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Esophageal capsule endoscopy: the string is the thing
EDITORIAL
Esophageal capsule endoscopy: the string is the thing Endoscopy (EGD) is the criterion standard for investigating mucosal disease of the esophagus. It allows prolonged and precisely targeted viewing, mucosal cleansing, insufflation of air to highlight anatomic landmarks, and performance of confirmatory biopsies. Unfortunately, EGD also requires sedation, which introduces a small but measurable risk and leads to lost time from work for both the patient and the responsible adult driver. Unsedated transnasal endoscopy has been advocated but has never caught on with the general public. Wireless capsule endoscopy (WCE) studies of the small intestine may provide images of the esophagus, but, because of a slow frame speed (4 frames per second) and rapid transit time, these images are inadequate for accurate evaluation of the esophagus.1 Specialized, single-use esophageal capsule endoscopes have been developed that address these shortcomings by increasing the frame speed to 14 frames per second through the addition of a second, rear-facing lens (PillCam ESO; Given Imaging, Ltd, Yoqneam, Israel) and by adopting a recumbent swallowing protocol to increase dwell time in the esophagus.2 However, even with these modifications, esophageal capsule endoscopy (ECE) is still a passive process, which may not provide adequate images for accurate diagnosis. Galmiche et al3 studied 77 patients who experienced chronic reflux symptoms and found ECE to have excellent specificity and sensitivity values for the diagnosis of esophagitis, defined as the presence or absence of mucosal breaks. However, the sensitivity for the diagnosis of esophageal metaplasia was only 60%, which limits its value as a screening tool for Barrett’s esophagus (BE). The study also showed a learning curve effect in the interpretation of ECE, which highlights the need for specific training.3 Delvaux et al4 prospectively evaluated the diagnostic yield of ECE in 98 patients with an indication for EGD. The study population was artificially enriched so that two thirds of the patients had esophageal pathology detected at EGD, which was then followed by ECE. The positive and negative predictive values of ECE were 80% and 61%, respectively. The overall agreement between EGD and ECE was only moderate
on both a per-patient basis (kappa Z 0.42) and a per-finding basis (kappa Z 0.40). The quality of the ECE studies was good or moderate in 74% and was graded as poor in 26%, primarily because of inadequate visualization of the gastroesophageal junction. The investigators concluded that ECE showed only moderate sensitivity and accuracy in detecting esophageal abnormalities in a group of patients with a heterogeneous mix of findings that would be typical of a screening population.4 The accuracy of ECE in detecting biopsy-proven BE was reported by Lin et al5 in a prospective, blinded study of 90 patients (66 screening and 24 surveillance). ECE correctly identified 14 of 21 patients with true BE (sensitivity
Larger studies are still needed to confirm the accuracy of string-controlled esophageal capsule endoscopy, and guidelines for its use need to be established.
Copyright ª 2009 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 doi:10.1016/j.gie.2008.12.057
67%) and 58 of 69 patients without BE (specificity 84%). The positive predictive value was only 22%, but ECE had a negative predictive value of 98% (calculated for the screening population). The investigators concluded that ECE, in its present form, was not suitable as a primary screening tool for BE.5 ECE has fared better in evaluating and grading esophageal varices. Eisen et al6 conducted a multicenter pilot study by using the Pillcam ESO to screen patients with cirrhosis for esophageal varices and portal hypertensive gastropathy.6 Twenty-three of 32 patients had varices detected by both ECE and EGD; one patient had small varices detected on ECE only. Overall concordance between ECE and EGD was 97% for varices and 91% for gastropathy. ECE was somewhat less accurate in a study published by Lapalus et al,7 with a concordance rate with EGD of only 84%. However, ECE correctly identified all patients with either grade 2 varices or red wale signs who would benefit from primary prophylaxis.7 Ramirez et al8 devised a method for attaching suture material to a capsule endoscopy device, which extended the dwell time and converted a passive process into an operator-controlled procedure. Real-time monitoring of the images on a standard video monitor provides accurate diagnosis of both BE and varices with a high degree of
210 GASTROINTESTINAL ENDOSCOPY Volume 70, No. 2 : 2009
www.giejournal.org
Hale
Editorial
