Validation of the Composite Autonomic Symptom Score 31 (COMPASS 31) for the assessment of symptoms of autonomic neuropathy in people with diabetes

Aim: To validate the Composite Autonomic Symptom Score (COMPASS) 31, in its Italian version, for the diagnosis of diabetic cardiovascular autonomic neuropathy in a clinic-based, single-centre study. Methods: A total of 73 participants with diabetes (age 55 ± 14 years) completed the COMPASS 31 questionnaire before undergoing cardiovascular autonomic neuropathy and diabetic polyneuropathy assessment according to cardiovascular reflex tests, neuropathic symptoms and signs, and vibration and thermal thresholds. Results: The COMPASS 31 total weighted score differed between participants with and without cardiovascular autonomic neuropathy (29.9 ± 19.5 vs 16.1 ± 14.7; P = 0.003) and with and without diabetic polyneuropathy (28.9 ± 19.1 vs 12.7 ± 11.3; P < 0.0001). It was related to cardiovascular reflex tests score (rho = 0.38, P = 0.0013) as well as diabetic polyneuropathy symptoms (rho=0.61, P < 0.0001) and signs scores (rho = 0.49, P < 0.0001). Receiver-operating curve analysis showed a fair diagnostic accuracy of total score for cardiovascular autonomic neuropathy (area under the curve 0.748 ± 0.068, 95% CI 0.599-0.861) and diabetic polyneuropathy (area under the curve 0.742 ± 0.061, 95% CI 0.611-0.845). The best score thresholds were 16 for early cardiovascular autonomic neuropathy (sensitivity 75.0%, specificity 64.9%, positive predictive value 37.5% and negative predictive value 90.2%), and 17 for both confirmed cardiovascular autonomic neuropathy and diabetic polyneuropathy (sensitivity 70.0% and 65.5%, respectively; specificity 66.7% and 79.5%, respectively; positive predictive value 25.0% and 67.9%, respectively; and negative predictive value 93.0% and 77.8%, respectively). COMPASS 31 had a good internal consistency according to Cronbach's α coefficient of 0.73. Conclusions: COMPASS 31 can represent a valid, easy-to-use, quantitative assessment tool for autonomic symptoms in diabetic neuropathy, with a fair diagnostic accuracy for both cardiovascular autonomic neuropathy and diabetic polyneuropathy.