Economic and humanistic burden of post-trauma and post-surgical neuropathic pain among adults in the United States

Abstract

Background: Neuropathic pain (NeP) can be chronic, debilitating, and can interfere with sleep, functioning, and emotional well being. While there are multiple causes of NeP, few studies have examined the disease burden and treatment patterns associated with post-traumatic/post-surgical (PTPS) NeP.

Objective: To characterize pain, health status, function, health care resource utilization, lost productivity, and costs among subjects with PTPS NeP in the United States.

Methods: This observational study enrolled 100 PTPS NeP subjects recruited during routine visits from general practitioner and specialist sites. Subjects completed a one-time questionnaire with validated measures of pain severity and pain interference, health status, sleep, anxiety and depression, productivity, and study-specific items on demographics, employment status, and out-of-pocket expenses. Investigators completed a case report form based on a 6-month retrospective chart review, recording subjects' clinical characteristics as well as current and previous medications/treatments for NeP. Subjects were stratified into mild, moderate, and severe pain groups.

Results: Subjects' demographic characteristics were: mean age of 54.9 years, 53% female, and 22% employed for pay. Mean pain severity score was 5.6 (0-10 scale), with 48% and 35% classified as having moderate and severe pain, respectively. The mean number of comorbidities increased with greater pain severity (P = 0.0009). Patient-reported outcomes were worse among PTPS NeP subjects with more severe pain, including pain interference with function, health state utility, sleep, and depression (P < 0.0001). Eighty-two percent of subjects were prescribed two or more NeP medications. The total mean annualized adjusted direct and indirect costs per subject were $11,846 and $29,617, respectively. Across pain severity levels, differences in annualized adjusted direct and indirect costs were significant (P < 0.0001).

Conclusion: PTPS NeP subjects reported high pain scores, which were associated with poor health utility, sleep, mood, and function, as well as high health care resource utilization and costs. The quality of life impact and costs attributable to PTPS NeP suggest an unmet need for effective and comprehensive management.

Keywords: costs; neuropathic pain; patient-reported outcomes; productivity; quality-of-life; trauma/surgery.

Figures

Figure 1

PTPS NeP subjects reported a variety of comorbid conditions.a Notes: aScores on the BPI-SF Pain Severity Index were used to classify average pain severity. Three subjects did not respond to all required items needed to calculate a BPI-SF average pain severity score, and thus were not included in any analysis by pain severity category; **statistically significant differences were observed across pain severity levels at the P < 0.05 level as follows: depressive symptoms (P = 0.0205), restless leg syndrome (P = 0.0293), and chronic fatigue syndrome (P = 0.0025). Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form.

Figure 2

PTPS NeP subjects with more severe pain reported significantly worse physical and mental health.a Notes:aScores on the BPI-SF Pain Severity were used to classify average pain severity. Three subjects did not respond to all required items needed to calculate a BPI-SF average pain severity score and thus were not included in any analysis by pain severity category. SF-12 PCS and MCS both scored on a scale of 0–100; population norms (PCS = 49.7 and MCS = 49.5), indicated by thick black horizontal lines. **Statistically significant differences were observed by pain severity levels at the P < 0.05 level for the PCS (P = 0.0004); ***statistically significant differences were observed by pain severity levels at the P < 0.0001 level for the MCS. Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form; PCS, Physical Component Summary; MCS, Mental Component Summary; SF-12, Short-Form Health Survey.

Figure 3

PTPS NeP subjects with more severe pain have significantly worse general health status.a Notes:aScores on the BPI-SF Pain Severity were used to classify average pain severity. Three subjects did not respond to all required items needed to calculate a BPI-SF average pain severity score and thus were not included in any analysis by pain severity category. EQ-5D scored on a scale of 0–1.0; the population norm (0.87) is indicated by black horizontal line. ***A statistically significant difference was observed across pain severity levels for EQ-5D health state utility: P < 0.0001. Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form; EQ-5D, EuroQol Five-Dimensions.

Figure 4

PTPS NeP subjects with more severe pain experience, more interference with function.a Notes:aScores on the BPI-SF Pain Severity were used to classify average pain severity. Three subjects did not respond to all required items needed to calculate a BPI-SF average pain severity score and thus were not included in any analysis by pain severity category. BPI-SF Pain Severity Index scored on a 0–10 scale. ***A statistically significant difference was observed across pain severity levels for BPI-SF Pain Interference Index: P < 0.0001. Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form.

