Association of patient-rated severity with other outcomes in patients with painful diabetic peripheral neuropathy

Abstract

Objective: To evaluate the association of patient-reported severity of painful diabetic peripheral neuropathy (pDPN) with other outcomes in a European population of patients using the Adelphi Disease Specific Programme for pDPN (DSP III, 2008).

Methods: The severity of patients' pDPN (mild, moderate, or severe) was rated independently by both patients and physicians. Relationships were evaluated between patient-reported pDPN severity and other patient-reported outcomes including pain, sleep, function, and work productivity. Physicians rated the severity of patients' pDPN (1 = mild, 2 = moderate, 3 = severe) and sleep interference.

Results: Patient-reported data were available from 634 individuals (56.2% male, mean age 63 years) from France, Germany, Italy, and the UK, of whom only 22.2% reported that they were currently employed. pDPN severity was rated as mild, moderate, and severe by 22.2%, 60.9%, and 16.9% of the patients, respectively. There was a significant association between patient-rated and physician-rated pDPN severity (P < 0.0001), although there were discrepancies in agreement (kappa = 0.37, 95% confidence interval [CI] 0.31, 0.43; weighted kappa = 0.43, 95% CI 0.37, 0.48) among physician and patient ratings in a substantial proportion of patients across severity categories. Higher pDPN severity was associated with greater interference of daily function including sleep (P < 0.0001 for all pairwise comparisons). Among employed patients, percent of pDPN-related impairment while at work (presenteeism) and overall work impairment increased with greater pDPN severity, resulting in indirect costs that increased significantly with pDPN severity; $8266, $15,449, and $24,300 for mild, moderate, and severe pDPN, respectively (overall P < 0.001).

Conclusion: Severity of patient-rated pDPN was significantly associated with outcomes, including function and productivity; poorer function and lower productivity were reported at higher pDPN severity levels. Moreover, physicians rated pDPN severity different from patients in a substantial proportion of patients.

Keywords: diabetic neuropathy; outcomes; pain.

Figure 1

Proportion of patients rating their painful diabetic peripheral neuropathy as mild, moderate, and severe.

Figure 2

Relationship between self-reported severity of painful diabetic peripheral neuropathy and the Brief Pain Inventory Severity Indices. Notes: *^,†P < 0.0001 for all pairwise comparisons between severity levels.

Figure 3

Relationship between self-reported severity of painful diabetic peripheral neuropathy and impact of pain on sleep. Notes: P < 0.0001 for overall effect within patient and physician ratings; *^,†P < 0.0001 for all pairwise comparisons between severity levels. Abbreviations: CI, confidence interval; pDPN, painful diabetic peripheral neuropathy.

Figure 4

Relationship between self-reported severity of painful diabetic peripheral neuropathy and productivity assessed using the Work Productivity and Activity Impairment (WPAI) scale. Notes: *P < 0.05; ^†P < 0.001 for overall effect. Abbreviation: CI, confidence interval.

Figure 5

Relationship between self-reported severity of painful diabetic peripheral neuropathy and indirect costs resulting from lost productivity. Notes: *P < 0.05 for all pairwise comparisons between severity levels; P = 0.002 for overall effect. Abbreviation: pDPN, painful diabetic peripheral neuropathy.