An assessment of nucleic acid amplification testing for active mycobacterial infection

Net financial implications to the MBS

Table 66 Number of patients who accessed MC&S services, 2009–13

A linear regression model fitted to the observed patient numbers (R² = 0.92) was projected to 2019 (Figure 37 and Table 67). This approach may overestimate the eligible population for NAAT, as patients tested who are suspected of M. leprae may be included (but would not be eligible for NAAT) and, as these tests are used to monitor treatment effectiveness, patients may receive testing across multiple years for the same infection. Further, as the current MBS items are not restricted to patients with clinical signs and symptoms of a mycobacterial infection, and as HESP member feedback has indicated that testing may be ordered as part of the initial work-up of a chronic obstructive pulmonary disease or some renal diseases, this approach may further overestimate the eligible population. This will be tested in a sensitivity analysis.

Figure 37 Number of patients who accessed MC&S services, observed 2009–13 and projected 2014–19

MC&S = acid-fast bacilli microscopy, culture and sensitivity

Furthermore, it is proposed that use of NAAT may earlier identify TB and MDR-TB, enabling faster treatment and decreasing the number of secondary transmissions. Neither the potential decrease in the rate of increasing cases due to reduced transmissions, nor the potential savings on treatment costs due to decreased transmissions, is captured in the financial estimates.

As the MBS items for MC&S do not distinguish between TB and NTM, and do not distinguish between those who do and do not have an AFB test, these projected patient numbers cannot be separated into the three proposed populations with any degree of confidence. As NAAT costs differ between TB and NTM, the applicant has estimated that approximately 50% of the patients currently tested for mycobacterial infections are suspected of TB, and so 50% are suspected of NTM.

Generally, one NAAT is assumed per eligible patient. However, this approach may underestimate the estimated number of tests (and so costs) in circumstances in which multiple mycobacteria are suspected. For example, TB may be initially suspected with a pulmonary infection (and therefore be tested using TB NAAT), and then may also be tested using NAAT for M. kansasii and/or MAC. It is unclear how often this situation would occur—the applicant has made an estimate of approximately 30% of patients initially suspected of TB. This is used in the estimation of the financial implications associated with NAAT for NTM and will be tested in sensitivity analyses.

NAAT for TB

The cost per TB NAAT is as used in the economic modelling ($130); the financial implications of a range of test costs are presented in Appendix J. Over the past 5 years average bulk-billing rates for the current MC&S items ranged from 59% to 62%; the midpoint (60.5%) will be used in the analysis. It is assumed that the provider does not charge above the MBS fee, and so the patient contribution, in those not bulk-billed, is 15% of the proposed NAAT fee.

Of all patients suspected of a mycobacterial infection, it is assumed that 50% are suspected of having TB (based on applicant advice). This estimate is tested in sensitivity analyses. Applying this proportion to the projected eligible population estimates, 18,800 patients are estimated to be eligible for TB NAAT in the first year, increasing to 22,200 in the fifth. The total MBS fees associated with the introduction of NAAT for TB increase from $2.4 million to $2.9 million over the 5-year period, of which $2.1 million in year 1 to $2.5 million in year 5 are paid by the MBS. Safety net effects to the MBS have not been considered in these calculations, as MBS data relating to the proportion of patients eligible for the safety net are not available. Patient contributions are estimated to increase from $145,000 to $171,000 over the 5 years. This may be an overestimate as, due to the contagious nature of TB, state TB services may waive all patient fees associated with the investigation of TB.

Table 67 Number of patients eligible and cost of NAAT for TB

-	2015	2016	2017	2018	2019
Projected no. of patients eligible for NAAT	37,575	39,299	41,022	42,745	44,468
Population suspected of TB	-	-	-	-	-
Proportion of patients suspected of TB	50%	50%	50%	50%	50%
Number of patients suspected of TB	18,788	19,650	20,511	21,373	22,234
Proposed NAAT fee:	$130.00	$130.00	$130.00	$130.00	$130.00
MBS benefit (85%)	$110.50	$110.50	$110.50	$110.50	$110.50
Patient contribution (15%)	$19.50	$19.50	$19.50	$19.50	$19.50
Proportion of patients bulk-billed	61%	61%	61%	61%	61%
MBS fees associated with TB listing:	$2,442,440	$2,554,500	$2,666,430	$2,778,490	$2,890,420
MBS benefits payable (85%)	$2,076,074	$2,171,325	$2,266,466	$2,361,717	$2,456,857
Patient co-payments a	$144,715	$151,354	$157,986	$164,626	$171,257

