Of the 2360 participants who were included in the analyses, 69% reported no history of opioid overdoses (n = 1,619), 24% reported a lifetime history of opioid overdose (n = 562), and 8% reported history of an ED visit for opioid overdose in the last year (n = 179).
In Table 1 we present the demographic and clinical characteristics of participants by overdose history. Individuals with an ED visit for overdose in the last year were generally younger, with a mean age of 35 years (SD = 10) compared to a mean age of 39 years (SD = 11) in all participants. The highest rates of unemployment were seen in participants with an ED visit for overdose in the last year; only 17% of individuals were employed.
With respect to treatment characteristics, 79% of patients were receiving methadone while the remainder received buprenorphine-naloxone. This ratio is similar in all groups. Participants who had an ED visit for overdose in the last year were receiving lower mean doses of both methadone (59 mg/day, SD = 32) and buprenorphine-naloxone (11 mg/day, SD = 6) when compared to both of the other groups. Participants with no reported overdoses were receiving on average 70 mg of methadone/day or 12 mg of buprenorphine-naloxone/day, while those with a history of overdoses were receiving around 77 mg of methadone/day and 13 mg of buprenorphine-naloxone/day. Additionally, participants with an ED visit for overdose were receiving treatment for a median of 0.6 years (IQR = 0.2, 2), which is a shorter length of time when compared to both of the other groups, who had spent a median length of 3 and 2.4 years, respectively, in MAT.
Examining substance use characteristics, participants with an ED visit for overdose in the last year had the highest rates of IV drug use at 47% and only 16% of individuals were abstinent from opioid use at baseline. Rates of alcohol and cannabis use were similar across all groups. However, participants who had an ED visit for overdose in the last year had the highest rate of non-prescription use of benzodiazepines, with 16% reporting use in the last 30 days. Additionally, this group also had the lowest rates of prescription benzodiazepine use. Of note, access to naloxone kits and knowledge on using naloxone were both highest in participants who had an ED visit in the last year for overdose. Lastly, individuals with an ED visit for overdose initiated opioid usage at an average age of 24 years compared to 26 and 23 years in the other groups.
Regarding physical and mental health, 32% of individuals with an ED visit for overdose reported suicidal ideation compared to 18% in individuals with no reported overdoes and 24% in those with a lifetime history of overdoses. Lastly, individuals with an ED visit for overdose also had higher total scores on both the physical and psychological components of the MAP.
Table 1
Baseline demographic and clinical characteristics, by opioid overdose history (N = 2,360)
Characteristic
|
Total Sample
N = 2,360
|
No reported overdoses
n = 1,619 (68.6%)
|
Lifetime history of overdoses
n = 562 (23.8%)
|
ED visit for overdose in the last year
n = 179 (7.6%)
|
Sociodemographic
|
Age; mean (SD)
|
39.3 (10.9)
|
40.0 (10.8)
|
38.8 (11.1)
|
34.9(9.6)
|
Female sexa; n (%)
|
1046 (44.3%)
|
728 (45%)
|
245 (43.7%)
|
73(40.8%)
|
Ethnicity; n (%)
Caucasian
Other
|
1705 (72.3%)
655 (27.8%)
|
1154 (71.3%)
465 (28.7%)
|
422 (75.1%)
140 (24.9%)
|
129 (72.1%)
50 (27.9%) (3)
|
Married or common law; n (%)
|
691 (29.3%)
|
515 (31.8%)
|
135 (24%)
|
41 (22.9%)
|
High school education; n (%)
|
668 (28.3%)
|
473 (29.2%)
|
153 (27.2%)
|
42 (23.5%)
|
Children; n (%)
|
1615 (68.4%)
|
1132 (69.9%)
|
366 (65.1%)
|
117 (65.4%)
|
Currently working; n (%)
|
780(33.1%)
|
592 (36.6%)
|
158 (28.1%)
|
30 (16.8%)
|
Receiving social assistanceb; n (%)
|
1298 (55%)
|
827 (51.1%)
|
350 (62.3%)
|
121 (67.6%)
|
Treatment
|
Type of MATc; n (%)
Methadone
Suboxone
|
1868 (79.3%)
488 (20.7%)
|
1270 (78.6%)
346 (21.4%)
|
456 (81.3%)
105 (18.7%)
|
142 (79.3%)
37 (20.7%)
