Real-world comparison of health care utilization between duloxetine and pregabalin initiators with fibromyalgia

Figures & data

Figure 1 Study design scheme.

Figure 2 Sample selection scheme.

Table 1 Patient demographic and clinical characteristics

Parameter	Duloxetine, estimates (STD)	Pregabalin, estimates (STD)	Differences, (D – P)
Number of greedy matches	1,265	1,265
Demographic characteristics on the initiation date
Males	12.1%	12.6%	−0.5%
Females	87.9%	87.4%	0.5%
Age at initiation (years)	49.3 (9.6)	49.6 (9.4)	−0.2
Residential regions
Northeast	6.9%	7.0%	−0.2%
North central	33.4%	33.9%	−0.5%
South	44.4%	43.3%	1.1%
West	14.8%	15.0%	−0.3%
Unknown region	0.6%	0.7%	−0.2%
Health plan types
Comprehensive health plans	4.1%	4.8%	−0.7%
HMOs	16.6%	16.8%	−0.2%
PPOs	63.3%	62.6%	0.8%
POSs	13.1%	13.4%	−0.3%
Other health plan types	2.8%	2.4%	0.5%
Top 15 fibromyalgia-related clinical conditions on initiation date
Neuropathic pain other than DPNP	51.1%	50.5%	0.6%
Low back pain	45.6%	45.7%	−0.1%
Cardiovascular disease	39.3%	39.4%	−0.2%
Hypertension	32.1%	31.5%	0.6%
Headache or migraine	24.1%	23.4%	0.7%
Osteoarthritis	21.8%	22.3%	−0.5%
Depression (new)	18.4%	17.9%	0.5%
Sleep disorder	18.7%	17.9%	0.9%
Chronic pulmonary disease	15.5%	14.7%	0.8%
Dyslipidemia	15.4%	14.6%	0.8%
Hypothyroidism	14.3%	13.5%	0.8%
Migraine	13.0%	12.2%	0.8%
Anemia	11.1%	10.1%	0.9%
Paresthesia	9.6%	9.9%	−0.2%
Generalized anxiety disorder	9.1%	9.7%	−0.7%

Notes: These patient characteristics were after propensity score greedy matching. All parameters had statistically nonsignificant cross-cohort differences (P>0.05).

Abbreviations: DPNP, diabetic peripheral neuropathic pain; HMO, health maintenance organization; POS, point-of-service health plan; PPO, preferred provider organization; STD, standard deviation; D, duloxetine cohort; P, pregabalin cohort.