^a Only payable by patients who are not bulk-billed

NAAT = nucleic acid amplification test; TB = tuberculosis

NAAT for NTM

The cost per NTM NAAT is assumed as per the Victorian Mycobacterium Reference Laboratory cost for M. ulcerans ($50). Sensitivity analysis will be conducted using the generic region Mycobacterium PCR test cost ($120) (also from the Victorian reference laboratory). Bulk-billing rates are assumed as per NAAT for TB.

Patients eligible for NAAT for NTM include those initially suspected of an NTM infection (i.e. 50% of all patients suspected of a mycobacterial infection) and those initially suspected of TB, who may also receive testing for NTM (30% of initial TB suspects). In year 1, 24,400 patients are considered eligible for NAAT for NTM, increasing to 28,900 in year 5.

The total MBS fees associated with the introduction of NAAT for NTM increase from $1.2 million to $1.4 million over the 5-year period, of which $1.0 million in year 1 to $1.2 million in year 5 are paid by the MBS. Safety net effects to the MBS have not been considered in these calculations. Patient contributions are estimated to increase from $72,400 to $85,600 over the 5 years.

Table 68 Number of patients eligible and cost of NAAT for NTM

-	2015	2016	2017	2018	2019
Projected no. of patients eligible for NAAT	37,575	39,299	41,022	42,745	44,468
Population suspected of NTM	-	-	-	-	-
Proportion of patients suspected of NTM	50%	50%	50%	50%	50%
Number of patients suspected of NTM	18,788	19,650	20,511	21,373	22,234
Proportion of initial TB suspects tested	30%	30%	30%	30%	30%
Number of initial TB suspects tested	5,636	5,895	6,153	6,412	6,670
Total no. of patients tested for NTM	24,424	25,545	26,664	27,785	28,904
Proposed NAAT fee:	$50.00	$50.00	$50.00	$50.00	$50.00
MBS benefit (85%)	$42.50	$42.50	$42.50	$42.50	$42.50
Patient contribution (15%)	$7.50	$7.50	$7.50	$7.50	$7.50
Proportion of patients bulk-billed	61%	61%	61%	61%	61%
MBS fees associated with NTM listing:	$1,221,220	$1,277,250	$1,333,215	$1,389,245	$1,445,210
MBS benefits payable (85%)	$1,038,037	$1,085,663	$1,133,233	$1,180,858	$1,228,429
Patient co-payments a	$72,357	$75,677	$78,993	$82,313	$85,629

^a Only payable by patients who are not bulk-billed

NAAT = nucleic acid amplification test; NTM = non-tuberculous mycobacteria; TB = tuberculosis

The total MBS fees associated with the introduction of NAAT increase from $3.7 million to $4.3 million over the 5-year period, of which $3.1 million in year 1 to $3.7 million in year 5 are paid by the MBS. Patient contributions are estimated to increase from $217,000 to $257,000 over the 5 years (Table 69).

Table 69 Total cost of NAAT for requested listings

-	2015	2016	2017	2018	2019
MBS fees associated with NAAT listings:	$3,663,660	$3,831,750	$3,999,645	$4,167,735	$4,335,630
MBS benefits payable (85%)	$3,114,111	$3,256,988	$3,399,698	$3,542,575	$3,685,286
Patient co-payments a	$217,072	$227,031	$236,979	$246,938	$256,886

^a Only payable by patients who are not bulk-billed

NAAT = nucleic acid amplification test

As described, the approach used to estimate the population suspected of having a mycobacterial infection may overestimate the population eligible for NAAT, as current MBS item numbers do not restrict testing to those with the clinical signs and symptoms of a mycobacterial infection.

As the implications of the Medicare Safety Net were not included in the analysis, the MBS benefits payable could be underestimated.

Uncertainty scenarios

Uncertainties flagged around estimates used in the financial analysis were tested in sensitivity analyses (Table 70).

The analyses were most sensitive to increases in the NAAT cost (TB or NTM), increasing the total cost of NAAT by more than 60%. The assumption that 25% of all patients currently tested are not eligible for NAAT (e.g. those who do not have clinical signs and symptoms of mycobacterial infection) decreased the total cost of NAAT by the same proportion (25%). Changes to variables that increased the proportion of patients tested for TB (relative to NTM), and increases in the proportion of patients initially suspected of TB tested for NTM, increased the total cost of NAAT slightly (16% and 3%, respectively).

