Time requirements and health effects of participation in colorectal cancer screening with colonoscopy or computed tomography colonography in a randomized controlled trial

• Introduction
• Methods
• Study population
• Recruitment
• Examinations
• Diary
• Statistical analysis
• Sample size
• Results
• Time requirements
• Factors influencing time requirements
• Health status measurements
• Discussion
• References

Background and study aims: Time limitations and unwanted health effects may act as barriers to participation in colorectal cancer (CRC) screening. The aim of the study was to measure the time requirements and health effects of colonoscopy and computed tomography colonography (CTC) screening.

Patients and methods: This was a prospective diary study in a consecutive sample within a randomized controlled CRC screening trial, comparing primary colonoscopy and CTC screening for average-risk individuals aged 50 – 74 years. The diary ended when all screening-related complaints had passed.

Results: The diary was returned by 75 % (241/322) of colonoscopy and 75 % (127/170) of CTC screenees. The median interval between leaving home and returning from the examination was longer for colonoscopy (4 hours and 18 minutes [4:18], interquartile range [IQR] 3:30 – 5:00) than for CTC (2:30 hours, IQR 2:06 – 3:00; P < 0.001). Similarly, the time to return to routine activities was longer after colonoscopy (3:54 hours, IQR 1:48 – 15:00) than after CTC (1:36 hours, IQR 0:54 – 4:42). The duration of screening-related symptoms after the examination was shorter for colonoscopy (11:00 hours, IQR 2:54 – 20:00) than for CTC (22:00 hours; IQR 5:30 – 47:00; P < 0.001). Abdominal complaints were reported more frequently after CTC. Anxiety, pain, and quality of life worsened during the screening process, with no differences between the two examinations.

Conclusions: Compared with colonoscopy, CTC screening required less time and allowed screenees to return to their daily activities more quickly. In contrast, CTC was associated with a twofold longer duration of screening-related symptoms. Feelings of anxiety, pain, and quality of life scores were similar during colonoscopy and CTC screening. These results should be incorporated into cost-effectiveness analyses of CRC screening techniques.

Introduction

Colorectal cancer (CRC) is the third most prevalent cancer in males and the second in females, with an estimated worldwide incidence of 1.2 million and 608 700 deaths in 2008 [1]. Screening reduces CRC mortality by early detection of CRC and endoscopic removal of premalignant precursors of CRC [2] [3] [4] [5] [6].

Colonoscopy and computed tomography colonography (CTC) are screening methods that allow visualization of the entire colon, and both have high sensitivities for CRC [7]. The main advantages of colonoscopy include the possibility of direct removal of lesions and the low frequency of screening required. One of the main disadvantages is the required bowel preparation prior to the procedure, which is often identified as the most burdensome aspect of the entire screening procedure [8] [9] [10]. CTC has more recently been introduced as a screening alternative, and is already recommended as a screening tool in one of the main American guidelines for CRC screening [11]. CTC has important advantages, such as its minimally invasive character and the possibility of limited bowel preparation [12]. Furthermore, the fact that CTC can be performed quickly and without the need for sedation and hence time to recover, has been mentioned as one of the aspects that makes CTC screening attractive [13]. However, findings on CTC do require follow-up by colonoscopy.

The time required by individuals to participate in screening may be a barrier to undergoing screening [14] [15] [16] [17]. Measuring time requirements can contribute to quality control by providing information about practice efficiency [18]. Furthermore, participants’ time requirements are important for an adequate evaluation of the cost-effectiveness of screening alternatives [19], and several guidelines recommend inclusion of patient time costs in cost-effectiveness analyses [20] [21]. For CTC, patient time costs have already been included in cost-effectiveness analyses, but these time requirements were based on assumptions due to a lack of data [22].

The aim of the current study was to determine the time required for participation in a CRC screening program using primary colonoscopy and CTC. As CRC screening involves the participation of healthy individuals, quality of life (QOL) during the screening process is an important factor to consider when evaluating screening alternatives. Therefore, the study also evaluated short-term QOL and health complaints before, during, and after screening.

