Preoperative Laboratory Testing in Patients Undergoing Elective, Low-Risk Ambulatory Surgery Jaime Benarroch-Gampel, Kristin M. Sheffield, Casey B. Duncan, Kimberly M. Brown, Yimei Han, Courtney M. Townsend, Jr., and Taylor S. Riall Department of Surgery Center for Comparative Effectiveness and Cancer Outcomes The University of Texas Medical Branch Galveston, TX Which of the following preoperative laboratory test is routinely indicated in an 80 years old male undergoing low-risk ambulatory surgery A.Complete blood count B.Chemistry panel C.Coagulation tests D.All of the test E.None of the test Preoperative Testing in Ambulatory Surgery INTRODUCTION • Ambulatory surgery – <1-2 hours in duration – Low expected blood loss – Low complication rates – Minimal expected postoperative care – Performed in patients with no medical problems or stable chronic medical conditions • 60-70% of procedures in the U.S. performed in the ambulatory setting Preoperative Testing in Ambulatory Surgery INTRODUCTION • Potential benefits of preoperative testing – Predicting patient risk for postoperative complications – Screening for unsuspected abnormalities – Establishing baseline values for tests that may change after surgery – Providing medical-legal protection Preoperative Testing in Ambulatory Surgery INTRODUCTION • Potential risks of preoperative testing – Cost: estimated between 3-18 billion – Increased pain and inconvenience – Anxiety for patients – Abnormal results in some cases are of questionable clinical significance – Harm to patients due to overtreatment of false-positive results – Medical-legal risk Preoperative Testing in Ambulatory Surgery INTRODUCTION • Current recommendations based on 2002 Practice Advisory from American Society of Anesthesiologists (ASA) – Based on expert opinion and underpowered studies – Inconsistencies between societies – Imprecise language • Many advocate against routine testing • Fail to outline clear and consistent guidelines for specific tests Preoperative Testing in Ambulatory Surgery INTRODUCTION INDICATION Advanced age Bleeding disorders Hg/CBC Creatinine Electrolytes LFTs ASA OPTG ASA Cardiovascular disease Renal disease CAS OPTG CAS OPTG Liver disease CAS OPTG Hypertension OPTG Diabetes Smoking Alcohol abuse OPTG OPTG OPTG Albumin Coagulation Parameters OPTG ASA CAS OPTG CAS OPTG CAS OPTG OPTG ASA CAS OPTG ASA OPTG ASA CAS OPTG OPTG OPTG CAS OPTG CAS OPTG ASA: American Society of Anesthesiologists, CAS: Canadian Anesthesiologists’ Society, OPTG: Ontario Preoperative Testing Grid, LFT: Liver Function Tests Preoperative Testing in Ambulatory Surgery OBJECTIVES • Use population-based data (NSQIP) to: – Describe the current use of preoperative testing in elective, low-risk ambulatory surgery • All patients • Subgroup with no comorbidities – Identify patient factors associated with preoperative testing – Evaluate the association between preoperative testing and 30-day outcomes Preoperative Testing in Ambulatory Surgery METHODS Data Source • National Surgical Quality Improvement Program Participant Use Data File (PUF) • Study period: 2005-2010 • Contains 240 variables: – Patient characteristics – Procedure characteristics • Anatomic site • Open vs. laparoscopic • Initial vs. recurrent Preoperative Testing in Ambulatory Surgery METHODS Cohort Selection • Inclusion criteria: – >18 years old – Elective hernia repair (CPT codes) • • • • Inguinal hernia (49505, 49520, 49525, 49650, 49651) Umbilical hernia (49585) Epigastric hernia (49570) Femoral hernia (49550, 49555) – Same day admission – No surgery in previous 30 days – No additional surgical procedures at time of hernia repair Cohort Selection (continued) Preoperative Testing in Ambulatory Surgery METHODS Laboratory Testing • Preoperative testing defined as testing in the 30 days up to and including surgery • Normal values were defined using our institutional laboratory ranges LFTs Hematology Chemistry Coagulation Hematocrit WBC Platelets Sodium BUN creatinine PT PTT INR Albumin Total bilirubin AST Alkaline phosphatase 92% 90% 77% 89% Preoperative Testing in Ambulatory Surgery METHODS • Additional outcome variables: – Major complications: unplanned intubation, PE, stroke, coma >24h, acute renal failure, MI, cardiac arrest, sepsis/septic shock, blood transfusions, or death – Wound-related complications: superficial and deep surgical site infections, organ space infections, and wound dehiscence Preoperative Testing in Ambulatory Surgery METHODS Statistical Analysis • Use of preoperative testing described • Chi-square to compare categorical variables and T-test to compare continuous variables • Multivariate logistic regression models used to determine: – Factors associated with preoperative testing – Association between • Preoperative testing and 30-day outcomes • Abnormal results and 30-day outcomes RESULTS Demographics and Procedures NO LABS (N=26,619) 