Outcome trends and safety measures after 30 years of laparoscopic cholecystectomy: a systematic review and pooled data analysis

This review of outcomes for LC reconfirms the established principle that LC is safe and may be performed with minimum morbidity (pooled prevalence range 1.6–5.3%) and mortality (0.08–0.14%). LC remains the unchallenged gold standard, with conversion rates between 4.2 and 6.2%.

BDI outcomes analysis was limited by the fact that BDI was not universally reported and different classifications were used (without any formalized correspondence as to the grading); we were, therefore, unable to segregate bile leaks according to severity or nature of injury. Our findings, however, are consistent with recent Swedish population analyses of over 51,000 LCs which reported a 0.3% major BDI rate, [18] with an overall 1.5% bile leak rate [7]. At 0.32%, the lower estimate of pooled BDI rate in our overall analysis remained higher than the commonly accepted rates of 0.1–0.2% for open cholecystectomy reported at the dawn of the laparoscopic era over a quarter century ago [2]. Unadjusted pooled outcomes in our study suggested a modest decrease in reported BDI rates over the past 30 years. However, this was not reflected in the meta-regression analysis. Regardless, with nearly 1 million cholecystectomies performed per year in the United States alone, [19] the medical, psychological, and socioeconomic burdens represented by BDI remain substantial. This consideration is particularly true if one weighs it in the context of LC as an extremely common, and, by today’s standards, a typically outpatient or short stay procedure performed for benign disease. Furthermore, a large volume of performed LC are probably not included in any studies and their complication rate may be higher than the ones presented here. Yamashita et al., for example, reported Japanese national survey data suggesting little change in BDI rates over the past decade, with a mean incidence of 0.66% [20].

Technological and technical efforts to improve LC quality continue. However, despite the growing number of methods intended to reduce BDI, the evidence for their ability to impact BDI rates remains limited. A 2011 systematic review of interventions to prevent BDI identified a number of candidate techniques and procedures, including routine use of the critical view of safety approach and intraoperative cholangiography, but conclusive effects on BDI rates could not be shown [21]. In addition, series which have examined the mechanism of biliary injury have rarely described use of the critical view of safety as the method of ductal identification [22, 23]. However, several large retrospective series in which the critical view of safety was used routinely have been reported with no biliary injuries [24, 25].

A major challenge for assessing factors associated with BDI risk is its relatively low prevalence (0.3–0.5%). A study assessing a procedure to reduce BDI rates would, for example, require a sample size of 16,989 patients in each arm to detect a 50% reduction of the BDI rates from 0.3% (assuming a standard alpha = 0.05 at 80% power). The logistical obstacles and confounders involved in a study of this size means such a trial is highly unlikely to take place. Moreover, the true prevalence of BDI is difficult to ascertain from the literature, as there is wide confusion between prevalence and incidences in reports. Instead, we must, therefore, rely on cohort, expert, and surrogate data, such as the ability to accurately demonstrate and identify biliary anatomy intraoperatively, as is the aim with the critical view of safety, and other methods of ductal identification [26, 27]. Newer techniques such as infrared fluorescence cholangiography are generating considerable interest as a way to enhance identification of the anatomy during cholecystectomy, but must be evaluated by further study in larger numbers of patients before any recommendations can be made [28].

In the present study, we assessed the effect of technical, patient, and hospital characteristics on BDI rates. These factors had few detectable associations with BDI rates. It is crucial, therefore, to recognize the role that education, decision-making, and experience have to play in preventing BDI during LC. A recent insurance database review study of BDI illustrated the effect of surgeon experience and volume, wherein younger, less experienced surgeons reported BDI rates three times higher than their more experienced counterparts [29]. A European-based population study has suggested that a positive volume–outcome relationship for LC exists with reference to outcomes other than BDI as well, with high volume centers (defined as > 244 LC/year) reporting lower morbidity, mortality, and reoperation rates [30].

