Screening for prostatic cancer and its evolution within Britain

Development and validation of a utility weighting function for the patient-oriented prostate utility scale (PORPUS)

BACKGROUND

Previously, we developed a prostate cancer (PC)-specific health state classification system, the Patient Oriented Prostate Utility Scale (PORPUS). In this study, we developed a scoring system to allow indirect calculation of utilities from the PORPUS.

METHODS

We interviewed 234 PC outpatients, including those with newly diagnosed and metastatic disease, to obtain rating scale (RS) values on 4 to 6 levels of each of the 10 attributes of the PORPUS, and on 10 corner states (worst level on 1 attribute, best on 9). Patients also completed standard gamble (SG) and RS tasks on 4 multiattribute states (impotence and pain corner states, mild and severe PC symptoms). We used the RS and SG scores for multiattribute states to determine a risk aversion function for mapping values to utilities. We then tested 15 different strategies to estimate the multiattribute utility function (MAUF), using the single attribute disutilities for each level of the 10 PORPUS attributes, and the disutilities for the corner states. The root mean squared error (RMSE) of prediction of the SG on the 4 multiattribute states was used to identify the optimal strategy and scoring system.

RESULTS

The optimal strategy gave an RMSE of 0.06. Comparison of mean MAUF-predicted utilities to directly elicited SG utilities for the 2 multiattribute states from patients in 2 previously published studies (n = 248 and n = 141) supported the validity of the MAUF.

CONCLUSIONS

The scoring system together with the PORPUS comprise an indirect utility instrument, the PORPUS-U, which can be used in clinical and research settings.

Rates of prostate-specific antigen testing in general practice in England and Wales in asymptomatic and symptomatic patients: a cross-sectional study

OBJECTIVE

To assess the rate of prostate-specific antigen (PSA) testing for prostate cancer in general practice in asymptomatic and symptomatic patients.

SUBJECTS AND METHODS

The cross-sectional study took place in England and Wales, was population-based and covered 469 159 men aged 45-84 years. Pathology data on PSA tests requested between 19 November 1999 and 31 May 2002 by general practitioners (GPs) were provided by 28 pathology laboratories. The practices recorded reasons for the tests between 1 December 2001 and 31 May 2002. In all, 391 practices in which all GP partners participated were included in the analyses.

RESULTS

The overall annual rate of testing in men with no previous diagnosis of prostate cancer was estimated to be 6%, of which the annual rates of asymptomatic, symptomatic and re-testing were 2.0%, 2.8% and 1.2%, respectively, after adjusting for missing values. The rate decreased with increasing social deprivation, and with increasing proportions of black and Asian populations. The overall rate of PSA testing increased significantly from 1999 to 2002.

CONCLUSIONS

If the recommendations of the National Health Service Prostate Cancer Risk Management Programme were applied, 14% of asymptomatic tests and 23% of symptomatic tests would have led to a referral. As the rate of PSA testing is increasing and there are uncertainties about the benefit of screening, the workload and costs in general practice and hospitals should be monitored.

Screening for prostate cancer

Epidemiologically, screening is justified by the importance of the disease and the lack of prospects for primary prevention, but evidence from natural history is unhelpful since men are more likely to die with, rather than from, prostate cancer. The available screening tests do not always detect men whose lesions could result in future morbidity or mortality. Evidence is limited for the benefits of treatment for localised cancers detected through screening, whereas the evidence for harm is clear. Observational evidence for the effect of population screening programmes is mixed, with no clear association between intensity of screening and reduced prostate cancer mortality. Screening for prostate cancer cannot be justified in low-risk populations, but the balance of benefit and harm will be more favourable after risk stratification. Prostate cancer screening can be justified only in research programmes designed to assess its effectiveness and help identify the groups who may benefit.