Methods

Study population

Participants already enrolled in the COCOS-trial (Colonoscopy or CT-COlonography for Screening) [23], which has been described in detail elsewhere [24], were included in the current analysis. This diary study was decided upon prior to initiation of the main study. In brief, 8844 average-risk individuals aged 50 – 74 years from the Amsterdam and Rijnmond region were randomly selected from the regional municipal administration registrations. They were randomized 1:1:1 and invited to participate in colonoscopy with either a pre-screening consultation in the outpatient clinic (OPC) or with a pre-screening consultation by telephone, or to undergo CTC screening with a pre-screening consultation by telephone. For clarity, the two colonoscopy arms (pre-screening consultation in the OPC and pre-screening consultation by telephone) were merged after testing for differences in baseline characteristics and the time requirements reported in this paper (no significant differences were present). Randomization was done per household (individuals within the same household were invited for the same modality) and stratified for age, sex, and socioeconomic status.

Individuals with CRC symptoms in the previous 3 months (rectal blood loss and/or changed bowel habits) were advised not to participate and instead to contact their general practitioner. Exclusion criteria included a full colonic examination in the previous 5 years (complete colonoscopy, CTC, and/or double contrast barium enema), being scheduled for surveillance colonoscopy (given personal history of CRC, colonic adenomas or inflammatory bowel disease), and a life-expectancy of less than 5 years. Additionally, for CTC, individuals who were pregnant, exposed to ionizing radiation for research purposes within the previous 12 months, and any individuals with hyperthyroidism or iodine contrast allergy were excluded.

All participating individuals received an information brochure with the invitation, containing information on the CRC screening program in general, benefits and risks (see Appendix 1, available online) of the screening examination, and follow-up in case of a positive result.

Ethical approval for the trial was obtained from the Dutch Health Council (2009 /03WBO, The Hague, The Netherlands). The trial is registered in the Dutch Trial Register: NTR1829 (http://www.trialregister.nl).

Recruitment

Between 16 February 2010 and 27 May 2010, all consecutive trial participants were invited to this study on time investment at the end of the pre-screening consultation. Individuals unable to read and/or speak the Dutch language were excluded. Participants who provided informed consent were asked to complete a time diary, starting the day before the preparation for the examination and ending when they felt completely back to normal.

Consenting participants in the OPC group received information about the study and the diary during the consultation from the physician. Individuals in the telephone consultation groups received the documents by mail. Colonoscopy and CTC were scheduled within 4 weeks, unless participants wanted to be screened at a later time.

For the present analysis, the OPC and telephone consultation groups for colonoscopy were combined, as exploratory analyses revealed no relevant differences.

Examinations

Preparation for colonoscopy consisted of drinking a total of 2 L of polyethylene electrolyte glycol solution (Moviprep; Norgine bv, Amsterdam, The Netherlands) and 2 L transparent fluid as a split dose equally divided over the day before and the day of the examination. Intravenous midazolam and fentanyl were administered if desired. Antispasmodic medication was administered at the discretion of the endoscopist. All colonoscopies were performed by experienced endoscopists (≥ 1000 colonoscopies).

CTC preparation consisted of two 50-mL doses of iodinated contrast agent (Telebrix, Geurbet, Aulnay sous Bois, France) on the day prior to CTC (starting at lunchtime) and 50 mL 1.5 hours before the examination. Colonic distension was achieved with CO₂ insufflation after intravenous administration of 1 mL butylscopolamine or (when contraindicated) 1 mg of glucagonhydrochloride intravenously. All CTC examinations were performed by experienced personnel.

