Original Article
Painful diabetic neuropathy: a cross-sectional survey of health state impairment and treatment patterns

https://doi.org/10.1016/j.jdiacomp.2005.09.007Get rights and content

Abstract

Aims

To determine the patient burden of painful diabetic peripheral neuropathy (DPN) with respect to pain intensity and impact on patient functioning and to characterize relevant DPN treatment patterns.

Methods

Patients (n=140) with painful DPN identified during an observational survey of neuropathic pain syndromes in six European countries were included in the current analysis. Patients primarily recruited from community-based general practices answered a questionnaire that included pain severity and interference items from the modified Short-Form Brief Pain Inventory, the EuroQol survey, and questions related to productivity and health resource utilization. Physicians provided information on disease duration and current medications prescribed for painful DPN and pain-related comorbidities.

Results

The mean patient age was 65.6±11.2 years; 58% of the patients were ≥65 years. Duration of painful DPN was >1 year in 74% of patients. The mean Pain Severity Index was 5.0±2.0; 57% of patients reported moderate pain and 25% reported severe pain. Patients reported moderate interference with functioning despite 91% of patients reporting use of prescription medications for painful DPN including antiepileptics (56%), standard analgesics (63%), and amitriptyline (26%). Use of prescription medication for concomitant anxiety, depression, or sleep disturbance was reported for 43% of the patients. Disruption in employment was reported by 35% of the patients. Pain severity was significantly associated with reduced health state valuation (P<.001), greater pain interference scores (P<.001), greater employment disruption (P<.05), and more physician visits (P<.05).

Conclusions

Painful DPN is associated with substantial patient burden resulting from interference with daily functioning, especially in patients with suboptimal pain management.

Introduction

The increasing prevalence and earlier onset of diabetes (Haire-Joshu & Nanney, 2002, Kaufman, 2002, King et al., 1998, Rosenbloom et al., 1999) add to its already substantial societal impact. Annual direct medical costs among eight European countries exceed 29 billion Euros (Jonsson & CODE-2 Advisory Board, 2002), and estimates from the United States suggest that indirect costs may be at least as high as direct costs (American Diabetes Association, 1998; Hodgson & Cohen, 1999).

While glycemic control is central to managing diabetes and its costs in diagnosed patients, diabetic complications contribute substantially to overall costs even among patients with adequate glycemic control (Brandle et al., 2003, Gordois et al., 2003, O'Brien et al., 1998, Williams et al., 2002).

Painful diabetic peripheral neuropathy (DPN) is a common complication of diabetes. It is estimated that in patients with a 25-year history of diabetes, approximately 50% will develop neuropathic pain (Pirart, 1978). Neuropathic pain is defined by the International Association for the Study of Pain as “pain initiated or caused by a primary lesion or dysfunction in the nervous system” (Merskey & Bogduk, 1994). In patients with diabetes, these lesions arise from several pathophysiological mechanisms, including a persistent hyperglycemic state. The overall duration and degree of hyperglycemia correlates with the extent of nerve damage (Greene, Sima, Stevens, Feldman, & Lattimer, 1992). The medical costs of DPN and its complications may account for up to 27% of the direct medical costs of diabetes, although the proportion due to the painful component is unclear (Gordois et al., 2003). However, given the nature of neuropathic pain and its potential effects on patient functioning and quality of life (Haythornthwaite & Benrud-Larson, 2000, Meyer-Rosberg et al., 2001), the burden of this complication is more than economic, it affects health status and quality of life as shown in several studies (Ahroni & Boyko, 2000, Benbow et al., 1998, Coffey et al., 2002, Galer et al., 2000, Gore et al., 2005).

In a study evaluating the responsiveness of the SF-36 to health status changes in U.S. veterans with diabetes and its complications (Ahroni & Boyko, 2000), the authors reported a greater deterioration in health status among patients who developed neuropathy compared with patients who did not develop neuropathy. This deterioration was manifested by significantly greater worsening in five of the eight SF-36 domains. The greatest impairments were observed in the physical functioning and physical role scales. The presence of painful neuropathy in patients with diabetes was also associated with lower (i.e., worse) health utility scores relative to patients without complications in another U.S. study (Coffey et al., 2002). In the case of painful DPN, a U.K. study demonstrated that patients with this condition had significantly worse scores on five out of six domains of the Nottingham Health Profile than diabetic patients without DPN and nondiabetic controls (Benbow et al., 1998). Similarly, a U.S. postal survey showed that in greater than 50% of patients with painful DPN, neuropathic pain substantially interfered with daily functioning including mobility, normal work, recreational activities, sleep, and enjoyment of life (Galer et al., 2000).

More recently, a study of 255 patients with painful DPN recruited from community-based general practices and non-pain specialists in the United States reported a substantial patient burden resulting from functional and sleep impairment, decreased physical and emotional functioning, and moderate to severe symptom levels of anxiety and depression in approximately one third of the patients (Gore et al., 2004).

While the above studies suggest that painful DPN is associated with poor health status, few studies were designed to specifically evaluate the impact of painful DPN on patient functioning. Additionally, there is limited information on the health status and treatment patterns of patients with painful DPN in Europe. The purpose of the present analysis is to evaluate the burden of painful DPN with respect to the impact of pain on patient functioning and to characterize treatment patterns associated with this complication in a group of patients in primary care settings in six European countries.

Section snippets

Population and eligibility

The study sample consisted of a subset of patients with painful DPN (n=140) identified during a larger observational, cross-sectional study of broad neuropathic pain syndromes (N=602) (McDermott, Toelle, Rowbotham, Schaefer, & Dukes, 2005). We were interested in patient experience and treatment patterns in primary care, as this is the most common locus of chronic pain management. Therefore, sampling was limited to general practitioners and non-pain specialists (e.g., diabetologists). Patients

Results

The sample consisted of 140 patients: 13 in France, 62 in Germany, 11 in Italy, 14 in the Netherlands, 21 in Spain, and 19 in the United Kingdom. Table 1 provides the demographic and clinical characteristics of the DPN patients. The mean age was 65.6±11.2 years, and 59% of the patients were ≥65 years of age. Males comprised 58% of the population. The majority of patients (57%) were retired and 13% were currently working either full or part time.

Approximately half of the patients (52%) had

Discussion

Results from this survey confirm and extend those reported in other studies that evaluated the patient burden of neuropathic pain in general (McDermott et al., 2005, Meyer-Rosberg et al., 2001) and painful DPN in particular (Benbow et al., 1998, Galer et al., 2000, Gore et al., 2004). As in those studies, patients were characterized by moderate overall levels of pain that reduced functioning and quality of life, as indicated by low EQ-5D and overall health rating scores.

Importantly, the current

Acknowledgments

This study was supported by funding from Pfizer.

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