ORIGINAL INVESTIGATION Self-reported Exercise Tolerance and the Risk of Serious Perioperative Complications Dominic F. Reilly, MD; Marguerite J. McNeely, MD, MPH; Diane Doerner, MD, PhD; Deborah L. Greenberg, MD; Thomas O. Staiger, MD; Michael J. Geist, MD; Philip A. Vedovatti, MD; John E. Coffey, MD; Marc W. Mora, MD; Timothy R. Johnson, MD; Eugenia D. Guray, MD; Gail A. Van Norman, MD; Stephan D. Fihn, MD, MPH Background: Impaired exercise tolerance during for- Results: Patients reporting poor exercise tolerance had mal testing is predictive of perioperative complications. more perioperative complications (20.4% vs 10.4%; However, for most patients, formal exercise testing is not P,.001). Specifically, they had more myocardial ische- indicated, and exercise tolerance is assessed by history. mia (P = .02) and more cardiovascular (P = .04) and neu- rologic (P = .03) events. Poor exercise tolerance pre- Objective: To determine the relationship between self- dicted risk for serious complications independent of all reported exercise tolerance and serious perioperative com- other patient characteristics, including age (adjusted odds plications. ratio, 1.94; 95% confidence interval, 1.19-3.17). The like- lihood of a serious complication occurring was inversely Methods: Our study group consisted of 600 consecu- related to the number blocks that could be walked tive outpatients referred to a medical consultation clinic (P= .006) or flights of stairs that could be climbed (P = .01). at a tertiary care medical center for preoperative evalu- Other patient characteristics predicting serious compli- ation before undergoing 612 major noncardiac proce- cations in multivariable regression analysis included his- dures. Patients were asked to estimate the number of tory of congestive heart failure, dementia, Parkinson dis- blocks they could walk and flights of stairs they could ease, and smoking greater than or equal to 20 pack-years. climb without experiencing symptomatic limitation. Pa- tients who could not walk 4 blocks and climb 2 flights Conclusion: Self-reported exercise tolerance can be used of stairs were considered to have poor exercise toler- to predict in-hospital perioperative risk, even when us- ance. All patients were evaluated for the development of ing relatively simple and familiar measures. 26 serious complications that occurred during hospital- ization. Arch Intern Med. 1999;159:2185-2192 ISK ASSESSMENT is an impor- tive complications.12-17 McPhail et al13 tant component of the pre- showed that among patients undergoing operative evaluation. It is vascular surgery, those with a good per- used in planning periop- formance during treadmill testing or arm erative treatment1 and to ergometry had fewer postoperative car- help shape decisions about the advisabil- diovascular complications. In addition, R 2 12,17 ity and extent of surgery. Factors consid- Gerson et al showed that geriatric pa- ered in assessing an individual’s risk for tients who were unable to exercise for 2 surgery include the nature of the proce- minutes with supine bicycle ergometry had dure to be performed and the severity of more cardiovascular and pulmonary com- comorbid medical problems. Prolonged plications. Other studies, in highly se- procedures3-5 and those with significant lected populations, have also shown that physiologic stress3,6,7 (eg, thoracic sur- patients who perform poorly on standard- gery) are associated with increased risk. ized testing have a worse prognosis after From the Division of General The presence and severity of medical ill- surgery.14-16 Internal Medicine (Drs Reilly, ness correlate with an increased risk for Unfortunately, formal exercise test- McNeely, Doerner, Greenberg, perioperative complications,6-11 espe- ing is expensive, time-consuming, and not Staiger, Geist, Vedovatti, cially in the setting of emergent surgery.7 specifically indicated for most patients. As Coffey, Mora, Johnson, Guray, and Fihn) and the Department Exercise tolerance may be another im- a result, clinicians usually determine a pa- of Anesthesiology portant factor to consider when assess- tient’s exercise tolerance from the pa- 1,2 (Dr Van Norman), University ing a patient’s surgical risk. Patients with tient’s history. Patients are asked to de- of Washington Medical Center, poor exercise tolerance on formal testing scribe the nature and frequency of their Seattle. have been shown to have more periopera- physical activities. This is then considered ARCH INTERN MED/ VOL 159, OCT 11, 1999 WWW.ARCHINTERNMED.COM 2185 ©1999 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/02/2021 PATIENTS AND METHODS We asked each patient to estimate the number of blocks they could walk (0-4) on level ground and the number of flights