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Background National databases are being used with increasing frequency to conduct orthopaedic research. However, there are important differences in these databases, which could result in different answers to similar questions; this important potential limitation pertaining to database research in orthopaedic surgery has not been adequately explored. Questions/purposes The purpose of this study was to explore the interdatabase reliability of two commonly used national databases, the Nationwide Inpatient Sample (NIS) and the National Surgical Quality Improvement Program (NSQIP), in terms of (1) demographics; (2) comorbidities; and (3) adverse events. In addition, using the NSQIP database, we identified (4) adverse events that had a higher prevalence after rather than before discharge, which has important implications for interpretation of studies conducted in the NIS. Methods A retrospective cohort study of patients undergoing operative stabilization of transcervical and intertrochanteric hip fractures during 2009 to 2011 was performed in the NIS and NSQIP. Totals of 122,712 and 5021 patients were included from the NIS and NSQIP, respectively. Age, sex, fracture type, and lengths of stay were compared. Comorbidities common to both databases were compared in terms of more or less than twofold difference between the two databases. Similar comparisons were made for adverse events. Finally, adverse events that had a greater postdischarge prevalence were identified from the NSQIP database. Tests for statistical difference were thought to be of little value given the large sample size and the resulting fact that statistical differences would have been identified even for small, clinically inconsequential differences resulting from the associated high power. Because it is of greater clinical importance to focus on the magnitude of differences, the databases were compared by absolute differences. Results Demographics and hospital lengths of stay were not different between the two databases. In terms of comorbidities, the prevalences of nonmorbid obesity, coagulopathy, and anemia in found in the NSQIP were more than twice those in the NIS; the prevalence of peripheral vascular disease in the NIS was more than twice that in the NSQIP. Four other comorbidities had prevalences that were not different between the two databases. In terms of inpatient adverse events, the frequencies of acute kidney injury and urinary tract infection in the NIS were more than twice those in the NSQIP. Ten other inpatient adverse events had frequencies that were not different between the two databases. Because it does not collect data after patient discharge, it can be implied from the NSQIP data that the NIS does not capture more than 1 .

The aim of this study was to compare the operating time, length of stay (LOS), adverse events and rate of re-admission for elderly patients with a fracture of the hip treated using either general or spinal anaesthesia. Patients aged ≥ 70 years who underwent surgery for a fracture of the hip between 2010 and 2012 were identified from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. Of the 9842 patients who met the inclusion criteria, 7253 (73.7%) were treated with general anaesthesia and 2589 (26.3%) with spinal anaesthesia. On propensity-adjusted multivariate analysis, general anaesthesia was associated with slightly increased operating time (+5 minutes, 95% confidence interval (CI) +4 to +6, p < 0.001) and post-operative time in the operating room (+5 minutes, 95% CI +2 to +8, p < 0.001) compared with spinal anaesthesia. General anaesthesia was associated with a shorter LOS (hazard ratio (HR) 1.28, 95% CI 1.22 to 1.34, p < 0.001). Any adverse event (odds ratio (OR) 1.21, 95% CI 1.10 to 1.32, p < 0.001), thromboembolic events (OR 1.90, 95% CI 1.24 to 2.89, p = 0.003), any minor adverse event (OR 1.19, 95% CI 1.09 to 1.32, p < 0.001), and blood transfusion (OR 1.34, 95% CI 1.22 to 1.49, p < 0.001) were associated with general anaesthesia. General anaesthesia was associated with decreased rates of urinary tract infection (OR 0.73, 95% CI 0.62 to 0.87, p < 0.001). There was no clear overall advantage of one type of anaesthesia over the other, and surgeons should be aware of the specific risks and benefits associated with each type.

Study Design Retrospective cohort study of the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2005 to 2010 that included 1,861 patients who had undergone elective posterior lumbar fusion. Objective To characterize factors that were independently associated with increased hospital length of stay (LOS) in patients who had undergone elective posterior lumbar fusion. Summary of Background Data Posterior lumbar spine fusion is a common surgical procedure used to treat lumbar spine pathology. LOS is an important clinical variable and a major determinant of inpatient hospital costs. There is lack of studies in the literature using multivariate analysis to specifically examine the predictors of LOS after elective posterior lumbar fusion. Methods Patients who underwent elective posterior lumbar fusion from 2005 to 2010 were identified in the ACS-NSQIP database. Preoperative and intraoperative variables were extracted for each case and a multivariate linear regression was performed to assess the contribution of each variable to LOS. Results A total of 1,861 elective posterior lumbar fusion patients were identified. The average age for patients in this cohort was 60.6 ± 13.9 years (mean ± standard deviation [SD]) with a body mass index (BMI) of 30.3 ± 6.2 kg/m2. 44.7% of patients were male. LOS ranged from 0 days to 51 days. Multivariate linear regression identified age (p < 0.001), morbid obesity (BMI ≥ 40 kg/m2, p < 0.001), American Society of Anesthesiologists (ASA) class (p = 0.001), operative time (p < 0.001), multilevel procedure (p = 0.001), and intraoperative transfusion (p < 0.001) as significant predictors of extended LOS. Conclusion The identified preoperative and intraoperative variables associated with extended LOS after elective posterior lumbar fusion may be helpful to clinicians for patient counseling and postoperative planning.

As database studies become more prevalent in orthopaedic surgery, authors, reviewers, and readers should view these studies with caution. This study shows that two commonly used databases can identify demographically similar patients undergoing a common orthopaedic procedure; however, the databases document markedly different rates of comorbidities and inpatient adverse events. The differences are likely the result of the very different mechanisms through which the databases collect their comorbidity and adverse event data. Findings highlight concerns regarding the validity of orthopaedic database research.