Table 6B.

Characteristics of the first antidepressant treatment episode among persons with a diagnosis of chronic pain

Characteristics	Canada						USA		UK		Taiwan
	Ontario		Montreal sample		Quebec city and Montreal		Boston		CPRD		NHIRDB
	n	%	n	%	n	%	n	%	n	%	n	%
All patients, all changes	16 045	100	3276	100	349	100	2657	100	5360	100	6029	100
No treatment change	10 650	66	2220	68	261	75	1793	67	4017	75	4761	79
Treatment change	5395	34	1056	32	88	25	864	33	1343	25	1268	21

	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD	Mean	SD
All patients, all changes
Dose*	0.9	0.7	0.7	0.5	0.8	0.6	1.0	0.8	0.6	0.5	0.5	0.4
Duration (days)	416.3	312.8	407.8	313.7	437.0	263.6	384.6	261.7	257.6	270.8	168.9	227.3
No treatment change†
Dose	0.6	0.5	0.4	0.3	0.6	0.5	0.8	0.7	0.40	0.4	0.4	0.3
Duration (days)	198.7	271.4	202.1	270.2	300.9	238.6	247.4	223.3	122.3	192	83.6	154.6
Treatment change†
Dose	1	0.7	0.8	0.5	1.0	0.6	1.1	0.7	0.7	0.5	0.5	0.4
Duration (days)	534.6	260.5	534.7	265.1	590.0	201.5	482.2	239.6	398.0	266.9	264.4	252.8

	n	%	n	%	n	%	n	%	n	%	n	%
Type of changes‡
Added molecule (different class)	1776	11	267	8	30	9	189	7	159	3	245	4
Added molecule (same class)	375	2	31	1	5	1	69	3	68	1	90	1
Dose decrease	2291	14	455	14	32	9	243	9	629	12	569	9
Dose increase	3980	25	818	25	58	17	611	23	1032	19	809	13
Removed molecule (different class)	1547	10	245	7	26	7	47	2	14	0	262	4
Removed molecule (same class)	372	2	32	1	4	1	6	0	7	0	95	2
Switch class	30	0	120	4	–	–	92	3	77	1	15	0
Switch molecule (same class)	22	0	30	1	–	–	27	1	29	1	4	0

*Dose is the proportion of the WHO recommended daily dose (dose prescribed/recommended daily dose).

†Treatment change in the first antidepressant episode, defined as continuous therapy with gaps of no greater than 90 days.

‡Patients can have more than one type of change in the episode of antidepressant use.

CPRD, Clinical Practice Research Datalink; NHIRDB, National Health Insurance Research Database.