Supplementary Table 1. Identification of variables associated with primary and secondary outcome measures among patients presenting for cesarean delivery
Table 1a. Variables associated with opioid consumption during 1st 24 hours following cesarean delivery (primary outcome)
n Median total opioid dose, 1st 24 hours
[IQR] in MME, or rho (ρ) p-value Smoking
Never 1955 22.5 [0, 1087.5] <0.01a
Former 653 37.5 [0, 1140]
Current 281 75 [0, 375]
Unknown 90 22.5 [0, 139.5]
Parity
Nulliparous 1305 30 [0, 1140] 0.03b
Multiparous 1674 30 [0, 718.5]
Gestation type
Singleton 2767 30 [0, 1140] 0.43b
Multiple 212 30 [0, 428.5]
Marital status
Married 1990 22.5 [0, 1140] <0.01b
Other 989 45 [0, 718.5]
Race
White 2585 30 [0, 1140] 0.10b
Other 394 22.5 [0, 718.5]
Comorbidities Depression
Yes 242 60 [0, 1140] <0.001b
No 2737 30 [0, 718.5]
Anxiety
Yes 173 60 [0, 1087.5] <0.001b
No 2806 30 [0, 1140]
PTSD
Yes 48 67.5 [0, 265.5] <0.001b
No 2931 30 [0, 1140]
Chronic pain
Yes 169 60 [0, 265.5] <0.001b
No 2810 30 [0, 1140]
Hypertension
Yes 571 45 [0, 718.5] <0.001b
No 2408 22.5 [0, 1140]
Liver disease
Yes 3 22.5 [0, 82.5] 0.87b
No 2976 30 [0, 1140]
Renal insufficiency
Yes 15 60 [0, 125] 0.32b
No 2964 30 [30, 1140]
Intraoperative intrathecal morphine
Yes 2149 22.5 [0, 375] <0.001b
No 830 39.2 [0, 1140]
Maternal age at delivery 2979 ρ = -0.106 <0.001c
1b. Variables associated with highest pain score during 1st 24 hours following cesarean delivery (secondary outcome)
N Mean highest pain score, 1st 24 hours
(SD) in NRS, or rho (ρ) p-value Smoking
Never 1955 5.2 (2.1) <0.001a
Former 653 5.9 (2.2)
Current 281 7.4 (2.1)
Unknown 90 5.1 (2.0)
Parity
Nulliparous 1305 5.5 (2.1) 0.03b
Multiparous 1674 5.7 (2.3)
Gestation type
Singleton 2767 5.6 (2.2) 0.41b
Multiple 212 5.5 (2.3)
Marital status
Married 1990 5.3 (2.1) <0.001b
Other 989 6.2 (2.4)
Race
White 2579 5.6 (2.2) 0.41b
Other 394 5.6 (2.4)
Comorbidities Depression
Yes 242 6.6 (2.3) <0.001b
No 2737 5.5 (2.2)
Anxiety
Yes 173 6.8 (2.3) <0.001b
No 2806 5.5 (2.2)
PTSD
Yes 48 7.2 (2.2) <0.001b
No 2931 5.5 (2.2)
Chronic pain
Yes 169 7.0 (2.3) <0.001b
No 2810 5.5 (2.2)
Hypertension
Yes 571 6.1 (2.4) <0.001b
No 2408 5.5 (2.2)
Liver disease
Yes 3 3.7 (0.6) 0.08b
No 2976 5.6 (2.2)
Renal insufficiency
Yes 15 5.3 (2.7) 0.85b
No 2964 5.6 (2.2)
Intraoperative intrathecal morphine
Yes 2149 5.4 (2.1) <0.001b
No 830 6.1 (2.4)
Maternal age at delivery 2979 ρ = -0.131 <0.001c
1c. Variables associated with length of stay after cesarean delivery (secondary outcome) n Median length of stay [full range] in
hours; or rho (ρ) p-value
Smoking
Never 1950 71 [21, 435] 0.16a
Former 653 71 [27, 206]
Current 280 70 [21,408]
Unknown 90 74 [36, 194]
Parity
Nulliparous 1303 73 [21, 435] <0.001b
Multiparous 1670 70 [21, 248]
Gestation type
Singleton 2762 71 [21, 435] <0.001b
Multiple 211 73 [38, 248]
Marital status
Married 1990 71 [21, 435] <0.01b
Other 989 73 [21, 428]
Race