Table 2 Health care utilization rates in pre- and postinitiation years

Parameters	Utilization rates in preinitiation year						Utilization rates in postinitiation year
	Duloxetine		Pregabalin		Differences		Duloxetine		Pregabalin		Differences
	%	N (STD)	%	N (STD)	%	N	%	N (STD)	%	N (STD)	%	N
Inpatient care	15.7	0.2 (0.6)	16.1	0.2 (0.6)	−0.3	0.0	16.8	0.2 (0.6)	19.3	0.5 (0.6)	−2.5	−0.3
Fibromyalgia-related	3.4	0 (0.2)	2.8	0 (0.2)	0.6	0.0	2.2	0 (0.2)	3.2	0 (0.2)	−1.0	0.0
Not fibromyalgia-related	13.4	0.2 (0.6)	13.3	0.2 (0.6)	0.1	0.0	14.5	0.2 (0.6)	16.0	0.5 (0.8)	−1.5	−0.3
Outpatient care	100.0	83.8 (70)	100.0	83.7 (67.5)	0.0	0.1	99.5	81.5(76.4)	99.8	90 (72.2)	−0.2	−8.5
Fibromyalgia-related	98.1	6.1 (9.5)	98.8	6.1 (10.5)	−0.7	0.0	51.8	4.4(11.1)	62.1	10.8(8.9)	−10.3	−6.4
Not fibromyalgia-related	99.8	77.7 (68.8)	99.8	77.6 (65.9)	−0.1	0.1	99.3	77.1 (74.8)	99.5	79.1 (71.3)	−0.2	−2.1
Primary care	93.4	18.4(24)	93.8	18.3 (23.8)	−0.4	0.1	91.7	16.9(24.5)	92.3	16.2(20.6)	−0.6	0.7
Specialist care	91.4	28.5 (32)	91.7	27.9 (34.9)	−0.3	−0.7	91.3	28.4 (37.4)	91.3	38.1 (37.9)	0.0	−9.7
Other types	95.2	36.9 (45.6)	94.5	37.6(42.1)	0.7	−0.7	93.5	36.1 (49.6)	93.4	35.6 (44.2)	0.1	0.5
All medications	98.7	43.7 (34.8)	97.9	43.2 (32.6)	0.7	0.6	100.0	53.6 (36.4)	100.0	51.7(33.3)	0.0	1.9
Duloxetine	8.5	0.2(1)	7.6	0.2 (0.9)	0.8	0.1	100.0	5.6 (4.2)	15.1	0.6(1.9)	84.9	5.0
Pregabalin	7.9	0.2 (0.7)	7.2	0.1 (0.6)	0.7	0.0	13.4	0.5(1.7)	100.0	4.2 (3.6)	−86.6	−3.7
NSAIDs	44.0	1.4(2.5)	43.2	1.3(2.4)	0.9	0.1	39.6	1.3(2.7)	41.5	1.4(2.6)	−1.9	−0.1
Topicals	10.3	0.2 (0.8)	9.8	0.2 (0.8)	0.5	0.0	12.9	0.3 (1.1)	14.0	0.3(1)	−1.1	0.0
Opioids	76.9	6.8 (9.2)	77.2	6.6 (8.5)	−0.2	0.2	77.5	7.8 (9.8)	79.9	7.7 (9.3)	−2.4	0.2
TCAs	15.3	0.6(2.1)	15.1	0.6(2.1)	0.2	0.0	13.9	0.6(1.8)	15.8	0.7 (2.2)	−1.9	−0.1
SSRIs	34.9	1.8 (3.2)	34.7	1.8(3.3)	0.2	−0.1	20.1	0.9 (2.3)	34.0	1.9(3.3)	−13.9	−0.9
SNRIs	18.3	0.9 (2.5)	18.4	0.8 (2.5)	−0.2	0.1	100.0	5.8 (4.3)	25.2	1.3(3.1)	74.8	4.5
SNRIs, nonduloxetine	10.8	0.6 (2.3)	10.7	0.6 (2.3)	0.2	0.0	4.7	0.2(1.1)	11.9	0.7 (2.5)	−7.2	−0.5
Antidepressants	63.0	4.4 (5.5)	62.6	4.3 (5.7)	0.4	0.1	100.0	8.6 (6.5)	67.2	4.9 (5.8)	32.8	3.7
Antidepressants, nonduloxetine	60.3	4.1 (5.4)	59.8	4.1 (5.6)	0.5	0.1	47.9	3 (4.8)	60.0	4.3 (5.6)	−12.1	−1.3
Anticonvulsants	44.4	2.4 (4.3)	43.6	2.2 (4)	0.8	0.2	50.3	3.4 (5.3)	100.0	6.3 (5.4)	−49.7	−2.9
Anticonvulsants, nonpregabalin	40.9	2.3 (4.2)	40.2	2.1 (3.9)	0.7	0.2	43.6	2.9 (4.9)	39.3	2.1 (4.1)	4.3	0.8
Dopamine agonist	5.4	0.3 (1.3)	4.7	0.2(1.1)	0.8	0.1	5.7	0.3 (1.6)	5.5	0.2(1.2)	0.2	0.1
Sleep/antianxiety medications	34.4	1.8 (3.5)	34.0	1.8(3.6)	0.4	−0.1	36.8	2.3(4.1)	34.8	2 (3.8)	2.0	0.3
5-HT3 antagonists	2.8	0.1 (0.8)	3.3	0.1 (0.5)	−0.6	0.0	5.0	0.1 (0.9)	3.4	0.1 (0.8)	1.6	0.0
Skeletal muscle relaxants	47.5	2.1 (4)	46.7	1.9(3.4)	0.8	0.2	45.3	2.2 (4)	48.2	2.2 (3.8)	−2.9	0.0

Note: Nonbold cross-cohort differences were statistically insignificant at P>0.05.

