1. Psychometric Properties of the Ambulatory Surgery-Inventory of Nausea, Vomiting and Retching (AS-INVR)

2. Jan Odom-Forren, PhD, RN, CPAN, FAAN 1 Lynne Hall, DrPH, RN 2 Susan Fetzer, PhD, RN 3 Christian Apfel, PhD, MD 4 1 College of Nursing, University of Kentucky, Lexington, KY 2 School of Nursing, University of Louisville, Louisville, KY 3 School of Nursing, University of New Hampshire, Durham, NH 4 Anesthesia and Perioperative Care, University of California, San Francisco, CA Funded by an unrestricted grant from Merck and Co., Inc., North Wales (PA) awarded to University of California, San Francisco and from Dr. Apfel’s Discretionary Fund for the Perioperative Clinical Research Core 2

3. Purpose To evaluate the psychometric properties of the AS-INVR in adults who required ambulatory surgery and experienced post discharge nausea and vomiting (PDNV). 3

4. Background Over 34 million patients in the U.S. undergo ambulatory surgery each year and PDNV affects 35-55% of outpatients. Reliable and valid measures of the incidence and severity of PDNV are lacking. The Ambulatory Surgery-Inventory of Nausea, Vomiting and Retching (AS-INVR) is a short measure of PDNV adapted from the Rhodes Index of Nausea and Vomiting for the ambulatory surgery population. The psychometric properties of the AS-INVR were evaluated in only one prior study with ambulatory surgery patients. 4

5. Specific Aims 1. Explore the dimensionality of the AS-INVR. 2. Examine the internal consistency reliability of the AS-INVR. 3. Evaluate the construct validity of the AS-INVR. 5

6. Hypothesis Testing for Construct Validity H1: Persons with PDNV will have a higher mean AS-INVR score than those ` without. H2: Higher AS-INVR scores will be associated with lower quality of life scores related to nausea. H3: Higher AS-INVR scores will be associated with lower quality of life scores related to vomiting. 6

7. Methods Design and Sample –Multi-site prospective study of a convenience sample of 203 adults after ambulatory surgery from Day of Surgery through Day 5 post-op. –The purpose of the larger study was to identify the incidence and management strategies of adult patients after ambulatory surgery. –Eligible participants were recruited consecutively either in preadmission testing or in the preoperative area on the day of surgery. 7

8. Inclusion/Exclusion Criteria Inclusion Criteria – –At least 18 years of age or older and undergoing outpatient surgery – –Received general anesthesia requiring an endotracheal tube or laryngeal mask anesthesia Exclusion Criteria – –Unable to communicate in English – –Transferred to inpatient stay – –Current pregnancy – –Persistent or recurrent nausea and/or vomiting before anesthesia 8

9. Measures Post Discharge Nausea (PDN) Severity Quality of Life (QOL) Ambulatory Surgery-Inventory of Nausea, Vomiting and Retching Sociodemographic characteristics Clinical characteristics 9

10. Procedure Protocol approved by Institutional Review Board Written informed consent obtained Data collected via phone interview and mailed patient diary 10

11. Data Analysis Principal components analysis followed by exploratory factor analysis with Varimax rotation to determine the instrument’s dimensionality Cronbach’s alpha to assess internal consistency reliability. Coefficients greater than.70 were considered to represent good internal consistency. Independent samples t-test and correlational analysis for hypothesis testing to evaluate construct validity. 11

12. RESULTS 12

13. Sample Description Mean age 55 + SD 15.4; range 23-87 years Female 72%; Caucasian 93% Presence of PDNV 56% Conventional surgery 36%; laparoscopic surgery 35% American Society of Anesthesiologists’ Physical Status II—70% 13

14. Exploratory Factor Analysis withVarimax Rotation of Two Factors a Day 1 (n = 202) Day 2 (n = 203) Day 3 (n = 201)Day 4 (n = 200) Day 5 (n = 197) ItemFactor 1Factor 2Factor 1Factor 2Factor 1Factor 2Factor 1Factor 2Factor 1Factor 2 4. In the last 24 hours, I have felt nauseated or sick at my stomach..89.16.91.25.91.21.92.26.97.02 7. In the last 24 hours, I have felt nauseated or sick at my stomach _ times..86.24.91.19.91.18.99.10.96.04 5. In the last 24 hours, I have felt nauseated or sick at my stomach ____hours..83.27.90.20.96.16.90.25.98.05 2. In the last 24 hours, from retching or dry heaves I have felt ___distress..44.38.40.45.33.02.26.35.47.19 3. In the last 24 hours, from vomiting or throwing up, I have felt ___distress.23.91.19.63.18.83.15.68.10.995 6. In the last 24 hours, each time I threw up I produced a ____amount..19.78.16.87.09.90.17.86.10.995 1. In the last 24 hours, I threw up _____times..23.74.17.88.15.88.12.84.10.995 a Sample size varies from 197-203. Note: Factor 1 = Nausea; Factor 2 = Vomiting. 14