patient satisfaction. Moderate discomfort during capsule retrieval was noted in only 17% of patients. After high-level glutaraldehyde disinfection, the capsules were reused multiple times, thus providing significant cost savings.8,9 In this issue of Gastrointestinal Endoscopy, Liao et al10 reported on their simplification of string-controlled ECE by using a single lens device (OMOM; Chongquing Jinshan Science and Technology Group Co Ltd, Chongquing, China) covered in a removable latex sheath and controlled by a string tied to the sheath. As in the studies by Ramirez et al,8,9 the operator is able to control the capsule while viewing the images in real time, which allowed careful inspection of all areas of interest (mean viewing time 4.3 minutes). After retrieval of the device, the sheath is discarded, and the device is reused after simple cleansing with 75% alcohol. This pilot study included only 10 examinations, 8 patients and 2 normal controls, but did show 100% correlation with EGD findings. Patient acceptance was high and, with one exception, image quality was rated as very good. Unfortunately, none of the patients examined had BE.10 String-controlled ECE with real-time video monitoring has the potential to provide highly accurate diagnostic images of the esophagus and the proximal stomach at a low per procedure cost. Ramirez et al8 obtained more than 20 studies with each capsule. The latex sheath system described by Liao et al10 has apparent advantages in terms of design simplicity and ease of use, but questions remain regarding image quality through the sheath, appropriate capsule reprocessing procedures, and the risk of latex allergy. Larger studies are still needed to confirm the accuracy of string-controlled ECE, and guidelines for use need to be established. However, BE has a prevalence in Western populations between 1.2% and 7.2% for long-segment BE and 5.5% to 17.2% for short-segment BE, similar to the 6.2% to 7.7% prevalence of colon polyps more than 9 mm reported in a recent, multicenter study of screening colonoscopy results.11,12 Given the bleak prospects for those patients who develop invasive esophageal adenocarcinoma and the development of new techniques for ablation of premalignant BE (EMR, radiofrequency ablation, and liquid nitrogen cryotherapy), a strong case can be made for performing screening endoscopy on all middle-aged patients with chronic reflux symptoms. String-controlled ECE may well prove to be the most cost-effective method for large-scale esophageal screening programs.
DISCLOSURE
www.giejournal.org
Volume 70, No. 2 : 2009 GASTROINTESTINAL ENDOSCOPY 211
The author disclosed no financial relationships relevant to this publication. William Hale, MD, FACG Norwalk Hospital/Yale University School of Medicine Norwalk, Connecticut, USA Abbreviations: BE, Barrett’s esophagus; ECE, esophageal capsule endoscopy; WCE, wireless capsule endoscopy.
REFERENCES 1. Ginsberg GG, Barkun AN, Bosco JJ, et al. Technology status evaluation report: wireless capsule endoscopy. Gastrointest Endosc 2002;56:621-4. 2. Sharma VK, Eliakim R, Sharma P, et al. ICCE consensus for esophageal capsule endoscopy. Endoscopy 2005;37:1060-4. 3. Galmiche JP, Sacher-Huvelin S, Coron E, et al. Screening for esophagitis and Barrett’s esophagus with wireless esophageal capsule endoscopy: a multicenter prospective trial in the patients with reflux symptoms. Am J Gastroenterol 2008;103:538-45. 4. Delvaux M, Papanikolaou IS, Fassler I, et al. Esophageal capsule endoscopy in the patients with suspected esophageal disease: double-blinded comparison with esophagogastroduodenoscopy and assessment of interobserver variability. Endoscopy 2008;40:16-22. 5. Lin OS, Schembre DB, Mergener K, et al. Blinded comparison of esophageal capsule endoscopy versus conventional endoscopy for diagnosis of Barrett’s esophagus in patients with chronic gastroesophageal reflux. Gastrointest Endosc 2007;65:577-83. 6. Eisen G, Eliakim R, Zaman A, et al. The accuracy of PillCam ESO capsule endoscopy versus conventional upper endoscopy for the diagnosis of esophageal varices: a prospective three-center pilot study. Endoscopy 2006;38:31-5. 7. Lapalus M, Dumortier J, Fumex F, et al. Esophageal capsule endoscopy versus esophagogastroduodenoscopy for evaluating portal hypertension: a prospective comparative study of performance and tolerance. Endoscopy 2006;38:36-41. 8. Ramirez FC, Shaukat MS, Young MA, et al. Feasibility and safety of string wireless capsule endoscopy in the diagnosis of Barrett’s esophagus. Gastrointest Endosc 2005;61:741-6. 9. Ramirez FC, Akins R, Shaukat M. Screening of Barrett’s esophagus with string capsule endoscopy: a prospective blinded study of 100 consecutive patients using histology as the criterion standard. Gastrointest Endosc 2008;68:25-31. 10. Liao Z, Gao R, Xu C, et al. Sleeve string capsule endoscopy for real-time viewing of the esophagus: a pilot study. Gastrointest Endosc 2009;70: 201-9. 11. Musana AK, Resnick JM, Torbey CF, et al. Barrett’s esophagus: incidence and prevalence estimates in a rural mid-western population. Am J Gastroenterol 2008;103:516-24. 12. Lieberman DA, Holub JL, Moravec MD, et al. Prevalence of colon polyps detected by colonoscopy screening in asymptomatic black and white patients. JAMA 2008;300:1417-22.
