Orthopedic procedures and related treatment choices have recently been identified as a prime target for comparative effectiveness research.13
While the focus lies on the evaluation of the success of a number of surgical implants and procedures, the subject of perioperative outcomes and safety of competing clinical decision making processes has received less attention. In this context, orthopedic procedures represent a unique entity in so far as multiple component surgeries can be performed during the same or different surgical sessions, i.e. bilateral total hip and knee arthroplasty as well as combined circumferential spinal procedures. In view of the paucity of data comparing the perioperative outcomes of circumferential spine surgery performed on either the same or different days of the same hospitalization, this study sought to analyze this entity utilizing data from the largest all payer database in the US.
The results of this study revealed that staging circumferential spine surgical procedures during the same hospitalization resulted in an increased overall morbidity without lower mortality rates. Indeed, the odds of either of these events occurring were found to be 29% higher among the staged group when compared to the population undergoing surgery during one session. This relationship was sustained even after controlling for several confounding factors, including patient characteristics, hospital specific demographics, admission type, comorbidity burden and surgical pathology. Patient and hospital related factors that significantly increased the risk for perioperative morbidity and mortality were advanced age and procedures performed in rural and large hospitals, as were deformity and oncologic indications. Pulmonary circulatory disease and coagulopathies were associated with the highest increase in the adjusted risk for perioperative morbidity and mortality with regards to associated medical comorbidities.
Limited data is available comparing the perioperative outcomes of circumferential spine surgery performed on either the same or different days of the same hospitalization. The previously published literature consists mainly of case reports,3,14,15
and series limited by small numbers without a control group for comparison.16
Shufflebarger et al.17
noted greater correction of deformity in those procedures performed on the same day compared with separate days, which was also subsequently seen in later series.16
One of the largest series was published by Wright.18
Among 14 patients, half were treated as simultaneous circumferential reconstructions while the remainders were treated with staged procedures. The findings reported in this series included an 86% complication rate among the staged group compared to no complications seen in the simultaneous group, as well as significantly increased length of stay and total operative duration in the former population. Improved neurological outcomes were also evident in the simultaneous group as was a diminished blood loss (although this did not reach significance). However, the findings of this study may have limited generalizability given the small sample size and single institution design.
This study identified several distinct patient and health care system related demographic patterns between the two groups. Patients with emergent admissions, deformity, and traumatic surgical indications were more prevalent in the staged group. To our knowledge, this finding has not been previously reported in the spine literature and no direct comparison can be made with the total joint arthroplasty data, given the different nature of the surgery and the overwhelming majority of diagnoses falling into the degenerative disease category.2
In this context it is likely that emergent and traumatic admissions require treatment for associated injuries that are potentially life-threatening.19
This may limit the length and extent of surgery patients may tolerate at a single point in time. In addition, deformity cases are among the most complex and lengthy spinal procedures, which may predispose this patient population to a performance in a staged manner.16
Other differences noted between the two patient populations were that a higher proportion of admissions undergoing same day surgery were privately insured, and more staged procedures were performed in rural centers. Whether or not these differences are related to regional and/or economic disparities is beyond the scope of this study and merits further investigation.
Patient and hospital related factors that significantly increased the risk for perioperative morbidity and mortality were age over 65 years, and procedures performed in rural and large hospitals compared to urban and small institutions. Age greater than 65 years has been previously reported as a risk factor.1,20
It is thought that advanced age may be a risk factor for decreased end organ reserve. Interestingly, we noted that larger hospital size was associated with increased complication rates. Although high hospital volume has been associated with better outcomes in the past,1
the relationship between size and outcomes has not been studied in detail. We speculate that this may be related to the inclusion of higher severity cases among these institutions. However, this conclusion cannot be reached from the available data. The findings among rural hospitals is likely related to a decrease in available resources as noted above, although further investigation is needed to demonstrate this relationship.
