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Cochrane Database of Systematic Reviews Protocol - Intervention

Interventions for improving uptake of population‐based screening for colorectal cancer using fecal occult blood testing

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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

The objectives of this review are:

1. To assess the effectiveness of interventions designed to improve the uptake of an initial (first‐time) FOBT by those regarded to be at average risk of colorectal cancer.

2. To assess the effectiveness of interventions undertaken to improve adherence to repeat (serial) FOBT screening by those regarded to be at average risk of colorectal cancer.

The term "average risk" applies to persons without a predisposition to the disease, whose only risk factor is that their age is greater than 50 years.

Background

Colorectal cancer (CRC) is one of the three most common cancers in Europe, North America, Northern Africa, Western Asia, South Eastern Asia and Australia ( WHO 2003a) In the United States, in 2003 it was predicted to account for 10% of all cancer‐related deaths (ACS 2003, quoted in Chorost 2004). In the European Union, in 1995 CRC accounted for 13% of new cancer cases (ACCP 2000). In Australia, in 1990 CRC was responsible for 14% of cancer deaths (NHMRC 1999) and is the most frequently occurring cancer for new cases (AIHW 2003). Most CRCs are believed to evolve from adenomatous polyps (pre‐cancerous, visible protrusions that can develop on the mucosal surface of the colon or rectum), although most polyps do not evolve into cancer. Bowel cancer is rare in people under the age of 50, and the risk increases with age. In Australia, there is currently a 1 in 17 lifetime risk for males of being diagnosed with colorectal cancer by the age of 75 years and a 1 in 26 risk for females (AIHW 2003).

At the primary prevention level, it is believed that eating a healthy diet and exercising regularly could prevent 66‐75% of bowel cancer cases (Anonymous 2002). Unfortunately, strategies to address such risk factors as physical inactivity, overweight and consumption of foods that are high in saturated fat and/or low in fibre, require a great deal of concerted, coordinated effort, extending to the global level (WHO 2003a). Even so, It is not certain that individual risk reduction through such lifestyle modifications would ensue, and they may not be sufficiently effective as an approach to disease control (Levin 2002). In addition, some predisposing factors for colorectal cancer cannot be changed. They include older age, family history of CRC, individual history of CRC or polyps, certain hereditary conditions and inflammatory bowel disease (Gazelle 2000). However, the majority of CRCs are diagnosed in asymptomatic people whose only risk factor is age, who therefore could be considered as being at average risk (Barry 2002).

CRC is highly curable if it is diagnosed early, because it has a long pre‐clinical phase that allows detection by screening before it becomes surgically incurable (Chorost 2004). Data from South Australia show that the 5‐year survival rate is 88% for Stage A (localised disease) compared to only 7% for Stage D (distant metastases), which equates with international experience (NHMRC 1999). Screening is recommended for those of 50 years and older because the incidence of CRC begins to rise between 40 and 50 years of age. Screening guidelines vary with the method used‐for fecal occult blood testing, screening is recommended at least biennially, and preferably annually (ACCP 2000; Winawer 2003).

Fecal Occult Blood Testing (FOBT) is the most commonly used screening modality in the United States (Ransohoff 2002) and has been the focus of national bowel screening program pilots in Australia and the UK (AIHW 2003; UK CRC Pilot 2003). FOBT screening can be regarded as "a sequence of risk refinement leading to a final decision as to whether or not one should undertake the definitive diagnostic test" (NHMRC 1999). FOBT detects blood in the stool and is useful because cancers and adenomatous polyps bleed more than normal (it has been estimated that around two thirds of colon cancers bleed in the course of a week) (Chorost 2004). To date, two types of FOBT are available ‐ guaiac tests (rehydrated and non‐rehydrated) and immunochemical tests. Guaiac tests are based upon the psuedoperoxidase activity of haem. Immunochemical tests utilise antibodies against human haemoglobin. A positive result indicates the need for a diagnostic examination such as a sigmoidoscopy or colonoscopy.

