“Unequivocally Abnormal” vs “Usual” Signs and Symptoms for Proficient Diagnosis of Diabetic Polyneuropathy

Abstract

Neuropathy signs and symptoms are used to diagnose and scale the severity of distal symmetric sensorimotor polyneuropathy, such as the typical variety associated with diabetes mellitus, diabetic sensorimotor polyneuropathy (DSPN). One usually assumes that physicians can accurately elicit signs and symptoms and, with their use, diagnose DSPN sensitively and accurately and judge its severity.^1-5 This assumption had not been rigorously tested until recently,^6,7 perhaps because the use of signs and symptoms for this purpose had been endorsed by expert consensus panels.^5,8,9 In the first of 2 studies addressing the accuracy of signs and symptoms for this purpose, 3 neurologists from the Mayo Clinic independently examined 20 patients with diabetes mellitus without and with DSPN on 2 occasions and judged the scored abnormality of neuropathic signs and symptoms.^6,10 These researchers found a high degree of reproducibility of their clinical judgments, and clinical assessments were closely correlated with nerve conduction (NC) and abnormal quantitative sensation test results. However, quite different results were obtained in the Cl vs N Phys Trial 1 (Trial 1), the forerunner of the present Cl vs N Phys Trial 2 (Trial 2), in which 12 expert international physicians examined each of 24 masked patients with diabetes mellitus without and with DSPN on 2 consecutive days, without conferring among themselves or receiving instruction as to how they should elicit or judge neuropathy signs or symptoms or diagnose DSPN.⁷ In Trial 1, the physicians used their “usual” presumably sensitive criteria for eliciting signs, symptoms, and clinical diagnosis of DSPN.⁷ Individual physician test-retest reproducibility (κ value) of signs, symptoms, and diagnosis were generally good to very good, but judgments were excessively variable and inaccurate among physicians when compared with a highly standardized and referenced composite standard normal deviate score of 5 attributes of NC abnormality (Σ 5 NC nds ≤2.5th percentile). Poor physician proficiency (accuracy among investigators) was attributed to significant excessive and incorrect judging of clinical signs and, to a lesser degree, of symptoms and diagnosis. Recognizing that even experts are not as proficient as desired, we decided to retest proficiency using more specific pretrial criteria for eliciting signs and symptoms. Whereas in Trial 1 expert physicians had used usual presumably sensitive elicitation of signs and symptoms, in Trial 2 they agreed to use only “unequivocal” or certain abnormal signs and symptoms (presumably more specific than usual criteria) indicative of DSPN, with age, sex, physical fitness, and physical variables taken into account in judging abnormality.