Comparing healthcare costs of Medicaid patients with postherpetic neuralgia (PHN) treated with lidocaine patch 5% versus gabapentin or pregabalin

Figures & data

Figure 1.  Sample Selection.

Table 1.  Baseline characteristics and comorbidities.

Characteristics and comorbidities	Before matching			After matching
	Lidocaine 5% patch	Gabapentin/pregabalin	p-value*	Lidocaine 5% patch	Gabapentin/pregabalin	p-value*
Sample size, n	337	1,416	–	312	312	–
Demographic characteristics
Age on index date, mean (SD)	60.4 (16.9)	62.4 (17.3)	0.0509	61.3 (15.6)	61.3 (15.3)	0.9826
Female, %	73.6	72.0	0.5659	72.8	74.0	0.7127
State, %
Florida	26.1	23.7	0.3583	26.6	27.2	0.1573
Iowa	0.3	3.2	0.0026	0.3	0.6	0.5637
Missouri	31.5	42.7	0.0002	32.4	32.7	0.7055
New Jersey	42.1	30.4	<0.0001	40.7	39.4	0.0455
PHN diagnosis type, %
PHN	39.5	49.3	0.0013	40.1	40.7	0.8720
HZ with use of PHN-recommended medication	60.5	50.7	0.0013	59.9	59.3	0.8720
Charlson Comorbidity Index, mean (SD)	2.0 (2.4)	2.1 (2.4)	0.3477	2.0 (2.4)	1.9 (2.1)	0.4027
Comorbidity profile, %
Mental health-related conditions	25.0	21.1	0.1282	24.4	23.4	0.7758
Anxiety	4.2	2.8	0.2043	4.5	4.8	0.8527
Depression	11.6	10.0	0.4024	11.5	9.9	0.5151
Sleep disorders	2.7	1.7	0.2362	2.2	2.6	0.7963
Other mental health-related conditions	12.2	11.4	0.7083	11.5	11.2	0.9028
Other painful conditions	56.8	54.8	0.5188	54.5	53.8	0.8711
Neuropathic pain	0.6	0.8	1.0000	0.6	0.0	0.5000
Fibromyalgia	3.0	2.8	0.8311	2.9	2.6	0.8084
Migraines/headaches	9.8	11.9	0.2833	9.9	8.0	0.3961
Cancer	8.0	9.1	0.5245	8.0	6.4	0.4458
Low back pain	20.5	15.9	0.0429	19.2	18.3	0.7505
Other spinal and neck pain	19.0	13.9	0.0186	17.0	15.1	0.5127
Osteoarthritis	11.3	9.3	0.2760	10.9	11.2	0.9028
Other arthropathies and musculoskeletal pain	31.8	30.9	0.7512	31.7	30.4	0.7335
Other conditions	19.3	23.0	0.1461	19.6	21.5	0.5563
Diabetes	18.2	22.2	0.1012	18.6	20.8	0.4817
Epilepsy	1.5	0.9	0.3661	1.3	0.6	0.4142
PHN-recommended medication use, %	16.4	16.6	0.9026	14.4	12.2	0.4061
Lidocaine patch 5%	2.7	0.9	0.0238	1.6	0.3	0.1025
Gabapentin/pregabalin	1.8	3.4	0.1243	1.9	0.6	0.1573
Tricyclic antidepressants	11.9	12.9	0.6255	11.2	10.9	0.8997
Duloxetine	2.1	1.1	0.1670	1.9	1.3	0.5271
Other PHN-related medication use, %	89.6	90.7	0.5500	89.1	91.3	0.3270
Analgesic medication	82.1	87.0	0.0219	81.7	85.3	0.2159
Hydroxyzine	8.3	8.6	0.8887	8.0	9.0	0.6617
Promethazine	12.2	8.3	0.0245	10.3	12.2	0.4386
Anxiolytics†	33.9	29.3	0.1100	33.7	35.3	0.6801
Opioids	70.3	72.6	0.4029	69.9	69.9	1.0000
Skeletal muscle relaxants	16.4	14.8	0.4716	14.7	15.7	0.7449
NSAIDs‡	40.9	41.2	0.9405	41.3	37.2	0.3056
Antiviral therapy§	57.1	59.7	0.3520	57.7	56.4	0.7472
Corticosteroids	25.5	24.9	0.8223	25.3	26.3	0.7778
Healthcare resource utilization, %
Inpatient	20.8	25.0	0.1033	21.8	21.5	0.9183
Emergency department	51.8	55.2	0.2746	52.6	50.6	0.6242
Outpatient/other	98.8	99.0	0.7630	98.7	99.0	0.7055
Long-term care	2.7	5.6	0.0280	2.9	2.9	1.0000
Total direct costs, mean (SD)	$8531 (10,827)	$9278 (14,845)	0.2605	$8592 (10,569)	$8596 (12,536)	0.9734
Total medical costs, mean (SD)	$5396 (9118)	$6516 (13,861)	0.0563	$5454 (8918)	$5523 (11,120)	0.9082
Total drug costs, mean (SD)	$3135 (3437)	$2762 (3417)	0.0683	$3138 (3502)	$3073 (3706)	0.8294

*Bias-corrected bootstrapping was used to compare continuous variables; Chi-square tests were used to compare categorical variables prior to matching; McNemar tests were used to compare categorical variables after matching.

