Costs of pregabalin or gabapentin for painful diabetic peripheral neuropathy

Figures & data

Table 1.  Sample size attrition table.

Attrition criterion	n
All patients in MarketScan® database 2007–2009	48,358,810
Patients with pregabalin or gabapentin prescription in 2008	416,676
Patients newly prescribed pregabalin or gabapentin in 2008	270,684
Excluding patients with both pregabalin or gabapentin prescriptions on the index date	270,434
Continuous enrollment during 12 month pre-index through 12 month post-index study period	143,793
Patients ≥18 years of age	142,677
Pregabalin	56,410
Gabapentin	86,267
Patients with pDPN diagnosis ≤1 year prior to or on the index date	5368
Pregabalin	2105
Gabapentin	3263
Patients with pDPN diagnosis ≤30 days prior to or on the index date	2362
Pregabalin	948
Gabapentin	1414
Propensity score matching
Pregabalin patients	910
Matched gabapentin patients	910

Table 2.  Demographic and clinical characteristics of the matched study cohorts.

Characteristic	Pregabalin (n = 910)	Gabapentin (n = 910)	p-value*
Age, years
Mean (SD)	63.3 (12.1)	63.3 (12.1)	0.8976
Median	62	62
Age group, n (%)
18–34 years	10 (1.1)	9 (1.0)	0.8893
35–44 years	49 (5.4)	40 (4.4)
45–54 years	146 (16.0)	153 (16.8)
55–64 years	309 (34.0)	325 (35.7)
≥65 years	396 (43.5)	383 (42.1)
Gender, n (%)
Male	468 (51.4)	466 (51.2)	0.9235
Female	442 (48.6)	444 (48.8)
Geographic region, n (%)
Northeast	72 (7.9)	75 (8.2)	<0.0001
North Central	304 (33.4)	262 (28.8)
South	433 (47.6)	354 (38.9)
West	101 (11.1)	216 (23.7)
Unknown	0	3 (0.3)
Type of benefit plan, n (%)
Comprehensive†	182 (20.0)	171 (18.8)	<0.0001
Exclusive provider organization	12 (1.3)	8 (0.9)
Health maintenance organization	87 (9.6)	200 (22.0)
Point of service	83 (9.1)	60 (6.6)
Preferred provider organization	517 (56.8)	441 (48.5)
Point of service with capitation	3 (0.3)	4 (0.4)
Consumer driven health plan	13 (1.4)	8 (0.9)
Missing/unknown	13 (1.4)	18 (2.0)
Deyo-Charlson Comorbidity Index, mean (SD)	3.4 (1.8)	3.4 (1.8)	0.6876
Pre-specified comorbidities, n (%)
Sleep disorders	124 (13.6)	118 (13.0)	0.6698
Major depressive disorder	38 (4.2)	34 (3.7)	0.6326
Dysthymic disorder	8 (0.9)	10 (1.1)	0.6374
Depressive disorder	28 (3.1)	29 (3.2)	0.8946
Fatigue	97 (10.7)	108 (11.9)	0.4161
Headache	61 (6.7)	61 (6.7)	1.0000
Chest pain, palpitations	57 (6.3)	41 (4.5)	0.0953
Anxiety, not otherwise specified	18 (2.0)	24 (2.6)	0.3545
Abdominal pain	183 (20.1)	156 (17.1)	0.1122
Myocardial infarction	18 (2.0)	21 (2.3)	0.6219
Old myocardial infarction	13 (1.4)	20 (2.2)	0.2230
Congestive heart failure	86 (9.5)	105 (11.5)	0.1343
Peripheral vascular disease	97 (10.7)	93 (10.2)	0.7590
Cerebrovascular disease	127 (14.0)	106 (11.7)	0.1444
Dementia	2 (0.2)	4 (0.4)	0.4142
Chronic pulmonary disease	160 (17.6)	159 (17.5)	0.9491
Rheumatologic disease	22 (2.4)	25 (2.8)	0.6473
Peptic ulcer disease	13 (1.4)	9 (1.0)	0.3938
Mild liver disease	7 (0.8)	9 (1.0)	0.6171
Moderate-to-severe liver disease	2 (0.2)	7 (0.8)	0.0956
Diabetes	783 (86.0)	776 (85.3)	0.6299
Diabetes with chronic complications	704 (77.4)	689 (75.7)	0.3888
Hemiplegia or paraplegia	7 (0.8)	4 (0.4)	0.3657
Renal disease	79 (8.7)	99 (10.9)	0.1206
Malignancy, including leukemia and lymphoma	73 (8.0)	75 (8.2)	0.8597
Metastatic solid tumor	5 (0.6)	6 (0.7)	0.7389
AIDS	1 (0.1)	1 (0.1)	1.0000

*McNemar, Bowker, or paired t-tests were used to calculate the statistical significance of differences between pregabalin and gabapentin for proportions and for means, respectively.