White 2585 71[21, 428] <0.01b
Other 394 72 [37, 435]
Comorbidities Depression
Yes 242 72 [38, 408] <0.01b
No 2731 71 [21. 435]
Anxiety
Yes 173 73 [38, 215] 0.04b
No 2800 71 [21-435]
PTSD
Yes 48 72 [44, 154] 0.14b
No 2925 71 [21, 435]
Chronic pain
Yes 169 72 [25, 408] 0.25b
No 2804 71 [21, 435]
Hypertension
Yes 571 71 [21, 435] <0.001b
No 2402 70 [21, 428]
Liver disease
Yes 3 60 [51, 73] 0.27b
No 2970 71 [21, 435]
Renal insufficiency
Yes 15 76 [48, 118] <0.01b
No 2958 71 [21, 435]
Intraoperative intrathecal morphine
Yes 2149 70 [25, 206] <0.001b
No 830 72 [21, 435]
Maternal age at delivery 2973 ρ = 0.012 0.50c
Abbreviations: IQR, interquartile range; MME, morphine milligram equivalents; PTSD, posttraumatic stress disorder; NRS, numerical rating scale, 0-10
a: Kruskal Wallis test was used to compare differences in outcome measures among variable categories b: Mann-Whitney U test was used to compare differences in outcome measures between variable categories
c: Spearman’s correlation was used to examine the bivariate relationship between maternal age at delivery and each outcome measure.
Supplementary Table 2: Details of postoperative and discharge analgesic medications Treatment with opioid agonist
pharmacotherapy
Yesa No Overall
Sample size, n 123 2856 2979
Postoperative opioids dispensed, n (%)b
None 6 (4.9) 882 (30.9) 888 (29.8)
Oxycodone 105 (85.4) 1839 (64.4) 1944 (65.3)
Hydromorphone 29 (23.6) 139 (4.9) 168 (5.6)
Hydromorphone injection 12 (9.8) 100 (3.5) 112 (3.6)
Fentanyl injection 5 (4.1) 85 (3.0) 90 (3.0)
Tramadol 1 (0.8) 28 (1.0) 29 (1.0)
Morphine injection 6 (4.9) 19 (0.7) 26 (0.8)
Hydrocodone-acetaminophen 0 (0.0) 20 (0.7) 20 (0.7)
Fentanyl infusion (critical care) 0 (0.0) 7 (0.2) 7 (0.2)
Oxycodone-acetaminophen 0 (0.0) 5 (0.2) 5 (0.2)
Hydromorphone infusion (critical care) 0 (0.0) 2 (0.1) 2 (0.1)
Received PCA opioids, n (%)d 7 (6.1) 60 (2.2) 67 (2.3)
PCA dose MME, median [IQR]
Postoperative non-opioids, n (%) 63 [42,126] 44 [18,75] 44 [20,84]
Ketorolac 93 (75.6) 2228 (78.0) 2321 (77.9)
Ibuprofen 38 (30.9) 630 (22.1) 668 (22.4)
Acetaminophen 113 (91.9) 2541 (89.0) 2654 (89.1)
Opioids prescribed at discharge, n (%)
Oxycodone 79 (64.2) 2235 (78.2)c 2314 (77.7)
Hydromorphone 33 (26.8) 193 (6.8) 226 (7.6)
Tramadol 0 (0.0) 53 (1.9) 53 (1.8)
Hydrocodone/acetaminophen 0 (0.0) 2 (0.1) 2 (0.1)
None 11 (8.9) 373 (13.1) 384 (12.9)
Abbreviations: PCA, patient controlled analgesia; IQR, interquartile range; MME, morphine milligram equivalents a:Includes 86 patients taking buprenorphine and 37 patients taking methadone b:Unless specified, all medications were given orally. With the exception of those who had no postoperative opioids dispensed, patients received one or more types of opioid medication.
c: 9 patients were also prescribed tramadol
d: PCA data were available for n=114 patients taking opioid agonist pharmacotherapy and n=2756 patients not taking opioid agonist pharmacotherapy