36% LABS (N=46,977) 64% PATIENT CHARACTERISTICS Age 48.6 ± 16.0 yrs 57.7 ± 15.9 yrs Male gender 84.3% 84.4% White 82.7% 79.5% ASA Class 3 11.4% 26.0% At least 1 comorbidity 56.6% 71.1% PROCEDURE DETAILS General anesthesia 76.1% 78.1% 72.6% 74.5% Inguinal hernia Laparoscopic repair 17.3% 18.4% Recurrent hernia 6.7% 7.3% P-value <0.0001 0.66 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 0.0002 0.001 Preoperative Testing in Ambulatory Surgery RESULTS Preoperative Testing Use Preoperative Testing in Ambulatory Surgery RESULTS Preoperative Testing Use OVERALL COHORT (N=73,596) % Use % Abnormal Any Test 63.8% 61.6% Hematology 58.6% 39.3% Chemistry 53.5% 40.2% Coagulation 18.7% 11.3% LFT 23.7% 22.8% Preoperative Testing in Ambulatory Surgery RESULTS Preoperative Testing Use SUBGROUP WITHOUT COMORBIDITIES N=25,146 (34% of overall cohort) % Use % Abnormal Any test 54.0% 54.1% Hematology 51.8% 36.2% Chemistry 41.8% 33.0% Coagulation 14.8% 5.9% LFT 19.6% 18.4% Preoperative Testing in Ambulatory Surgery RESULTS Preoperative Testing Use SAME-DAY TESTING N=7,209 (9.7% of overall cohort) % Use % Abnormal Any Test 100.0% 61.6% Hematology 86.0% 41.9% Chemistry 76.5% 40.9% Coagulation 35.4% 22.9% LFT 25.8% 33.2% Preoperative Testing in Ambulatory Surgery RESULTS Preoperative Testing Use Age group All patients Younger than 20y 21y – 30y 31y – 40y 41y – 50y 51y – 60y 61y – 70y 71y – 80y Older than 81y 34.9% 42.1% 47.9% 56.5% 66.2% 73.8% 79.5% 83.2% Without comorbidities 33.5% 40.0% 43.7% 49.9% 58.5% 66.3% 71.8% 75.0% RESULTS Multivariate Analysis: Factors Predicting Testing • Factors associated with receipt of testing across all test types: – – – – – – – – – – Increased age Black or Hispanic race ASA class 2 and 3 Receipt of general anesthesia Laparoscopic procedures Hypertension Diabetes Ascites Bleeding disorders Steroid use RESULTS Adverse Outcomes and Testing • Major complications: 0.3% (N=239) • Wound complications: 0.8% (N=567) Major Complications OR 95% CI OVERALL COHORT Wound-Related OR 95% CI Hematology 1.17 (0.88 – 1.56) 0.99 (0.83 – 1.18) Chemistry 1.30 (0.97 – 1.75) 1.03 (0.87 – 1.24) Coagulation 1.25 (0.93 – 1.67) 1.05 (0.84 – 1.30) LFT 1.02 (0.77 – 1.36) 1.07 (0.88 – 1.30) Preoperative Testing in Ambulatory Surgery RESULTS Adjusted Outcomes: Tested vs. Not Tested Major Complications Wound-Related OR 95% CI OR 95% CI SUBGROUP WITHOUT COMORBIDITIES Hematology 0.77 (0.40 – 1.49) 1.36 (0.91 – 2.03) Chemistry 1.00 (0.52 – 1.96) 1.35 (0.91 – 2.02) Coagulation 1.38 (0.63 – 3.05) 1.04 (0.60 – 1.78) LFT 0.94 (0.42 – 2.08) 1.07 (0.66 – 1.75) Preoperative Testing in Ambulatory Surgery RESULTS Adjusted Outcomes: Abnormal vs. Normal Tests Major Wound-related OR 95% CI OR 95% CI ABNORMAL vs. NORMAL (Tested patients only) Hematology 1.29 (0.95 – 1.75) 0.96 (0.76 – 1.20) Chemistry 1.28 (0.93 – 1.75) 1.15 (0.90 – 1.46) Coagulation 1.52 (0.81 – 2.53) 1.16 (0.66 – 2.08) LFT 1.50 (0.90 – 2.49) 1.14 (0.79 – 1.65) Preoperative Testing in Ambulatory Surgery LIMITATIONS • Selection bias • Unable to identify patients who had changes in planned surgery or repeat testing due to abnormal results • NSQIP does not report all tests types • Unable to identify ordering physician nor can we evaluate variation among providers Preoperative Testing in Ambulatory Surgery MEDICARE TESTING RATES HERNIA REPAIR Test All patients (N=13,029) No comorbidities (N=3,187) Any test 84.5% 78.9% CXR EKG 43.5% 38.1% 62.0% 59.5% Hg/Hematocrit 53.1% 51.8% 49.6% 48.3% Creatinine Electrolytes 27.0% 23.2% 53.6% 48.2% LFTs 35.2% 16.2% 30.9% 9.2% Platelets Coagulation Preoperative Testing in Ambulatory Surgery MEDICARE TESTING RATES ARTHROSCOPY Test All patients (N=21,993) No comorbidities (N=5,515) Any test 81.2% 73.4% CXR EKG 41.0% 34.9% 57.6% 51.0% Hg/Hematocrit 57.3% 54.1% 49.1% 46.0% Creatinine Electrolytes 29.9% 24.9% 60.6% 50.4% LFTs 35.9% 18.8% 27.9% 12.4% Platelets Coagulation Preoperative Testing in Ambulatory Surgery MEDICARE: VARIATION IN TESTING Preoperative Testing in Ambulatory Surgery MEDICARE: GEOGRAPHIC VARIATION Preoperative Testing in Ambulatory Surgery SUMMARY • Preoperative testing is overused • Increased age was associated with increased rates of preoperative testing irrespective of presence of comorbidities • Overuse of preoperative testing is not only limited to laboratory tests but include chest x-ray and EKG, both mostly used in the elderly • Neither preoperative testing nor abnormal results were associated with worse outcomes Preoperative Testing in Ambulatory Surgery CONCLUSIONS • Future studies must evaluate the comparative effectiveness of testing for specific age groups • Clear guidelines need to be developed for testing in the elderly • Goals: – Decrease unnecessary testing – Decrease cost • In order to succeed physician awareness must be increase and all parties must be willing to participate
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