†A ‘comprehensive’ plan is defined as one that has no incentive for the patient to use a particular list of providers; coverage is handled by only one policy, with a deductible and coinsurance.

Table 3.  Differences in 12-month all-cause and painful diabetic peripheral neuropathy (pDPN)-attributable healthcare resource utilization per patient.

Resource category	Utilization per patient
	Pregabalin (n = 910)		Gabapentin (n = 910)		DID*	p-value
	Pre-index	Post- minus pre-index	Pre-index	Post- minus pre-index
All-cause, mean (SD) per patient
Physician office visits	11.5 (7.2)	1.1	12.2 (10.8)	0.9	−0.2	0.4794
Emergency department visits	1.0 (2.1)	0.1	1.0 (2.1)	0.1	0	0.7649
Outpatient visits	27.9 (25.0)	3.5	29.4 (26.9)	4.0	0.5	0.5067
Prescriptions filled	48.4 (31.7)	7.1	48.1 (31.6)	7.8	0.7	0.6590
Inpatient stays	0.5 (1.0)	−0.1	0.5 (1.0)	0.0	0.1	0.7350
Average length of stay, days	1.6 (3.4)	0	1.7 (3.3)	0.1	0.1	0.7564
pDPN-attributable, mean (SD) per patient
Physician office visits	1.2 (1.6)	0.2	1.1 (1.8)	0.4	0.2	0.0590
Emergency department visits	0.1 (0.3)	0.0	0.1 (0.4)	0.0	0.0	0.7476
Outpatient visits	2.1 (3.2)	0.2	2.0 (2.9)	0.5	0.3	0.1082
Prescriptions filled	6.8 (8.2)	4.4	6.7 (8.1)	4.7	0.3	0.3822
Inpatient stays	0.3 (1.7)	−0.1	0.2 (1.3)	−0.1	0.0	0.9688
Average length of stay, days	0.4 (1.7)	−0.1	0.3 (1.4)	0.0	0.1	0.4211

*Difference-in-differences are calculated as gabapentin pre-to-post-index differences minus pregabalin pre-to-post-index differences.

Table 4.  Differences in selected pain-related medications prescribed to patients on pregabalin or gabapentin (percentage of patients with ≥1 prescription, 12 months pre- and post-index).

Variable	Percentage of patients
	Pregabalin (n = 910)		Gabapentin (n = 910)		DID*	p-value
	Pre-index	Post- minus pre-index	Pre-index	Post- minus pre-index
Opioids	60.1	6.1	64.2	1.8	−4.3	0.3490
NSAIDs	35.2	1.8	33.3	−1.3	−3.1	0.0045
Antidepressants	38.0	1.2	37.6	2.6	1.4	0.9849
Topical anesthetics	3.3	1.1	2.2	2.0	0.9	0.8922

*Difference-in-differences is gabapentin pre- to-post-index differences minus pregabalin pre- to-post-index differences.

Table 5.  Differences in 12-month all-cause and painful diabetic peripheral neuropathy (pDPN)-attributable healthcare costs per patient.

