Diagnostic accuracy of the COMPASS-31 orthostatic intolerance domain for detecting cardiovascular autonomic...

Cardiac autonomic neuropathy (CAN) is a frequent but under-recognized complication of type 2 diabetes mellitus (T2DM) that is strongly associated with arrhythmia, silent myocardial ischemia, and cardiovascular mortality. The use of cardiovascular autonomic reflex tests (CARTs) to assess CAN is often limited in resource-constrained clinical settings. Therefore, symptom-based tools such as the Composite Autonomic Symptom Score-31 (COMPASS-31) have been proposed as screening approaches, but evidence on their feasibility remains scarce. This study assessed the feasibility, diagnostic accuracy, and agreement of the COMPASS-31 for identifying cardiovascular autonomic dysfunction assessed using standardized CARTs among adults with T2DM in Zanzibar.

A cross-sectional study was conducted among adults with T2DM attending the diabetes clinic at Mnazi Mmoja Hospital, Zanzibar. Participants were recruited using a systematic random sampling technique. Orthostatic symptoms were assessed using the COMPASS-31 questionnaire. Objective autonomic function was assessed using an automated CAN analyser implementing standardized CARTs, including resting heart rate variability, deep breathing test, Valsalva maneuver, heart rate response to standing, postural hypotension, and sustained handgrip test. Agreement between the COMPASS-31 orthostatic intolerance domain and CARTs findings was assessed using Cohen's kappa. Diagnostic performance measures included sensitivity, specificity, predictive values, likelihood ratios, and accuracy.

Among 364 participants, the COMPASS-31 orthostatic intolerance domains classified 260 (71.4%) as abnormal, while 291 (79.9%) demonstrated abnormal autonomic findings on CARTs assessment. Overall agreement was 86.0%, with substantial agreement beyond chance (κ = 0.62). Sensitivity and specificity of the COMPASS-31 domain were 85.9% and 86.3%, respectively, with positive and negative likelihood ratios of 6.27 and 0.16. Internal consistency of the orthostatic intolerance domain was good (Cronbach's alpha = 0.82). However, correlations between the orthostatic intolerance domain and CAN analyser findings were weak, and ROC analyses demonstrated poor discrimination (AUC 0.51-0.56).

The COMPASS-31 orthostatic intolerance domain showed substantial agreement and moderate screening performance for detecting CAN in adults with T2DM. These findings support its use as a practical symptom-based screening adjunct to identify individuals who may benefit from further objective autonomic testing, particularly in resource-limited settings.