Diary

Participants were asked to maintain a diary at several time points, from starting the preparation until they felt completely normal again (see Appendix 2 and Appendix 3, available online). The time of commencement and conclusion of the examination, and the time the participant left the recovery unit were recorded by staff. All other measurements were completed by the participants themselves. The diary included a health status measurement at five different time points (the day before the start of preparation, i. e. 2 days before the examination; the morning before the examination; the evening of the examination; the day after the examination; and up until the moment of feeling completely normal again). The health status measurement included general health on a five point Likert scale (excellent, very good, good, fair, and poor), a visual analog scale (0 – 10) for both QOL and pain, the anxiety instrument STAI-6, and a registration of health complaints. The STAI-6 assesses general anxiety; it is a validated short version of the State Trait Anxiety Inventory and contains six items such as feeling at ease or upset. Higher scores (20 – 80) indicate higher levels of generic anxiety [25] [26], with a score of over 44 defining an individual as highly anxious [27]. The diary also included questions on background variables and method of transportation. When completed, the diary was mailed to the study coordinator in a self-addressed, postage-paid envelope.

A pilot study (n = 10) was conducted to ascertain whether respondents could manage the length of the diary and to examine its intelligibility and acceptability.

Statistical analysis

The main outcome measures were differences in time intervals between individuals undergoing colonoscopy and those undergoing CTC. Time intervals were described by median and interquartile range (IQR). No attempt was made to impute missing values, as time spent was dependent on multiple factors, which we believed could not be adequately corrected for with imputation models. Differences in time intervals between both groups were assessed using Mann-Whitney U-tests. Linear regression analysis was performed to assess the relationship between time requirements and several pre-defined factors, based on reasoning and the literature [18]: sex, age (continuous), employment status (paid work “yes/no”), method of transportation, couple (“yes/no”), and general health (baseline measurement). As randomization was done per household and couples frequently requested same-day examinations, the differences between screenees who were part of a couple when both partners were participating and those with no participating partner were tested (couple “yes/no”). For the interval from the end of the examination until feeling normal again, the reported health complaints on the day after the examination (abdominal complaints, nausea, tiredness, headache, pain, QOL, STAI-6) were added to the model as possible explanatory factors.

For all health status measurements a Generalized Estimating Equations Model [28] was used, which included sex and age, and adjusted for baseline factors to ensure that the health status measurements were not influenced by baseline differences. An interaction term between test and time moment was also included to evaluate whether there were differences in the course of complaints between colonoscopy and CTC.

Statistical significance was defined as a two-sided P value < 0.05. Statistical analyses were performed using SPSS PASW, version 18 (SPSS Inc., Chicago, Illinois, USA).

Sample size

This study was a sub-study within an randomized controlled trial (RCT). The sample size was calculated for the primary aim of the RCT. A formal sample size calculation for the current diary study was difficult as no data were available on time requirements for CTC. A previous study investigated screenees’ time requirements for colonoscopy, and the sample size (n = 110) in that study was sufficient to show differences in time requirements between subgroups [18]. These results motivated the sample size chosen for the current diary study. Alternatively, the sample size could be calculated formally, using default alpha (5 %) and beta (20 %) settings: an effect size of at least 0.4 SD (Cohen’s d) with 80 % power would require a sample size of at least 100 individuals per arm.

The aim was to include 130 individuals per arm, to guarantee enough analyzable data, assuming that some diaries would be completed erroneously. Based on the power analysis, not all of the 2258 participants of the RCT were approached [23], instead a consecutive sample of at least 130 subjects was invited for each group. The sample was a consecutive sample to minimize selection bias.

Results

Overall, 241 /322 (75 %) of eligible colonoscopy and 127/170 (75 %) of eligible CTC screenees returned their diaries ([Fig. 1]). There was a greater number of colonoscopy screenees due to the merging of both colonoscopy arms (see Methods section). The sample was 50 % male, mostly of Dutch ethnicity (98 %), and about 50 % of participants were currently employed. Baseline characteristics of both groups were similar ([Table 1]), except that more colonoscopy screenees were part of a couple where both partners participated.

Of colonoscopy screenees, 210 (88 %) received premedication; 17 (7 %) fentanyl and 193 (80 %) fentanyl and midazolam. The dose of midazolam was 2.5 – 5 mg in 93 % of cases, and the dose of fentanyl was 0.05 mg in 92 %. Butylscopolamine was administered to 50 % of colonoscopy screenees. For CTC, butylscopolamine was administered in 61 % and glucagonhydrochloride in 38 %; sedation was not administered.

