Preoperative Factors Associated with Remote Postoperative Pain Resolution and Opioid Cessation in a Mixed Surgical Cohort: Post Hoc Analysis of a Perioperative Gabapentin Trial

Figures & data

Table 1 Baseline Preoperative Characteristics of Patients^a

Patients (no.)	410
Age-yr.	56.8(11.6)
Male Gender-no. (%)	165(40.4)
Marital Status- no.(%)
Never Married	34(8.5)
Married	292(73.0)
Living with someone	15(3.8)
Divorced or separated	46(11.5)
Widowed	13(3.3)
Disability Claim Pending- no.(%)	46(11.8)
Employment Status-no.(%)
Full-time	171(43.4)
Part-time	36(9.1)
Unemployed	79(20.1)
Retired	108(27.4)
Type of Operation- no.(%)
Thoracotomy	15(3.7)
Total Knee Replacement	151(36.8)
Total Hip Replacement	97(23.7)
Mastectomy	41(10.0)
Lumpectomy	30(7.3)
VATS	29(7.1)
Hand Surgery	24(5.9)
Carpal Tunnel Surgery	5(1.2)
Knee Arthroscopy	8(2.0)
Shoulder Surgery	4(1.0)
Shoulder Arthroscopy	6(1.5)
Baseline pain at surgical site (0–10)	5(3)
Baseline pain other than surgical site (0–10)	2(2)
Self-Perceived Likelihood of Developing Chronic Pain After Surgery- no.(%)
Not at all	89(22.2)
Unlikely	244(60.9)
Somewhat likely	58(14.5)
Very likely	10(2.5)
Self-Perceived Likelihood of Chronic Pain After Injury- no. (%)
More Likely	68(17.1)
Less Likely	329(82.9)
Self-Perceived Sensitivity to Pain- no. (%)
More than average	35(8.8)
Average	228(57.0)
Less than average	137(34.3)
Self-Reported Unexpectedly Long Recovery Times from Past Injuries-no. (%)	64(16.0)
Past 30-Day Prescription Opioid Use- no.(%)	36(8.8)
Self-Perceived Likelihood of Addiction to Pain Medication After Surgery- no.(%)
Not at all	206(51.4)
Unlikely	172(42.9)
Somewhat likely	19(4.7)
Very likely	4(1.0)
Opioid Risk Tool Score^c	2(3)
History of Illicit Drug Use- no.(%)	46(11.2)
History of Alcohol or Drug Abuse Treatment- no.(%)	20(5.1)
Marlow-Crowne Social Desirability Scale Score^d	20(6)
Barratt Impulsivity Scale Score^e	69(7)
PTSD Checklist-Civilian Version (PCL-C) Score^f	25(9)
State Anxiety Inventory Score^g	35(11)
Trait Anxiety Inventory Score^h	33(10)
Beck Depression Inventory-ll Score^i	10(7)
Euroqol VAS ^j	72(19)
Postoperative Pain Duration-days^b	79(36–230)
Postoperative Opioid Use Duration-days^b	27(9–55)

Notes: ^aAll values presented as mean (SD) unless otherwise noted, percentages do not include patients with missing data; ^bCensored patients not meeting study endpoints were excluded from calculation of these particular variables, Median (IQ Range); ^cScore range, 0–26, with 0–3 indicating low risk; 4–7 indicating moderate risk, and ≥ 8 indicating high risk; ^dScore range, 0–33, with 0–8 indicating low concern for social approval, and 20–33 indicating high concern for social approval; ^eScore range, 30–120, with higher scores representing greater impulsiveness; ^fScore range, 17–85, with increasing scores representing more self-reported posttraumatic stress disorder symptoms; ^gScore range, 20–80, with higher scores representing increasing state anxiety or anxiety in response to a specific situation. 395 of 410 participants (96%) completed the State Anxiety Inventory; ^hScore range, 20–80, with higher scores representing increasing trait anxiety or propensity to experience anxiety. 390 of 410 (95%) participants completed the Trait Anxiety Inventory; ⁱScore range, 0–63, with 0–13 indicating minimal depression;14–19 mild depression;20–28 moderate depression; and 29–63, severe depression. 398 of 410 (97%) participants completed the Beck Depression Inventory-II; jScore range for self-assessment of health, 0–100, with 0 representing the worst imaginable health state and 100 representing the best imaginable health state.

Table 2 Time to Pain and Opioid Cessation

Endpoint^a	No. (%) Reaching Endpoint	Cumulative No. (%) Censored by End of Interval
Time to Pain Cessation			No. (%) with Persistent Pain
Day 30	81 (19.8)	32 (7.8)	297 (72.4)
Day 60	162 (39.5)	47 (11.5)	201 (49.0)
Day 90	206 (50.2)	56 (13.7)	148 (36.1)
Day 180	254 (62.0)	75 (18.3)	81 (19.8)
Year 1	277 (67.6)	94 (22.9)	39 (9.5)
Year 2	281 (68.5)	129 (31.5)
Time to Opioid Cessation			No. (%) with Persistent Opioid Use
Day 30	205 (50.0)	29 (7.0)	176 (42.9)
Day 60	296 (72.2)	40 (9.8)	74 (18.0)
Day 90	329 (80.2)	42 (10.2)	39 (9.5)
Day 180	350 (85.4)	50 (12.2)	10 (2.4)
Year 1	353 (86.1)	50 (12.2)	7 (1.7)
Year 2	355 (86.6)	55 (13.4)

Note: ^a410 patients were included in the analysis.

