More than half of the 1000 surveyed records had at least 1 unnecessary test based on our institutional guidelines (Fig. 1, 95% lower CL = 52%). The finding motivated our national survey.
The 17 preoperative directors unanimously considered 36 of the 72 combinations of test or consult (“test”) and scenario to be unnecessary (Table 2). These 36 tests were designated the “unnecessary tests” for analysis of the following survey results.
Among the 175 anesthesiologists responding, 54% did not order an unnecessary test, and 24% ordered just one. The maximum was 10 unnecessary tests. The probability distribution of the number of unnecessary tests was geometric (χ2 test of fit P = 0.323), with the proportion unnecessary tests p = 50%. This finding is important because p is the geometric distribution's sole parameter. Thus, knowing the percentage of the physicians ordering at least 1 unnecessary test provides just as much information as the number of such tests. This is the basis for our subsequent analysis.
Comparison was made between anesthesiologists and gynecologists for the gynecology case, anesthesiologists and otolaryngologists for the otolaryngology case, etc (Tables 1 and 4). Anesthesiologists were 53% less likely to order at least 1 unnecessary test relative to gynecologists for the cystectomy scenario, 64% less likely than general surgeons for the herniorrhaphy scenario, 66% less likely than otolaryngologists for the thyroidectomy scenario, and 67% less likely than orthopedists for the hip replacement scenario. The 95% lower CLs were all >40%.
Of the specialty organizations queried, only the American College of Surgeons and the American Association of Orthopedic Surgeons responded. Both reported no guidelines regarding preoperative laboratory testing.
Because these results suggest value to anesthesiologists being engaged institutionally in preoperative testing, we explored how anesthesia departments can achieve consistent performance. Among 17 potential predictors studied, only year of training was statistically significant (Table 3). Anesthesiologists trained after 1979 were 48% less likely to order at least 1 unnecessary test than those completing training in or before 1979 (95% CL >29%).
More than half of our patients had at least 1 unnecessary test despite repeated dissemination of testing guidelines within the institution. This adds to the cost of health care, without appreciable benefit. Similarly, the national survey showed not even a suggestion of a benefit in reducing unnecessary tests from institutional or anesthesia department guidelines. Tests can become simply part of an expected routine.13 We recommend other facilities screen for unnecessary tests.
Our data suggest that institutions can reduce costs by having anesthesiologists order the preoperative tests, which is itself a function of anesthesiologists' institutional engagement.14 However, anesthesia groups should be cognizant of potential heterogeneity within groups based on time since training, because their younger physicians may be more cognizant of what are unnecessary tests.
The number of unnecessary tests per simulated patient followed a geometric distribution. This result reveals that the percentage of an anesthesiologist's patients with at least 1 unnecessary test may provide just as much information over a long period as the number of unnecessary tests per patient. Feedback on adherence to guidelines could be done simply by reporting to each anesthesiologist the percentage of his or her patients with any unnecessary tests. We recommend that future multicenter observational studies aim to confirm this result using real data from many hospitals, because guidelines alone have far less influence on anesthesiologists' behavior influencing costs15 than guidelines combined with individualized feedback.16–19
Many studies have demonstrated that routine preoperative testing rarely changes management or improves surgical outcome.1–4 History and physical examination, not laboratory testing, may be the most important components of a preoperative evaluation.20,21 The American Society of Anesthesiologists has stated that routine laboratory and diagnostic screening testing is unnecessary for asymptomatic patients.22 Chung et al.3 recently concluded that no laboratory tests are needed for healthy, ambulatory patients. We are unaware of any nationally accepted guidelines on preoperative testing. Strikingly, there was not a single test in Table 2 that the anesthesiologist directors of preoperative clinics unanimously agreed was necessary. In contrast, Table 2 shows consensus for many tests and labs for what is unnecessary. We considered the extremes of complete agreement as to what was unnecessary to enhance validity of our results, and followed up with sensitivity analysis as well (Table 4). Future studies should focus on mechanisms to establish more uniformly accepted guidelines for preoperative laboratory testing.
