Inequalities in Implementation and Different Outcomes During the Growth of Laparoscopic Colorectal Cancer Surgery in England: A National Population-Based Study from 2002 to 2012

This study presents evidence of clear and persistent inequality in the application laparoscopic techniques for colorectal cancer surgery in the English NHS between 2002 and 2012. Despite uptake reaching 50.8% in 2011–12, laparoscopic resection continued to be associated with lower comorbidity and socioeconomic deprivation. However, re-intervention rates were higher among patients undergoing laparoscopic surgery, despite the lower risk profile of this patient population.

This study has important, well-described strengths and limitations associated with the use of national administrative datasets. These tend to capture a more complete picture of national activity than voluntary registers [19, 20], have been shown to permit accurate modelling of patient outcomes [21] and allow identification of clinically important events [22]. Limitations include the lack of data on cancer stage, which may have had implications for patient selection, although this should have had limited impact on 30-day outcomes of elective resection. This study included both colonic and rectal cancer surgery, and rectal surgery is considered more technically challenging. This could have affected patient selection. However, sensitivity analysis of separate colonic and rectal surgical groups did not alter the key findings of this study regarding comorbidity, socioeconomic deprivation, mortality and length of stay. Another limitation of this study was the focus on unadjusted outcomes. However, this was a deliberate choice. This study has highlighted differences in the populations of patients undergoing laparoscopic and open surgery across measured characteristics. It is therefore likely that these two patient populations were also different across unmeasured characteristics, which cannot be controlled for using statistical techniques. Appropriately interpreted, unadjusted outcomes may yield important insights and reveal granular changes in trends that may be hidden as average effects in multiple regression analysis.

Differential application of laparoscopic surgery persisted throughout the study period, despite the accumulation of experience and attainment of high levels of adoption in later study years. Previous, non-longitudinal research in Canada [10] and the USA [11, 12] also found an association between laparoscopic surgery and lower comorbidity. Differences in comorbidity and socioeconomic status between laparoscopic and open patient groups may have arisen at the surgeon level, through case selection, or at the unit level, through geographic variation. During early adoption, novice surgeons may have selected ‘easier’, less comorbid patients for whom a prolonged operation and anaesthetic should not cause untoward problems. With progression along the learning curve, it may reasonably be expected that surgeons would apply the technique to all suitable patients. The narrowing of the differences in comorbidity in the early years of this study may support this contention. However, lower comorbidity and deprivation in the laparoscopic group stubbornly persisted over the latter half of the study. Differences in application may have occurred at the unit level, with surgeons trained in laparoscopic techniques perhaps practicing in less socioeconomically deprived areas, where patients are also likely to be less comorbid.

Further research to specifically explore this finding should be conducted, across other types of surgery and in other healthcare systems. The level at which selection is occurring needs to be determined, as this may have important clinical, ethical and policy implications. If laparoscopic surgery is associated with improved outcomes, surgeons have a moral duty to ensure that all suitable patients benefit from this approach. There may also be ramifications for policy makers, to ensure the benefits of laparoscopic surgery are delivered widely across the healthcare system. Analysis of more recent data is also needed to establish whether differences in application have persisted beyond the end of the study period, as laparoscopic surgery has become even more embedded into routine practice.

The lower mortality rate after laparoscopic compared with open surgery is consistent with other large observational studies of colorectal surgery [23, 24]. However, data from RCTs have shown no difference in mortality rates between the two operative approaches [3‐6], with a number of systematic reviews and meta-analyses reaching the same conclusion [25‐27]. The present study has already discussed clear evidence of patient selection for laparoscopic surgery, and the lower levels of comorbidity and deprivation among laparoscopically treated patients may be key explanatory factors for the lower mortality rates observed. RCTs are designed to tackle biases due to patient selection, and findings from such study designs take priority over observational research in determining whether any survival benefit may be attributed to the laparoscopic approach.

Higher re-intervention rates after laparoscopic surgery in the present study also contrast with data from RCTs and meta-analyses, which have reported comparable or lower complication rates associated with the laparoscopic technique [3‐5, 26]. The authors are unaware of any other studies presenting a similar finding. While further work is required specifically to explore this finding, we propose some possible explanations. Surgeons who self-select to participate within RCTs may have greater laparoscopic experience or above average laparoscopic skill, and be enthusiasts for the technique. Conversely, the wider population of surgeons represented in this study may have had less experience, or simply represent the average level of surgical skill, with associated higher complication rates. In addition, clinical care within an RCT may be more structured and closely monitored than usual clinical care, resulting in lower complication rates. During the study period, there may also have been changes in the management of post-operative complications within the surgical community. Research has suggested that a key determinant of outcome is not necessarily the rate of complications, but the ability to successfully ‘rescue’ patients when complications occur [18, 28]. When learning laparoscopic surgery, surgeons may have had a higher index of suspicion for complications and had a lower threshold to investigate and treat during the post-operative period. Over time, experience with successful rescue may have consolidated an aggressive approach to complication management as a standard of care after both laparoscopic and open surgery. This study provides tentative support for this argument, as the rate of re-intervention after open surgery rose during later years of the study.

It is interesting to note that the conversion rate from laparoscopic to open did not change during the study period. This may arise from the population-level nature of this study. While individual surgeons will have had demonstrable learning curves, gradual introduction of laparoscopy will have resulted in staggering of these learning curves over several years, smoothing out the surgeon-level effect on outcomes. The stable conversion rate may also suggest that the surgical profession has been effective in managing the introduction of laparoscopic techniques without compromising care during the early learning curve. For example, the national training program in laparoscopic colorectal surgery instituted a structured process of mentoring to allow supervised development of laparoscopic skills by existing consultants keen to learn this technique. Data on participation in the program are not available within HES to explore the role of this program in more detail.

Overall, this study has documented substantial improvements in the outcomes of all patients, regardless of the operative approach, with a 48.0% fall in 30-day mortality from 2004–2005 to 2011–2012, exceeding the survival benefit associated with laparoscopic surgery. Length of stay has also fallen significantly for all patients. These improvements may owe to a wide range of improvements in all relevant aspects of modern medical and surgical care. In particular, the reduction in post-operative length of stay may have been driven by widespread adoption of Enhanced Recovery After Surgery (ERAS) protocols [29]. Beyond this, there may have been improvements in medical optimisation of patients and more effective perioperative management, such as higher quality intensive care [30, 31].

The present findings should stimulate further research into patterns of uptake in other fields of minimal access surgery, and in other healthcare systems. Specific considerations relevant to colorectal cancer surgery, including screening and the national laparoscopic training program, may have influenced the findings presented, potentially limiting generalisation to other settings.

This study has shown that significant inequality in the utilisation of laparoscopy for colorectal cancer has persisted despite high levels of adoption, meaning that the benefits of the laparoscopic approach are not yet being fully realised within the NHS as a whole. Mortality and length of stay outcomes improved dramatically after both laparoscopic and open surgery during this ten-year study. However, the rate of re-intervention after laparoscopic surgery was higher than after open surgery, an unexpected finding that requires further examination. It is appropriate that future innovations and new techniques may be selectively applied in their early stages, but long-term population- or disease-based studies will be required to ensure medical advances are applied equitably to achieve the greatest benefit for patients.