| Background and aimSmall-bowel capsule endoscopy(CE) has been accepted as one of the most valuable diagnostic procedures for lesions in the small intestine, especially for Crohn’s disease(CD) and obscure gastrointestinal(GI) bleeding. The capability of lesion detection is not only used for comparing CE with other approaches but also for evaluating the superiority among different CEs. Globally, five CEs, including PillCam SB, EndoCapsule, MiroCam, CapsoCam and OMOM respectively, are available.The size, weight, capture rate, field of view and other technical characteristics may vary in different CEs, which may also result in different lesion detection rate, gastric transit time(GTT), small-bowel transit time(SBTT) or completion rate(CR). Therefore, it is necessary to compare different CEs.Most of the comparative researches focus on the first four CEs(PillCam SB, EndoCapsule, MiroCam and CapsoCam). As PillCam SB has been widely assessed, newly developed CE would often be compared with it. Diagnostic yield was the predominant outcome measurement while some studies also compared CR or image quality among the different CEs. Results of prospective randomized comparisons showed comparable efficiency of the MiroCam and PillCam SB. Cave DR et al indicated that without electromechanical interference between the two different capsules, both PillCam SB and EndoCapsule were safe and had a comparable diagnostic yield and there was a subjective difference in image quality favoring the EndoCapsule in patients with obscure GI bleeding. Hartmann D et al demonstrated that no statistically differences existed between EndoCapsule and PillCam SB in detecting bleeding sources in patients with suspected small bowel bleeding although there was trend which may have been due to the longer operation time of EndoCapsule. The randomized head-to-head study by Dolak W et al showed that MiroCam and EndoCapsule were not statistically different with regard to rates of complete small-bowel examinations or diagnostic yield in patients presenting with obscure GI bleeding, chronic diarrhea, and anemia of unknown origin. Pioche M et al demonstrated that CapsoCam and PillCam SB2 capsule systems had comparable efficiency in terms of diagnostic yield and image quality. Few compared OMOM with the other CEs.In fact, much differences of the size, weight, capture rate, field of view and other technical characteristics exist in OMOM and MiroCam. The OMOM capsule measures 13mm*27.9mm, weighs 6g, has a field of view of 140 degrees, takes 2 images per second(variable), and has an operation time of more than 8 hours while the above technical characteristics of MiroCam is 10.8mm*24mm,3.4g,170 degrees, 3 images per second and about 12 hours respectively. The image sensors are also different:charge-coupled device(CCD) for OMOM and complementary metal oxide semiconductor(CMOS) for MiroCam. The image transmission system of the OMOM capsule is radiofrequency. Instead, MiroCam uses electric field propagation, which transmitting the image data from the capsule to the receiver by using the human body as a communication medium to transmit electric signals and consuming much less power. Whether the differences in all the technical characteristics above would lead to difference of lesion detection rate between OMOM and MiroCam is still not known and related researches are few.Moreover, it is anticipated to complete the examination of whole small bowel within its limited battery life to achieve a reliable result. However, previous studies showed that about 20% of examinations failed to reach the cecum and the proportion of incomplete examinations is approximately 10% even when the operation time of CE has been extended to 12 hours. Efforts, such as CE placement by gastroscopy, right lateral position and utility of prokinetics, have been taken in an attempt to improve CR. However, it should be noted that most of the measures taken focus on the patients, which brings much inconvenience to both physicians and patients, weakening the advantage of CE being a simple, painless, well tolerated and noninvasive approach. With the development of new CE with longer battery life, CR could be potentially increased, but procedure time and the time required to browse the images is simultaneously prolonged. It is inappropriate to let the time for CE procedure be too long. Therefore, it still makes sense to assess the factors influencing the GTT, SBTT and CR of CE. Studies on the factors associated with the CE itself have rarely been done. Given the fact that advance of capsule endoscope is largely dependent on the peristalsis of digestive tract and with the advancement of technology, both the size and weight of CE may be decreased, whether the change in the size and weight has any effect on GTT, SBTT or CR is still not