1. Haug RH, Reifeis RL. A prospective evaluation of the value of preoperative laboratory testing for office anesthesia and sedation. J Oral Maxillofac Surg 1999;57:16–20
2. Bryson GL, Wyand A, Bragg PR. Preoperative testing is inconsistent with published guidelines and rarely changes management. Can J Anaesth 2006;53:236–41
3. Chung F, Yuan H, Yin L, Vairavanathan S, Wong DT. Elimination of preoperative testing in ambulatory surgery. Anesth Analg 2009;108:467–75
4. Georges P, Kremer Y, Ledent M, Lechat JP, De Kock M. Does the KCE restrictive policy for preoperative testing lead to increased postoperative complications rate? Acta Anaesthesiol Belg 2010;61:5–11
5. Bass EB, Steinberg EP, Luthra R, Schein OD, Tielsch JM, Javitt JC, Sharkey PD, Petty BG, Feldman MA, Steinwachs DM. Do ophthalmologists and internists agree about preoperative testing in healthy patients undergoing cataract surgery? Arch Ophthalmol 1995;113:1248–56
6. Ferrando A, Ivaldi C, Buttiglieri A, Pagano E, Bonetto C, Arione R, Scaglione L, Gelormino E, Merletti F, Ciccone G. Guidelines for preoperative assessment: impact on clinical practice and costs. Int J Qual Health Care 2005;17:323–9
7. Larocque BJ, Maykut RJ. Implementation of guidelines for preoperative laboratory investigations in patients scheduled to undergo elective surgery. Can J Surg 1994;37:397–401
8. Mancuso CA. Impact of new guidelines on physicians' ordering of preoperative tests. J Gen Intern Med 1999;14:166–72
9. Fischer SP. Development and effectiveness of an anesthesia preoperative evaluation clinic in a teaching hospital. Anesthesiology 1996;85:196–206
10. Mosteller F, Youtz C. Tables of the Freeman-Tukey transformations for the binomial and Poisson distributions. Biometrika 1961;48:433–40
11. Dexter F, Marcon E, Epstein RH, Ledolter J. Validation of statistical methods to compare cancellation rates on the day of surgery. Anesth Analg 2005;101:465–73
12. Kahn RL, Stanton MA, Tong-Ngork S, Liguori GA, Edmonds CR, Levine DS. One-year experience with day-of-surgery pregnancy testing before elective orthopedic procedures. Anesth Analg 2008;106:1127–31
13. Velanovich V. How much routine preoperative laboratory testing is enough? Am J Med Qual 1998;8:145–51
14. Dexter F, Epstein RH. Calculating institutional support that benefits both the anesthesia group and hospital. Anesth Analg 2008;106:544–53
15. Horrow JC, Rosenberg H. Price stickers do not alter drug usage. Can J Anaesth 1994;41:1047–52
16. Cohen MM, Rose DK, Yee DA. Changing anesthesiologists practice patterns: can it be done? Anesthesiology 1996;85:260–9
17. Lubarsky DA, Glass PSA, Ginsberg B, Dear GDL, Dentz ME, Gan TJ, Sanderson IC, Mythen MG, Dufore S, Pressley CC, Gilbert WC, White WD, Alexander ML, Coleman RL, Rogers M, Reves JG; for the SWiPE group. The successful implementation of pharmaceutical practice guidelines: analysis of associated outcomes and costs savings. Anesthesiology 1997;86:1145–60
18. Freund PR, Bowdle TA, Posner KL, Kharasch ED, Burkhart VD. Cost-effective reduction of neuromuscular blocking drug expenditures. Anesthesiology 1997;87:1044–9
19. Overdyk FJ, Harvey SC, Baldwin D, Rust P, Multani M, Marcell J. Individualized outcome feedback produces voluntary antiemetic prescribing practice changes. J Clin Anesth 1999;11:17–23
20. Alsumait BM, Alhumood SA, Ivanova T, Mores M, Edeia M. A prospective evaluation of preoperative screening laboratory tests in general surgery patients. Med Princ Pract 2002;11:42–5
21. Roizen MF. Preoperative laboratory testing: necessary or overkill? Can J Anaesth 2004;51:R1–6
22. American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Practice advisory for preanesthesia evaluation: a report by the American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Anesthesiology 2002;96:485–96
Robert I. Katz, MD, helped design the study, conduct the study, analyze the data, and write the manuscript. This author has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files. Franklin Dexter, MD, PhD, helped analyze the data and write the manuscript. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript. Kenneth Rosenfeld, MD, helped design the study. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript. Laura Wolfe, BA, helped conduct the study. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript. Valerie Redmond, BA, helped conduct the study. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript. Deepti Agarwal, MD, helped conduct the study. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript. Irim Salik, MD, helped conduct the study. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript. Karen Goldsteen, PhD, helped design the study and analyze the data. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript. Melody Goodman, PhD, helped analyze the data. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript. Peter S.A. Glass, MB, helped design the study and write the manuscript. This author has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.
Franklin Dexter is the Statistical Editor and Section Editor for Economics, Education, and Policy for the Journal. This manuscript was handled by Steve Shafer, Editor-in-Chief, and Dr. Dexter was not involved in any way with the editorial process or decision.
Peter S.A. Glass is Section Editor of Ambulatory Anesthesiology for the Journal. This manuscript was handled by Steve Shafer, Editor-in-Chief, and Dr. Glass was not involved in any way with the editorial process or decision.