NIS vs SAGES: a comparison of national and voluntary databases

The National Hospital Discharge Survey and Nationwide Inpatient Sample: the databases used affect results in THA research

BACKGROUND

The National Hospital Discharge Survey (NHDS) and the Nationwide Inpatient Sample (NIS) collect sample data and publish annual estimates of inpatient care in the United States, and both are commonly used in orthopaedic research. However, there are important differences between the databases, and because of these differences, asking these two databases the same question may result in different answers. The degree to which this is true for arthroplasty-related research has, to our knowledge, not been characterized.

QUESTION/PURPOSES

We tested the following null hypotheses: (1) there are no differences between the NHDS and NIS in patient characteristics, comorbidities, and adverse events in patients with hip osteoarthritis treated with THA, and (2) there are no differences between databases in factors associated with inpatient mortality, adverse events, and length of hospital stay after THA.

METHODS

The NHDS and NIS databases use different methods of data collection and weighting to provide data representative of all nonfederal hospital discharges in the United States. In 2006 the NHDS database contained 203,149 patients with hip arthritis treated with hip arthroplasty, and the NIS database included 193,879 patients. Multivariable analyses for factors associated with inpatient mortality, adverse events, and days of care were constructed for each database.

RESULTS

We found that 26 of 42 of the factors in demographics, comorbidities, and adverse events after THA in the NIS and NHDS databases differed more than 10%. Age and days of care were associated with inpatient mortality with the NHDS and the NIS although the effect rates differ more than 10%. The NIS identified seven other factors not identified by the NHDS: wound complications, congestive heart failure, new mental disorder, chronic pulmonary disease, dementia, geographic region Northeast, acute postoperative anemia, and sex, that were associated with inpatient mortality even after controlling for potentially confounding variables. For inpatient adverse events, atrial fibrillation, osteoporosis, and female sex were associated with the NHDS and the NIS although the effect rates differ more than 10%. There were different directions for sources of payment, dementia, congestive heart failure, and geographic region. For longer length of stay, common factors differing more than 10% in effect rate included chronic pulmonary disease, atrial fibrillation, complication not elsewhere classified, congestive heart failure, transfusion, discharge nonroutine compared with routine, acute postoperative anemia, hypertension, wound adverse events, and diabetes mellitus, whereas discrepant factors included geographic region, payment method, dementia, sex, and iatrogenic hypotension.

CONCLUSIONS

Studies that use large databases intended to be representative of the entire United States population can produce different results, likely related to differences in the databases, such as the number of comorbidities and procedures that can be entered in the database. In other words, analyses of large databases can have limited reliability and should be interpreted with caution.

LEVEL OF EVIDENCE

Level II, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.

Reducing the burden of surgical harm: a systematic review of the interventions used to reduce adverse events in surgery

OBJECTIVE

To perform a systematic review of interventions used to reduce adverse events in surgery.

BACKGROUND

Many interventions, which aim to improve patient safety in surgery, have been introduced to hospitals. Little is known about which methods provide a measurable decrease in morbidity and mortality.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched from inception to Week 19, 2012, for systematic reviews, randomized controlled trials (RCTs), and cross-sectional and cohort studies, which reported an intervention aimed toward reducing the incidence of adverse events in surgical patients. The quality of observational studies was measured using the Newcastle-Ottawa Scale. RCTs were assessed using the Cochrane Collaboration's tool for assessing risk of bias.

RESULTS

Ninety-one studies met inclusion criteria, 26 relating to structural interventions, 66 described modifying process factors. Only 17 (of 42 medium to high quality studies) reported an intervention that produced a significant decrease in morbidity and mortality. Structural interventions were: improving nurse to patient ratios (P = 0.008) and Intensive Care Unit (ITU) physician involvement in postoperative care (P < 0.05). Subspecialization in surgery reduced technical complications (P < 0.01). Effective process interventions were submission of outcome data to national audit (P < 0.05), use of safety checklists (P < 0.05), and adherence to a care pathway (P < 0.05). Certain safety technology significantly reduced harm (P = 0.02), and team training had a positive effect on patient outcome (P = 0.001).

CONCLUSIONS

Only a small cohort of medium- to high-quality interventions effectively reduce surgical harm and are feasible to implement. It is important that future research remains focused on demonstrating a measurable reduction in adverse events from patient safety initiatives.

A comparison of pre-operative comorbidities and post-operative outcomes among patients undergoing laparoscopic nissen fundoplication at high- and low-volume centers

INTRODUCTION

Commonly cited data promoting laparoscopic Nissen fundoplication (LNF) as safe and efficacious are typically published by single centers, affiliated with teaching institutions with a high volume of cases, but LNF is not universally performed at these hospitals. The purpose of this study is to assess where these procedures are being done and to compare pre-operative comorbidities and post-operative outcomes between high-and low-volume centers using a state-wide inpatient database.

METHODS

This is a retrospective study using data from the North Carolina Hospital Association Patient Data System. Selected patients include adults (>17 years old) that have undergone laparoscopic Nissen fundoplication for gastroesophageal reflux disease as an inpatient from 2005 to 2008. Patients that underwent operative management for emergent purposes or had associated diagnoses of esophageal cancer or achalasia were excluded from the study. High-volume centers were defined as institutions that performed ten or more LNFs per year averaged over a period of 4 years. Comparative statistics were performed on comorbidities and complications between high- and low-volume centers.

