Using Database Research to Affect the Science and Art of Medicine

IN the current issue of ANESTHESIOLOGY, Turan et al. 1 report on research employing a massive healthcare database to determine the effects of prolonged corticosteroid use on intraoperative blood replacement in noncardiac surgical patients. Database research is a growing trend in medicine, influenced by the rich collections of computerized data that are part and parcel of efforts to better record and access patientand healthcare-delivery information. Low funding rates for competitive grants and the stigma attached to research funding from the pharmaceutical and device industries are steering investigators away from high-budget prospective studies. Collectively, these factors will continue to move creative, energetic researchers toward database research to address the science and art of contemporary medicine. For database research to function optimally, it must have several critical elements: (1) the parent database must contain meticulously collected and recorded data, (2) the database should be exposed to periodic audits or other quality-assurance exercises, (3) the research should begin with an evidence-based hypothesis, (4) the numbers should provide adequate statistical power, and (5) if possible, a given research project should contain secondary information that validates the credibility of the research. Using these criteria, the research of Turan et al. scores well. As reviewed by Turan et al., there is some evidence in the literature that corticosteroids per se affect the underpinnings of blood coagulation; however, the nature of these alterations make it difficult to predict the direction and magnitude on clinical hemostasis. Offsetting any uncertainty is an appreciation that patients with prolonged corticosteroid excess (e.g., Cushing syndrome) have a propensity to bruise. Turan et al. addressed the hypothesis that long-term steroid use will affect intraoperative blood transfusion by probing the massive 363,897-patient American College of Surgeons National Surgical Quality Improvement Program database. After applying exclusion criteria to eliminate patients who would unduly confound data interpretation (e.g., those having disseminated cancer, perioperative infections, known bleeding disorders), the researchers were left with 296,059 patients (or 81% of the original). Thereafter, the investigators identified 7,760 patients who were taking steroids preoperatively for any reason, and they offered a detailed description of baseline patient characteristics and a cursory calculation of the transfusion requirements compared with 288,299 patients who were not taking steroids. However, the forte of the Turan et al. research was that the investigators were able to use sophisticated patient-matching techniques to pair 6,350 steroid users with the same number of highly comparable patients not taking steroids. The quality of patient matching (quantified in tables 1 and 2) and the approach to data analysis are exemplary. Based on their research, Turan et al. were able to determine, perhaps better than any other researchers to date, that long-term corticosteroid use, per se, has no meaningful independent effect on intraoperative blood transfusion in noncardiac surgical patients. By using blood transfusion records as an endpoint for bleeding tendency, the authors removed some of the errors inherent to assessing blood loss. If there were clinical shortcomings linking blood loss and blood replacement (e.g., undertransfusion or overtransfusion), Turan et al. did not report whether these correlated with adverse cardiovascular and neurologic outcomes. Lest readers have concerns that, by matching patients so rigorously between the steroid and nonsteroid groups, the authors abolished the potential for identifying any corticosteroid effect, the Turin et al. research had positive results as well: steroid users were more likely to experience 30-day postoperative systemic infections and postoperative wound infections. Such findings increase the believability of the overall study results. One of the peculiarities of the Turin et al. research is that by highly focusing the research on the isolated effects of steroids, independent of confounding baseline disease states, the research improved its scientific authority but may have diminished its relevance to practicing anesthesiologists. Specifically, anesthesiologists are probably less interested in knowing whether steroids per se enhance bleeding than in being able to answer the question, “If I have a patient whose disease state warrants the long-term use of steroids, will that patient experience increased perioperative blood loss and, if so, how should I better prepare for monitoring and replacing that blood loss?” Here, there is an amusing relationship be-