†Anxiolytics include benzodiazepines and meprobamate.

‡NSAIDs include nonsteroidal anti-inflammatory agent combinations, indomethacin and COX-2 inhibitors.

§Antiviral therapy includes only antivirals specific to herpes.

Table 2. Study period (6-month) healthcare resource utilization.

Healthcare resource utilization	Lidocaine 5% patch (n = 312)	Gabapentin/pregabalin (n = 312)	Difference or ratio*	p-value†
Prescription drugs
Index medication days of supply, mean (median)	48.1 (30)	77.3 (60)
PHN-related medication use, %
PHN-recommended medication
Tricyclic antidepressants	16.3	15.7	1.0	0.8312
Duloxetine	1.9	1.0	2.0	0.3173
Other PHN-related medication	91.0	88.8	1.0	0.3701
Analgesic medication‡	85.9	84.3	1.0	0.5737
Antiviral therapy§	37.2	34.6	1.1	0.4959
Corticosteroids	20.5	25.0	0.8	0.1779
Medical services
Proportion with at least one visit, %
Any cause
Hospital inpatient	17.3	15.0	1.15	0.9115
Emergency department	38.8	40.1	0.97	0.7503
Outpatient/other	97.8	98.4	0.99	0.5637
Long-term care	2.9	3.5	0.82	0.6374
PHN-related¶
Hospital inpatient	2.2	3.5	0.64	0.3173
Emergency department	8.3	9.0	0.93	0.7815
Outpatient/other	60.9	64.4	0.95	0.3610
Long-term care	0.0	0.0	0.00	1.0000
Number of visits, mean
Any cause
Hospital inpatient	0.3	0.3	0.0	0.9676
Emergency department	1.8	1.6	0.3	0.6573
Outpatient/other	28.0	27.1	0.9	0.7254
Long-term care	0.0	0.1	0.0	0.5091
PHN-related¶
Hospital inpatient	0.0	0.0	0.0	0.6296
Emergency department	0.1	0.1	0.0	0.8843
Outpatient/other	1.0	1.3	−0.2	0.0366
Long-term care	0.0	0.0	0.0	1.0000

*Ratios were calculated for proportions; differences were calculated for continuous/count variables.

†p-values based on bias-corrected bootstrapping for continuous variables and McNemar tests for matched pairs for categorical variables.

‡Analgesic medication includes hydroxyzine, promethazine, anxiolytics (including benzodiazepines and meprobamate), opioids, skeletal muscle relaxants and NSAIDs (including nonsteroidal anti-inflammatory agent combinations, indomethacin and COX–2 inhibitors).

§Antiviral therapy includes only antivirals specific to herpes.

¶PHN-related resource utilization was calculated using medical claims associated with an ICD-9-CM code for PHN or HZ.

Table 3.  Mean study period (6-month) healthcare costs.

Healthcare costs, $	Lidocaine 5% patch (n = 312)	Gabapentin/pregabalin (n = 312)	Difference	p-value*
Total healthcare costs	9,446	9,448	−2	0.9834
Total medical costs	6,042	5,687	355	0.7590
Hospital inpatient	2,076	1,777	299	0.7235
Emergency department	160	154	6	0.9133
Outpatient/other	3,223	3,249	−26	0.9509
Long-term care	582	506	76	0.8052
Total prescription drug costs	3,404	3,761	−357	0.2341
PHN-related healthcare costs	999	1,173	−174	0.3123
PHN-related medical costs†	145	353	−208	0.1207
Hospital inpatient	84	273	−188	0.1472
Emergency department	7	7	1	0.8470
Outpatient/other	53	74	−20	0.2107
Long-term care	0	0	0	1.0000
PHN-related prescription drug costs	854	820	35	0.7465
PHN-recommended medications	337	256	81	0.0023
Lidocaine patch	325	0	325	<0.0001
Gabapentin/pregabalin	0	250	−250	<0.0001
Tricyclic antidepressants	3	4	−1	0.3819
Duloxetine	8	1	7	0.2588
Other PHN-related medications	518	564	−47	0.5800
Analgesic medications‡	431	485	−54	0.4993
Antiviral therapy§	81	73	8	0.6803
Corticosteroids	5	6	0	0.8824

*p-values based on bias-corrected bootstrapping.

†PHN-related medical costs were estimated using medical claims associated with an ICD-9-CM code for PHN or HZ.

‡Analgesic medication includes hydroxyzine, promethazine, anxiolytics (including benzodiazepines and meprobamate), opioids, skeletal muscle relaxants and NSAIDs (including nonsteroidal anti-inflammatory agent combinations, indomethacin and COX-2 inhibitors).

§Antiviral therapy includes only antivirals specific to herpes.

Figure 2.  Study period (6-month) differences in mean PHN-related costs – lidocaine patch vs. gabapentin/pregabalin. Dotted lines represent 95% confidence intervals; costs were compared using bias-corrected bootstrapping. PHN-related costs were calculated over the 6-month study period and inflated to 2007 US dollars using the CPI for medical care. Differences in mean costs were defined as mean per-patient costs in the lidocaine patch group minus mean per-patient costs in the gabapentin/pregabalin group.