Routine audit is an ethical requirement of screening

Editor—Cervical screening saves about 1300 lives each year in England and Wales.¹ We regard audit as an essential part of the screening programme and urge health authorities to continue this activity despite recent concerns about using patient information without informed consent.

Poor quality screening is ineffective and may do more harm than good. Women screened in the NHS can expect a high quality service in which smears are properly taken and read to a high standard and the results stored to ensure appropriate management. Audit is part of the quality assurance that is integral to the screening that each woman receives.

Since 1988 records of every smear test have been entered on to health authority databases. The dates and results of all smear tests are linked to NHS numbers since they are used to determine the timing of future tests. The clinical value of these databases is enormous. Before they existed, coverage was poor and follow up of women with abnormal results was often inadequate.

To evaluate the effectiveness of a screening programme and to identify its strengths and weaknesses screening histories sampled from the entire target population must be audited. This enables rational decisions to be made about modifications on issues such as quality, screening interval, target age groups, the need for an improved screening test, the importance of improving failsafe mechanisms, and the potential gain from improved coverage. Reliable audits cannot depend on consenting women but must be representative of the whole population. Analyses based only on consenting women are likely to be biased and misleading.

Such an audit has been running under the auspices of the national screening programmes since 1992. After linking screening histories to women diagnosed with cervical cancer, health authorities have sent anonymised records from over 7500 women (including 2500 with cancer) to the Imperial Cancer Research Fund for analysis. The data are stored on a secure computer system in password protected directories and are made public only in aggregated form. No one at the fund knows the identity of the women whose screening histories are held in this audit.

We believe that routine audit is an ethical requirement of a screening programme. The benefit in terms of cancer prevention is sufficiently great to warrant the secretary of state making regulations in accordance with clause 68 of the Health and Social Care Bill, and we urge him to do so.

The issues go far beyond cervical screening. Disease prevention and health promotion activities must be audited for the future public health of the country. Only in this way can we ensure that these initiatives are achieving their goals and giving the best protection possible.