Esophageal capsule endoscopy: the string is the thing Endoscopy (EGD) is the criterion standard for investigating mucosal disease of the esophagus. It allows prolonged and precisely targeted viewing, mucosal cleansing, insufflation of air to highlight anatomic landmarks, and performance of confirmatory biopsies. Unfortunately, EGD also requires sedation, which introduces a small but measurable risk and leads to lost time from work for both the patient and the responsible adult driver. Unsedated transnasal endoscopy has been advocated but has never caught on with the general public. Wireless capsule endoscopy (WCE) studies of the small intestine may provide images of the esophagus, but, because of a slow frame speed (4 frames per second) and rapid transit time, these images are inadequate for accurate evaluation of the esophagus.1 Specialized, single-use esophageal capsule endoscopes have been developed that address these shortcomings by increasing the frame speed to 14 frames per second through the addition of a second, rear-facing lens (PillCam ESO; Given Imaging, Ltd, Yoqneam, Israel) and by adopting a recumbent swallowing protocol to increase dwell time in the esophagus.2 However, even with these modifications, esophageal capsule endoscopy (ECE) is still a passive process, which may not provide adequate images for accurate diagnosis. Galmiche et al3 studied 77 patients who experienced chronic reflux symptoms and found ECE to have excellent specificity and sensitivity values for the diagnosis of esophagitis, defined as the presence or absence of mucosal breaks. However, the sensitivity for the diagnosis of esophageal metaplasia was only 60%, which limits its value as a screening tool for Barrett’s esophagus (BE). The study also showed a learning curve effect in the interpretation of ECE, which highlights the need for specific training.3 Delvaux et al4 prospectively evaluated the diagnostic yield of ECE in 98 patients with an indication for EGD. The study population was artificially enriched so that two thirds of the patients had esophageal pathology detected at EGD, which was then followed by ECE. The positive and negative predictive values of ECE were 80% and 61%, respectively. The overall agreement between EGD and ECE was only moderate
on both a per-patient basis (kappa Z 0.42) and a per-finding basis (kappa Z 0.40). The quality of the ECE studies was good or moderate in 74% and was graded as poor in 26%, primarily because of inadequate visualization of the gastroesophageal junction. The investigators concluded that ECE showed only moderate sensitivity and accuracy in detecting esophageal abnormalities in a group of patients with a heterogeneous mix of findings that would be typical of a screening population.4 The accuracy of ECE in detecting biopsy-proven BE was reported by Lin et al5 in a prospective, blinded study of 90 patients (66 screening and 24 surveillance). ECE correctly identified 14 of 21 patients with true BE (sensitivity
Larger studies are still needed to confirm the accuracy of string-controlled esophageal capsule endoscopy, and guidelines for its use need to be established.
Copyright ª 2009 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 doi:10.1016/j.gie.2008.12.057
67%) and 58 of 69 patients without BE (specificity 84%). The positive predictive value was only 22%, but ECE had a negative predictive value of 98% (calculated for the screening population). The investigators concluded that ECE, in its present form, was not suitable as a primary screening tool for BE.5 ECE has fared better in evaluating and grading esophageal varices. Eisen et al6 conducted a multicenter pilot study by using the Pillcam ESO to screen patients with cirrhosis for esophageal varices and portal hypertensive gastropathy.6 Twenty-three of 32 patients had varices detected by both ECE and EGD; one patient had small varices detected on ECE only. Overall concordance between ECE and EGD was 97% for varices and 91% for gastropathy. ECE was somewhat less accurate in a study published by Lapalus et al,7 with a concordance rate with EGD of only 84%. However, ECE correctly identified all patients with either grade 2 varices or red wale signs who would benefit from primary prophylaxis.7 Ramirez et al8 devised a method for attaching suture material to a capsule endoscopy device, which extended the dwell time and converted a passive process into an operator-controlled procedure. Real-time monitoring of the images on a standard video monitor provides accurate diagnosis of both BE and varices with a high degree of
210 GASTROINTESTINAL ENDOSCOPY Volume 70, No. 2 : 2009
www.giejournal.org
Hale
Editorial
