Pain behavior mediates the relationship between perceived injustice and opioid prescription for chronic pain: a Collaborative Health Outcomes Information Registry study

Figures & data

Table 1 Sample demographic characteristics

Variables	n (%)
Sex
Men	114 (33)
Women	230 (67)
Age, years
18–30	49 (14)
31–40	70 (20)
41–50	69 (20)
51–60	88 (26)
61–70	48 (14)
71–80+	18 (5)
Marital status
Separated/divorced	21 (6)
Cohabitating	41 (12)
Widowed	83 (24)
Married	184 (54)
Never married	14 (12)
Education
No high school diploma	32 (9)
High school diploma or equivalent	30 (9)
Some college, no degree	76 (22)
Some university/associate’s degree	37 (11)
Bachelor’s degree	88 (25)
Graduate degree	81 (24)
Pain type
Nerve	169 (49)
Musculoskeletal	79 (23)
Disk	72 (21)
Unknown cause	107 (31)

Note: N = 344.

Table 2 Results of t-tests comparing perceived injustice, pain intensity, depressive symptoms and pain behavior on opioid prescription

Variables	Active opioid prescription		t-Test
	No, M (SD)	Yes, M (SD)
Perceived injustice	15.60 (11.40)	20.17 (10.51)	−3.82**
Pain intensity	4.44 (2.78)	5.68 (2.37)	−3.26**
Depressive symptoms	54.12 (9.9)	57.89 (9.5)	−3.15**
Pain behavior	57.87 (6.05)	60.58 (4.34)	−3.69**

Notes: Mean scores and standard deviation for the study variables according to opioid prescription are shown. t-test, independent samples t-test.

** p < 0.001.

Abbreviations: M, mean; SD, standard deviation.

Table 3 Correlations among study variables

Variables	1	2	3
1. Perceived injustice
2. Pain intensity	0.333**
3. Depressive symptoms	0.656**	0.308**
4. Pain behavior	0.374**	0.522**	0.403**

Note:

** p < 0.001.

Figure 1 The mediating effect of pain intensity, depressive symptoms and pain behavior on the association between perceived injustice and opioid prescription.

Notes: Analyses controlled for age and sex. Path coefficients are presented. *p < 0.05; **p < 0.001.
Abbreviations: IV, independant variable; DV, dependant variable; MV, mediating variable.

Table 4 Bootstrapped multiple mediation analysis testing the indirect effect of perceived injustice on opioid prescription through pain intensity, depressive symptoms and pain behavior

Variables	Path coefficient	Bootstrap SE	t	95% BC CI
Path c	0.394	0.124	3.172*
Path c1	0.164	0.168	0.974
Path a1	0.332	0.051	6.497*
Path a2	0.656	0.041	15.986*
Path a3	0.379	0.050	7.573*
Path b1	0.169	0.153	1.110
Path b2	0.048	0.181	0.271
Path b3	0.499	0.239	2.092**
Specific indirect effects
a1 × b1	0.057	0.053		LL = −0.0436, UL = 0.1686
a2 × b2	0.031	0.129		LL = −0.2187, UL = 0.2932
a3 × b3	0.189	0.122		LL = 0.0122, UL = 0.4936
Total indirect effects
a1b1 × a2b2 × a3b3	0.276	0.148		LL = 0.0307, UL = 0.5767

Notes: Standardized path coefficients for the total and specific indirect effects are shown. Path c, total effect of perceived injustice on opioid prescription; path c1, direct effect of perceived injustice on opioid prescription; path a1, effect of perceived injustice on pain intensity; path a2, effect of perceived injustice on depressive symptoms; path a3, effect of perceived injustice on pain behavior; path b1, direct effect of pain intensity on opioid prescription; path b2, direct effect of depressive symptoms on opioid prescription; path b3, direct effect of pain behavior on opioid prescription; path a1 × b1, indirect effect of perceived injustice on opioid prescription through pain intensity; path a2 × b2, indirect effect of perceived injustice on opioid prescription through depressive symptoms; path a3 × b3, indirect effect of perceived injustice on opioid prescription through pain behavior; path a1b1 × a2b2 × a3b3, total indirect effect of perceived injustice on opioid prescription through pain intensity, depressive symptoms and pain behavior. Path coefficients are based on 5,000 bootstraps for the indirect effect. LL and UL CIs were used to determine statistical significance of indirect effects. All analyses controlled for age and sex.

* p < 0.001;

** p < 0.05.

Abbreviations: BC, bias corrected; CI, confidence interval; LL, lower limit; SE, standard error; UL, upper limit.