However, universal consensus does not exist for the choice of FOBT as a screening programme tool (Autier 2002). Concerns exist about the sensitivity (the effectiveness of a test in detecting a cancer in those who have the disease) and specificity (the extent to which a test gives negative results in those that are free of the disease) of FOBT screening. Reported sensitivity for the detection of cancer ranges from around 40% to 90%, but only from 10% to 25% for the detection of polyps. The specificity of FOBT ranges from around 90% to 98%, depending on the type of test, (whether rehydrated or non‐rehydrated) (Gazelle 2000). This means that up to 10% of patients who undergo FOBT screening will have a false‐positive result. This propensity need not necessarily be regarded as a negative; it has been suggested that the high incidence of false‐positive results contribute towards the effectiveness of FOBT screening (Gazelle 2000). Indeed, Australian clinical practice guidelines stress that individuals should be told that it is not a diagnostic test, but a "selection process for those who should undergo colonoscopy" (NHMRC 1999). A problem arising from this approach is that those individuals with a false positive result may undergo needless anxiety, as well as the discomfort, cost and risk of colonoscopy.

Despite these limitations, FOBT screening is the safest and least expensive of the currently available screening tests (Chorost 2004; Gazelle 2000). The results of randomised trials of FOBT screening have indicated a reduction in mortality of 23% in the population that were actually screened, as well as a favourable shift in the stage distribution of colorectal cancers in the screening groups (Towler 1998). FOBT trials suggest that, after an interval of about 10 years, there could be a reduction of up to 20% in CRC mortality from biennial screening and even more from annual screening (WHO 2003b). However, these projections depend on high uptake and adherence to regular screening.

Unfortunately, initial uptake and continuing adherence to annual FOBT screening is low (Vernon 1997). A national survey undertaken in the United States in 2001 found that only 23.5% of those over 50 years had a FOBT within one year (Seeff 2003). A population uptake of less than 20% was achieved in Japan in 1998, and in Germany FOBT compliance, after a screening programme of 25 years, was only 20% for men and 30% for women (Baker 2004). Screening uptake tends to be even lower in minority groups; a survey conducted in California in 2001 found that Hispanics, Asians, and Native Hawaiians are less likely to be screened than whites or African Americans, even after adjusting for sociodemographic factors (Ponce 2003). The same survey also found that women as a population group were screened less frequently than men. A recent review examining factors affecting the utilisation of CRC screening tests (not just FOBT) in the United States concluded that fear of finding cancer and the belief that cancer is fatal results in low adherence, while a positive attitude toward screening and physician recommendation results in high adherence (Subramanian 2004). Other factors reported to be associated with reduced utilisation of FOBT include fear of pain, embarrassment, distaste, lack of perceived need, fear of the results, fatalism (belief that nothing can be done) and feeling well (Baker 2004; Rex 2002).

Intervention strategies can employ a number of "social cognitive" models which have proven effective in describing individual motivation to perform a variety of health behaviours by identifying a range of attitudinal predictors. These include the Health Belief Model (Rosenstock 1974), Protection Motivation Theory (Rogers 1975), and the Theory of Planned Behaviour (Ajzen 1991). These models can successfully map variables that describe individual differences in the intention to perform a behaviour. However, the relationship between behavioural intention and actual behaviour is less than perfect (Sheppard 1988).

There is a clear need for a deeper understanding of what are effective strategies to promote increased uptake of FOBT screening, bearing in mind that one of the most common reasons given for not having a recent colorectal screening test is the absence of any current health problems (Ponce 2003). Differences in FOBT uptake may also exist between gender, ethnic and socio‐economic groups. As an additional complication, those who choose to have an initial FOBT may not necessarily choose to adhere to repeat screenings (Craven 2001). Therefore, approaches to promote long‐term CRC screening change may differ from those required to promote the uptake of screening.

Objectives

The objectives of this review are:

1. To assess the effectiveness of interventions designed to improve the uptake of an initial (first‐time) FOBT by those regarded to be at average risk of colorectal cancer.

2. To assess the effectiveness of interventions undertaken to improve adherence to repeat (serial) FOBT screening by those regarded to be at average risk of colorectal cancer.

The term "average risk" applies to persons without a predisposition to the disease, whose only risk factor is that their age is greater than 50 years.

Methods

Criteria for considering studies for this review

Types of studies

All prospective studies evaluating the effectiveness of an intervention designed to increase FOBT screening use are eligible for inclusion if they include a control group. Thus, studies can encompass randomised controlled trials (RCTs), cluster RCTs, quasi‐RCTs (for example, using pseudo randomisation such as alternation or date of birth), and controlled trials (non‐randomised cohorts, pre‐post studies with concurrent controls and one group pre/post intervention). The control group comparison can be no intervention or another type of intervention. Studies can be in any language, although inclusion of non‐English language studies will depend upon resources available for translation.