patient satisfaction. Moderate discomfort during capsule retrieval was noted in only 17% of patients. After high-level glutaraldehyde disinfection, the capsules were reused multiple times, thus providing significant cost savings.8,9 In this issue of Gastrointestinal Endoscopy, Liao et al10 reported on their simplification of string-controlled ECE by using a single lens device (OMOM; Chongquing Jinshan Science and Technology Group Co Ltd, Chongquing, China) covered in a removable latex sheath and controlled by a string tied to the sheath. As in the studies by Ramirez et al,8,9 the operator is able to control the capsule while viewing the images in real time, which allowed careful inspection of all areas of interest (mean viewing time 4.3 minutes). After retrieval of the device, the sheath is discarded, and the device is reused after simple cleansing with 75% alcohol. This pilot study included only 10 examinations, 8 patients and 2 normal controls, but did show 100% correlation with EGD findings. Patient acceptance was high and, with one exception, image quality was rated as very good. Unfortunately, none of the patients examined had BE.10 String-controlled ECE with real-time video monitoring has the potential to provide highly accurate diagnostic images of the esophagus and the proximal stomach at a low per procedure cost. Ramirez et al8 obtained more than 20 studies with each capsule. The latex sheath system described by Liao et al10 has apparent advantages in terms of design simplicity and ease of use, but questions remain regarding image quality through the sheath, appropriate capsule reprocessing procedures, and the risk of latex allergy. Larger studies are still needed to confirm the accuracy of string-controlled ECE, and guidelines for use need to be established. However, BE has a prevalence in Western populations between 1.2% and 7.2% for long-segment BE and 5.5% to 17.2% for short-segment BE, similar to the 6.2% to 7.7% prevalence of colon polyps more than 9 mm reported in a recent, multicenter study of screening colonoscopy results.11,12 Given the bleak prospects for those patients who develop invasive esophageal adenocarcinoma and the development of new techniques for ablation of premalignant BE (EMR, radiofrequency ablation, and liquid nitrogen cryotherapy), a strong case can be made for performing screening endoscopy on all middle-aged patients with chronic reflux symptoms. String-controlled ECE may well prove to be the most cost-effective method for large-scale esophageal screening programs.
DISCLOSURE
www.giejournal.org
Volume 70, No. 2 : 2009 GASTROINTESTINAL ENDOSCOPY 211
The author disclosed no financial relationships relevant to this publication. William Hale, MD, FACG Norwalk Hospital/Yale University School of Medicine Norwalk, Connecticut, USA Abbreviations: BE, Barrett’s esophagus; ECE, esophageal capsule endoscopy; WCE, wireless capsule endoscopy.
REFERENCES 1. Ginsberg GG, Barkun AN, Bosco JJ, et al. Technology status evaluation report: wireless capsule endoscopy. Gastrointest Endosc 2002;56:621-4. 2. Sharma VK, Eliakim R, Sharma P, et al. ICCE consensus for esophageal capsule endoscopy. Endoscopy 2005;37:1060-4. 3. Galmiche JP, Sacher-Huvelin S, Coron E, et al. Screening for esophagitis and Barrett’s esophagus with wireless esophageal capsule endoscopy: a multicenter prospective trial in the patients with reflux symptoms. Am J Gastroenterol 2008;103:538-45. 4. Delvaux M, Papanikolaou IS, Fassler I, et al. Esophageal capsule endoscopy in the patients with suspected esophageal disease: double-blinded comparison with esophagogastroduodenoscopy and assessment of interobserver variability. Endoscopy 2008;40:16-22. 5. Lin OS, Schembre DB, Mergener K, et al. Blinded comparison of esophageal capsule endoscopy versus conventional endoscopy for diagnosis of Barrett’s esophagus in patients with chronic gastroesophageal reflux. Gastrointest Endosc 2007;65:577-83. 6. Eisen G, Eliakim R, Zaman A, et al. The accuracy of PillCam ESO capsule endoscopy versus conventional upper endoscopy for the diagnosis of esophageal varices: a prospective three-center pilot study. Endoscopy 2006;38:31-5. 7. Lapalus M, Dumortier J, Fumex F, et al. Esophageal capsule endoscopy versus esophagogastroduodenoscopy for evaluating portal hypertension: a prospective comparative study of performance and tolerance. Endoscopy 2006;38:36-41. 8. Ramirez FC, Shaukat MS, Young MA, et al. Feasibility and safety of string wireless capsule endoscopy in the diagnosis of Barrett’s esophagus. Gastrointest Endosc 2005;61:741-6. 9. Ramirez FC, Akins R, Shaukat M. Screening of Barrett’s esophagus with string capsule endoscopy: a prospective blinded study of 100 consecutive patients using histology as the criterion standard. Gastrointest Endosc 2008;68:25-31. 10. Liao Z, Gao R, Xu C, et al. Sleeve string capsule endoscopy for real-time viewing of the esophagus: a pilot study. Gastrointest Endosc 2009;70: 201-9. 11. Musana AK, Resnick JM, Torbey CF, et al. Barrett’s esophagus: incidence and prevalence estimates in a rural mid-western population. Am J Gastroenterol 2008;103:516-24. 12. Lieberman DA, Holub JL, Moravec MD, et al. Prevalence of colon polyps detected by colonoscopy screening in asymptomatic black and white patients. JAMA 2008;300:1417-22.