Indications for surgery that were associated with increased odds of experiencing morbidity and mortality were scoliosis and oncologic pathologies. This finding appears to be consistent with earlier reports.14,16
Increased complication rates have been previously noted in severe scoliosis cases treated with an circumferential approach due to the complexity of the deformity, abnormal anatomy, and potentially diminished physiological reserve in certain patients.16
With regards to oncologic procedures, it has been theorized that diminished physical reserve, a weakened immune system, and adjuvant therapy contribute to a higher rate of perioperative complications among this group.12
Among comorbidities, pulmonary circulatory disease and coagulopathies were associated with the highest increase in the adjusted risk for perioperative morbidity and mortality. This is consistent with recent findings based on NIS data used to compare mortality based on surgical approaches.1
We hypothesized that patients with pulmonary hypertension and decreased right ventricular reserve may be less likely to deal with the consequences of pulmonary embolization of bone and marrow material during instrumentation, resulting in increases in pulmonary vascular resistance as shown in previous studies.21–23
It is intuitive that patients with coagulation abnormalities had increased complication rates. Although speculative, we attribute this to an increased propensity to bleeding complications, which have been associated with higher perioperative morbidity.23
Interestingly, diminished blood loss has been previously documented in small series of simultaneous vs. staged circumferential spine procedures as well.17
In the setting of increased national concerns over total health care expenditures, it is noteworthy that several potentially relevant health care related characteristics were found to be favorable in the simultaneous group relative to the staged group. Specifically, a higher proportion of same day operation recipients were discharged to their primary residence compared to staged patients, thus eliminating the need for additional costs related to stay at an extended care facility. This finding has not been reported, to our knowledge, in the previously published smaller series. As would be expected, the total length of hospital stay was significantly longer (approximately 3 days) for staged procedures compared to same day surgeries. This observation is consistent with the previous findings of Shufflebarger et al.17
and Dick et al.16
Although a direct cost-comparison analysis was not performed in this study, these findings are noteworthy and may provide basis for future studies. Further, our results should be viewed in the context increased complication rates in the staged group, which can be expected to increase health care expenditures.
There are several inherent limitations to our study. Because only in-patient data are collected for the NIS, complications and events that occurred after discharge are not captured. In addition, detailed clinical information regarding the surgical procedure (i.e. type of anesthesia, estimated blood loss, length of surgery etc.) available in the NIS is limited and controlling for these factors in the analysis may have influenced our results. While it cannot be excluded that data entry may be subject to some form of coding or reporting bias, there is no reason to believe that reporting should differ between groups within the database, thus exposing both groups to the same bias within the same data collection construct. Comparative analysis should therefore be less likely affected by such bias. Further, the performance of simultaneous circumferential surgery may not always be practical depending on the surgical skills and practice design of the treating surgeon, as well as the resources of the institution. Such procedures are physically demanding on the surgical team and require a large block of the surgeon’s schedule to be dedicated to the care of a single patient at one time. Several different surgical indications were included in our analysis thus representing a non-homogeneous population with inherent differences. We were careful to control for factors associated with high risk settings such as thoracic procedures, those involving trauma, scoliosis and oncologic indications as well as urgent and emergent surgeries in our initial analysis. In addition, we performed a secondary analysis excluding entries with the aforementioned characteristics without affecting our results and conclusions.
Additionally, the definition of complications utilizing ICD-9-CM diagnosis codes has its limitations and severity and exact details of such complications can often not be discerned. In order to test our hypothesis using a separate definition that focuses on major perioperative complications (cerebrovascular accident, pulmonary failure, cardiorespiratory arrest, pulmonary embolism, cardiac arrhythmias, myocardial infarction, sepsis and pneumonia) we reanalyzed data with this approach.24
We found that staged procedures were again associated with an increased rate (12.85% vs. 8.36%, P<0.0001) and risk (OR 1.30 (1.17; 1.45) of adverse outcome compared to procedures performed on the same day.
Lastly, it has to be mentioned that no causal relationships can be established with data available in the NIS. In the setting of many crucial clinical variables missing that influence medical care, our results of increased morbidity after staged procedures should not be used as a case against performing complex surgeries in multiple surgical sessions.