Specialist services should have formal evaluation of their contact tracing programs. The ideal outcome measures to use in both audits and comparative trials remain open to debate. In the United Kingdom, national management standards of the satisfactory management of at least 0.4 contacts per case of chlamydia and gonorrhoea in large cities, and 0.6 contacts per case of chlamydia and gonorrhoea outside large cities, were based on published contact tracing program audits. Audits have also been published in Australia and provide an opportunity for comparison.
The following quantitative measures are suggested for use in audits as they enable comparisons both across time and between services.
- Number of index patients
- Number of contacts identified for notification
- Number of contacts known to be notified, and calculation of notification index = number of contacts notified divided by number of index patients
- Number of contacts known to be treated, and calculation of treatment index = number of contacts treated divided by number of index patients
- Prevalence of infection among contacts of index patient, if known
- Prevalence of infection among clients attending as contacts
- Cost of program
The following qualitative measures are also suggested:
- Acceptability of the program or intervention to index patients
- Acceptability of the program or intervention to contacts
- Staff perceptions of the program or intervention
- Community perception, particularly in relation to confidentiality
- Adverse outcomes of the program or intervention.
For comparative trials the previous outcomes may be used; however, biological outcomes should be considered. In a number of recent randomised trials of partner notification, the primary outcome has been the reduction in repeat or persistent infection in the index patient. This may be measured as the index patient testing positive at some time, at least six weeks after initial treatment.