of stairs (0-4) they could climb without experienc- The study was conducted at the University of Washington ing symptomatic limitation. We chose these measures for Medical Center, Seattle, a 450-bed academic medical cen- their simplicity and familiarity to the average clinician (they ter providing tertiary surgical and medical care to the resi- are similar to the Canadian classification system used for dents of the northwestern United States. All outpatients aged quantifying the severity of angina6). Limiting symptoms were 18 years and older referred to the medical consulting ser- recorded when available. Complete exercise tolerance in- vice clinic for preoperative consultation prior to noncar- formation was unavailable for 4 patients. These patients were diac surgery from October 17,1995, through June 9,1997, conservatively classified as having poor exercise tolerance were eligible to participate. All participants provided writ- for the purposes of analysis. There was a higher rate of com- ten informed consent. The study was approved by our in- plications in the group with poor exercise tolerance when stitutional review committee. these 4 patients were excluded from analysis. A atient was considered to have a medical problem if PATIENTS 2 or more of the following criteria were satisfied: history consistent with the diagnosis, supportive physical find- Patients were referred to the clinic by the surgical team or ings, positive diagnostic test results, or treatment for the by anesthetists when they had concerns about the pa- illness. Patients were classified as having ventricular ar- tient’s medical problems. Approximately 15% of patients rhythmias when they had more than 5 premature ventricu- undergoing surgery at the University of Washington are re- lar contractions per minute.7 The diagnosis of obstructive ferred to the clinic for preoperative evaluation. Of the 951 lung disease included patients with either emphysema or consecutive patients referred to the clinic during the study asthma. A patient’s age was calculated as of the day of period, 896 (94%) consented to participate. Of these, 229 surgery. Goldman7 and Detsky6 scores were calculated (26%) were undergoing a minor procedure and were ex- for all patients, using previously published definitions cluded. Minor procedures, defined as those with mini- (Appendix 1 and Appendix 2). mum risk for serious complications,6 included biopsy, cen- If a patient’s surgical procedure was directly related tral venous catheter placement, lumpectomy without node to the treatment or diagnosis of a possible malignant neo- dissection, transurethral resection of the prostate or blad- plasm, it was considered to be oncology related. The Ameri- der tumor, inguinal hernia repairs, and all ophthalmo- can Society of Anesthesiologists (ASA) classification11,19 was logic procedures except enucleation. assigned by the attending anesthesiologist on the day of sur- Of the 667 patients having major procedures, 67 (10%) gery (Table 1). Anesthesia data were obtained from the had their procedures canceled, leaving 600 patients to form Department of Anesthesia’s existing quality improvement our study group. Procedures were considered to be can- database or the anesthesia record. The length of stay was celed if not scheduled at the University of Washington Medi- calculated from the date of surgery until discharge. Length cal Center within 90 days of the evaluation. Twelve pa- of stay data for 3 patients admitted to the physiatry ward tients underwent 2 procedures, each with a distinct directly after surgery were excluded. Their long hospital admission and discharge. To be as inclusive as possible, all stays (25, 88, and 99 days) were planned in advance and analyses were based on 612 procedures. Reanalysis using reflected, in large part, their need for other services. only 1 procedure per patient (n = 600) while randomly ex- cluding 12 procedures resulted in no appreciable change PERIOPERATIVE COMPLICATIONS in the results. A list of perioperative complications and their definitions DATA COLLECTION was composed before the study was started (Table 2). Five major categories of complications were established: Each patient provided an extensive history and under- cardiovascular, pulmonary, neurologic, infectious, and went a thorough physical examination. These evaluations miscellaneous. We also recorded deaths, unexpected were conducted by an attending internist or a senior medi- transfers to the intensive care unit (ICU) or cardiac telem- cal resident. Outside records were sought and preopera- etry ward, and activation of the medical center’s emer- tive testing was ordered as clinically indicated. No addi- gency response system (code blue). Other complications tional testing