Cost category	Cost per patient, US $
	Pregabalin (n = 910)		Gabapentin (n = 910)		DID*	p-value
	Pre-index	Post- minus pre-index	Pre-index	Post- minus pre-index
All-cause, mean (SD) per patient
Physician office costs	$972 ($739)	$112	$1,244 ($3,051)	$137	$25	0.8624
Emergency department costs	$476 ($1,427)	0	$645 ($2,924)	$94	$94	0.3955
Outpatient costs	$9,301 ($19,698)	$1943	$11,351 ($34,082)	$1963	$20	0.8248
Prescription costs	$4,838 ($4,821)	$1313	$4,457 ($4,357)	$750	−$563	<0.0001
Inpatient costs	$7,533 ($24,247)	−$174	$7,347 ($20,275)	$1970	$2144	0.3966
Total costs (inpatient + outpatient + prescription)	$21,673 ($38,301)	$3081	$23,155 (43,729)	$4684	$1603	0.8474
pDPN-attributable, mean (SD) per patient
Physician office costs	$97 ($148)	$14	$97 ($166)	$33	$19	0.0172
Emergency department costs	$21 ($152)	−$9	$115 ($2,388)	−$86	−$77	0.4960
Outpatient costs	$395 ($1,474)	−$63	$498 ($2,331)	−$21	$42	0.0762
Prescription costs	$636 ($2,319)	$697	$473 ($1,037)	$265	−$432	<0.0001
Inpatient costs	$624 ($3,746)	−$93	$769 ($4,723)	−$89	$4	0.6064
Total costs (inpatient + outpatient + prescription)	$1,655 ($4,756)	$540	$1,740 ($5,535)	$155	−$385	<0.0001

*Difference-in-differences is gabapentin pre- to-post-index differences minus pregabalin pre- to-post-index differences.

Table 6.  Demographic and clinical characteristics of the matched study cohorts of patients ≥65 years old.

Characteristic	Pregabalin (n = 384)	Gabapentin (n = 384)	p-value*
Age, years
Mean (SD)	74.6 (6.2)	74.7 (6.5)	0.8063
Median	74	74
Gender, n (%)
Male	190 (49.5)	187 (48.7)	0.8096
Female	194 (50.5)	197 (51.3)
Geographic region, n (%)
Northeast	35 (9.1)	37 (9.6)	0.0013
North Central	164 (42.7)	135 (35.2)
South	143 (37.2)	122 (31.8)
West	42 (10.9)	88 (22.9)
Unknown	0	2 (0.5)
Type of benefit plan, n (%)
Comprehensive†	146 (38.0)	131 (34.1)	<0.0001
Health maintenance organization	12 (3.1)	59 (15.4)
Point of service	10 (2.6)	9 (2.3)
Preferred provider organization	211 (55.0)	179 (46.6)
Consumer driven health plan	0	2 (0.5)
Missing/unknown	5 (1.3)	4 (1.0)
Deyo-Charlson Comorbidity Index, mean (SD)	3.7 (2.0)	3.7 (2.0)	0.7607
Pre-specified comorbidities
Sleep disorders	53 (13.8)	45 (11.7)	0.3711
Major depressive disorder	11 (2.9)	14 (3.7)	0.5485
Dysthymic disorder	1 (0.3)	2 (0.5)	0.5637
Depressive disorder	10 (2.6)	5 (1.3)	0.1967
Fatigue	35 (9.1)	45 (11.7)	0.2386
Headache	24 (6.3)	12 (3.1)	0.0396
Chest pain, palpitations	26 (6.8)	19 (5.0)	0.2967
Anxiety, not otherwise specified	8 (2.1)	11 (2.9)	0.4913
Abdominal pain	86 (22.4)	69 (18.0)	0.1253
Myocardial infarction	12 (3.1)	14 (3.7)	0.6949
Old myocardial Infarction	11 (2.9)	10 (2.6)	0.8185
Congestive heart failure	52 (13.5)	57 (14.8)	0.5919
Peripheral vascular disease	51 (13.3)	50 (13.0)	0.9165
Cerebrovascular disease	89 (23.2)	63 (16.4)	0.0167
Dementia	1 (0.3)	3 (0.8)	0.3173
Chronic pulmonary disease	79 (20.6)	90 (23.4)	0.3252
Rheumatologic disease	12 (3.1)	11 (2.9)	0.8348
Peptic ulcer disease	8 (2.1)	4 (1.0)	0.2482
Mild liver disease	5 (1.3)	1 (0.3)	0.1025
Moderate to severe liver disease	2 (0.5)	1 (0.3)	0.5637
Diabetes	317 (82.6)	321 (83.6)	0.7029
Diabetes with chronic complications	292 (76.0)	299 (77.9)	0.5480
Hemiplegia or paraplegia	3 (0.8)	0	0.0833
Renal disease	37 (9.6)	53 (13.8)	0.0772
Malignancy, including leukemia and lymphoma	43 (11.2)	44 (11.5)	0.9068
Metastatic solid tumor	5 (1.3)	3 (0.8)	0.4142
AIDS	0	0	1.000

*McNemar, Bowker, or paired t-tests were used to calculate the statistical significance of differences between pregabalin and gabapentin for proportions and for means, respectively.