known.The aim is to conduct comprehensive comparisons between two CEs(OMOM and MiroCam) with differences in the size, weight, capture rate, field of view to investigate whether the lesion detection rate, GTT, SBTT or CR is different between them and the possible reasons.Materials and methodsPatient inclusion and exclusion criteriaOur hospital had the experience of using two small-bowel CE systems, OMOM and MiroCam, respectively. The OMOM CE system was in use in our hospital before August 2013,since when MiroCam has been put into use instead. We retrospectively included consecutive patients who were 18 years old or older and had undergone capsule endoscopy for various reasons in our hospital between July 2012 and September 2014. The exclusion criteria were as follows:examination failed (technical failure occurred or CE was taken out because of stricture of digestive tract), data were incomplete (whether the CE had reached the cecum could not be decided as a result of poor bowel preparation or patient’s complaint had not been recorded), or anatomical structure were altered (stomach or small bowel had been resected partly or completely).Capsule endoscopy procedureThe size, weight, capture rate, field of view, data transmission technology and image sensor of OMOM were 13mm*27.9mm,6g,2 frames per second(fps)(variable), 1400, radiofrequency, and CCD respectively while these technical characteristics of MiroCam were 10.8mm*24mm,3.4g,3 fps,1700, electric field propagation, and CMOS respectively. Both OMOM and MiroCam had the function of real-time viewing. It should be mentioned that the operation time of OMOM was over 8 hours and in fact, its operation time varied by the capture rate and lower capture rate resulted in longer operation time. For example, the operation time of OMOM would be extended to about 12 hours if the capture rate was set at 1 fps. The operation time of MiroCam was relatively fixed and was about 12 hours.Same CE procedure adopted in the routine clinical practice in our hospital was applied for the two CE systems.Data and outcome measurementsDemographic data of patients, indications for CE, hospital status (inpatient or outpatient), GTT, SBTT, whether a complete examination of the small bowel had been achieved and diagnosis in each examination were recorded. The main outcome measurement was lesion detection rate and the secondary outcome measurements were GTT, SBTT and CR.Lesion detection rate was calculated as the total number of cases in which the lesion was detected in the small bowel divided by the number of patients included. GTT was defined as the time between the first image of stomach and the first image of duodenum while SBTT was defined as the time between the first image of duodenum and the first image of large intestine.CR was calculated as the total number of cases in which the complete examination of whole small bowel was achieved divided by the number of patients included.Statistical analysisQuantitative data were expressed by mean and standard deviation. The differences of quantitative data between groups were assessed by student’s test and Satterthwaite’s approximate t test was used when variances were unequal. Qualitative data were presented as frequency, percentage or ratio and were compared using chi-square test. Logistic regression was used to analyse the risk factors of outcome. Comparisons between OMOM and MiroCam were also made according to the three main indications. In order to avoid the potential bias caused by difference in operation time of the two CE systems, comparisons of SBTT and CR between OMOM and MiroCam were made after setting the operation time to 8 hours and a complete examination of the whole small bowel was considered to have been achieved only when the total time (GTT plus SBTT) was no more than 8 hours. All statistical analyses were performed with IBM SPSS Statistics (version 19) and Microsoft Office Excel 2007. A P value<0.05 was considered statistically significant.ResultsWhole patientsA total of 1448 patients (628 in OMOM group and 820 in MiroCam group) were finally included. Accounting for over 80 percent of the total, CD or suspected CD, GI bleeding and abdominal pain, bloating or diarrhea were the three main indications in both groups. There was no significant difference in sex ratio or hospital admission rate between OMOM and MiroCam(P> 0.05). The mean age in OMOM group was significantly higher than that in MiroCam group (44.3±15.5 years vs 42.5±15.0 years, P=0.025).In all patients(both complete examination and incomplete examination were included), the lesion detection rate in MiroCam was significantly higher than that in OMOM [65.9%(540/820) vs 56.5%(355/628), P= 0.000]. In the patients who underwent complete examination, the lesion detection rate in MiroCam was also significantly