Prevalence of Large Fiber Neuropathy in Nondiabetic Older Adults Seeking Routine Foot Care

Older adults qualifying for routine foot care (RFC) under the Medicare program are often diagnosed with diabetes, peripheral artery disease (PAD), or neuropathy. Specifically, large fiber neuropathy (LFN) has been shown to increase during the aging process, rendering patients more susceptible to unperceived trauma because of loss of protective sensation and an increased fall risk because of balance deficits. This study assessed the prevalence of LFN as diagnosed by the timed vibration test (TVT) in the nondiabetic segment of the Medicare population seeking RFC. A comparison was made between this group and those patients identified with PAD.

A retrospective electronic medical record review of Medicare patients seeking RFC (Current Procedural Terminology codes 11720, 11721, and 11055) was conducted in a community health center-based podiatry clinic over a 5-year period. The prevalence of LFN as diagnosed by the TVT (International Statistical Classification of Diseases, Tenth Revision code G62.9 and TVT ≤4 sec at the hallux) and PAD as diagnosed per Medicare class findings for vascular impairment (International Statistical Classification of Diseases, Tenth Revision codes I70.203 and I73.9) was identified in nondiabetic Medicare patients seeking RFC.

The prevalence of LFN and PAD within the nondiabetic Medicare population seeking RFC was found to be 21.1% (91 of 431) and 27.6% (119 of 431), respectively. There was a 6.5% difference between the proportions of the LFN and PAD groups, which was significantly different (P = .026, confidence interval = 0.77-12.2%). A total of 10.9% of the population was found to have LFN and PAD concurrently. There was no significant difference between the ages of patients in the LFN and PAD groups (P = .36, standard deviation [SD] = 1.65), the LFN and LFN/PAD groups (P = .3, SD = 1.95), or the PAD and LFN/PAD groups (P = .07, SD = 1.95).

LFN and PAD are both present in substantial proportions in nondiabetic Medicare patients seeking RFC. The prevalence of LFN in this at-risk population highlights the importance of accurate diagnosis and implementation of preventative measures designed to mitigate unperceived foot trauma and potential falls. This is especially relevant, as neuropathy in geriatric patients has been associated with earlier mortality.