Studies that seek only to measure informed uptake or the psychological impact of screening, or intention to undertake screening, will be excluded. However, where these studies include uptake of screening as a secondary outcome they will be included. Studies employing compulsory FOBT screening (for example in prisons or mental institutions) will be excluded. Review articles will be retrieved and examined for possible relevant studies.

Types of participants

All those individuals or groups eligible to participate in a voluntary FOBT screening programme as defined by the entry criteria for that programme. Participants should be at average risk of colorectal cancer.

Types of interventions

Interventions can be any individual, group or population strategies directed towards the public or health professionals or both, that aim to increase the uptake of FOBT screening. Certain specific interventions will not be included as they are the subject of separate Cochrane protocols or reviews. These are informed decision making (Broclain 2004), counselling (Doust 2004), and personalised risk‐factor assessment (Edwards 2004). Screening can be universal (when the entire population is the target) or opportunistic (when physicians propose or patients ask for a screening test in ordinary consultations).

All other interventions will be classified in the same manner as that employed by (Jepson 2000) in the preparation of their systematic review of interventions for increasing screening uptake. Specifically, these will be:

Interventions aimed at individuals

Invitations
Invitations to people eligible for screening (either first round or subsequent round). Does not include people who are overdue for screening. Includes fixed or open appointments, letters, telephone calls, verbal recommendations, prompts and follow‐up letters.

Reminders
Reminders to people who are overdue for screening and have not responded to the first round of screening. Includes fixed or open appointments, letters, telephone calls, verbal recommendations, prompts and follow‐up letters.

Education
Educational interventions aiming to increase knowledge of the screening programme or the disease being screened for. Does not contain a counselling component. Includes printed educational materials, audio visual materials, group and individual teaching, and home visits.

Procedures
Interventions to increase screening uptake by making the screening procedure easier or more acceptable to individuals undergoing screening. Includes varying diets, method of specimen collection, method of specimen delivery for analysis, opportunistic testing.

Economic
Removal of financial barriers or economic incentives. Includes reduced or free screening tests, transport costs, free postage for returning tests and 'rewards' for completion of a screening test.

Community interventions
Interventions aimed at whole communities. Often involve multiple interventions. Includes mass media campaigns, community participation, workplace programmes.

Interventions aimed at physicians or other healthcare workers

Reminders
Reminders to physicians to prompt or encourage individuals to undergo screening. Includes chart reminders, forms, computer‐generated reminders and lists of overdue patients.

Education
Continuing medical education. Includes seminars, workshops and meetings.

Office systems
Assistance to physicians from facilitators in design and implementation of office routines and tools.

Audit and feedback
Audit and feedback to physicians on their performance, and sometimes that of their peers.

Studies will be subject to sub‐group analysis based on the above list of interventions. Only studies with one or more of these interventions will be included in the review.

Types of outcome measures

  • Initial screening uptake or non‐uptake of FOBT as recorded by health service records or self report

  • Adherence to a first repeat FOBT screening following no indication for further investigation at initial screening, as recorded by health service records or self report.

  • Continuous adherence to long term programs which include a number of annual or biennial screening rounds, as recorded by health service records or self report.

The psychological impact of FOBT screening will not constitute a formal outcome measure as this topic is the subject of a separate protocol (Doust 2004). However, where this outcome is reported upon it will be recorded.

Search methods for identification of studies

Relevant studies published after 1971, the year it was demonstrated that detection of occult rectal bleeding by means of a guaiac‐based chemical slide test could uncover subclinical bowel disease (Greegor 1971) will be sought. Conference abstracts (either published or presented at scientific meetings) will also be searched. Leading researchers in the field will be contacted and asked if they are aware of any relevant articles or studies that should be included in the review.