higher than that in OMOM [63.7%(469/736) vs 54.0%(294/544), P= 0.000]. Logistic regression analysis revealed several variables(capsule type, sex, age, hospitalization, indication, completed examination) significantly related to the lesion detection rate and MiroCam, compared with OMOM, was a risk factor for lesion detection(OR= 1.441, P=0.001), increasing lesion detection rate.In general, OMOM group, compared with MiroCam group, did not show a significant difference on GTT, CR or CR after operation time adjustment (P> 0.05). SBTT in OMOM was significantly shorter than that in MiroCam (287.9±108.4 minutes vs 301.5±125.8 minutes, P=0.038) but the difference between the two groups was not observed when the operation time was set to 8 hours (268.5±91.0 minutes vs 265.2±95.4 minutes, P=0.565).Patients with three main indicationsWhen comparisons were made based on the three main indications, no difference was found in age, sex ratio or hospital admission rate between OMOM and MiroCam(P>0.05).CD or suspected CDIn all CD or suspected CD patients, the lesion detection rate in OMOM was comparable with that in MiroCam[77.8%(112/144) vs 79.3%(203/256), P=0.721]. In the patients who underwent complete examination, the lesion detection rate in OMOM was also comparable with that in MiroCam (P=0.497). Logistic regression analysis did not reveal capsule type was a risk factor for lesion detection, P=0.544.In these patients, the mean GTT of OMOM was significantly longer than that of MiroCam (53.4±52.6 minutes vs 41.1±47.9 minutes, P=0.022) while SBTT or SBTT after operation time adjustment did not differ in the two groups(P> 0.05). MiroCam had a significantly higher CR than OMOM (89.1%[228/256] vs 8.1.3% [117/144], P= 0.029) but the adjustment of operation time eliminated the difference (73.8%[189/256] vs 72.9%[105/144], P= 0.843). Logistic regression analysis in this group of patients revealed that capsule type significantly related to long GTT and MiroCam, compared with OMOM, benefited the transit of CE in stomach by decreasing the GTT (OR=0.589, P=0.014).GI bleedingIn all patients presenting with GI bleeding, the lesion detection rate in OMOM and MiroCam were 63.8%(67/105) and 72.3%(94/130) respectively (P= 0.163). In the patients who underwent complete examination, the lesion detection rate in OMOM in OMOM and MiroCam were also comparable (P> 0.05). Logistic regression analysis also did not reveal capsule type was a risk factor for lesion detection, P=0.142.In all patients in this indication, mean GTT in OMOM group was shorter than that in MiroCam group (42.1±44.8 minutes vs 62.0±78.6 minutes, P=0.016). No significant difference in SBTT, CR, SBTT after operation time adjustment, or CR after operation time adjustment (P> 0.05) was observed between OMOM and MiroCam. Logistic regression analysis in this group of patients did not reveal any variable (capsule type, sex, age, hospitalization) significantly related to long GTT.Abdominal pain, bloating or diarrheaIn all patients with abdominal pain, bloating or diarrhea, MiroCam, compared with OMOM, achieved a significantly higher lesion detection rate[54.4%(180/331) vs 44.5%(130/292), P=0.014] and this significant difference also existed in the patients undergoing complete CE examination [53.3%(169/317) vs 44.2%(117/265), P= 0.028]. Logistic regression analysis revealed several variables(capsule type, sex, age) significantly related to the lesion detection rate and MiroCam, compared with OMOM, was a risk factor for lesion detection(OR= 1.541, P=0.008), increasing lesion detection rate.In these patients, GTT, SBTT and SBTT after operation time adjustment were comparable between OMOM and MiroCam(P> 0.05). MiroCam achieved a significantly higher CR than OMOM (95.8%[317/331] vs 90.8%[265/292], P= 0.012) but the adjustment of operation time eliminated the difference (81.9% [271/331] vs 82.2%[240/292], P= 0.918).ConclusionThrough comparing the clinical data of two kinds of CEs with differences in size, weight, capture rate, field of view, this study shows that CE with larger view of field and higher capture rate could achieve much higher lesion detection rate, especially in the patients presenting with abdominal pain, bloating or diarrhea, suggesting that the advancement in certain technical characteristics of CE could bring increase in the diagnostic yield; GTT of smaller and lighter CE is shorter in patients with CD or suspected CD, while in patients with GI bleeding, GTT of larger and heavier CE is shorter, suggesting that the weight and size of CE may have an effect on GTT in some patients and GTT may be decreased by modulating the weight or size of CE to avoid further intervention, decrease procedure time and spare more electric power for small-bowel examination. |
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