Endoscopy 2019; 51(01): 96-99
DOI: 10.1055/a-0754-5859
Letter to the editor
© Georg Thieme Verlag KG Stuttgart · New York

Is laser lithotripsy the most successful and the safest advanced lithotripsy technique for retained biliary tract stones?

Zheng Jin
1  Hangzhou Geriatric Hospital, Hangzhou First People’s Hospital Group, Hangzhou, China
2  Department of Gastroenterology, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
,
Jing Yang
2  Department of Gastroenterology, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
,
Hangbin Jin
2  Department of Gastroenterology, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
,
Xiaofeng Zhang
2  Department of Gastroenterology, Affiliated Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
› Author Affiliations
Further Information

Publication History

Publication Date:
20 December 2018 (online)

We read with interest the recent systematic review by Veld et al. [1] comparing the efficacy and safety of electrohydraulic lithotripsy (EHL), laser lithotripsy, and extracorporeal shock wave lithotripsy in the management of retained biliary tract stones. The authors concluded that laser lithotripsy was currently the most successful and the safest advanced lithotripsy technique for retained biliary tract stones. However, we believe that several issues need to be addressed.

First, the literature search missed 12 studies [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]: 9 studies were published online between 1 January 2000 and 1 January 2017 (within the time interval of the search) [2] [3] [4] [5] [6] [7] [8] [9] [10], and 3 were published online between January 2017 and October 2017 (before submission) [11] [12] [13]. Among these studies, one was a randomized controlled trial [12], and one study had a large number of patients (n = 407) [13]. We think these omissions may affect the final results. The characteristics and outcomes of the missed studies are shown in [Table 1].

Table 1

Characteristics and outcomes of the missed studies.

Study (Epub year) and location

Setting and study design

Indication

Type of scope

Patients, n

Procedure

Max. stone size, median (range), mm

Location of > 50 % of stones

Single-session stone clearance, n/N (%)

Complete stone clearance, n/N (%)

Adverse events, n (%)

Sessions needed for stone clearance, mean (SD), n

NOS

Fishman et al. (2009) [2]
USA

Multicenter
Retrospective

Large, intrahepatic stones, Mirizzi syndrome, stones proximal to a stricture

Cholangioscope (Spyglass)

41

EHL + Laser

NR

NR

37 /41 (90.2)

41 /44 (100)

0/44 (0)

1.1 (0.3)

4

Chen et al. (2011) [3]
USA

Multicenter
Prospective

Failure of previous therapy

Cholangioscope (Spyglass)

66

EHL + Laser

19 (5 – 60)

CBD

47/66 (71.2)

61/66 (92.4)

NR

1.4 (0.7)

4

Sepe et al. (2012) [4]
USA

Single center
Retrospective

Cystic duct stones

Cholangioscope (Spyglass)

13

EHL

8 (4 – 20)

Cystic duct

7/13 (53.8)

10/13 (76.9)

0/13 (0)

1.2 (0.4)

4

Tieu et al. (2015) [5]
USA

Single center
Retrospective

Failure of previous therapy

Cholangioscope (Spyglass)

13

EHL

NR

NR

10 /13 (76.9)

13 /13 (100)

NR

NR

4

Kurihara et al. (2016) [6]
Japan

Multicenter
Prospective

Failure of previous therapy

Cholangioscope (Spyglass)

31

EHL + Laser

20.6
(5 – 48)

CBD

3/31 (9.7)

23/31 (74.2)

NR

1.9 (1.3)

4

Bhandari et al. (2016) [7]
India

Single center
Retrospective

Mirizzi syndrome and cystic duct stones not amenable to conventional means

Cholangioscope (Spyglass)

34

Laser

21 (6 – 41)

Cystic duct

32/34 (94.1)

34/34 (100)

6/34 (17.6)

1.1 (0.2)

4

Navaneethan et al. (2016) [8]
USA

Multicenter
Retrospective

Failure of previous therapy

Cholangioscope (Spyglass)

31

Laser

Mean 14.9 (SD 5.3)

CBD

27/31 (87.1)

31/31 (100)

NR

1.1 (0.3)

4

Laleman et al. (2016) [9]
Belgium

Single center
Prospective

Failure of conventional therapy (> 15 mm, number, impaction, intrahepatic location or the presence above a stricture)

Cholangioscope (Spyglass)

39

EHL

NR

CBD

26/39 (66.7)

32/39 (82.1)

NR

1.2 (0.4)

4

Wong et al. (2017) [10]
Hong Kong

Single center
Prospective

Impacted stones > 15 mm, not amenable to conventional means

Cholangioscope (Spyglass)

17

Laser

20 (10 – 45)

CBD

10/17 (58.8)

16/17 (94.1)

2/17 (11.8)

Median 1 (range 1 – 3)

4

Shah et al. (2017) [11]
USA

Multicenter
Retrospective

Failure of previous therapy

Cholangioscope (Spyglass)

19

EHL + Laser

NR

CBD

17/19 (89.5)

19/19 (100)

NR

1.2 (0.5)

4

Buxbaum et al. (2017) [12]
USA

Single center
RCT

Stones > 10 mm

Cholangioscope (Spyglass)

42

Laser

Mean 18 (SD 0.6)

NR

12/42 (28.6)

39/42 (92.9)

4/42 (9.5)

1.9 (0.7)

6

Brewer et al.
(2017) [13]
USA/UK/Korea

Multicenter
Retrospective

Large (> 15 mm), multiple (> 3), intrahepatic duct/cystic duct, barrel-shaped or impacted stones, a stricture below the stone, difficult anatomic access to the papilla

Cholangioscope (Spyglass)

407

EHL + Laser

Mean 16.01 (SD 7.14)

CBD

315/407 (77.4)

396/407 (97.3)

15/407 (3.7)

Median 1 (range 1 – 4)

4

CBD, common bile duct; EHL, electrohydraulic lithotripsy; NOS, Newcastle – Ottawa Scale; NR, not reported; RCT, randomized controlled trial.

Second, the author calculated overall rates (stone fragmentation rate, ductal clearance rate, and adverse event rate) by taking a weighted average of the rates from each of the studies. However, this method only takes into account the variation within a study; it does not account for the between-study variation. To account for both sources of variation, performing a proportion meta-analysis would have been more appropriate [14].

Third, some errors occurred during data extraction. Two of the studies (Alameel et al. [15] and Chen et al. [16]) included patients who underwent diagnostic procedures and patients who underwent stone therapy, but the authors mistakenly attributed the complications to the therapy group. Thus, the complication rate of EHL calculated from these two studies was overestimated. Additionally, both lithotripsy methods (EHL and laser lithotripsy) were reported by Draganov et al. [17]; however, the authors mistakenly thought that only EHL was used.

Fourth, assessment of publication bias and statistical heterogeneity were lacking. The review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The PRISMA statement consists of a 27-item checklist including publication bias and measures of consistency. We ask whether these should be assessed using some established tools.

Finally, as listed in Supplemental Table e8 of the review, hemobilia and bleeding were two independent complications; the incidence of hemobilia was higher than that of bleeding. However, it is well known that hemobilia is a type of bleeding and thus some clarification would be helpful.

Owing to the above problems with the review, we cannot rely solely on the statistical results, which could lead us to false answers.