In this study, we found that the rate of preoperative IABP placement in patients awaiting CABG was significantly higher when the patient was admitted on a weekend (Saturday/Sunday) compared to a weekday. To our knowledge, this is the first study to investigate the association between day of admission and the rate of IABP placement.
Variation as an indicator of healthcare quality is a novel goal of investigation, with the aim of improving patient-centered care by removing variability based on non-clinical factors. There have been few examples looking at variations in practice patterns by non-clinical factors. The most notable example is from the Dartmouth Atlas of Healthcare which found significant variations in practice patterns across geographic regions in the U.S.  Similarly, variations in Cesarean section delivery rates were found across different days of the week . Many factors have been speculated to cause practice pattern variations along non-clinical factors, such as convenience, financial incentive, market competitions, and so on. Most of this literature focuses on procedures that are discretionary and less invasive. We extend this line of investigation to cardiac surgery which, as a complex procedure, would be thought to be controlled under strict clinical guidelines and not be influenced by non-clinical factors.
Previous studies have investigated the effect of day of admission on the clinical outcomes of various procedures. However, the literature is mixed regarding surgical outcomes when comparing weekend to weekday admission. For example, Baid-Agrawal and colleagues examined the outcomes of renal transplantation when performed on a weekend versus a weekday using the UNOS database. They concluded that the outcomes for deceased donor kidney transplantation in the US were not affected by the day of surgery . This is in contrast to the findings of Glance and colleagues who utilized the Healthcare Cost and Utilization Project Nationwide Inpatient Sample (HCUP NIS) to evaluate patients undergoing major surgeries, including CABG, to determine if they were more likely to die or experience a major complication when the surgery was performed on a weekend compared to a weekday. The investigators determined that patients undergoing non-emergent major cardiac and non-cardiac surgery on a weekend had a significantly increased risk of death and major complications compared to those undergoing surgery on a weekday . This raises the question of potential system-based and non-clinical factors associated with a “weekend effect.” Our study differs and expands on this work by focusing on variations in the rate of procedure, in addition to clinical complications and mortality. Variation itself is the primary outcome because it indicates a lack of standardization in clinical practice for reasons not explained by a specific clinical indicator.
Our focus on non-clinical variation as an outcome is critical in improving the quality of care that patients receive. Placement of IABPs are associated with many risks, such as major limb ischemia and mortality . Medically unnecessary procedures subject patients to risks with no clinical benefit. Ensuring the appropriateness of any clinical procedure is vital to improving healthcare quality. The existence of this variation in IABP procedure rates among days of the week indicates that the application of an invasive procedure is not only widely variable amongst institutions, but is highly subject to non-clinical factors and is impacted by day of week variability. Healthcare decisions should be evidence-based and patient centered. It is important that non-clinical factors are minimized in the administration of healthcare.
The need to minimize non-clinical factors is highlighted by several interesting ancillary findings found in this study. For example, we found evidence of disparity along race and insurance status. Black populations were less likely to receive IABPs compared to white populations despite no difference in clinical presentation. We also found that insurance status was a predictor for IABP placement. This is consistent with a growing body of literature on surgical disparities. Even though the investigation into these other disparities is beyond the scope of this study, the existence of these non-clinical influences underlines a concern regarding the influence of non-clinical factors on practice patterns.
This study has certain strengths and limitations. One major strength is the large sample size captured by use of a statewide database. The OSHPD database is powerful and allowed us to evaluate a wide range of both clinical and non-clinical data over a five-year period. This afforded us the ability to exclude comorbidities that serve as clear clinical contraindications to placement of IABP. Because of the large and diverse population, we could control for a variety of different factors which were further stratified to determine significant differences between groups. This study is subject to the inherent limitations of a retrospective database analysis. Large administrative databases often lack clinical granularity and there is a potential for a substantial amount of residual confounding. This precludes us from making sweeping conclusions about the nature of our findings and makes salient the need for further investigations. These investigations must capture other relevant and individual information that was not captured in OSHPD, such as STS scores, urgency of clinical intervention, and any other relevant and individualized clinical influences that cannot be captured on a broader scale. Similarly, because OSHPD does not provide the data necessary to distinguish between emergent, elective, and urgent patient cases, this study was unable to stratify on the basis of severity and urgency of cases. Additionally, as this topic is subject to the bias of surgeon and interventional cardiologist, a specific limitation is the inability to account for physician preference and practice technique which may confound the results. This is an important consideration, as there may be a variety of factors which may preclude a patient from undergoing an operation on a weekend, including surgeon preference, operating room time and staff availability, and hospital policies. Furthermore, the age of the data (2006–2010) available from the database limits the scope of our findings and warrants further investigations to determine if this trend has held. These types of factors will be critical to understand in future investigations to quantify and identify practice pattern variability based on weekday versus weekend admission. In addition, it will be important to investigate if financial or patient outcomes are affected by these decisions. We were also unable to account for a potential “weekday bias” among patients. We were unable to measure whether patients with less-serious cases do not admit themselves into the hospital on weekends, which would therefore create a weekend population of patients who present a more intense morbidity and therefore cannot avoid going to the hospital. Therefore, further qualitative research should investigate the role of patient behaviors on this weekend effect to determine the best way to standardize the procedure.
Our study has important implications. The discovery of this trend indicates the need for further investigations into the clinical reasons given for placement of IABP and may reflect an underlying disagreement with current practice guidelines. Future guideline refinement should ensure broad-based input in the development process to ensure larger buy-in, and thus broader compliance. It has been shown that the process by which consensuses are developed may influence the results and acceptability of the results. For example, details such as how consensus is defined, how disagreement is handled, and how sensitive the group is to process issues may all impact the ultimate acceptability of the proposed guideline. Additionally, given our findings, it is important to suggest guidelines for placement of IABP. Patients should have IABP placed if they present with unstable angina, active and on-going chest pain, cardiogenic shock, and have favorable femoral arterial anatomy for placement of IABP. IABP should not be placed due to concern over high risk anatomy, in unfavorable femoral arterial configurations, or in patients without active chest pain on presentation. Inasmuch, the care of patients who present with cardiac conditions has increasingly become more team based and multidisciplinary. It is important to assess patients on an individualized basis, and in those with coronary disease, utilize the institutional heart team to ensure the highest quality care. Using this multi modality approach ensures that the patient not only receives the most appropriate pre-procedural care, but also the best revascularization strategy, be it surgical or PCI for the patient.