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There are no estimates of the likely cost of a prostate cancer screening programme in the UK, but the cost to the health service of the first year of a national screening programme for those aged 50–74 years in the USA has been estimated as being between $5.2 billion and $14.1 billion,370_{with a}

further estimate that screening men aged 50–70 years would change the allocation of spending to this area from 0.06% of the total health care budget to more than 5%.371_{Against such levels}

of costs must be weighed the likely benefits associated with screening.

As with estimates of the cost-effectiveness of prostate cancer treatment, evaluations of the economics of screening for prostate cancer have had to work with the limited data available on all aspects of screening; in particular, the effectiveness of treatment and the sensitivity of diagnostic tests. Although a review of the whole area151_{has conclud-}

ed that the most cost-effective approach to screen- ing seems to be a combination of DRE and PSA for primary screening, with TRUS as a diagnostic tool for those with abnormal findings, there is a broader question concerning whether, given the expected costs and benefits, screening should be attempted at all.

61 Studies from the USA by Littrup and collea-

gues372–376_{have attempted to apply the approach}

of cost-benefit analysis to prostate cancer screen- ing. The cost-benefit analysis approach is the only method of economic appraisal that is able to quan- tify whether or not a programme is worthwhile. This is because benefits are valued in monetary terms and, hence, are commensurate with cost.377

The difficulty with applying this method is, of course, the problem of valuing health outcomes in monetary terms.

The studies by Littrup and colleagues have esti- mated the net benefit per individual screened for prostate cancer from the societal viewpoint. The benefits included were future medical savings from treating earlier cancer, reduced suffering from pre- vention of advanced disease, lost wages and the value of reassurance from a negative test. Costs in- cluded were the costs of the screening test, the cost of subsequent staging and treatment, the cost of adverse effects of screening tests and morbidities of therapy, and the psychic cost of false-positive test results.372,373_{No information is provided about the}

year of cost data, but the analysis is conducted in US$, with publications occurring mainly during 1993 and 1995.372–375,378_{Data on the probability of}

the main clinical events are drawn mainly from the ACS–NCDCP.376_{Many of the valuations of cost}

and benefit included in the equation are based on judgement but there is also extensive sensitivity analysis. This sensitivity analysis shows that the most important economic parameters are, first, the sensitivity of the screening test, second, the economic benefits from early therapy (which com- prise the sum of future medical benefits, reduced suffering and lost wages resulting from the pro- portionate increase in earlier stage disease) and, third, disease prevalence.373

The analyses initially reported by the authors show net costs resulting from each of the different screening methods. These varied from $474 per in- dividual screened using DRE alone (performed by a highly skilled examiner), to $5544 per individual screened using DRE plus PSA assay at 2 ng/ml.372

(Assuming a drop in the ability of the practitioner performing DRE, however, results in a large change in the net cost of DRE, making this option one of the most costly.372,376_{) It is of interest, although un-}

surprising, that the authors found that greatest can- cer yield occurs when all three tests are performed but that this option also resulted in the highest net cost per individual screened, $10,092.376

Later analyses look at the benefit per unit cost asso- ciated with screening particular groups,375_{and the}

use of a tailored biopsy approach.374_{A modified}

benefit-cost equation illustrates that if early detec- tion is not deemed worthwhile in general, there is an underlying potential for economic gains to be made by discouraging participation by those at highest risk. This is likely, however, as the authors state, to be socially unacceptable.375_{Other modifi-}

cations show that improving early detection efforts for African-American men (for whom there is high- er incidence of the disease) leads to a smaller range of potential net benefit values, but these are still clustered around zero.375_{Assuming the use of a}

tailored biopsy (where this refers to biopsy of all patients with PSAD > 0.12 ng/ml/cc or with con- currently suspicious DRE/TRUS), the authors show, leads to lower net costs for the use of PSA assay and DRE compared with the use of a systematic biopsy.374

What is perhaps of most interest about these stud- ies, however, is the fact that the authors do not explicitly accept the implication of their results, which suggest that screening for prostate cancer is not worthwhile. The studies consistently demon- strate net costs (i.e. negative benefits) from screen- ing,372–375_{and, given that they have deliberately}

chosen the cost–benefit methodology, it is surpris- ing that they do not pursue their results to the logical conclusion: since the benefits of screening are lower than the costs, programmes for prostate cancer screening should not be implemented. The value of screening is also questioned in cost– utility analyses conducted by Krahn and colleagues and Cantor and colleagues.379,380_{Krahn and collea-}

gues’ analysis took the perspective of the third party payer, and estimated utilities from ten clinicians on the basis of study specific scenarios using the time trade-off approach. The analysis found that all pro- grammes result in a net increase in cost compared to no screening, with cost-effectiveness ratios ranging from $113,000 to $729,000 per incremental life-year saved (1992, US$). Although screening with PSA assay alone appears to be the most attractive screen- ing policy, each screening programme resulted in QALY loss (the gains in life expectancy and meta- static morbidity were outweighed in all cases by the short- and long-term effects of the therapy). Even within the sensitivity analysis, all bar one (the most optimistic) screening policy was dominated by no screening, with results being sensitive only to assumptions about the effectiveness of treatment. As with the other evaluations of prostate cancer screening, there are concerns about the low quality of evidence, but the study deliberately biases its results in favour of screening where there are ques- tions about the quality of data inputs to the model.

62

Cantor and colleagues also developed a decision- analytic model, basing utilities on the preferences of ten male patients with no history of prostate disease and, again, using the time trade-off method).380_{The model evaluated annual screen-}

ing (DRE, PSA assay initially, plus biopsy/TRUS and biopsy). The Markov model used found that there was a small gain in life expectancy as a result of screening (24.86 versus 24.22 years). Once quality of life was incorporated into the decision there was a fall in QALYs (24.14 versus 23.47). The authors concluded that the decision to screen is sensitive to changes in preferences regarding adverse effects of treatment, but concluded that where quality of life is considered important, annual screening should not be recommended.380

Costs of different