PubMed, EMBASE, Cancerlit, ISI Current Contents, ISI Web Of Science, PsycInfo, Cochrane database of systematic reviews, and ISI Proceedings will be searched for relevant studies, as well as the Specialised Trials Register of the Cochrane Colorectal Cancer Group. Additionally, bibliographies of related protocols and reviews will be examined for relevant studies. The Pubmed search strategy will be as follows:

(colorectal neoplasms/ OR colorectal cancer OR colon cancer OR CRC OR bowel cancer OR colorectal carcinoma OR colorectal neoplasia) combined with
(occult blood/ OR fobt OR fecal occult blood test* OR faecal occult blood test*) AND
(mass screening/ OR screening OR surveillance OR screening behavio* OR population screening OR screening program*) combined with
(intervention* OR letter OR mail* OR phone OR telephone OR reminder system* OR videotape recording* OR questionnaire* OR strateg* OR alert* OR hotline OR community OR media OR education* OR campaign*) combined with
(uptake OR complian* OR particip* OR adher* OR patient‐compliance/ OR patient acceptance of health care/ OR utilisation OR utilization OR attend* OR incidence OR prevalence OR prevelence OR satisfaction OR cooperat* OR behavio*)

Data collection and analysis

The review will be undertaken by four reviewers (I Flight, C Wilson, L Griffiths, R Myers), one of whom (RM) has conducted cancer prevention, control, and population science research for over 18 years. The search strategy previously described will be used by LG to obtain titles and abstracts of studies that are potentially relevant to the review. She will discard studies that are clearly ineligible but will aim to be overly inclusive rather than risk losing relevant studies. Where there is insufficient information to determine relevance, full paper copies of articles will be obtained (LG) and examined. A random sample (5%) of included and excluded papers will be checked by IF. Full copies of relevant papers will be obtained (LG).

Complete copies of papers will be independently screened by IF and CW, who will assess whether the studies meet the inclusion criteria, with disagreements to be resolved by discussion with the fourth reviewer (RM).

Data extraction will be performed by IF and the completed data extraction forms will be double‐checked against the original paper by CW. The quality of all studies which are deemed eligible for the review will then be independently assessed by IF and CW against quality criteria. Any discrepancies will be resolved by discussion between the reviewers. Methodological and quality assessment will be modelled upon the tool developed by the Canadian Effective Public Health Practice Project (Anonymous 2004), because it provides the capability to assess other types of trial designs in addition to randomised or quasi‐randomised controlled trials. Content and construct validity for this tool have been established (as reported by Ellis 2003), and it has been recommended as being suitable for use in a systematic review (Deeks 2003). Briefly, the following questions will be addressed:

  • Are the individuals selected to participate in the study likely to be representative of the target population?

  • Is assignment to intervention groups random?

  • If described as random, was assignment truly random (allocation concealment)?

  • Are those assessing outcomes blind to the intervention allocation?

  • Are the control and intervention groups comparable at entry?

  • Were the data collection tools shown to be valid and reliable?

  • Is relatively complete follow‐up achieved?

  • Are the outcomes of those who withdrew described and included in the analysis?

  • Is there adequate outcome measurement (verifiable data versus self‐report)?

  • Is the analysis appropriate (eg cluster randomisation taken into account in the analysis)?

For each included trial, information will be collected regarding the location of the study, methods of the study (as per the quality assessment criteria), the participants, the nature of the interventions, and data relating to the outcomes specified above. If an intervention is stated by the researchers as being based on a particular behavioural model, this information will be recorded. Where possible, missing data will be sought from the authors.

Statistical analyses will be performed for controlled trials described as being randomised (using relative risks (RR) as the measure of effect for each outcome) and for non‐randomised controlled trials (using rate difference as the measure of effect for each outcome). Initial, first repeat and continuous adherence to screening will each be treated as a dichotomous outcome for individuals. Where there are sufficient data, a summary statistic for each outcome will be calculated using a Random Effects model. Heterogeneity in the data will be noted and cautiously explored using previously identified characteristics of the study, particularly assessments of quality. Detailed sensitivity analyses will be undertaken to examine the stability of the results in relation to a number of factors including study quality, source of the data (published or unpublished) and publication bias (using a funnel plot‐based method, Duval 2000) . FOBT uptake as measured by medical records and self‐reported uptake will also be subjected to sensitivity analysis. (Whereas some researchers have found that self‐reports of colon cancer screening can be reliably used as end points for intervention trials when carefully phrased questions are asked (Baier 2000), others have found that that the specificity of self‐reports (those who correctly reported having had the test and who could be shown to have actually had the test as indicated by medical records) is relatively low (Gordon 1993).

Subgroup analysis will also be considered on gender, ethnicity, and socio‐economic status.