A Study of Cardiovascular Autonomic Neuropathy in Adult Patients with Diabetes Mellitus at Levy Mwanawasa University Teaching Hospital

Abstract

Cardiac autonomic neuropathy (CAN) is the diminished capacity of autonomic regulation of the cardiovascular system occurring in the presence of diabetes mellitus (DM) and in the absence of other aetiologies. Diabetes mellitus is a well- known cause of peripheral neuropathy. However, in comparison to somatic neuropathy, autonomic neuropathy is an under-diagnosed and under-treated chronic complication of diabetes mellitus despite its serious and significant contribution to morbidity and mortality in the diabetes mellitus population. A variety of tests, based on evaluation of the cardiovascular reflexes triggered by performing specific provocative manoeuvres, have been proposed to measure autonomic function. This study used four cardiovascular reflex tests to estimate appropriate autonomic function by examining heart rate, heart rate variation and the baroreceptor reflex. The aim of this study was to determine the presence of cardiovascular autonomic neuropathy in adult patients with diabetes mellitus at Levy Mwanawasa University Teaching Hospital in Lusaka, Zambia. Adult patients with diabetes mellitus, aged between 21 and 70 years, participated in this cross-sectional study. Four, non-invasive, cardiac autonomic reflex tests to assess for cardiac autonomic neuropathy were employed according to Ewing’s method. The parasympathetic function was analysed based on the heart rate response to paced deep breathing and to Valsalva manoeuvring. The sympathetic function was assessed by measuring heart rate and blood pressure response to postural change. Ewing`s criteria was used for the categorisation of cardiac autonomic neuropathy. Data were analysed using SPSS version 20. Continuous data were presented as means and standard deviation. Categorical data were analysed using a Fishers’ Exact Test (χ2) and a logistic regression was performed to verify the effects of diabetes mellitus’ duration, sex and age on the probability that the participants have cardiac autonomic neuropathy. A total of 52 patients participated in the study. The prevalence of Cardiac autonomic neuropathy was 48.1%. Out of 52 patients, 42.3% had definite cardiac autonomic neuropathy and 5.8% had severe cardiac autonomic neuropathy. Early cardiac autonomic neuropathy was observed in 34.6% of patients while 17.3% had no signs of cardiac autonomic neuropathy. The mean age of patients with cardiac autonomic neuropathy was 54.44 ± 10.90 years and the mean duration of diabetes mellitus from diagnosis was 5.36 ± 6.78 years. The probability of developing cardiac autonomic neuropathy increased with increasing age and hypertensive participants were more likely develop cardiac autonomic neuropathy (ѵ = 5.82, p = .001). In conclusion, cardiac autonomic neuropathy was present in a significant proportion of adult patients with diabetes mellitus at Levy Mwanawasa University Teaching Hospital, reflecting the increased morbidity encountered by this population. In order to improve patient quality of life and reduce disease burden, screening for cardiac autonomic neuropathy should be implemented using cardiovascular autonomic reflex tests which are relatively simple, safe and affordable.