Data published by Way et al., [31] in which root causes of over 200 BDIs were identified, highlighted the fact that over 97% of errors were related to non-technical, predominantly perceptual errors. In response to this and other data, a recent international Delphi consensus study headed by the Society for American Gastrointestinal Endoscopic Surgeons (SAGES) Safe Cholecystectomy Task Force identified the most important factors to safety in LC as (1) establishing the CVS, (2) understanding of anatomy, (3) adequate exposure, (4) ability to call a senior colleague for help, and (5) recognizing when to convert or abandon [32]. Education and practice, the group recommended, should be focused around these key principles, with technical factors such as choice of dissection tool, duct securing technique, or use of cholangiography ranking lower in priority.

This review and its conclusions are subject to several limitations. As discussed, we had limited statistical power to identify differences in BDI rates by a range of factors because of its relatively low prevalence and/or incidence rates. Secondly, we imposed minimum sample sizes to reduce the risk of selection bias from smaller studies. This approach may have had the effect of excluding studies that might otherwise have been included in secondary outcome analyses, and meant that no more than two studies were available for analysis of each assessed intervention. It was, however, our expressed aim to focus on BDI and complication rates and numerous other reviews (including those already cited) for individual interventions and secondary outcomes exist which incorporated smaller studies not included here. The ranges reported here for pooled outcomes reflect the inconsistency of data reporting, even for large-scale studies focused on outcomes for LC. For the lower range, assuming a 0% prevalence or incidence for studies which did not report a given outcome will invariably underestimate the pooled rate as it combines studies which did not report prevalence/incidence due to a true 0% rate, with those with incomplete outcomes reporting. Interpretation of our findings must take this aspect into account.

In addition, it is almost certain that many BDI are neither reported nor published except for national database reporting requirements such as in Sweden, and therefore, the true prevalence/incidence of BDI in most of the world is not precisely known and may be higher than identified herein. Administrative databases accounted for a large proportion of the retrospective studies included here; their advantageous large numbers are tempered by the fact that they likely lack detailed coding with reference to prevalence/incidence of BDI, and do not allow differentiation between types of injury. Further, if BDIs are recorded without severity, based on reoperation (hepaticojejunostomy) alone, this surrogate endpoint presents the dual problem of skewing injuries to the severe end of the scale, as well as underestimating overall injury rates—potentially accounting in part for the apparent reduction observed in our pooling of recent data of BDI.

Although our inclusion criteria aimed to maintain high overall study quality, the thoroughness of outcomes reporting was highly variable. In many cases, the quality of reporting in recent literature was worse than 20 years ago; duration of stay and morbidity were reported for 49 and 52% of studies included, respectively, compared to 82 and 98% in the previous 1996 analysis by Shea et al. [12]. This finding highlights the need for standardized reporting of outcomes for these procedures [33]. Finally, analysis of funnel plots suggested significant publication bias. This finding potentially also accounts for the differences seen in conversion rates between developed and developing countries, with a much higher bias coefficient seen in developing countries.

Future advances to improve outcomes in LC will need to consider technological, educational, and structural approaches. Technological developments offer new techniques for the identification of biliary anatomy but have limited evidence demonstrating their effectiveness. Though some show promise, it is unlikely that interventions will be able to detect an effect on BDI within the context of a randomized trial due to limitations of sample size. It is incumbent upon researchers, therefore, to identify and focus on selected surrogate outcome measures, and particularly to ensure the standardization of reporting, for example including complications, BDI, and ductal injury type, which continues to elude LC-related research. The establishment of international registries should be prioritized.

Education, training, and mentorship, with emphasis on techniques such as the critical view of safety, will continue to be the mainstay of surgical expertise. Modern teaching paradigms have enhanced educators’ understanding of the often unconsciously carried knowledge which constitutes surgical expertise, with teaching frameworks designed to reveal and convey these to learners [34]. Aided by technological teaching adjuncts, including virtual reality and box trainers, these have the potential to accelerate improvement and abbreviate learning curves [35]. The technology, training, and expertise required for LC, coupled with the severity of BDI as a potential complication, calls for a reassessment of how LC is taught and what educational strategies could be used to impact this problem.