|
Dose; mean (SD)
Methadone
Suboxone
|
70.5 (40.6)
12.0 (6.8)
|
69.5(42.4)
11.9 (6.9)
|
76.9(37.1)
12.6 (6.4)
|
58.9 (31.5)
11.2 (6.4)
|
Years in treatment; median (Q1, Q3)
|
2.6 (0.8, 6)
|
3(1, 6.75)
|
2.4 (0.8, 7)
|
0.6(0.2,2)
|
Previous Treatment for Opioid Dependencea; n (%)
|
804 (34.1%)
|
500 (30.9%)
|
217 (38.6%)
|
87 (48.6%)
|
Abstinent from opioid use at study entryd; n(%)
|
732 (31.1%)
|
537 (33.3%)
|
166 (29.7%)
|
29 (16.3%)
|
Percentage of opioid-positive urine drug screens if non-abstinent at study entryd; mean (SD)
|
16.3 (23.3)
|
15.1 (22.9)
|
16.7 (22.8)
|
25.9 (25.9)
|
Substance use
|
Age start using opioids regularlya; mean (SD)
|
24.9 (9.3)
|
25.9 (9.6)
|
22.7 (8.3)
|
22.4 (8.1)
|
IV drug use (past 30 days); n(%)
|
375 (15.9%)
|
164 (10.1%)
|
127 (22.6%)
|
84 (46.9%)
|
Alcohol use (past 30 days)e; n (%)
|
870 (36.9%)
|
588 (36.3%)
|
208 (37%)
|
74 (41.6%)
|
Prescription benzodiazepine use, n (%)
|
369 (15.6%)
|
242 (15%)
|
103 (18.3%)
|
24 (13.4%)
|
Non-prescription use of benzodiazepines(past 30 days)e; n (%)
|
180 (7.6%)
|
88 (5.4%)
|
64 (11.4%)
|
28 (15.7%)
|
Cannabis use (past 30 days)e; n (%)
|
1257 (53.3%)
|
846 (52.3%)
|
301 (53.6%)
|
110 (61.8%)
|
Have access to naloxone kits; n (%)
|
1840 (78%)
|
1210 (74.7%)
|
472 (84%)
|
158 (88.3%)
|
Know how to use naloxone; n (%)
|
1907 (80.8%)
|
1243 (76.8%)
|
493 (87.7%)
|
171 (95.5%)
|
Mental and physical health
|
Suicidal ideation; n(%)
|
489 (20.7%)
|
298 (18.4%)
|
134 (23.8%)
|
57 (31.8%)
|
Total physical symptoms score on MAPc; mean (SD)
|
14.3 (8.0)
|
13.8 (7.9)
|
15.2 (8.0)
|
16.0 (8.5)
|
Total psychological symptoms score on MAPf; mean (SD)
|
11.7 (9.0)
|
10.7 (8.8)
|
13.4(8.9)
|
14.6 (9.5)
|
SD = Standard Deviation, MAT = Medication Assisted Treatment, IV = intravenous, MAP = Maudsley Addiction Profile
a Data available for 2359 participants.
b Data available for 1580 participants.
c Data available for 2356 participants.
d Data available for 2352 participants.
e Data available for 2358 participants.
f Data available for 2354 participants.
|
In Table 2 we present the results of our multinomial regression analysis, identifying factors associated with overdose history. Adjusting for other demographic and clinical factors, both participants with a history of overdose and those with an ED visit for overdose in the last year were younger in age when compared to the group with no reported overdoses (OR = 0.93, 95% CI = 0.89, 0.98, p = 0.007 and OR = 0.84, 95% CI = 0.77, 0.92, p < 0.001, respectively). Compared to the group with no reported overdoses, those with an ED visit in the last year have spent less time in treatment (OR = 0.92, 95% CI = 0.87, 0.97, p = 0.001). Both those with a history of overdose and those with an ED visit for overdose in the last year were more likely to report access to naloxone kits compared to the group with no reported overdoses (OR = 1.59, 95% CI = 1.23, 2.06, p < 0.001 and OR = 1.90, 95% CI = 1.17, 3.08, p = 0.01, respectively). Additionally, both groups were reporting higher numbers of physical symptoms on the MAP (OR = 1.02, 95% CI = 1.01, 1.03, p = 0.005 and OR = 1.03, 95% CI = 1.01, 1.05, p = 0.005, respectively) as well as higher rates of non-prescription use of benzodiazepines (OR = 1.87, 95% CI = 1.32, 2.66, p < 0.001 and OR = 2.34, 95% CI = 1.43, 3.81, p = 0.001, respectively). Patients with an ED visit for overdose in the last year were less likely to be abstinent from opioids at study entry (OR = 0.49, 95% CI = 0.32, 0.75, p = 0.001). Adjusting for other covariates, we did not identify a statistically significant association between overdose status and suicidal ideation for both groups with a history of overdose as well as those with an ED visit for overdose in the last year (OR = 1.17, 95% CI = 0.92, 1.50, p = 0.202 and OR = 1.40, 95% CI = 0.97, 2.03, p = 0.071, respectively). Lastly, no association was found between overdose status and sex, type of MAT, alcohol use in the past 30 days as well as use of prescription benzodiazepines.
