In order to ensure health-care equality, we covered 100% of the available population aged 50-74 years, and 84% of them received the test package at their home address. Sometimes in our program, we were faced with problems such as a lack of educated colonoscopists and/or equipment in some counties. However, this also makes it possible for us to test feasibility in this part of the national health-care system and to plan program costs and the additional resources needed in leading time (mainly colonoscopies and education of population). This study of Croatian colonoscopic practice indicates that there are centers with practice of the highest quality, but considerable effort is required to improve the overall quality of colonoscopy. High quality of endoscopic service, early training, regular refresher courses, and continuous audit of standards at local and national levels must be a priority for all endoscopists performing colonoscopy[16
Additional efforts must be made to improve the quality of FOBT performance in public health institutes in order to avoid false positives.
Another problem is increasing the uptake, which is in our country significantly lower for CRC than for breast cancer (the uptake for mammography is up to 70%). On one hand, this issue results from unwillingness to take stool specimens and, on the other hand, from non- compliance with avoiding complicated food and therapy restriction before testing. In order to increase the uptake, newly written recommendations by the Group for Quality Control of the International CRC Network support the decision that the procedure and prescriptions have to be simplified, so that they can be changed for the next cycle immediately[15
]. We are aware that guaiac FOBT shows notable variations in the performance characteristics between different studies[17
]. These differences most likely reflect the different populations tested and the methods for identifying neoplasia. Indeed, from the first results by Allison et al[17
] and Greenberg et al[18
] to meta-analysis by Soares-Weiser et al[19
], different sensitivities for the same tests in different populations or conditions have been reported[20
]. In the same reports, some advantages and disadvantages of immuno-FOBT are discussed. In the process of decision making on which test to choose for the Croatian Program, we considered the arrangement of mailing the tests, time from taking specimens to testing, and relatively high surrounding temperatures in almost half a year which all can influence the accuracy of immuno-FOBT[21
]. So, we have decided that guaiac card-based tests are more convenient for screening in Croatia. Data about higher percentage of FOBT-positive persons indicated that the population screened so far was not really asymptomatic; people who returned tests most frequently had evident symptoms; mostly blood in stool or impairment of bowel discharge, constipation or diarrhea, with or without pain in the distal abdomen. Thus, there is a need actively to include the individuals who are in the “normal and healthy” population. This is frequently seen at the start of every screening program[22,23
]. It is well known that the effectiveness of any screening program depends not only on the diagnostic performance of the screening, but also on the uptake and general acceptance of the test by the public[23,24
]. In a field trial, urban-rural differences in the screening uptake were detected[25
]. Among some other issues, one of the important problems is to find how to improve uptake. There is clear evidence in our national program of early diagnosis of breast cancer, where we reached a 70% uptake level, that education of a focused population group can increase uptake[25
]. We must continue to improve awareness that screening for CRC can reduce the mortality associated with the disease. According to other studies, compliers with CRC screening are less deprived; they have higher education than non-compliers. There is also a need to advance knowledge and promote engagement of primary care physicians, according to other data[21
]. However, the Croatian Adult Health Survey showed that self-reported compliance for CRC screening was 4.5% for females and 6.1% for males included in study[26
]. It is obvious that the response in the National Screening Program was higher and it depended on the age group of the invited population and county. The results of a control field trial showed a significantly higher response rate to FOBT when given by primary care physicians[27
], but, unfortunately, in that study a small number of physicians was voluntarily included, precluding us from achieving conclusive results on the whole population. In addition, this experience cannot be easily implemented to the whole country due to organizational difficulties and presence or absence of willingness of physicians to be included in organized national screening. The results of a population study from Italy confirmed that there is a higher response if the FOBT kit was sent by mail, but in non-responders it incurred higher costs[28
]. Response to screening depends on population education but also on willingness of all included in the program, and it has to be carefully planned[29-34
]. We still do not have a detailed analysis of costs and possible differences if the test kit is not sent by mail, so this remains to be done for the next cycle.
There are some other reasons for nonparticipation which could be targeted in interventions aimed at increasing participation rates in Croatia. For example, it may be difficult to make arrangements for colonoscopy for people who live on islands and must travel to hospitals in the nearest city on the coast; they feel uncomfortable traveling by ferry while prepared for colonoscopy and must be near the toilet during that journey. Hence, in that case, it might be reasonable to provide a mobile colonoscopy service.
Another problem of CRC screening is people with false-positive FOBT results, who occupy time in colonoscopic units and represent unnecessary procedures. According to our data, most false positive FOBT persons (false-positive to CRC but not to bleeding) had hemorrhoids or anal fissures, which is consistent with the other data[35
]. This can be avoided with adequate education of the population and active inclusion of primary care physicians[36
Successful intervention strategies include organizational changes, such as providing reminders to healthcare providers or users about screening opportunities, better financial support and educational strategies to improve awareness and attitudes toward CRC screening[37,38
]. In our future work we also must think about reducing inequalities related to socio economic position and ethnicity in the uptake of screening (e.g., Roma population).
In conclusion, the main characteristics of the Croatian CRC National Program are as follows: low percentage of returned FOBTs, a relatively higher number of FOBT-positive persons, but still in the range for population-based program; and a higher number of pathologic findings (CRC at the upper range and polyps above the upper range)[39
There are many possible strengthening mechanisms for this activity, which include multifactorial interventions that target more than one level of the screening process and likely can have greater effects. Firstly, much effort must be given to population education and mass campaign with whole society inclusion.