Time requirements

There were five implausible extreme values regarding the interval from starting the preparation until leaving home (≥ 48 hours), and two in the time from leaving the recovery (colonoscopy)/end of examination (CTC) until arriving back home (≥ 4 hours; these individuals indicated that they first went to work after the examination, and they erroneously included this time in travel time until arriving home). These extreme values were excluded.

The median time requirements for the different aspects of colonoscopy and CTC screening are presented in [Table 2]. The median time between leaving home for the examination and returning to routine activities was 6 hours (IQR 4 – 17 hours) for colonoscopy and 3 hours (IQR 2 – 6 hours) for CTC. The median total time invested in the screening process, from starting the preparation until feeling back to normal was significantly shorter for colonoscopy (35 hours, IQR 22 – 39) compared with CTC (43 hours, IQR 26 – 67; P < 0.001).

Factors influencing time requirements

The variables influencing the time requirements are shown in [Table 3]. The duration between the end of the examination and feeling completely normal again was only related to the presence of abdominal complaints on the day after the examination (with the health status measurements on the day after the examination added to the model as explanatory variables): for those with abdominal complaints, median 35 hours (IQR 17 – 69 hours), and for those without complaints, 9 hours (IQR 3 – 20 hours; P < 0.001).

Health status measurements

Abdominal complaints were reported on at least one time point by 52 % of colonoscopy screenees compared with 85 % of CTC screenees (P < 0.001), tiredness by 30 % and 34 % (P = 0.40), headache by 27 % and 20 % (P = 0.20), and nausea by 21 % and 18 % (P = 0.60), respectively ([Fig. 2]). Taking into account baseline factors, abdominal complaints were reported more frequently during the screening process by CTC screenees (P < 0.001), with no differences regarding other health complaints or experienced pain. Overall, there were no differences in QOL scores between colonoscopy and CTC screenees (P = 0.85). For both groups combined, the QOL was significantly reduced on the evening of the examination compared with the baseline measurement (P < 0.001). When feeling completely normal again, QOL was significantly increased compared with the baseline measurement (P < 0.01). Anxiety scores were somewhat lower for colonoscopy than for CTC screenees (30 and 31 respectively; P = 0.04), and were significantly reduced for both tests when feeling completely normal again compared with baseline.

Discussion

This study investigated the time required for and the effects on experienced health of primary colonoscopy and CTC screening, within a population-based randomized controlled screening trial. The time between leaving home for the examination until returning to routine activities was significantly shorter for CTC than for colonoscopy. The time it took to feel completely normal again was considerably longer following CTC than after colonoscopy. With the exception of abdominal complaints, which were reported more frequently by CTC screenees, there were few differences in experienced health between the two screening groups.

The study has several strengths. The study recruited consecutive screenees within a randomized controlled screening trial, thereby minimizing selection bias. Furthermore, the screening-naïve individuals were directly selected from the population registry without any pre-selection criteria, making the results representative for the Dutch population. The response rate to the diary was high (75 % in both groups).

The study also has some limitations. First, participation in colonoscopy in the screening trial was lower than participation in CTC screening (22 % vs. 34 %) [23], which may have influenced the results. A significantly larger proportion of CTC than colonoscopy participants reported abdominal complaints (4 % vs. 17 %) on the baseline measurement. Although this difference was corrected for by applying a generalized estimating equations model, this finding may suggest that individuals who are familiar with abdominal complaints may be more inclined to participate in CTC screening than in colonoscopy screening, therefore resulting in a selection bias. Furthermore, the phrase “feeling completely normal again” is subject to expectations about the procedure and therefore introduces subjectivity to the results. Individuals may interpret “completely back to normal” differently, as confirmed by the finding that some measurements had not returned to baseline values when individuals indicated that they were feeling completely normal again. We feel it is unlikely that this fully explains the differences between both groups, as the diaries of colonoscopy and CTC screenees were identical on this point. The pilot study revealed no difficulties regarding this matter. The results may not be unconditionally generalizable to patients undergoing colonoscopy or CTC outside the context of screening; for example, due to the fact that many couples participated, the time spent in the screening unit was likely overestimated as individuals waited for their partners. Finally, the time required for colonoscopic follow-up of a positive test result on CTC was not measured. This may be different from a primary screening colonoscopy due, for example, to logistical differences.

