sensitivity Analyses

Incremental Cost per
Analysis                            QALY Hip Fracture
Gained

Averted

Base Case                       $l6,l58

$l7,649

Fracture Costs
Low                         $26,608

$29,063

High                                      $5,708

$6,234

Utility Values
Low                         $29,763

$l7,649**

High                                    $11,089

$l7,649**

Therapy Discontinuation       $29,458

$35,044

Efficacy
Risedronate (Actonel®)
Low                  Risedronate dominated by alendronateHigh
$l,748                        $l,88l
Alendronate (Fosamax canadian)

Low

$l36,772*                $3,926,926*

High

Risedronate dominated by alendronate
Relative Risk
4                           $46,250

$54,7ll

5                            $29,l90

$34,564

6                           $l7,854

$2l,l6l

7                                          $9,788

$ll,6l2

Lifetime Observation Period     $980

$4,578

Table 6 Effect of Starting Age of Therapy on Incremental Cost-Effectiveness Outcomes for Risedronate Compared to No Therapy

Starting Age of Therapy Cost per QALY Gained Cost per Hip Fracture Averted
55

$42,395

$45,336

60

$37,778

$56,050

65

$l6,l58

$l7,649

70

$l5,697

$l8,086

75

Dominant*

Dominant*

A budget impact sensitivity analysis was conducted using the same scenarios from the cost-effectiveness analysis (Table 7). The budget impact results were consistent with the cost-effectiveness results, such that scenarios in which risedronate had the best cost-effectiveness results also had the most favorable budget impact. In most scenarios, risedronate resulted in an additional cost compared to no treatment and cost savings when compared to alen-dronate. Compared to not treating patients, cost savings were observed when patients aged 75 were treated with risedronate and observed for three years. Risedronate use was virtually cost-neutral compared to no therapy under two scenarios: (1) when the base case cohort of patients was given therapy for three years and followed until death or age 100 and (2) when the upper confidence limit for risedronate hip fracture efficacy (80% reduction in RR of fracture) was used (Table 7).

Table 7 Budget Impact by Type of Care from Sensitivity Analyses

Cost (in Thousands)

Cost of Risedronate

(per 1,000 Patients)

(in Thousands) vs.
Analysis Scenarios

No Therapy

Risedronate

Alendronate

No Therapy

Generic Alendronate

Base Case Scenario

$2,720

$3,331

$3,773

$6ll

($442)

Alternative Scenarios
Age 65: Lifetime Follow-up

$36,520

$36,641

$37,l56

$l2l

($5l4)

Low Efficacy (A,F)

$2,720

$4,340

$4,98l

$l,620

($64l)

Low Efficacy (A)*

$2,720

$4,340

$3,672

$l,620

$667

Low Efficacy (F)**

$2,720

$3,33l

$4,98l

$6ll

($l,650)

High Efficacy (A,F)

$2,720

$2,807

$3,l24

$87

($3l7)

High Efficacy (A)*

$2,720

$2,807

$3,773

$87

($966)

High Efficacy (F)*

$2,720

$3,33l

$3,l24

$6ll

$207

Therapy Discontinuation

$2,720

$3,378

$3,655

$658

($277)

Low Fracture Costs

$2,040

$3,046

$3,434

$l,005

($388)

High Fracture Costs

$3,400

$3,6l6

$4,ll2

$2l6

($496)

Low-Risk Population***

$872

$2,558

$2,853

$l,685

($295)

Age 55: Base Case for Age Group

$l,948

$3,028

$3,4l0

$l,080

($382)

Age 60: Base Case for Age Group

$l,820

$2,980

$3,343

$l,l59

($363)

Age 70: Base Case for Age Group

$2,693

$3,307

$3,744

$6l4

($437)

Age 75: Base Case for Age Group

$5,083

$4,259

$4,903

($824)

($644)

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