Routine laboratory testing in the elderly: is it indicated?

Over the past decade, there has been a clear and conscious effort to define the indications for laboratory testing before surgery. Up through much of the 1980s, there was a standard battery of tests that was considered routine and required for all but the simplest of procedures (1). The last decade has witnessed a marked change in this approach, in part because of economic pressures but also because there is a better understanding of the meaning and predictive value of abnormal tests (2–5). Clearly, there is an imperative today to limit preoperative testing to those that are “indicated. ” One such frequently cited indication has been advanced age. The study by Dzankic et al. (6) in this issue of Anesthesia & Analgesia clearly adds to the data regarding indications for preoperative diagnostic laboratory testing. To understand how the indications for preoperative testing have evolved, it is important to review the history of preoperative testing research. Of note, the American Society of Anesthesiologists (ASA) had attempted to develop Practice Parameters on preoperative testing, but after an extensive review of the literature, they settled instead on producing a Practice Advisory. Why was this route taken? The simplest answer is the lack of strong evidence. Until recently, there have been no randomized trials designed to determine the utility of preoperative laboratory data. Virtually all of the literature in this field has reported on prospective cohort studies and case series that have evaluated outcomes (morbidity, mortality, and perioperative management changes) in patients who have and/or have not had specific laboratory tests (7). Using a standard for evidence of the randomized clinical trial, the initial Task Force on Preoperative Testing did not find sufficient evidence to advocate any specific testing. Importantly, the lack of evidence regarding specific tests is not evidence that there is no value to testing (8). That is to say, there is insufficient evidence to either advocate routinely performing any given test or to clearly define preoperative tests that are without value. Therefore, more data are needed. Of note, strong evidence regarding the value of preoperative testing has recently been published in the form of a large-scale randomized trial. Schein et al. (9) performed a study of almost 20,000 patients undergoing cataract surgery who were randomized to either routine laboratory testing or no-routine testing. They reported no difference in perioperative morbidity and mortality between those who did versus those who did not receive routine testing. In interpreting the study, it is important to take into account some of the comments made by Roizen (10) in his accompanying editorial. Specifically, all of these patients were evaluated by their primary medical doctor and therefore deemed to be in optimal medical condition to undergo elective cataract surgery. Patients in their no-routine testing group underwent tests “when the history or a finding on physical examination would have indicated the need for a test even if surgery had not been planned. ” Schein et al. (9) excluded patients who required medical care with laboratory testing within 28 days before enrollment. Second, the actual rates of morbidity and mortality are exceedingly low after cataract surgery and therefore few if any interventions could be shown to statistically affect outcome. Therefore, the ability to generalize these results beyond this setting (low-risk surgery performed under conscious sedation) is limited. In the absence of more generalizable randomized clinical trial data, what is the best method to define the value of a test? Several studies have focused on the lack of morbidity associated with the elimination of tests in healthy subjects, yet few focus on patients with known risk factors other than cardiopulmonary disease (1–4). In virtually all risk indices, including the ASA physical status classification, advanced age (.70 yr) is defined as a high risk or high classification group (11,12). Therefore, age is frequently used as an indication for routine testing. In this issue of Anesthesia & Anlagesia, Dzankic et al. (6) attempt to address the implications of advanced age using a prospective cohort study of a consecutive group of patients . 70 yr of age undergoing noncardiac surgery requiring general Accepted for publication April 16, 2001. Address correspondence to: Lee A. Fleisher, MD, The Johns Hopkins Hospital, 600 N. Wolfe Street, Carnegie 280, Baltimore, MD 21287. Address e-mail to lfleishe@jhmi.edu.