Figure 1 Time to Pain and Opioid Cessation Overall.

Table 3 Determinants of Pain Cessation Rate: Univariate Analysis

Characteristics^a	Hazard Ratio	Hazard Ratio 95% Confidence Interval	p-value
Baseline pain at surgical site (0–10)^b	0.92	(0.87–0.98)	0.008
Self-reported unexpectedly long recovery times from past injuries	0.65	(0.45–0.94)	0.021
Euroqol VAS^c	1.10	(1.02–1.17)	0.009
Beck Depression Inventory-II Score^d	0.82	(0.74–0.91)	0.0002
PTSD Checklist-Civilian Version (PCL-C) Score^e	0.84	(0.73–0.96)	0.011
State Anxiety Inventory Score^f	0.81	(0.72–0.91)	0.0005
Trait Anxiety Inventory Score^g	0.81	(0.71–0.92)	0.001
Disability claim pending	0.58	(0.38–0.88)	0.011

Notes: ^aHazard Ratio units represent the minimal clinically important difference for a given continuous variable; ^bEvery 1-point increase in the Numeric Pain Rating Scale; ^cEvery 10-point increased in the Euroqol VAS; ^dEvery 5-point increase in the Beck Depression Inventory-II Score; ^eEvery 8-point increase in the PCL-C Score; ^fEvery 10-point increase in the State Anxiety Inventory Score; ^gEvery 10-point increase in the Trait Anxiety Inventory Score.

Table 4 Determinants of Pain Cessation Rate: Multivariable Analysis

Characteristics^a	Hazard Ratio	Hazard Ratio 95% Confidence Interval	p-value
Baseline pain at surgical site (0–10)^b	0.93	(0.87–1.00)	0.034
Self-reported unexpectedly long recovery times from past injuries	0.62	(0.40–0.96)	0.034
Trait Anxiety Inventory Score^c	0.79	(0.68–0.92)	0.002

Notes: ^aHazard Ratio units represent the minimal clinically important difference for a given continuous variable. Results are stratified by operation; ^bEvery 1-point increase in the Numeric Pain Rating Scale; ^cEvery 10-point increase in the Trait Anxiety Inventory Score.

Table 5 Determinants of Opioid Cessation Rate: Univariate Analysis

Characteristics^a	Hazard Ratio	Hazard Ratio 95% Confidence Interval	p-value
Baseline pain at surgical site (0–10)^b	0.93	(0.88–0.98)	0.008
Self-Perceived Likelihood of Developing Chronic Pain After Surgery	0.042
Not at all-Reference
Unlikely	1.04	(0.79–1.37)
Somewhat likely	0.74	(0.51–1.07)
Very likely-Reference	0.44	(0.19–1.04)
Self-Perceived Likelihood of Chronic Pain After Injury			0.019
More Likely	0.7	(0.52–0.94)
Less Likely-Reference
Beck Depression Inventory-II Score^c	0.86	(0.78–0.94)	0.0006
State Anxiety Inventory Score^d	0.89	(0.81–0.99)	0.028
Female Gender	0.76	(0.60–0.96)	0.024
Treatment Group			0.050
Gabapentin	1.24	(1.00–1.54)
Placebo-Reference
Past 30-Day Prescription Opioid Use	0.53	(0.35–0.79)	0.002

Notes: ^aHazard Ratio units represent the minimal clinically important difference for a given continuous variable; ^bEvery 1-point increase in the Numeric Pain Rating Scale; ^cEvery 5-point increase in the Beck Depression Inventory-II Score; ^dEvery 10-point increase in the State Anxiety Inventory Score.

Table 6 Determinants of Opioid Cessation Rate: Multivariable Analysis

Characteristics^a	Hazard Ratio	Hazard Ratio 95% Confidence Interval	p-value
Past 30-Day Prescription Opioid Use	0.60	(0.39–0.92)	0.020
Beck Depression Inventory-II Score^b	0.88	(0.80–0.98)	0.017
Treatment Group			0.016
Gabapentin	1.37	(1.06–1.77)
Placebo-Reference
Baseline pain other than surgical site (0–10)^c	0.94	(0.89–1.00)	0.046

Notes: ^aHazard Ratio units represent the minimal clinically important difference for a given continuous variable. Results are stratified by operation; ^bEvery 5-point increase in the Beck Depression Inventory-II Score; ^cEvery 1-point increase in the Numeric Pain Rating Scale.