15. Internal Consistency Reliability Cronbach’s alphas were >.80 for the 7-item AS- INVR and the shortened 6-item AS-INV, indicating strong internal consistency of both measures in this sample of ambulatory surgery patients. 15

16. Factor Structure and Cronbach’s Alphas for the 7-Item AS-INVR by Day Factor Structure and Cronbach’s Alphas for the 7-Item AS-INVR by Day Post-surgery a,b Postoperative Day Items Composing Factor 1 Nausea c Items Composing Factor 2 Vomiting c Mean Inter- Item Correlations Range of Corrected Item- Total Correlations Range of Alphas if One Item Deleted Cronbach’s Alpha 12,4,5,71,3,6.49.54-.78.82-.86.87 24,5,71,2,3,6.48.44-.85.78-.85.87 34,5,7,1,3,6.41.30-.91.69-.81.83 44,5,71,3,6.44.37-.89.74-.83.85 52,4,5,71,3,6.43.25-.89.71-.83.84 a AS-INVR = Ambulatory Surgery-Inventory of Nausea, Vomiting, Retching b Sample size varies from 197-203. c Results based on exploratory factor analysis with Varimax rotation; all factor loadings were.40 or greater. 16

17. Internal Consistency of the AS-INV Internal Consistency of the AS-INV a,b Cronbach’s Alphas for 6-item Version AS-INV by Dimension and Postoperative Day a,b Day Factor 1Factor 2 1.92.88 2.95 3.96 4.97 5.98 17 a Ambulatory Surgery-Inventory of Nausea and Vomiting b Sample size varies from 197-203.

18. CONSTRUCT VALIDITY 18

19. Differences in Mean AS-INVR and AS-INV Scores by Presence of PDNV and Post-Op Day Differences in Mean AS-INVR and AS-INV Scores by Presence of PDNV and Post-Op Day a, b Post-op Day Measure 12345 AS-INVR PDNV 5.62 + 4.445.34 + 4.074.53 + 3.134.74 + 3.594.00 + 2.38 No PDNV.19 +.81.51 + 1.64.23 + 1.15.20 +.90.15 + 1.11 AS-INV PDNV 5.17 + 3.885.04 + 3.594.44 + 2.914.52 + 3.403.94 +2.24 No PDNV.19 +.81.49 + 1.52.21 + 1.11.20 +.90.11 +.85 a Sample size varies from 197-203. b All comparisons significant at p <.001. 19

20. Correlations of the 6-Item AS-INV Scores with QOL-N, QOL-V, and Mean PDN Scores by Post-Operative Day a Post-Operative DayMeasure QOL-NQOL-VPDN Day 1.38*.23*.43* Day 2.46*.18*.49* Day 3.51*.32*.55* Day 4.56*.07.45* Day 5.58*--.56* a Sample size varies from 195-203. *p <.01 Note: --Unable to compute because of lack of vomiting 20

21. Discussion The results of dimensionality assessment support shortening the 7-item AS-INVR to form the 6- item AS-INV. Both versions demonstrated strong internal consistency. Construct validity was supported via hypothesis testing: – –Patients with PDNV had higher AS-INVR and AS-INV mean scores than those without PDNV. – –Higher AS-INVR and AS-INV scores were associated with lower quality of life scores related to nausea. – –Higher AS-INVR and AS-INV scores were associated with lower quality of life scores related to vomiting. 21

22. Conclusions The AS-INV is an inexpensive, easy to administer measure of nausea and vomiting in adults after ambulatory surgery. The 6-item AS-INV is recommended based on this psychometric evaluation of the 7-item AS-INVR. This shortened scale provides a reliable and valid measure of the amount and distress of nausea and vomiting in adult patients after ambulatory surgery. The 6-item version should be considered for use in future studies. 22