Burden of illness associated with painful diabetic peripheral neuropathy among adults seeking treatment in the US: results from a retrospective chart review and cross-sectional survey

Alesia Sadosky,¹ Caroline Schaefer,² Rachael Mann,³ Felicia Bergstrom,² Rebecca Baik,² Bruce Parsons,¹ Srinivas Nalamachu,⁴ Edward Nieshoff,⁵ Brett R Stacey,⁶ Alan Anschel,⁷ Michael Tuchman<sup>8

1</sup>Pfizer Inc, New York, NY, ²Covance Market Access Services Inc, Gaithersburg, MD, ³Covance Market Access Services Inc, San Diego, CA, ⁴International Clinical Research Institute, Overland Park, KS, ⁵Rehabilitation Institute of Michigan/Wayne State University, Detroit, MI, ⁶Oregon Health and Science University, Portland, OR, ⁷Rehabilitation Institute of Chicago, Chicago, IL, ⁸Palm Beach Neurological Center, Palm Beach Gardens, FL, USA

Background: The purpose of this study was to characterize the burden of illness among adult subjects with painful diabetic peripheral neuropathy (pDPN) seeking treatment in the US.
Methods: This observational study recruited 112 subjects with pDPN during routine visits from general practitioner and specialist sites. Subjects completed a one-time questionnaire, which included demographics, symptom duration, health care resource use, out-of-pocket costs, employment status, and validated measures that assessed pain, functioning, sleep, anxiety and depression, health status, and productivity. Investigators completed a case report form based on a 6-month retrospective chart review to capture clinical information, pDPN-related treatments, and other pDPN-related health care resource use over the past 6 months. Annualized costs were extrapolated based on reported 6-month health care resource use.
Results: The mean age of the subjects was 61.1 years, 52.7% were female, and 17.9% were in paid employment. The most common comorbid conditions were sleep disturbance/insomnia (43.8%), depressive symptoms (41.1%), and anxiety (35.7%). The mean pain severity score was 5.2 (0–10 scale), and 79.5% reported moderate or severe pain. The mean pain interference with function score was 5.0 (0–10 scale) overall, with 2.0 among mild, 5.1 among moderate, and 7.0 among severe. The mean Medical Outcomes Study sleep problems index score was 48.5 (0–100 scale). The mean health state utility score was 0.61. Among subjects employed for pay, mean overall work impairment was 43.6%. Across all subjects, mean overall activity impairment was 52.3%. In total, 81.3% were prescribed at least one medication for their pDPN; 50.9% reported taking at least one nonprescription medication. Adjusted mean annualized total direct and indirect costs per subject were $4841 and $9730, respectively. Outcomes related to pain interference with function, sleep, health status, activity impairment, prescription medication use, and direct and indirect costs were significantly worse among subjects with more severe pain (P < 0.0020).
Conclusion: Subjects with pDPN exhibited high pain levels, which were associated with poor sleep, function, and productivity. Health care resource utilization in pDPN was prevalent and costs increased with greater pain severity. The burden of pDPN was greater among subjects with greater pain severity.

Keywords: painful diabetic peripheral neuropathy, pain assessment, burden of illness, quality of life, treatment patterns, health care resource use, costs, productivity