RESULTS

A total of 1,019 patients underwent LNF for GERD in North Carolina between 2005 and 2008 in the inpatient setting. High-volume centers performed 530 LNFs (52%) while low-volume centers performed 489 LNFs (48%). Patients at high-volume centers were older (median 52.5 years old vs. 49.0 years old, p = 0.019), had a higher incidence of diabetes (13.4% vs. 8.8%, p = 0.026), chronic obstructive pulmonary disease (5.1% vs. 2.0 %, p = 0.015), hyperlipidemia (9.6% vs. 4.7%, p = 0.004), and cystic fibrosis (2.8% vs. 0.8%, p = 0.03). Patients with a history of transplantation were also more likely to undergo LNF at a high-volume center (15.8% vs. 1.6%, p < 0.0001). There were no deaths among the two groups and also no difference between median length of stay (2.7 days for high-volume center vs. 2.6 days for low-volume center). Low-volume centers had a higher incidence of intraoperative accidental puncture or laceration (3.3% vs. 0.9%, p = 0.017) while high-volume centers had a higher incidence of atelectasis (5.3% vs. 2.5%, p = 0.031).

CONCLUSION

A significant proportion of the LNFs in North Carolina are performed at low-volume centers. High-volume centers perform LNF on older patients with more comorbidities. Low-volume centers have three times more accidental perforations, yet there is no detectable difference in mortality or median length of stay. It is impossible to tell if these perforations are managed at these low-volume centers or transferred to facilities with a higher level of care. These findings argue for regionalization of LNF and for a reevaluation of the global safety of this operation.

Minimally invasive surgery is underutilized for colon cancer

BACKGROUND

The Clinical Outcomes of Surgical Therapy Group (COST) trial published in 2004 demonstrated that minimally invasive surgery (MIS) for colorectal cancer provided equivalent oncologic results and better short-term outcomes when compared to open surgery. Before this, MIS comprised approximately 3% of colorectal cancer cases. We hypothesized that there would be a dramatic increase in the use of MIS for colon cancer after this publication.

METHODS

The National Inpatient Sample database was used to retrospectively review MIS and open colon resections from 2005 through 2007. ICD-9-specific procedure codes were used to identify open and MIS colon cancer resections. Statistical analyses performed included Pearson χ(2) tests and dependent t tests, and Cramer's V was used to measure the strength of association.

RESULTS

A total of 240,446 colon resections were performed between 2005 and 2007. The percentage of resections performed laparoscopically increased from 4.7% in 2005 to 6.7% in 2007 for colon cancer and remained relatively unchanged for benign disease (25.2% in 2005 vs. 27.4% in 2007, P < 0.007). Patients undergoing laparoscopic colectomy were younger, had lower comorbidity scores, had lower rates of complications (20.1 vs. 25.1%, P < 0.001), had shorter lengths of stay (7.2 vs. 9.6 days, P < 0.001), and had lower mortality (1.5 vs. 3.0%, P < 0.001). Furthermore, when evaluating adoption trends, urban teaching hospitals adopted laparoscopy more rapidly than rural nonteaching centers.

CONCLUSIONS

Adoption of MIS for the treatment of colorectal cancer has been slow. Additional studies to evaluate barriers in the adoption of MIS for colon cancer resection are warranted.

Geographic variation in lumbar fusion for degenerative disorders: 1990 to 2000

BACKGROUND CONTEXT

Past studies have shown that proportion of lumbar fusion surgery to all forms of lumbar surgery is variable among geographic regions. At present, no studies have investigated whether fusion outcome is associated with geographic region.

PURPOSE

The purpose of this study was to examine the postoperative complication rate, postoperative mortality rate, hospital length of stay (LOS), hospital routine discharge rate, and total charges associated with surgical care across the geographic regions.

STUDY DESIGN/SETTING

Retrospective cohort study using national sample administrative data.

PATIENT SAMPLE

The study included 23,143 patients who underwent lumbar spine fusion surgery with a principal diagnosis of lumbar spine disease related to degeneration.

OUTCOME MEASURES

Functional measures included complication rate, mortality rate, and hospital LOS; routine discharge; and total charges for care.

METHODS

Selected variables from the Nationwide Inpatient Sample database were used for comparison across the geographic regions of the South, Midwest, Northeast, and West. Bivariate statistical analyses compared postoperative complication rates, mortality rates, hospital LOS, routine discharge rate, and total charges associated with surgical care across the geographic regions.

RESULTS

Significant differences in routine discharge (p<.001), cauda equina complications (p=.001), LOS (p<.001), and inflation-adjusted charges (p<.001) were found for the South and the West (demonstrated lower routine discharges and higher rates of complications involving cauda equina syndromes) and the Northeast and the Midwest (involved higher LOS than the South and the West but lower reported charges after adjustments for inflation).

CONCLUSIONS

The findings suggest that surgical fusion outcome is associated with regional variations. It is likely that patient selection and physician preferences are associated with these findings. Similar to variations in proportion of lumbar fusion surgery among geographic regions, outcomes for surgical fusions also vary across regions.