Comparing Heart Rate Variability in Canadian Armed Forces Patients to Control Participants without Chronic Pain/Mental Health Issues

BackgroundThe autonomic nervous system is subserved by the sympathetic and parasympathetic which regulate vital involuntary physiological functions like heart rate. Parasympathetic activity can be measured from the high-frequency component of heart rate variability (HRV), measured via the amplitude of RSA, as a possible predictor for mental health and chronic pain disorders. Therefore, investigators looked to correlate HRV with chronic pain when compared healthy controls. MethodsAs part of a larger ongoing study, patients complete pre-defined questionnaires on their pain condition, potential risk factors, and function. For patients and controls investigators collected performance and cardiac measures (RSA, LF-HRV, heart period) while at rest, walking and lifting tests. This analysis focused on differences in heart rate variability measures between 100 patients and 48 controls. ResultsPreliminary analysis revealed demographic and anthropometric variables varied significantly between groups. When comparing HRV measures, respiratory sinus arrhythmia (RSA) during lying and sitting were significantly decreased in patients compared to controls while heart period lying and walking were significantly increased in patients. Correlation analysis revealed significant positive correlation between RSA during lying and sitting when looking at age, gender, and weight. Heart periods during lying and walking were negatively correlated with gender and weight. DiscussionTo our knowledge it is the first study to look at chronic pain and HRV in the Canadian Forces, while also collecting data on patient reported outcomes, and during various resting and activities. Many potential limitations exist for this study including challenges with respect to controlling for known confounders of heart variability. ConclusionBy establishing heart rate variability as a correlate of chronic pain, the outcome of this project could potentially improve quality of care for patients with these conditions. Further work controlling for confounders and relating HRV to pain severity, subtypes, patient reported outcomes and functional abilities will be required to determine the exact value for clinical decision making.