Importance: Distal symmetric polyneuropathy (DSP) is a prevalent condition that results in high costs from diagnostic testing. However, the role of neurologists and diagnostic tests in patient care is unknown.
Objective: To determine how often neurologists and diagnostic tests influence the diagnosis and management of DSP in a community setting.
Design, setting, and participants: In this retrospective cohort study, we used a validated case-capture method (International Classification of Diseases, Ninth Revision screening technique with subsequent medical record abstraction) to identify all patients with a new DSP diagnosis treated by community neurologists in Nueces County, Texas, who met the Toronto Diabetic Neuropathy Expert Group consensus criteria for probable DSP. Using a structured data abstraction process, we recorded diagnostic test results, diagnoses rendered (before and after testing), and subsequent management from April 1, 2010, through March 31, 2011.
Main outcomes and measures: Changes in DSP cause and management after diagnostic testing by neurologists.
Results: We identified 458 patients with DSP followed up for a mean (SD) of 435.3 (44.1) days. Neurologists identified a cause of DSP in 291 patients (63.5%) before their diagnostic testing. Seventy-one patients (15.5%) had a new DSP cause discovered after testing by neurologists. The most common new diagnoses were prediabetes (28 [6.1%]), vitamin B12 deficiency (20 [4.4%]), diabetes mellitus (8 [1.7%]), and thyroid disease (8 [1.7%]). Management changes were common (289 [63.1%]) and usually related to neuropathic pain management (224 [48.9%]). A potential disease-modifying management change was made in 113 patients (24.7%), with the most common changes being diabetes management in 45 (9.8%), treatment with vitamins in 39 (8.5%), diet and exercise in 33 (7.2%), and adjustment of thyroid medications in 10 (2.2%). Electrodiagnostic testing and magnetic resonance imaging of the neuroaxis rarely led to management changes.
Conclusions and relevance: Neurologists diagnosed the cause of DSP in nearly two-thirds of patients before their diagnostic testing. Inexpensive blood tests for diabetes, thyroid dysfunction, and vitamin B12 deficiency allowed neurologists to identify a new cause of DSP in 71 patients (15.5%). In contrast, expensive electrodiagnostic tests and magnetic resonance imaging rarely changed patient care.