HealthManagement, Volume 14, Issue 1/2012

Assessing the "Cost Versus Benefit" of Radiology

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All licensed drugs have trial evidence that  they work within their licensed indications,  otherwise they would not have been  granted a marketing authorisation by bodies  such as the European Medicines  Agency. Nevertheless they do not necessarily  have to work particularly well or sufficiently  well to justify their cost compared  with other available treatments.  

As the provision of healthcare has become  more complex and expensive,  health economics has emerged as an increasingly  important discipline. There are  three main ways in which the value for  money of a health intervention can be  assessed, as outlined here.  

Cost Effectiveness Analysis

This looks  at the costs of achieving a defined benefit.  Examples might be cost per life  saved, life year gained, hospital admission  avoided, 5mm drop in systolic blood  pressure, or 1% drop in HbA1c etc. Here  the outcome itself is known to be of benefit  either in health or societal terms, or  associated with a monetary value.  

Cost Utility Analysis

This uses a universal  measure of 'wellness' or 'illness' on a scale  of 0-1, where 1 is perfect health and 0 is  death. Everyone will be somewhere on that  scale and can be described in terms of their  'utility' (interestingly, it is possible to be in  a state less than 0 i.e. considered to be in  a health state worse than death). Utility declines  with age and illness. A cost utility  analysis looks at the average gain in utility  against the cost of a treatment, allowing  the success of any treatment for any condition  to be judged using the same units.  This is refined by the length of time for which  the intervention works, to give a calculation  of total health benefit gained as a result  of the treatment. The unit is a quality  adjusted life year (QAlY) which is a year of  perfect health. When the cost of the treatment  is known, a cost per QAlY can be calculated.  This represents what would have  to be spent on that intervention to 'buy' the  equivalent of a rise of 1 in the utility scale,  lasting for one year in the treated population.  This is looked at in relative terms i.e.  in comparison with treatments already available.  So in essence, an intervention which  gives a big rise in utility and lasts a long time  compared with alternative treatments will  generate many QAlYs in the treated population  and may be a good investment even  if it is relatively expensive.  

Cost Minimisation Analysis

This is simpler,  and can be used when two treatments are  equally beneficial. It evaluates which is the  cheaper, taking all costs related to the treatment  into account. These calculations can  only be made on the basis of excellent evidence  on the effectiveness of treatments,  and the costs involved. Complex economic  models are constructed to map the  course of the disease in relation to the  treatment(s) used, in order to calculate the  value for money provided. This methodology  is particularly widely used in the NHS in  the UK by the National Institute for Health  and Clinical Excellence (NICE) before being  funded for use in the NHS.  


Assessing the 'Value' of  Radiology  

These same principles can be applied to  radiology. There are however several examples  in relation to health screening, notably  population screening for breast cancer,  where similar analyses provided  evidence that mammographic breastscreening was a good investment in terms  of cost versus benefit for the population  in the selected age group.  

Interventional procedures are also  amenable to health economic evaluation,  particularly comparing image guided intervention  with open surgical techniques.  It is is perhaps surprising, and probably not  to radiology's benefit, that these analyses  have not been widely undertaken because  the generally lower cost of interventional  radiology might well work to its advantage  in several areas of practice. It can be done;  for example NICE evaluated the use of ultrasound  guided central venous line insertion  compared with 'blind' placement. The  analysis found ultrasound guidance to be  cost effective in cost per QAlY terms on  the basis of the number of complications  avoided and the medical time saved by fewer  attempts being required.

Evaluation of the health benefits of diagnostic  radiology outside population screening  is more problematic because here there  is a more indirect relationship between the  diagnostic test and the utility gain of the  patient. It would however be perfectly possible  in theory to calculate for example the  cost per QAlY of using MRI to diagnose  acoustic neuroma. Equally, in the case where  two different imaging methods could be  used to make the same diagnosis, it would  be possible to evaluate which provides the  better value for money based on their sensitivity,  specificity and cost. In circumstances  where a second test is used to confirm the  finding of a first, a calculation of the additional  information/ benefit gained relative  to the cost of another investigation would  give a measure of the incremental cost benefit  of carrying out the second test.  


The Future  

As an expensive service, radiology will not  be immune from scrutiny forever. In some  cases, investigations are done for reassurance,  for medico-legal reasons or to compensate  for clinical uncertainty and might  not be a good use of scarce resources. Cost  effectiveness evidence for the appropriate  and effective use of radiology resources  may not be a bad thing.  


All licensed drugs have trial evidence that  they work within their licensed indications,  otherwise they would not have been  granted a ma

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