Monday, 31 July 2017

Screening organisation

A number of indicators can be used to monitor the organisational performance of a screening programme.

Time interval between completion of test and receipt of results 
The time interval between performing a test and receipt of results will affect patient outcomes in terms of anxiety and potentially screening outcomes in terms of stage of diagnosis of disease. 

Time interval between positive test and follow-up colonoscopy 
A timely procedure is not critical in the context of primary screening but it is very important when endoscopy is performed following a previous positive screening test. A delayed procedure may not be critical biologically, but it can cause unnecessary anxiety for the screenee. 
To ensure that patient anxiety is not unnecessarily increased, it is recommended that follow-up colonoscopy after positive screening be performed as soon as reasonably possible but no later than within 31 days of referral. 

Time interval between positive endoscopy (CS or FS) and start of definitive management 
 The interval between the diagnosis of screen-detected disease and the start of definitive management is a time of anxiety for the patient and affords the opportunity, if prolonged, for disease progression. For these reasons, standards aimed at minimising delay have set the maximum interval at 31 days (NHS 2007) 

Time interval between consecutive primary screening tests 
The time interval between two consecutive primary screening tests will affect the coverage of the programme by invitation/screening. 
The interval between two consecutive primary screening tests should be monitored to remain within an acceptable level (depending on the screening interval). People should be re-invited according to the date of their last test and not that of their last invitation. 
If possible data pertaining to endoscopic surveillance should be monitored. Proportion of people referred for endoscopic surveillance and proportion of people complying to endoscopic surveillance. 

Long-term impact indicators
The primary objective of screening for CRC is to achieve a reduction in disease-specific mortality; in the case of FS or colonoscopy screening this will be achieved largely by a reduction in the incidence of CRC. However such a reduction in either mortality or incidence will not be discernible until many years after the introduction of the screening programme. (In some areas, opportunistic screening by colonoscopy may be widespread before the start of the programme, therefore diluting the effect of a programme). Methods for studying mortality reduction are discussed later in this chapter. In the meantime other indicators of the impact of screening on disease incidence and mortality should be monitored. These include rates of interval cancers, and surrogate outcome measures that can be used to predict the impact of screening on CRC mortality (or on the incidence of invasive disease) such as rates of overall (age-specific) incidence, stage-specific incidence rates

Costs associated with all aspects of the programme should be recorded. Estimates of cost effectiveness will vary according to the health care system in the area. Costs should be monitored carefully, but comparisons between countries will be complex. 

Finding the appropriate networking level for evaluation of incidence and mortality depends on the organisational structure of the programme. In some programmes (e.g. UK) this will be at a national level, whereas for others it will be at a regional level.  

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