Table 2
Univariate and multivariate multinomial analysis of demographic and clinical factors associated with overdose status (N = 2360)
|
|
Univariate Multinomial Analysis
|
Multivariate Multinomial Analysis
|
Overdose status
|
Covariate
|
OR
|
95% CI
|
p value
|
OR
|
95% CI
|
p value
|
No reported overdoses [reference]
|
-
|
-
|
-
|
-
|
-
|
-
|
-
|
Lifetime history of overdoses
|
Age by five-year increments
|
0.99
|
0.98, 1.00
|
0.024
|
0.93
|
0.89, 0.98
|
0.007
|
|
Sex
|
0.95
|
0.78, 1.15
|
0.595
|
0.88
|
0.72, 1.08
|
0.210
|
|
MAT
|
0.85
|
0.66, 1.08
|
0.175
|
1.19
|
0.88, 1.60
|
0.254
|
|
Dose
|
1.00
|
1.00, 1.01
|
< 0.001
|
1.00
|
1.00, 1.01
|
0.005
|
|
Years in treatment
|
1.02
|
1.00, 1.04
|
0.061
|
1.02
|
1.00, 1.04
|
0.082
|
|
Have access to naloxone kits
|
1.77
|
1.38, 2.28
|
< 0.001
|
1.59
|
1.23, 2.06
|
< 0.001
|
|
Suicidal Ideation
|
1.39
|
1.10, 1.75
|
0.005
|
1.17
|
0.92, 1.50
|
0.202
|
|
Total physical symptoms score on MAP
|
1.02
|
1.01, 1.04
|
< 0.001
|
1.02
|
1.01, 1.03
|
0.005
|
|
Alcohol use (past 30 days)
|
1.03
|
0.84, 1.26
|
0.776
|
1.01
|
0.82, 1.24
|
0.927
|
|
Prescription benzodiazepine use
|
1.28
|
0.99, 1.65
|
0.059
|
1.08
|
0.83, 1.42
|
0.559
|
|
Non-prescription use of benzodiazepines (past 30 days)
|
2.23
|
1.59, 3.13
|
< 0.001
|
1.87
|
1.32, 2.66
|
< 0.001
|
|
Opioid abstinence at study entry
|
0.85
|
0.69, 1.04
|
0.122
|
0.92
|
0.74, 1.14
|
0.445
|
ED visit for overdose in the last year
|
Age by 5-year increments
|
0.95
|
0.94, 0.97
|
< 0.001
|
0.84
|
0.77, 0.92
|
< 0.001
|
|
Sex
|
0.84
|
0.62, 1.15
|
0.286
|
0.77
|
0.55, 1.08
|
0.128
|
|
MAT
|
0.96
|
0.65, 1.40
|
0.819
|
0.73
|
0.45, 1.16
|
0.181
|
|
Dose
|
1.00
|
0.99, 1.00
|
0.015
|
1.00
|
0.99, 1.00
|
0.068
|
|
Years in treatment
|
0.88
|
0.84, 0.92
|
< 0.001
|
0.92
|
0.87, 0.97
|
0.001
|
|
Have access to naloxone kits
|
2.54
|
1.59, 4.06
|
< 0.001
|
1.90
|
1.17, 3.08
|
0.01
|
|
Suicidal Ideation
|
2.07
|
1.48, 2.91
|
< 0.001
|
1.40
|
0.97, 2.03
|
0.071
|
|
Total physical symptoms score on MAP
|
1.03
|
1.02, 1.05
|
< 0.001
|
1.03
|
1.01, 1.05
|
0.005
|
|
Alcohol use (past 30 days)
|
1.25
|
0.91, 1.71
|
0.170
|
1.02
|
0.73, 1.43
|
0.886
|
|
Prescription benzodiazepine use
|
0.88
|
0.56, 1.38
|
0.582
|
1.02
|
0.63, 1.63
|
0.944
|
|
Non-prescription use of benzodiazepines (past 30 days)
|
3.25
|
2.05, 5.13
|
< 0.001
|
2.34
|
1.43, 3.81
|
0.001
|
|
Opioid abstinence at study entry
|
0.39
|
0.26, 0.59
|
< 0.001
|
0.49
|
0.32, 0.75
|
0.001
|
OR = Relative Risk Ratio, CI = Confidence Interval
|