Yoeri Bemelmans

Postoperative urinary retention after hip and knee arthroplasty 65 5 Statistics All data collected for this study was entered into an Excel database (Microsoft Office 2003) and analyzed using the SPSS 17.0 (SPSS Inc. Chicago, IL) statistical program. A descriptive analysis of the sample was done using rates for categorical variables and the mean (SD) for continuous variables. The collected data were tested for normality with use of the Shapiro–Wilk test. Since data were not normally distributed, differences between the POUR and non- POUR group were tested with the use of Mann–Whitney U test. A p value ≤ 0.05 was considered to be statistically significant. If there was a significant difference for one of the secondary outcomes measures, the odds ratio (OR) with 95% confidence interval (CI) was calculated to determine possible risk factors for POUR. To create a cutoff point, median values of the total group were used. Results are presented as either frequencies (%) or mean (SD). Table 1. Pain protocol. Preoperative Postoperative 2hrs 4hrs 8hrs First day Day 2-14 Meloxicam (mg) 15 15 15 Paracetamol (g) 1 1 1 1 1 Gabapentine (mg) 600 300 300 Pantoprazol (mg) 40 40 40 Results The incidence of POURwas 12.9% ( n = 82; 95%CI 9.4–15.5%). There were no significant differences for patient demographics and pre- and perioperative outcome measures between POUR and non-POUR patients (Table 2). Table 2. Baseline demographics are presented as frequencies (%) or mean (SD) with p-value. Pour (n=82) Non-Pour (n=556) p-value Patient demographics Male/female, (%) 29/53 (35/65) 200/365 (36/64) 0.915 Age in years, (SD) 68.64 (11.04) 69.42 (8.72) 0.827 BMI in kg/m 2 , (SD) 28.63 (4.39) 28.94 (5.97) 0.742 ASA classification, I/II/III 7/43/5 35/332/20 0.312 Spinal/general anesthesia, (%) 59/23 (72/28) 398/158 (72/28) 1.000 THA/TKA, (%) 51/31 (62/38) 272/284 (49/51) 0.059 Fluid administration in ml, mean (SD) 941.89 (367.80) 881.49 (343.33) 0.231