22 Jan

Test and treat strategies for Helicobacter: RESULTS part 2

Test and treat strategies for Helicobacter: RESULTS part 2

The ICER of C-UBT versus serology ranged from $57/cure to over $32270/cure in sensitivity analysis and ex­ceeded $2000/cure only with variation in C-UBT cost and serology specificity (Table 5). In no case did C-UBT domi­nate serology. However, serology became dominant over 13C-UBT when the specificity of 13C-UBT fell below 81%. Two-way sensitivity analysis: Because the use of serology to diagnose H pylori in low prevalence populations has been criticized for its low positive predictive value, the initial two-way sensitivity analysis assessed the influence of simul­taneous variation in H pylori prevalence and serology speci­ficity on the ICER of serology versus empirical ranitidine and 13C-UBT versus serology (Figure 3).

The ICER of the C-UBT versus serology fell to $352/cure, with a serology specificity of 70% and an H pylori prevalence of 10%. However, high serology specificity (95%) with H pylori prevalence greater than 30% caused the serology strategy to become dominant over 13C-UBT.

The ICER of serology versus ranitidine rose as high as $1872/cure with low H pylori prevalence (10%) and low se­rology specificity (70%). The ICER of serology versus raniti­dine revealed dominance of serology when the prevalence of H pylori exceeded 29%, with a specificity of 95%, or ex­ceeded 38% with a specificity of 70%.

TABLE 5 One-way sensitivity analysis examining the incremental cost effectiveness ratio (ICER) of 13carbon urea breath test (13C-UBT) strategy versus serology strategy

Model parameter

Parameter range

ICER range ($/cure)

13C-UBT
dominant (threshold)

ICER >$1000/cure
(threshold)

13C-UBT sensitivity

0.70-1.00

871-1065

N/A

Below 0.89

13C-UBT specificity

0.70-1.00

712-infinity*

N/A*

Below 0.97

Serology sensitivity

0.70-0.95

806-1052

N/A

Below 0.74

Serology specificity

0.70-0.95

465-32270

N/A

Above 0.80

H pylori prevalence in dyspepsia

0.10-0.50

672-1654

N/A

Above 0.34

PUD prevalence if H pylori-positive

0.20-0.50

497-1855

N/A

Below 0.33

PUD recurrence if H pylori-positive

0.50-1.00

880-889

N/A

N/A

PUD recurrence if H pylori-negative

0.00-0.20

855-1004

N/A

Above 0.19

H pylori eradication effectiveness

0.60-1.00

795-1315

N/A

Below 0.80

Relapse rate of NUD

0.00-1.00

677-1270

N/A

Below 0.46

Proportion of PUD patients who are symptomatic

0.00-1.00

843-901

N/A

N/A

Cost of endoscopy

$250-$1250

465-1026

N/A

Below $300

Cost of 13C-UBT

$40-$120

167-2375

N/A

Above $70

Cost of serology

$5-$50

57-1298

N/A

Below $16

A second two-way sensitivity analysis assessed the influ­ence of simultaneous variation in serology specificity and se- rology cost (Figure 4). The ICER of C-UBT versus serology fell to zero, implying dominance of 13C-UBT over serology, in conditions of low serology specificity and high cost ($46 for a sensitivity of 70% or $49 for a sensitivity of 75%). The ICER of serology versus ranitidine reached a maximum of $953/cure with a specificity of 70% and cost of $50. This ICER also became negative, implying dominance of serol- ogy, when the cost fell below $21 with a specificity of 95% or $13 with a specificity of 70%.
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Figure 3) Two-way sensitivity analysis

Figure 3) Two-way sensitivity analysis testing the influence of Helicobacter pylori (HP) prevalence and serology specificity on the incremental cost effectiveness ratio (ICER) of serology versus ranitidine (upper panel) and the 13carbon urea breath test (UBT) versus serology (lower panel)

A third two-way sensitivity analysis was performed to test the impact of variation in both serology and 13C-UBT costs on the ICER of C-UBT versus serology (Figure 4). When serology cost $50 (baseline $20), this ICER fell to zero and 13C-UBT became dominant when its cost fell below ^$64 (baseline $66). The threshold cost for dominance of C-UBT fell to $39 if serology cost $25 and $17 if serology cost only $5. The ICER of the 13C-UBT relative to serology reached a maximum value of $2788/cure when the costs of serology fell to $5 and that of C-UBT increased to $120.

Figure 4) Two-way sensitivity analysis

Figure 4) Two-way sensitivity analysis testing the influence of serology cost and serology specificity on incremental cost effectiveness ratio (ICER) of serology versus ranitidine (upper panel) and 13carbon urea breath test (UBT) versus serology (middle panel). Two-way sensitivity analysis demonstrating the effect of simultaneous variation in serology and 13C-UBT costs on the ICER of 13C-UBT versus serology (lower panel)

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