While nearly half of colon resections for cancer were approached laparoscopically in the overall sample, the hospital-level laparoscopy rate varied substantially. Hospitals with higher laparoscopy rates achieved modestly shorter hospital stays. However, the morbidity outcomes were mixed: hospitals with higher laparoscopy rates tended to have higher risk-standardized, intra-operative morbidity rates, but lower post-operative morbidity. However, the ascertainment of post-operative morbidity may be different in laparoscopy and open cases given the shorter hospital stays with laparoscopy. Further, when this relationship was evaluated among hospitals in the highest quartile of laparoscopic colon resection volume, the relationship was no longer significant suggesting procedure-specific experience may be related to this outcome.
These findings are comparable to outcomes achieved in clinical trials: similar overall post-operative morbidity and mortality between operative approaches with shorter hospitalizations among those treated laparoscopically.25–27
Similarly, a recent meta-analysis has suggested more frequent intra-operative complications with the laparoscopic approach.13
The fact that we did not observe a significant relationship between laparoscopy rate and higher postoperative morbidity or in-hospital mortality, is a noteworthy finding. As this procedure has moved from the more idealized environment of clinical trials to clinical practice, we observe similar results.
Prior hospital-level studies have evaluated outcomes after colon resection for cancer in terms of mortality, length of stay, and 30-day readmission rates. These studies were conducted primarily among the Medicare population in the late 1990’s and the correlation was with overall hospital volume. At that time, hospitals with higher case volumes were noted to have comparable mortality rates and length of stay, but lower 30-day readmission rates.28–30
In the current study, we found a trend toward improved, in-hospital outcomes, excluding mortality, with higher laparoscopy rates even while considering overall hospital volume. While we were unable to evaluate outcomes beyond the initial hospitalization, it has been suggested that laparoscopy may be associated with fewer hospital readmissions.31
This outcome warrants further investigation as to ensure shorter hospitalizations are not gained at the expense of more frequent readmissions.
These data suggest less dramatic benefits than have been previously described from patient-level analyses.14–16
This difference may be related to several factors. First, the identification of laparoscopy cases has changed since these prior studies were conducted. Whereas earlier studies combined diagnostic laparoscopy with open colectomy coding to define an “laparoscopic” case, newer studies can use unique coding to designate a laparoscopic case. Second, the use of observational data, particularly at the patient-level, is associated with limitations that can over-estimate treatment effects or lead to inaccurate conclusions.32–33
We believe a hospital-level analysis evaluating risk-standardized outcomes helps address some limitations of patient-level studies, including selection bias. By conducting the study at the hospital-level, patients are not selected by procedure, fewer differences are seen between the hospital populations, and hospital differences can be described using the hierarchical generalized linear models (HGLM). Further, a hospital-level analysis using HGLM helps account for variation in hospital performance which can be important predictors of outcomes in addition to patient-level factors.
The results of this study should be interpreted with several limitations in mind. First, although administrative data sets based on ICD-9-CM coding now allow for the identification of laparoscopic colon resections, more specific detail does not exist to indicate what proportion used hand-assist, single-incision, or were only partly completed laparoscopically. Therefore, we cannot comment on how the specific laparoscopic technique may influence outcomes. Second, we cannot determine cause and effect in this cross-sectional data, but rather suggest an association between the laparoscopy rate and outcomes. Further, we are unable to determine whether laparoscopic surgery improves outcomes beyond the initial admission using the current data set. Understanding how longer-term outcomes are influenced by the surgical approach, including readmission rates, emergency department visit rates, incisional hernias, or obstruction, should be further evaluated. Finally, the source of variation in outcomes seen across hospitals is multi-factorial. We examined only one factor which may contribute to this variation. Future studies should evaluate other factors so that best practices can be identified.
In conclusion, despite broad utilization of laparoscopic colon resection for cancer outcomes remain favorable with trends toward mildly lower risk-standardized postoperative complication rates and modestly shorter hospitalizations. While there was also a small increase in risk-standardized intra-operative morbidity, this did not appear to impact the patient’s overall hospital course and was not seen among hospitals with high procedure volume.