To our knowledge, this is the first study to directly compare the time requirements and the health experienced during colonoscopy and CTC for CRC screening. A previous study from the USA that investigated time requirements for screening colonoscopy only, found that the median time between starting the preparation and feeling completely normal again was 40 hours compared with 35 hours in the current study [18]. The interval before returning to routine activities (16 hours after arriving back home) also seems longer than the interval in the current study. The interval between returning to routine activities and feeling normal again was much shorter in the American study. The studies used exactly the same definition of returning to routine activities and feeling completely normal again, so it is unclear how this difference may be explained. There might be differences in the time schedule for starting the preparation, explaining the difference in total time. Two Canadian studies, with a focus on nonmedical costs of CRC screening [29] [30] found a somewhat shorter travel time, and a longer time spent in the clinic for colonoscopy and CTC compared with the current findings. However, the method of data collection and exact time points recorded differed between the studies.

In the current study the duration to feeling completely normal again was unexpectedly longer for CTC screenees. When looking further at factors that may explain this difference, a multivariable analysis found the presence of abdominal complaints on the day after the examination to be significantly related to the time it took to feel normal again. This might be due to the bowel preparation used; Telebrix is a non-cathartic iodine-based bowel preparation, and several CTC screenees reported having diarrhea for several days after the examination. A previous study reported that nearly all CTC screenees reported diarrhea after using non-cathartic iodine-based bowel preparation [12]. So, the time before feeling completely normal again may be longer mainly due to the abdominal complaints caused by the preparation for CTC. Non-cathartic bowel preparation is a relatively new and promising alternative to the currently used cathartic bowel preparations, although it is not currently recommended as there is no evidence from direct comparative studies regarding diagnostic accuracy [23] [31]. For future research, it would be interesting to compare the influence of both preparations on the duration of abdominal complaints after CTC, as this may be an important aspect in determining the time required to feel completely normal again.

The finding that CTC screenees returned to their daily activities sooner is especially relevant for the comparative cost-effectiveness of colonoscopy and CTC, as a loss of productivity will be relevant in economic evaluations of screening strategies.

Screenees participating simultaneously with their partner spent more time in the hospital prior to the examination, and before returning home at the end of the examination. This may be explained by the fact that 75 % of all couples had a same-day examination. One might expect that in a nationwide population screening program, couples will also make same-day appointments.

As CRC screening involves the participation of healthy individuals, a possible loss of QOL induced by screening examinations may influence decisions about screening strategies. In the current study, QOL was reduced only on the evening of the examination, after which it returned to levels above that of baseline values. Furthermore, anxiety scores were significantly improved compared with baseline. This may be explained by the reassurance felt after participation, resulting in improved QOL and reduced anxiety. The change in anxiety may also partly be explained by the fact that the baseline measurement was on the day before the start of the preparation, at which point the prospect of participation may have already influenced anxiety levels.

In summary, this study showed that both colonoscopy and CTC screening require considerable time investment from participants. Time before returning to routine was shorter for CTC than for colonoscopy, but the time required to feel completely normal again was longer for CTC screening participants. Except for abdominal complaints, there were few differences between colonoscopy and CTC screenees with respect to several aspects of experienced health during participation.

Competing interests: None.

Acknowledgments

The authors would like to thank Lucille Maarschalkerweerd for language correction of this article. The authors acknowledge Hans ‘t Mannetje, Jacqueline Reijerink, research nurses Caroline van Bavel, Monique van Dijk, Laurens Groenendijk, Karin de Groot, Esther van Huissteden, and Lucille Maarschalkerweerd for their support, and Caspar Looman for statistical advice.

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Corresponding author

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