Abbreviations: %, percentage; N, number of claims per patient per year; NSAIDs, nonsteroidal anti-inflammatory drugs; SNRIs, serotonin/norepinephrine reuptake inhibitors; SSRIs, selective serotonin reuptake inhibitors; STD, standard deviation; TCAs, tricyclic antidepressants.

Table 3 Comparison of utilization changes

Parameters	Duloxetine		Pregabalin		Differences
	%	N	%	N	%	N
Inpatient care	1.1	0.0	3.2	0.3	−2.1	−0.3
Fibromyalgia-related	−1.2	0.0	0.4	0.0	−1.6	0.0
Not fibromyalgia-related	1.1	0.0	2.7	0.3	−1.6	−0.3
Outpatient care	−0.5	−2.3	−0.2	6.3	−0.3	−8.6
Fibromyalgia-related	−46.3	−1.7	−36.7	4.7	−9.6	−6.4
Not fibromyalgia-related	−0.5	−0.6	−0.3	1.5	−0.2	−2.1
Primary care	−1.7	−1.5	−1.5	−2.1	−0.2	0.6
Specialist care	−0.1	−0.1	−0.4	10.2	0.3	−10.3
Other types	−1.7	−0.8	−1.1	−2.0	−0.6	1.2
All medications	1.3	9.9	2.1	8.5	−0.8	1.4
Duloxetine	91.5	5.4	7.5	0.4	84.0	5.0
Pregabalin	5.5	0.3	92.8	4.1	−87.3	−3.8
NSAIDs	−4.4	−0.1	−1.7	0.1	−2.7	−0.2
Topicals	2.6	0.1	4.2	0.1	−1.6	0.0
Opioids	0.6	1.0	2.7	1.1	−2.1	−0.1
TCAs	−1.4	0.0	0.7	0.1	−2.1	−0.1
SSRIs	−14.8	−0.9	−0.7	0.1	−14.1	−1.0
SNRIs	81.7	4.9	6.8	0.5	74.9	4.4
SNRIs, other than duloxetine	−6.1	−0.4	1.2	0.1	−7.3	−0.5
Antidepressants	37.0	4.2	4.6	0.6	32.4	3.6
Antidepressants, other than duloxetine	−12.4	−1.1	0.2	0.2	−12.6	−1.3
Anticonvulsants	5.9	1.0	56.4	4.1	−50.5	−3.1
Anticonvulsants, other than Pregabalin	2.7	0.6	−0.9	0.0	3.6	0.6
Dopamine agonist	0.3	0.0	0.8	0.0	−0.5	0.0
Sleep and antianxiety medications	2.4	0.5	0.8	0.2	1.6	0.3
5-HT3 antagonists	2.2	0.0	0.1	0.0	2.1	0.0
Skeletal muscle relaxants	−2.2	0.1	1.5	0.3	−3.7	−0.2

Notes: These changes were derived through subtracting the utilization rates in the postindex year from the utilization rates in the preindex year. Nonbold cross-cohort differences were statistically insignificant at P>0.05.

Abbreviations: %, percentage of changes, N, number of claims per patient per year; NSAIDs, nonsteroidal anti-inflammatory drugs; SNRIs, serotonin/norepinephrine reuptake inhibitors; SSRIs, selective serotonin reuptake inhibitors; TCAs, tricyclic antidepressants.