Figure 5

PTPS NeP subjects with more severe pain reported worse sleep outcomes.a Notes:aScores on the BPI-SF Pain Severity were used to classify average pain severity. Three subjects did not respond to all required items needed to calculate a BPI-SF average pain severity score and thus were not included in any analysis by pain severity category. MOS-SS Sleep Disturbance and Sleep Problems Index are both scored on a scale from 0–100; the MOS-SS Sleep Problems Index population norm (25.8) is indicated by a black horizontal line. ***A statistically significant difference was observed across pain severity levels for the MOS-SS Sleep Disturbance and Sleep Problems Index; both P < 0.0001. Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form; MOS-SS, Medical Outcomes Study Sleep Scale.

Figure 6

PTPS NeP subjects with more severe pain experience, more anxiety and depression.a Notes:aScores on the BPI-SF Pain Severity were used to classify average pain severity. Three subjects did not respond to all required items needed to calculate a BPI-SF average pain severity score, and thus were not included in any analysis by pain severity category. Anxiety and depression were scored on a 0–21 scale: normal (0–7), mild (8–10), moderate (11–14), severe (15–21). The difference observed across pain severity levels for HADS Anxiety was not significant at the 0.05 significance level; P = 0.0553. ***A statistically significant difference was observed across pain severity levels for HADS depression: P < 0.0001. Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form; HADS, Hospital Anxiety and Depression Scale.

Figure 7

Use of PTPS NeP prescription medications. Notes:aFigure includes all reported classes, except miscellaneous agents, with >2% of subjects prescribed one or more medication(s) in the class; bopioids (all) includes strong short-acting opioids (47.0%), long-acting opioids (31.0%), and weak short-acting opioids (18.0%). Subjects may have been prescribed more than one type of opioids. Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; SNRI, serotonin–norepineprhine reuptake inhibitor; NSAIDs, nonsteroidal anti-inflammatory drugs; TCAs, tricyclic antidepressants.

Figure 8

PTPS NeP impact on employment status.a,** Notes:aScores on the BPI-SF Pain Severity were used to classify average pain severity. Three subjects did not respond to all required items needed to calculate a BPI-SF average pain severity score, and thus were not included in any analysis by pain severity category. **A statistically significant difference was observed across pain severity levels at the 0.05 level for the impact of PTPS NeP on employment status; P = 0.0002. Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form.

Figure 9

PTPS NeP subjects with more severe pain experienced greater losses in productivity.a Notes:aScores on the BPI-SF Pain Severity were used to classify average pain severity. Three subjects did not respond to all required items needed to calculate a BPI-SF average pain severity score and thus were not included in any analysis by pain severity category. WPAI overall work impairment among those employed, and activity impairment among both employed and unemployed scored on a 0%–100% scale. **A statistically significant difference was observed across pain severity levels at the 0.05 level for overall work impairment (P = 0.0026). ***A statistically significant difference was observed across pain severity levels at the <0.0001 level for activity impairment (P < 0.0001). Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form; WPAI, Work Productivity and Activity Impairment.

Figure 10

Adjusted average annualized cost per PTPS NeP subject, overall and by average pain severity.a Notes:aScores on the BPI-SF Pain Severity were used to classify average pain severity as follows: 0–3 represents mild pain, 4–6 represents moderate pain, and 7–10 represents severe pain; baverage annualized total direct cost per subject was significantly different by pain severity (P < 0.0001). Direct costs include physician visits, other health care provider visits, prescription medications, TENS device, outpatient tests/procedures, emergency room visits, hospital outpatient visits, hospitalizations, direct medical costs to subjects, and direct nonmedical costs (child care, help with house and/or yard work, and help with activities of daily living) due to PTPS NeP. cAverage annualized total indirect cost per subject was significantly different by pain severity (P < 0.0001). Total indirect costs include overall work impairment, activity impairment, disability, unemployment, early retirement, and reduced work schedule due to PTPS NeP. dAdjusted LS mean estimates from multiple linear regression adjusted for confounding demographic and clinical variables – specifically, covariates for direct costs: ethnicity, pain severity (mild/moderate/severe only), prescription coverage, and comorbidities (headache/migraine, major depressive disorder, irritable bowel syndrome, cognitive dysfunction, chronic fatigue syndrome [overall only], sleep disturbance/insomnia, chronic low back pain, and other); and for indirect costs: age, race, pain severity, and comorbidities (major depressive disorder and irritable bowel syndrome). Abbreviations: PTPS, post-traumatic/post-surgical; NeP, neuropathic pain; BPI-SF, Brief Pain Inventory-Short Form; TENS, transcutaneous electrical nerve stimulation; LS, least squares.