Table 1.

Clinical data of patients in the prospective and retrospective arms

Variables	PA (n=70), n (%)/mean (SD)	RA (n=26), n (%)/mean (SD)
Age of first use of opioids (years)	22.7 (5.03)	23.77 (5.01)
Duration of dependence (months)	52.81 (52.73)	59.54 (62.14)
Age at first use of tapentadol (years)	26.41 (6.63)	24.42 (5.61)
Duration of use (months)	10.33 (9.61)	20.58 (16.25)
Average daily dose (mg)	526.29 (475.77)	565.22 (462.80)
Concurrent opioid use
None	11 (15.7)	5 (19.2)
Natural	7 (10.0)	2 (7.7)
Heroin	32 (45.8)	4 (15.4)
Tramadol	16 (22.9)	10 (38.5)
Others	4 (5.6)	5 (19.2)
Urine testing
Not available	0 (0)	11 (42.3)
Opioid negative	15 (21.4)	2 (7.7)
Tramadol positive	12 (17.1)	6 (23.1)
Morphine positive	17 (24.3)	6 (23.1)
BPN positive	3 (4.3)	1 (3.8)
Intravenous opioid use
No	39 (55.7)	22 (84.6)
Yes	31 (44.3)	4 (15.4)
Route of tapentadol use
Oral	67 (95.7)	26 (100)
Parenteral	3 (4.3)	0 (0)
Formulation
Unknown	7 (10.0)	12 (46.2)
Instant release	61 (87.1)	9 (34.6)
Sustained release	1 (1.4)	3 (11.5)
Both	1 (1.4)	2 (7.7)
Brand name
Unknown	15 (21.4)	18 (69.2)
Tapal	37 (52.9)	6 (23.1)
Others	18 (25.7)	2 (7.7)
Past opioid use
None	8 (11.4)	4 (15.4)
Natural	19 (27.1)	2 (7.7)
Heroin	22 (31.4)	5 (19.2)
Tramadol	10 (14.3)	5 (19.2)
Others	13 (18.6)	10 (38.4)
History of other drug dependence
None	14 (20.0)	4 (15.4)
Alcohol	4 (5.7)	2 (7.7)
Cannabis	18 (25.7)	2 (7.7)
Benzodiazepine	5 (7.1)	3 (11.5)
Nicotine	29 (41.4)	15 (57.7)
Past history of treatment seeking
Nil	24 (34.3)	12 (46.2)
Government centers	12 (17.2)	3 (11.5)
Private centers	34 (48.5)	11 (42.3)
HCV status
No	66 (94.3)	25 (96.1)
Yes	4 (5.7)	1 (3.9)
Psychiatric illness
None	63 (90)	21 (84.6)
Present	7 (10)	4 (15.4)
Medical comorbidity
No	58 (82.9)	17 (65.4)
Yes	12 (17.1)	9 (34.6)

SD – Standard deviation; BPN – Buprenorphine; PA – Prospective arm; RA – Retrospective arm; HCV – Hepatitis C virus