†A ‘comprehensive’ plan is defined as one that has no incentive for the patient to use a particular list of providers; coverage is handled by only one policy, with a deductible and coinsurance.

Table 7.  Differences in 12-month all-cause and painful diabetic peripheral neuropathy (pDPN)-attributable healthcare resource utilization per patient in the matched study cohorts of patients ≥65 years old.

Resource category	Utilization per patient, mean (SD)
	Pregabalin (n = 384)		Gabapentin (n = 384)		DID*	p-value
	Pre-index	Post- minus pre-index	Pre-index	Post- minus pre-index
All-cause, mean (SD) per patient
Physician office visits	12.2 (7.4)	1.2	13.4 (8.6)	0.8	−0.4	0.7183
Emergency department visits	0.9 (1.5)	0.2	1.0 (2.0)	0.1	−0.1	0.5790
Outpatient visits	28.2 (20.4)	4.1	32.2 (25.0)	3.4	−0.7	0.4614
Prescriptions filled	50.6 (29.3)	5.6	47.8 (26.8)	5.3	−0.3	0.9373
Inpatient stays	0.4 (0.7)	0	0.5 (0.8)	0	0	0.8028
Average length of stay, days	1.8 (3.9)	0.2	1.7 (3.0)	0.4	0.2	0.5200
pDPN-attributable, mean (SD) per patient
Physician office visits	1.0 (1.6)	0.1	1.2 (2.0)	0.1	0	0.3319
Emergency department visits	0 (0.2)	0	0 (0.2)	0	0	0.6558
Outpatient visits	2.1 (3.6)	0.1	2.3 (3.2)	0.1	0	0.1505
Prescriptions filled	6.0 (7.3)	4.0	5.3 (5.9)	4.1	0.1	0.7512
Inpatient stays	0.1 (0.7)	0	0.2 (1.0)	0	0	0.5352
Average length of stay, days	0.2 (1.6)	0	0.2 (0.9)	0.1	0.1	0.9945

*Difference-in-differences are calculated as gabapentin pre- to-post-index differences minus pregabalin pre- to-post-index differences.

Table 8.  Differences in 12-month all-cause and painful diabetic peripheral neuropathy (pDPN)-attributable healthcare costs per patient in the matched study cohorts of patients ≥65 years old.

Cost category	Cost per patient, US $
	Pregabalin (n = 384)		Gabapentin (n = 384)		DID*	p-value
	Pre-index	Post- minus pre-index	Pre-index	Post- minus pre-index
All-cause, mean (SD) per patient
Physician office visits costs	$978 ($666)	$125	$1,215 ($2,436)	$123	−$2	0.3483
Emergency department costs	$310 ($742)	$17	$593 ($3,783)	−$142	−$159	0.8489
Outpatient costs	$8,150 ($11,458)	$1,595	$11,966 ($32,435)	$1,906	$311	0.9890
Prescription costs	$5,124 ($4,060)	$1,225	$4,595 ($3,427)	$540	−$685	0.0003
Inpatient costs	$5,189 ($16,721)	$1,237	$5,897 ($15,065)	$1,627	$390	0.9866
Total costs (inpatient + outpatient + prescription)	$18,462 ($24,286)	$4,058	$22,459 ($39,290)	$4,073	$15	0.6554
pDPN-attributable, mean (SD) per patient
Physician office costs	$85 ($135)	−$9	$95 ($177)	$14	$23	0.0511
Emergency department costs	$13 ($115)	−$10	$197 ($3,646)	−$186	−$176	0.7866
Outpatient costs	$399 ($1,684)	−$108	$410 ($1,048)	−$41	$67	0.4294
Prescription costs	$506 ($1,513)	$724	$422 ($940)	$243	−$481	<0.0001
Inpatient costs	$301 ($2,358)	−$160	$521 ($4,305)	$25	$185	0.9862
Total costs (inpatient + outpatient + prescription)	$1,206 ($3,417)	$456	$1,353 ($4,764)	$226	−$230	<0.0001

*Difference-in-differences is gabapentin pre- to-post-index differences minus pregabalin pre- to-post-index differences.