Table 70 Sensitivity analyses

-	2015	2016	2017	2018	2019
Base-case	-	-	-	-	-
Total cost of NAAT for TB	$2,442,440	$2,554,500	$2,666,430	$2,778,490	$2,890,420
Total cost of NAAT for NTM	$1,221,220	$1,277,250	$1,333,215	$1,389,245	$1,445,210
Total cost of NAAT	$3,663,660	$3,831,750	$3,999,645	$4,167,735	$4,335,630
Patients eligible for NAAT, 75% (base-case: 100%)	-	-	-	-	-
Total cost of NAAT for TB	$1,831,830	$1,915,810	$1,999,920	$2,083,900	$2,167,880
Total cost of NAAT for NTM	$915,915	$957,905	$999,960	$1,041,950	$1,083,940
Total cost of NAAT	$2,747,745	$2,873,715	$2,999,880	$3,125,850	$3,251,820
Proportion of patients suspected of TB, 75% (base-case: 50%)	-	-	-	-	-
Total cost of NAAT for TB	$3,663,530	$3,831,620	$3,999,710	$4,167,670	$4,335,630
Total cost of NAAT for NTM	$892,415	$933,360	$974,305	$1,015,185	$1,056,115
Total cost of NAAT	$4,555,945	$4,764,980	$4,974,015	$5,182,855	$5,391,745
Proportion of patients suspected of TB, 25% (base-case: 50%)	-	-	-	-	-
Total cost of NAAT for TB	$1,221,220	$1,277,250	$1,333,280	$1,389,180	$1,445,210
Total cost of NAAT for NTM	$1,549,960	$1,621,075	$1,692,190	$1,763,240	$1,834,305
Total cost of NAAT	$2,771,180	$2,898,325	$3,025,470	$3,152,420	$3,279,515
Proportion of initial TB suspects tested for NTM, 20% (base-case: 30%)	-	-	-	-	-
Total cost of NAAT for TB	$2,442,440	$2,554,500	$2,666,430	$2,778,490	$2,890,420
Total cost of NAAT for NTM	$1,127,280	$1,179,000	$1,230,660	$1,282,380	$1,334,040
Total cost of NAAT	$3,569,720	$3,733,500	$3,897,090	$4,060,870	$4,224,460
Proportion of initial TB suspects tested for NTM, 40% (base-case: 30%)	-	-	-	-	-
Total cost of NAAT for TB	$2,442,440	$2,554,500	$2,666,430	$2,778,490	$2,890,420
Total cost of NAAT for NTM	$1,315,160	$1,375,500	$1,435,770	$1,496,110	$1,556,380
Total cost of NAAT	$3,757,600	$3,930,000	$4,102,200	$4,274,600	$4,446,800
Cost of NAAT for NTM, $120 (base-case: $50)		-	-	-	-
Total cost of NAAT for TB	$2,442,440	$2,554,500	$2,666,430	$2,778,490	$2,890,420
Total cost of NAAT for NTM	$2,930,928	$3,065,400	$3,199,716	$3,334,188	$3,468,504
Total cost of NAAT	$5,373,368	$5,619,900	$5,866,146	$6,112,678	$6,358,924

NAAT = nucleic acid amplification test; NTM = non-tuberculous mycobacteria; TB = tuberculosis

Other Australian healthcare system costs

Costs to the state and territory health systems

There is some indication that NAAT is currently being used (though perhaps not routinely) in the diagnosis of mycobacterial infections. Advice from one state Mycobacterium Reference Laboratory indicated that these costs are currently covered by the states for public patients, and so listing of NAAT will shift these costs from state health budgets to the federal health budget.

Costs to the private health insurer and/or patient

Patient contributions associated with the proposed NAAT listings are estimated to increase from $217,000 to $257,000 over a 5-year period.

Some testing may currently be funded privately. It is assumed that some of these costs will shift to the federal health budget (subject to the fee and patient contribution).

Total Australian healthcare system costs

Given that some shifting of costs from state health budgets to the federal health budget is anticipated with the proposed listings, the net societal costs of NAAT may be lower than those presented in Table 69.

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