Dr Richard Jaine, Dr Giorgi Kvizhinadze, Prof Nick Wilson, Prof Tony Blakely
There is reasonably strong evidence screening for lung cancer with low-dose computed tomography (LDCT) scans is effective at reducing lung cancer mortality. However, new research suggests it is highly unlikely to be cost-effective in NZ. We have just published the first NZ study to examine the cost-effectiveness of lung cancer screening in the journal Lung Cancer, and we estimate that it would cost NZ$154,000 per quality-adjusted life-year (QALY) gained – even among heavy smokers . This means that gaining the equivalent of one year of life in perfect health from lung cancer screening comes with a price tag of about $150,000. This suggests that if we want to reduce the burden of lung cancer in NZ but still have to work within a finite health budget, we should consider more cost-effective means (e.g. enhanced tobacco control).
What did our study find?
Our study estimated the health gains, costs and cost-effectiveness of a programme of LDCT screening every second year compared to no screening . We modelled a population of 55-74 years olds with a smoking history of at least 30 pack-years, and (if a former smoker) having quit within last 15 years. That is, current or previous heavy smokers. We used NZ-specific lung cancer incidence epidemiology (e.g. incidence rates and case fatality), and merged it with LDCT intervention effectiveness from a large US study (the National Lung Screening Trial or NLST) . Whilst we found that smokers do receive health gains, we also found it cost (on average) NZ$154,000 per QALY gained. Or an incremental cost-effectiveness ratio (ICER) of $154,000. As a rule of thumb, interventions that costs more than $45,000 per QALY (NZ$45,000 is NZ’s approximate GDP per capita) gained are not considered cost-effective in NZ . By way of comparison, bowel cancer screening is much more cost-effective at only a few thousand dollars per QALY gained.
We also wanted to check if CT screening for lung cancer wasn’t cost-effective for anyone, or if it might be cost-effective just for some easily identified sub-populations. We found that the ICER was reduced for Māori at $101,000 per QALY – but still twice the usual cost-effectiveness threshold. Screening was not cost-effective for any population subgroup (based on age, sex, ethnicity or smoking status) – given the above stated rule of thumb for a threshold.
Might LDCT screening, or a similar test (e.g. MRI), ever be cost-effective? The two ‘best’ ICERs we estimated were increasing the screening uptake (implausibly) to 100% (ICER = NZ$74,000 per QALY gained), and improving the sensitivity and specificity of the screening test (to 98% and 95% respectively – possibly possible in the future with better test performance) (ICER = NZ$62,000 per QALY gained). In other words, perfect uptake and a near-perfect test would improve the cost-effectiveness significantly, but still not get it below that NZ$45,000 threshold.
How did our NZ study compare with previous international studies?
The ICER that we calculated (in US dollars: US$104,000 per QALY gained) is at the higher end of findings compared to other recent cost-effectiveness analyses of CT screening, but is not an outlier. The results of other studies have found ICERs of US$28,000 , US$34,000 , US$41,000 , US$81,000 , and US$126,000 to US$169,000 .
There are potential reasons for these differences:
- We used unrelated health costs in our model. This means that we account for the costs of people living longer if cured, which we think is a more comprehensive real-world picture of health system cost.
- There would be different costs within different health systems internationally.
- The cost-effectiveness analyses have not used identical model populations (e.g. ‘heaviness’ of smoking).
- We did not model a smoking cessation piggybacked onto CT screening, as some other studies have.
The latter point is important. If a LDCT programme was tied together with smoking cessation, maybe it might become cost-effective. But this is uncertain, even problematic, on at least two grounds. First, there is a danger that a screening programme that finds a person clear of lung cancer may actually discourage cessation. Second, cessation alone may be the best intervention – as adding LDCT screening to a targeted and intensified cessation programme may make a programme prohibitively cost-effective.
Related, some argue that ‘whole body screening’, or at least the fact that LDCT may find other pathology (e.g. renal tumours) might add benefits. However, we searched the literature and found no convincing evidence of this. Indeed, finding other things on a LDCT (which may often be benign) will come with additional costs and may even result in net harm.
What should we do in NZ now?
Currently, only the United States and Canada have approved national screening for lung cancer using LDCT. The Australian Standing Committee on Screening’s position statement does not recommend a national screening programme. While in Europe, there is a recommendation to start planning for LDCT screening, although being aware that trial data for the Dutch-Belgian NELSON trial (which is powered to detect a reduction in mortality) is still awaiting. So, what should we do in NZ?
Given our current best estimate of $154,000 per QALY gained for the NZ screening programme, it would seem that there are much better areas to spend our limited health resources in order to reduce the burden of lung cancer.
A quick look at the BODE3 league table  highlights a number of different tobacco control interventions that would lead to reduced lung cancer rates (and also reduced rates of other tobacco-related diseases) and are more cost-effective than LDCT screening. In fact, all the preventive tobacco interventions in the BODE3 league table are cost-saving. These include interventions such as tobacco tax increases, reducing the number of tobacco retail outlets and a tobacco-free generation.
We do acknowledge, however, that there is already a level of lung cancer burden in NZ that cannot be fully remedied by reducing smoking uptake and increasing cessation. In order to address this burden (which is disproportionately higher for Māori) we must ensure that: New Zealanders have fair and equal access to quality care for lung cancer; the public and health care providers have resources and material to make appropriate decisions about tests and treatment; and that there is timely access to diagnosis and treatment for lung cancer.
And, of course, we need to be aware of changes in the evidence. We need to keep an eye on the current research being undertaken in Europe. Many of these studies have been too small to detect mortality reductions, but it will be important to examine the findings of the NELSON trial which is powered to detect a reduction in mortality (final findings are due soon). There is also a move towards defining the screening population with more advanced risk stratification (e.g. for smokers who have also had past occupational exposure to asbestos). We will need to consider this evidence as it comes to hand and how it affects the cost-effectiveness estimate in NZ.
But for now, the answer on cost-effectiveness is “no”. Especially when the limited resources and capacity for NZ to get new screening programmes up and running is (rightfully) being focused on bowel cancer screening at the moment.
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